Attenuation characteristic measurement device and attenuation characteristic measurement method

Abstract

Provided is an attenuation characteristic measurement device and an attenuation characteristic measurement method that have high measurement accuracy in a wide dynamic range. In a transmission unit, a transmission-side light intensity modulation unit and a transmission-side light detection unit generate a measurement-subject electric signal of a frequency 4fRF from a transmission-side electric signal and laser light; in a reception unit, a reception-side light intensity modulation unit and a reception-side light detection unit generate a local oscillation electric signal of a frequency 2fLo from a reception-side electric signal of a frequency fLo and laser light; and in a measurement unit, through a fundamental wave mixer for reference signal generation generating a reference signal of a difference frequency fIF1 (fRF-fLo) and a doubler-type high-frequency mixer generating an intermediate frequency signal of a difference frequency fIF2 (4fRF-4fLo), a lock-in detection unit measures the amplitude and phase of a signal attenuation quantity of the measurement-subject electric signal of the frequency 4fRF using the reference signal of a frequency 2fIF1 or a frequency 4fIF1 and the intermediate frequency signal of the difference frequency fIF2 (4fRF-4fLo).

Description

Damping characteristic measuring device and damping characteristic measuring method

[0001] The disclosure in this specification relates to an apparatus and method for measuring attenuation of a high-frequency circuit, and more particularly to an apparatus and method for measuring attenuation of a signal in the millimeter-wave frequency band.

[0002] Attenuation is measured to evaluate the characteristics of high-frequency circuits in devices under test (DUTs), such as antennas. For example, the communication sensitivity of a mobile communication terminal is evaluated based on its minimum receiving sensitivity, which can be evaluated by testing how weak a signal it can receive. In this case, the weak signal is generated by applying the correct high-frequency attenuation to a test signal whose absolute value of high-frequency power is predetermined, and attenuating the signal accurately.

[0003] Conventionally, a network analyzer has been used as this type of measuring device. A network analyzer basically includes a signal source, a power splitter, a directional coupler, and a receiver, and can apply a signal to the DUT to measure the degree of attenuation of the DUT from the transmission characteristics calculated based on amplitude data from the S21 and S12 parameters and the phase characteristics calculated based on phase data from the S21 and S12 parameters (see, for example, Non-Patent Documents 1 and 2).

[0004] "Introduction to S-parameter measurement using network analyzers", Akihiro Sakurai, Yusuke Kato, Kazuyoshi Suzuki, Masahiro Horibe [Retrieved September 30, 2023], URL: https: / / apmc-mwe.org / mwe2016 / pdf / tut15 / WE5B-0.pdf "Fundamentals of vector network analysis", KEYSIGHT TECHNOLOGIES [Retrieved September 30, 2023], URL:

[0005] https: / / www.keysight.com / jp / ja / assets / 7018-06841 / application-notes / 5965-7707.pdf

[0006] However, when measuring weak high-frequency signals such as millimeter waves with the network analyzer, the input signal to be measured may fall below the noise floor, making it impossible to detect the input signal. Furthermore, if the signal level of the noise floor is high, the dynamic range may become narrow, potentially affecting measurement accuracy.

[0007] The disclosure in this specification is intended to solve the above-mentioned problems, and aims to provide an attenuation characteristic measuring device and an attenuation characteristic measuring method that have high measurement accuracy over a wide dynamic range, even for millimeter-wave level signals.

[0008] In order to solve the above problem, one aspect of the attenuation characteristic measuring device disclosed in this specification is a method for measuring attenuation characteristics at a frequency f ＲＦ a laser oscillator that outputs a laser beam via an optical fiber cable; an optical power divider that receives the laser beam and outputs a first laser beam and a second laser beam; a transmission-side optical intensity modulator that receives the first laser beam and the transmission-side electrical signal and generates a transmission-side optical signal; and a transmission-side optical signal that is quadrupled in frequency via an optical fiber cable to generate a transmission-side optical signal of frequency 4f. ＲＦ a transmitter section including a transmitter-side optical detector section for outputting an electrical signal to be measured of frequency f Ｌｏ a receiving-side signal generating unit that generates a receiving-side electrical signal of the second laser light; a receiving-side optical intensity modulating unit that receives the second laser light and the receiving-side electrical signal and generates a receiving-side optical signal; and a receiving-side optical intensity modulating unit that doubles the frequency of the receiving-side optical signal via an optical fiber cable to generate a frequency 2f Ｌｏ a receiving section including a receiving-side optical detection section that outputs a local oscillation electrical signal of the frequency 4f; ＲＦ a receiving device unit that receives the electrical signal to be measured, and the frequency 4f received by the receiving device unit ＲＦ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 4f generated by doubling the local oscillation electrical signal Ｌｏ and the local oscillation electrical signal of formula 4f ＲＦ -4f Ｌｏ The difference frequency f ＩＦ a double-harmonic mixer that outputs an intermediate frequency signal of the difference frequency fＩＦ By measuring the amplitude of the intermediate frequency signal of the frequency 4f ＲＦ and a measuring section configured to measure the amount of signal attenuation of the electrical signal under test.

[0009] The transmitting unit has a transmitting-side distribution unit that receives the transmitting-side electrical signal from the transmitting-side signal generating unit and outputs a first transmitting-side electrical signal and a second transmitting-side electrical signal, and the transmitting-side optical signal is generated from the first transmitting-side electrical signal and the first laser light by the transmitting-side optical intensity modulation unit; the receiving unit has a receiving-side distribution unit that receives the receiving-side electrical signal from the receiving-side signal generating unit and outputs a first receiving-side electrical signal and a second receiving-side electrical signal, and the receiving-side optical signal is generated from the first receiving-side electrical signal and the second laser light by the receiving-side optical intensity modulation unit; and the measuring unit calculates the second transmitting-side electrical signal received from the transmitting-side distribution unit and the second receiving-side electrical signal received from the receiving-side distribution unit by an equation f ＲＦ -f Ｌｏ The difference frequency f ＩＦ１ a reference signal generating fundamental mixer for generating a reference signal of the difference frequency f ＩＦ１ The frequency of the reference signal is doubled or quadrupled to a frequency of 2f ＩＦ１ or frequency 4f ＩＦ１ an output side multiplier unit for generating a reference signal of the frequency 4f received by the receiving device unit; ＲＦ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 4f generated by doubling the local oscillation electrical signal Ｌｏ and the local oscillation electrical signal of formula 4f ＲＦ -4f Ｌｏ The difference frequency f ＩＦ２ (=4f ＩＦ１ a doubling type harmonic mixer that outputs an intermediate frequency signal of the frequency 2f ＩＦ１ or frequency 4f ＩＦ１ The reference signal and the difference frequency f ＩＦ２ and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit. ＲＦ and a lock-in detection unit that measures the amplitude and phase of the signal attenuation of the electrical signal under measurement.

[0010] Furthermore, the receiving unit is configured such that the receiving-side optical intensity modulation unit generates the receiving-side optical signal from the second transmitting-side electrical signal output from the transmitting-side signal generation unit via the transmitting-side distribution unit and the second laser light from the optical power distribution unit, and the receiving-side optical detection unit doubles the frequency of the receiving-side optical signal to a frequency 2f ＲＦ and outputs a receiving-side electrical signal of frequency f ＩＦ１ and the reference signal of frequency 2f ＲＦ and the receiving side electrical signal of formula 2f ＲＦ -f ＩＦ１ The difference frequency f Ｌｏ The measuring unit has an up-conversion mixer that outputs a local oscillation electrical signal of frequency 4f, and the double-harmonic mixer outputs a local oscillation electrical signal of frequency 4f, which is a frequency quadrupled by the transmitting-side optical detection unit. ＲＦ The electrical signal to be measured and the difference frequency f Ｌｏ The frequency 2f generated by doubling the local oscillation electrical signal Ｌｏ and the local oscillation electrical signal of formula 4f ＲＦ -2f Ｌｏ The difference frequency f ＩＦ２ (=2f ＩＦ１ ), and the lock-in detection unit outputs an intermediate frequency signal of the frequency f ＩＦ１ The reference signal and the difference frequency f ＩＦ２ and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test may be measured.

[0011] In order to solve the above problem, one aspect of the attenuation characteristic measuring method disclosed in this specification is to: ＲＦ a transmitting-side optical signal having a frequency f of 1 / 2, ...ＲＦ is multiplied by 4 to get frequency 4f ＲＦ The receiving section outputs an electrical signal to be measured having a frequency f Ｌｏ a receiving-side optical intensity modulation unit receives the second laser light and the receiving-side electrical signal to generate a receiving-side optical signal, and receives a DC voltage input from a receiving-side bias control unit, and a receiving-side optical detection unit detects a frequency f of the receiving-side optical signal via an optical fiber cable. Ｌｏ is doubled to a frequency of 2f Ｌｏ In the measuring section, a double-harmonic mixer outputs a local oscillation electrical signal of the frequency 4f received by the receiving device section. ＲＦ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 4f generated by doubling the local oscillation electrical signal Ｌｏ The difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) and the spectrum analyzer outputs an intermediate frequency signal of the difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) by measuring the amplitude of the intermediate frequency signal of the frequency 4f ＲＦ The signal attenuation of the electrical signal under test is measured.

[0012] The attenuation characteristic measuring device and attenuation characteristic measuring method of the present invention have the effect of being able to measure the amount of attenuation with high precision over a wide dynamic range, even for signals at the millimeter wave level.

[0013] FIG. 1 is a configuration diagram of a damping characteristics measurement device according to a first embodiment disclosed herein. FIG. 2 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the first embodiment. FIG. 3 is a configuration diagram of a damping characteristics measurement device according to a first modified example of the first embodiment disclosed herein. FIG. 4 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the first modified example of the first embodiment. FIG. 5 is a configuration diagram of a damping characteristics measurement device according to a second embodiment disclosed herein. FIG. 6 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the second embodiment. FIG. 7 is a configuration diagram of a damping characteristics measurement device according to a first modified example of the second embodiment disclosed herein. FIG. 8 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the first modified example of the second embodiment. FIG. 9 is a configuration diagram of a damping characteristics measurement device according to a second modified example of the second embodiment disclosed herein. FIG. 10 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the second modified example of the second embodiment. FIG. 11 is a configuration diagram of a damping characteristics measurement device according to a third modified example of the second embodiment disclosed herein. FIG. 12 is a sequence diagram of a damping characteristics measurement method using a damping characteristics measurement device according to a third modified example of the second embodiment. FIG. 13 is a configuration diagram of a damping characteristics measurement device according to a fourth modified example of the second embodiment disclosed herein. FIG. 14 is a sequence diagram of a damping characteristics measurement method using a damping characteristics measurement device according to the fourth modified example of the second embodiment. FIG. 15 is a configuration diagram of a damping characteristics measurement device according to a fifth modified example of the second embodiment disclosed herein. FIG. 16 is a sequence diagram of a damping characteristics measurement method using a damping characteristics measurement device according to the fifth modified example of the second embodiment. FIG. 17 is a configuration diagram of a damping characteristics measurement device according to a sixth modified example of the second embodiment disclosed herein. FIG. 18 is a sequence diagram of a damping characteristics measurement method using a damping characteristics measurement device according to the sixth modified example of the second embodiment. FIG. 19 is a configuration diagram of a damping characteristics measurement device according to a seventh modified example of the second embodiment disclosed herein. FIG. 20 is a sequence diagram of a damping characteristics measurement method using a damping characteristics measurement device according to the seventh modified example of the second embodiment. FIG. 21 is a configuration diagram of a damping characteristics measurement device according to an eighth modified example of the second embodiment disclosed herein.FIG. 22 is a sequence diagram of a damping characteristics measurement method using a damping characteristics measurement device according to an eighth modified example of the second embodiment. FIG. 23 is a configuration diagram of a damping characteristics measurement device according to a third embodiment disclosed herein. FIG. 24 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the third embodiment. FIG. 25 is a configuration diagram of a damping characteristics measurement device according to a first modified example of the third embodiment disclosed herein. FIG. 26 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the first modified example of the third embodiment. FIG. 27 is a configuration diagram of a damping characteristics measurement device according to a second modified example of the third embodiment disclosed herein. FIG. 28 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the second modified example of the third embodiment. FIG. 29 is a configuration diagram of a damping characteristics measurement device according to a third modified example of the third embodiment disclosed herein. FIG. 30 is a sequence diagram of a damping characteristics measurement method using the damping characteristics measurement device according to the third modified example of the third embodiment. FIG. 31 is a configuration diagram of a damping characteristics measurement device according to a fourth modified example of the third embodiment disclosed herein. FIG. 32 is a sequence diagram of a damping characteristic measuring method using a damping characteristic measuring device according to a fourth modified example of the third embodiment.

[0014] Hereinafter, embodiments for implementing the disclosure of this specification will be described with reference to the drawings. When a subsequent embodiment has components corresponding to those of a previously described embodiment, the same reference numerals will be used and redundant description will be omitted. Furthermore, when only a portion of the configuration is described in each embodiment, the reference numerals of the previously described embodiment may be used for the remaining portions of the configuration. Even if each embodiment does not explicitly state that a specific combination is possible, it is also possible to partially combine embodiments together as long as there is no particular problem with the combination.

[0015] Hereinafter, with reference to the drawings, an attenuation characteristic measurement device and an attenuation characteristic measurement method using the attenuation characteristic measurement device according to first to third embodiments disclosed in this specification will be described, including modified examples of each embodiment. Note that in the first to third embodiments, a transmitting antenna (or a frequency modulated laser radar (FMCW radar)) will be described as an example of the device under test (DUT), but this is not intended to be limiting.

[0016] 1 is a block diagram of an attenuation characteristic measuring device according to Embodiment 1. The attenuation characteristic measuring device is composed of a transmitting unit 11, a receiving unit 21, and a measuring unit 31.

[0017] The transmitting section 11 is composed of a transmitting side signal generating section 111, a laser oscillator section 112, an optical power dividing section 113, a transmitting side optical intensity modulator section 114, a transmitting side bias controller section 115, a transmitting side optical detector section 116, and a transmitting antenna 117.

[0018] The transmitting side signal generating unit 111 generates an output signal of the transmitting antenna 117 (DUT) at a frequency f ＲＦ The transmitter generates an electrical signal of frequency f ＲＦ The transmitting-side electrical signal is output to the transmitting-side optical intensity modulation section 114 .

[0019] The laser oscillator 112 outputs laser light to the optical power distributor 113 via an optical fiber. In Fig. 1, the open arrows represent optical fibers, and the filled arrows represent coaxial cables. The same applies to the following drawings corresponding to the second and third embodiments.

[0020] In optical transmission, the higher the modulation speed, the greater the waveform degradation due to the influence of chromatic dispersion in optical fibers. To reduce this influence, it is preferable to reduce the number of emission wavelengths of the semiconductor laser. Therefore, a distributed feedback laser diode (DFB laser diode), for example, is suitable for the laser oscillator 112.

[0021] The optical power distribution unit 113 distributes the laser light received from the laser oscillation unit 112 into a first laser light and a second laser light and outputs them. In this embodiment, the first laser light is output to the transmission-side optical intensity modulation unit 114, and as will be described later, the second laser light is output to the reception unit 21. Note that a laser oscillation unit may be provided in each of the transmission unit 11 and the reception unit 21 without going through the optical power distribution unit 113.

[0022] The transmission side optical intensity modulation unit 114 modulates the frequency f ＲＦ The transmission-side optical signal is generated from the transmission-side electrical signal and the first laser light. That is, the transmission-side optical intensity modulation unit 114 converts the electrical signal to be transmitted into an intensity change or a phase change of light. Therefore, the transmission-side optical intensity modulation unit 114 generates an optical signal having the frequency f ＲＦ The transmitting-side optical intensity modulator 114 in this embodiment may be, for example, a LiNbO3 optical intensity modulator.

[0023] The transmission-side optical detector 116 receives the transmission-side optical signal output from the transmission-side optical intensity modulator 114 via the optical fiber, converts it into an electrical signal, and converts it into an electrical signal having a frequency f ＲＦ is multiplied by 4 to get frequency 4f ＲＦ In this embodiment, the transmitting-side photodetector 116 uses, for example, a UTC-PD (uni-traveling-carrier photodiode). A UTC-PD has the property of simultaneously achieving ultra-high speed and high output compared to conventional photodiodes.

[0024] The transmitting-side bias control unit 115 outputs a bias voltage (DC voltage) to the transmitting-side optical intensity modulation unit 114. Specifically, the transmitting-side optical intensity modulation unit 114 is provided with a DC input port, and the bias voltage is output to the DC input port. In the transmitting-side optical intensity modulation unit 114, the operating point of the bias voltage drifts due to, for example, temperature changes, aging deterioration, etc., and the optical output characteristics change. For this reason, the transmitting-side bias control unit 115 automatically controls the bias voltage to an appropriate voltage. The transmitting-side bias control unit 115 controls the bias voltage to a suitable voltage based on the frequency f ＲＦ Maximize the level of the transmitting electrical signal.

[0025] If a minute signal such as a millimeter wave is simply converted into an optical signal and then photoelectrically converted again, the S / N ratio may be degraded due to noise dependent on the DC component of the optical power. In this embodiment, the above-described configuration improves the S / N ratio, enabling measurement of signals with higher accuracy and a wider dynamic range.

[0026] The receiver 21 comprises a receiver signal generator 211 , a receiver optical intensity modulator 212 , a receiver bias controller 213 , and a receiver optical detector 214 .

[0027] The receiving side signal generator 211 receives a signal of frequency f Ｌｏ The receiving side generates an electrical signal of frequency f Ｌｏ The receiving-side electrical signal is output to the receiving-side optical intensity modulation section 212 .

[0028] The receiving side optical intensity modulation unit 212 modulates the frequency f Ｌｏ The receiving-side optical signal is generated from the receiving-side electrical signal and the second laser light. As with the transmitting-side optical intensity modulator 114, the receiving-side optical intensity modulator 212 may use, for example, a LiNbO3 optical intensity modulator.

[0029] The receiving-side optical detector 214 receives the receiving-side optical signal output from the receiving-side optical intensity modulator 212 via an optical fiber, converts it into an electrical signal, and converts it into an electrical signal at a frequency f Ｌｏ is doubled to a frequency of 2f Ｌｏ In this embodiment, the receiving-side photodetector 214 may use, for example, a photodiode-coupled-impedance amplifier (PD-TIA) that converts the resistance (impedance) of the input current into double the voltage.

[0030] In this embodiment, the frequency 2f ＬｏA receiver amplifier 215 is provided to further amplify the locally oscillated electrical signal. Amplification by the receiver amplifier 215 increases the signal strength, which has the effect of improving the S / N ratio. Note that in the second and third embodiments described below, amplifiers are provided not only in the receiver 21 but also in various parts of the transmitter 11 and the measuring unit 31. However, in both cases, similar to the above, they are provided to amplify each electrical signal (not limited to the locally oscillated electrical signal), increase the signal strength, and improve the S / N ratio. In the second and third embodiments described below, a detailed description of the specific functions of each amplifier will be omitted.

[0031] The measurement unit 31 comprises a receiving device unit 311 , a double-type harmonic mixer 312 , and a spectrum analysis unit 313 .

[0032] The receiving device section 311 receives the frequency 4f transmitted from the transmitting antenna 117 of the transmitting section 11. ＲＦ The electrical signal to be measured is received.

[0033] The double-harmonic mixer 312 (subharmonic mixer) mixes the frequency 4f received by the receiving device section 311. ＲＦ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 4f generated by doubling the local oscillation electrical signal Ｌｏ The difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ The double-harmonic mixer 312 outputs an intermediate frequency signal of the frequency 4f ＲＦ an RF port that receives the electrical signal to be measured at frequency 2f Ｌｏ a Lo port that receives a local oscillation electrical signal of the difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ The doubling harmonic mixer 312 has a function for calculating the difference frequency, and can calculate other frequencies if a target set value is available for any frequency. The doubling harmonic mixer 312 also enables low-loss conversion.

[0034] The spectrum analyzer 313 calculates the difference frequency f ＩＦ (4fＲＦ -4f Ｌｏ ) by amplitude measurement (scalar measurement) of the intermediate frequency signal of the frequency 4f ＲＦ The signal attenuation of the electrical signal under test is measured.

[0035] As described above, the attenuation characteristic measuring device disclosed in this specification enables measurements via optical fiber, enabling more accurate measurements than measurements via coaxial cables, as in conventional network analyzers. Furthermore, optical fiber has the characteristic of low signal loss, making remote measurements possible. Furthermore, conventional network analyzers require at least four coaxial cables, which makes the setup of the device cumbersome, leading to connection errors and time-consuming adjustments. However, the attenuation characteristic measuring device disclosed in this specification makes it possible to use optical fiber, thereby reducing the workload involved in the setup.

[0036] FIG. 2 is a sequence diagram of the attenuation characteristic measuring method according to the first embodiment.

[0037] In the transmitter 11, the transmitter signal generator 111 outputs a frequency f ＲＦ to the transmitting-side optical intensity modulation unit 114. Furthermore, the laser oscillator 112 outputs a laser beam to the optical power distributor 113. The optical power distributor 113 outputs the first laser beam to the transmitting-side optical intensity modulation unit 114. Furthermore, the transmitting-side bias controller 115 outputs a bias voltage (DC voltage) to the transmitting-side optical intensity modulation unit 114.

[0038] The transmission-side optical intensity modulation unit 114 receives the first laser light and the transmission-side electrical signal and generates a transmission-side optical signal. The generated transmission-side optical signal is output to the transmission-side optical detection unit 116. The transmission-side optical detection unit 116 detects the frequency f of the transmission-side optical signal via an optical fiber cable. ＲＦ is multiplied by 4 to get frequency 4f ＲＦ The electrical signal to be measured is transmitted from the transmitting antenna 117 to the receiving device section 311 of the measuring section 31 .

[0039] In the receiving unit 21, the receiving side signal generating unit 211 outputs a frequency f Ｌｏto the receiving-side optical intensity modulation unit 212. The receiving-side bias control unit 213 also outputs the second laser light output from the optical power distribution unit 113 to the receiving-side optical intensity modulation unit 212. The receiving-side bias control unit 213 also outputs a bias voltage (DC voltage) to the receiving-side optical intensity modulation unit 212.

[0040] The receiving-side optical intensity modulation unit 212 receives the second laser light and the receiving-side electrical signal and generates a receiving-side optical signal. The generated receiving-side optical signal is output to the receiving-side optical detection unit 214. The receiving-side optical detection unit 214 detects the frequency f of the receiving-side optical signal via an optical fiber cable. Ｌｏ is doubled to a frequency of 2f Ｌｏ The local oscillation electrical signal is transmitted to the double-harmonic mixer 312 of the measuring unit 31 .

[0041] In the measurement unit 31, the frequency 4f received by the receiving device unit 311 ＲＦ The electrical signal under test is output to a double-harmonic mixer 312 .

[0042] The double-harmonic mixer 312 is a frequency converter for converting the frequency 4f ＲＦ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 4f generated by doubling the local oscillation electrical signal Ｌｏ The difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) to the spectrum analyzer 313.

[0043] The difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ The spectrum analyzer 313 receives the intermediate frequency signal of the difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) by measuring the amplitude of the intermediate frequency signal of the frequency 4f ＲＦ The signal attenuation of the electrical signal under test is measured.

[0044] <First Modification of First Embodiment> Fig. 3 is a configuration diagram of a damping characteristic measuring device according to a first modification of the first embodiment (hereinafter referred to as "Modification 1-1"). Differences from the first embodiment described above will be explained below. Note that for each modification of the second and third embodiments described below, only differences from the respective embodiments will be explained.

[0045] In the first-1 modification, the transmitter 11 transmits a signal having a frequency f ＦＭＣＷ The frequency modulation laser radar 118 outputs an electrical signal to be measured having the frequency f ＦＭＣＷ The electrical signal to be measured is a frequency sweep signal having a predetermined range.

[0046] In the receiving section 21 of the first-1 modification, the receiving-side optical intensity modulation section 212 receives the laser light from the laser oscillator section 112 and the frequency f Ｌｏ The receiving side optical signal is generated by receiving the receiving side electrical signal.

[0047] The measuring unit 31 measures the frequency f received by the receiving device unit 311 using a double-harmonic mixer 312. ＦＭＣＷ The electrical signal to be measured and the frequency 4f Ｌｏ and the difference frequency f ＩＦ (f ＦＭＣＷ -4f Lo ) intermediate frequency signal.

[0048] 4 is a sequence diagram of the attenuation characteristic measuring method according to the first modified example. Differences from the first embodiment will be described below. Regarding the modifications of the second and third embodiments described below, only differences from the respective embodiments will be described.

[0049] In the transmitter 11, the frequency f ＦＭＣＷ The electrical signal to be measured is transmitted to the receiving device section 311 of the measuring section 31 .

[0050] In the receiver 21 , the receiver-side optical intensity modulator 212 directly receives the laser light from the laser oscillator 112 .

[0051] In the measuring section 31, a double-harmonic mixer 312 mixes the frequency f received by the receiving device section 311. ＦＭＣＷ The electrical signal to be measured and the frequency 4f Ｌｏ The difference frequency f ＩＦ (f ＦＭＣＷ -4f Lo ) intermediate frequency signal.

[0052] The difference frequency f ＩＦ (f ＦＭＣＷ -4f Lo The spectrum analyzer 313 receives the intermediate frequency signal of the difference frequency f ＩＦ (f ＦＭＣＷ -4f Lo ) by measuring the amplitude of an intermediate frequency signal of the frequency f ＦＭＣＷ The signal attenuation of the electrical signal under test is measured.

[0053] 5 is a configuration diagram of an attenuation characteristic measuring device according to a second embodiment. In the first embodiment, one difference frequency generator such as the double-type harmonic mixer 312 is provided, and the amount of attenuation of the signal under measurement is measured in amplitude (scalar measurement). However, in the second embodiment, two difference frequency generators are provided, and the amount of attenuation of the signal under measurement is measured in amplitude and phase (vector measurement) by lock-in detection.

[0054] The transmitting unit 11 has the same configuration as in the first embodiment, that is, a transmitting-side signal generating unit 111, a laser oscillator 112, an optical power dividing unit 113, a transmitting-side optical intensity modulator 114, a transmitting-side bias controller 115, a transmitting-side optical detector 116, a transmitting antenna 117, and also a transmitting-side divider 119.

[0055] The transmitting side distributor 119 receives the frequency f ＲＦ In the first embodiment, the transmission-side optical intensity modulation unit 114 receives a transmission-side electrical signal of frequency f from the transmission-side signal generation unit 111 and outputs a first transmission-side electrical signal and a second transmission-side electrical signal. ＲＦ In the second embodiment, the first transmitting-side electrical signal of the transmitting-side distributor 119 is output to the transmitting-side optical intensity modulator 114 .

[0056] The receiving unit 21 also has the same configuration as in the first embodiment, that is, it has a receiving side signal generating unit 211, a receiving side optical intensity modulating unit 212, a receiving side bias control unit 213, a receiving side optical detecting unit 214, and also has a receiving side distributing unit 216.

[0057] The receiving side distributor 216 receives the frequency f Ｌｏ In the first embodiment, the receiving-side optical intensity modulation unit 212 receives a receiving-side electrical signal of frequency f from the receiving-side signal generation unit 211 and outputs a first receiving-side electrical signal and a second receiving-side electrical signal. Ｌｏ In the second embodiment, the first receiving-side electrical signal of the receiving-side distributor 216 is output to the receiving-side optical intensity modulator 212 .

[0058] The measurement unit 31 has the same configuration as in the first embodiment, i.e., a receiving device unit 311 and a double-multiplier harmonic mixer 312, as well as a fundamental wave mixer 318 for generating a reference signal, an output side multiplier unit 319, and a lock-in detection unit 320.

[0059] The reference signal generating fundamental wave mixer 318 generates a difference frequency f from the second transmitting side electrical signal received from the transmitting side distribution unit 119 and the second receiving side electrical signal received from the receiving side distribution unit 216. ＩＦ１ (f ＲＦ -f Ｌｏ ) reference signal.

[0060] The output side multiplier 319 multiplies the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) the reference signal of frequency 4f ＲＦ The difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) frequency of the reference signal is multiplied by two or four to obtain a frequency 2f ＩＦ１ or frequency 4f ＩＦ１ A reference signal is generated.

[0061] The double-harmonic mixer 312 converts the frequency 4f received by the receiving device section 311 into ＲＦThe electrical signal to be measured and the frequency 2f Ｌｏ The frequency 4f generated by doubling the local oscillation electrical signal Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) intermediate frequency signal.

[0062] The lock-in detector 320 detects the frequency 2f ＩＦ１ or frequency 4f ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) and the frequency 4f output from the transmitting side photodetector. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal to be measured are measured. ＩＦ２ (4f ＲＦ -4f Ｌｏ ) is the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is a reference signal multiplied by four, i.e., frequency 4f ＩＦ１ is equal to.

[0063] The difference frequency f output from the double-harmonic mixer 312 is ＩＦ２ (4f ＲＦ -4f Ｌｏ ) may be input to the lock-in detector 320 via a coaxial cable. In the second embodiment, however, the electro-optic converter 315 ＩＦ２ (4f ＲＦ -4f Ｌｏ) into a measurement-side optical modulated signal, which the measurement-side optical detector 316 converts into an electrical signal via an optical fiber and outputs to the lock-in detector 320. This configuration simplifies the overall structure of the attenuation characteristic measuring device, and the dynamic range is widened, enabling more accurate measurements. In the modified examples of this embodiment described later, similarly, intermediate frequency signals output by various mixers from the electrical signal under measurement and the local oscillation signal can be output to the lock-in detector 320 via a coaxial cable, or alternatively, the signals can be output to the lock-in detector 320 via an optical fiber by the electro-optic converter 315 and the measurement-side optical detector 316. In the modified examples of this embodiment described later, a detailed description of the specific functions of the electro-optic converter 315 and the measurement-side optical detector 316 will be omitted.

[0064] In this specification, the lock-in detector 320 detects the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) and an oscilloscope having a frequency characteristic capable of measuring the intermediate frequency signal of the above-mentioned type, and an oscilloscope having a configuration capable of converting a time signal that is the measurement result into a frequency characteristic, and calculating and outputting amplitude and phase characteristics. In each of the modifications of the first embodiment, as well as the second embodiment (including each of the modifications), and the third embodiment (including each of the modifications), the lock-in detection unit 320 that receives each intermediate frequency signal output from the double-multiplier harmonic mixer 312 or the octa-multiplier harmonic mixer 322 described later, and the fundamental mixer 323 for generating an intermediate frequency signal, includes an oscilloscope having a frequency characteristic capable of measuring the intermediate frequency signal of the above-mentioned type, and an oscilloscope having a frequency characteristic capable of converting a time signal that is the measurement result into a frequency characteristic, and calculating and outputting amplitude and phase characteristics.

[0065] Furthermore, in addition to the receiving side amplifier 215 described in the first embodiment, ＲＦ In order to amplify the electrical signal to be measured, a transmitting amplifier 120 is interposed between the transmitting optical detector 116 and the transmitting antenna 117, and a first measuring amplifier 314 is interposed between the receiving device 311 and the double-harmonic mixer. ＩＦ２ (4f ＲＦ -4f Ｌｏ) an intermediate frequency signal, a second measurement-side amplifier 317 is interposed between the measurement-side optical detector 316 and the lock-in detector 320.

[0066] Fig. 6 is a sequence diagram of the attenuation characteristic measuring method according to the second embodiment. For convenience of explanation, the amplifiers described in Fig. 1 and the electro-optical converter 315 and measurement-side optical detector 316 described in Fig. 5 are omitted from Fig. 6, but these components may be included. The same applies to sequence diagrams of the attenuation characteristic measuring methods according to the modified examples of the second embodiment and the third embodiment described below.

[0067] In the transmitting section 11, the frequency f output from the transmitting side signal generating section 111 is ＲＦ The transmitting side electrical signal of frequency f is output to the transmitting side distributor 119. ＲＦ The transmitting-side distributor 119, which has received the input of the transmitting-side electrical signal, outputs a first transmitting-side electrical signal to the transmitting-side optical intensity modulator 114. The transmitting-side optical intensity modulator 114, which has received the input of the first transmitting-side electrical signal, outputs the transmitting-side optical signal to the transmitting-side optical detector 116 via an optical cable. The transmitting-side optical detector 116, which has received the input of the transmitting-side optical signal, outputs the transmitting-side optical signal to the transmitting-side optical detector 116 via an optical cable. ＲＦ The electrical signal under test is output to the receiving device section 311 .

[0068] In the receiving unit 21, the frequency f output from the receiving side signal generating unit 211 is Ｌｏ The receiving-side electrical signal of frequency f is output to the receiving-side distributor 216. Ｌｏ The receiving-side distributor 216, which has received the input of the receiving-side electrical signal, outputs the first receiving-side electrical signal to the receiving-side optical intensity modulator 212. The receiving-side optical intensity modulator 212, which has received the input of the first receiving-side electrical signal, outputs the receiving-side optical signal to the receiving-side optical detector 214 via an optical cable. The receiving-side optical detector 214, which has received the input of the receiving-side optical signal, outputs the frequency 2f Ｌｏ The local oscillator electrical signal is output.

[0069] In the measurement unit 31, the reference signal generating fundamental wave mixer 318 receives the second transmitting side electrical signal from the transmitting side distribution unit 119 and the second receiving side electrical signal from the receiving side distribution unit 216, and generates a difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) and outputs it to the output side multiplier 319.

[0070] The difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ The output side multiplier 319 receives the output of the reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) frequency of the reference signal is multiplied by two or four to obtain a frequency 2f ＩＦ１ or frequency 4f ＩＦ１ and outputs the reference signal to the lock-in detection section 320.

[0071] As described above, the double-harmonic mixer 312 generates a difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) and outputs it to the lock-in detection section 320.

[0072] The lock-in detector 320 detects the frequency 2f ＩＦ１ or frequency 4f ＩＦ１ The reference signal and the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0073] <First Modification of Second Embodiment> FIG. 7 is a diagram showing the configuration of a damping characteristic measuring device according to a first modification of the second embodiment (hereinafter referred to as "Modification 2-1").

[0074] In the second modification, similar to the first modification, the transmitter 11 transmits a frequency f ＦＭＣＷ That is, the frequency modulation laser radar 118 outputs a measured electrical signal of the frequency f ＦＭＣＷ The electrical signal to be measured is a frequency sweep signal having a predetermined range.

[0075] In the receiving section 21 of the second modified example, similarly to the first modified example, the receiving-side optical intensity modulation section 212 receives the laser light from the laser oscillator section 112 and the frequency f Ｌｏ The receiving side optical signal is generated by receiving the receiving side electrical signal.

[0076] The measuring unit 31 measures the frequency f received by the receiving device unit 311 using a double-harmonic mixer 312. ＦＭＣＷ The electrical signal to be measured and the frequency 4f Ｌｏ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Lo ) intermediate frequency signal.

[0077] On the other hand, the reference signal generating fundamental wave mixer 318 receives the frequency f ＲＦ and receives the transmitting side electrical signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) reference signal.

[0078] The output side multiplier 319 multiplies the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ A reference signal is generated.

[0079] The lock-in detection unit detects the frequency f ＬＡ_ｒｅｆ The reference signal and the difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Ｌｏ ) and an intermediate frequency signal of frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0080] FIG. 8 is a sequence diagram of the attenuation characteristic measuring method according to the 2-1st modified example.

[0081] In the transmitter 11, the frequency f ＦＭＣＷ The electrical signal to be measured is transmitted to the receiving device section 311 of the measuring section 31 .

[0082] In the receiver 21 , the receiver-side optical intensity modulator 212 directly receives the laser light from the laser oscillator 112 .

[0083] In the measuring section 31, a double-harmonic mixer 312 mixes the frequency f received by the receiving device section 311. ＦＭＣＷ The electrical signal to be measured having the frequency 2f output from the receiving side optical detection unit 214 is Ｌｏ and receives the local oscillator electrical signal of difference frequency f ＩＦ (f ＦＭＣＷ -4f Lo ) intermediate frequency signal.

[0084] On the other hand, the reference signal generating fundamental wave mixer 318 receives the frequency f ＲＦ The transmitting-side electrical signal is received together with the second receiving-side electrical signal output from the receiving-side distributor 216, and the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) reference signal.

[0085] The transmitting signal generating unit 111 may be configured with an antenna or the like capable of receiving the FMWC signal transmitted from the frequency modulation laser radar 118. The same applies to the second to fifth modifications, the seventh modification, and the third embodiment.

[0086] The output side multiplier 319 receives the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) and doubles or quadruples the frequency to produce a reference signal of frequency f ＬＡ_ｒｅｆ A reference signal is generated.

[0087] The lock-in detector 320 detects the frequency f output from the output multiplier 319. ＬＡ_ｒｅｆ and the difference frequency f output from the double-harmonic mixer 312. ＩＦ (f ＦＭＣＷ -4f Lo ) and an intermediate frequency signal of frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0088] <Second Modification of Second Embodiment> FIG. 9 is a diagram showing the configuration of a damping characteristic measuring device according to a second modification of the second embodiment (hereinafter referred to as "Modification 2-2").

[0089] The configuration of the second modified example 2-2 is the same as that of the first modified example, except that the receiving-side optical detector 214 multiplies the frequency of the receiving-side optical signal by four to produce a frequency 4f Ｌｏ The double-harmonic mixer 312 outputs a local oscillation electrical signal of the frequency f ＦＭＣＷ and the electrical signal to be measured at frequency 4f Ｌｏ The frequency 8f is generated by doubling the local oscillation electrical signal Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) intermediate frequency signal.

[0090] FIG. 10 is a sequence diagram of the attenuation characteristic measuring method according to the second modified example.

[0091] As described above, in the 2-2 modification, the frequency multiplication number of the receiving-side optical signal output from the receiving-side optical detection unit 214 is 4 times, whereas in the 2-1 modification, it is 2 times. In the 2-1 modification, the intermediate frequency signal output from the doubling type harmonic mixer 312 to the lock-in detection unit 320 is the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) is an intermediate frequency signal, whereas the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) intermediate frequency signal.

[0092] <Third Modification of Second Embodiment> FIG. 11 is a configuration diagram of a damping characteristic measuring device according to a third modification of the second embodiment (hereinafter referred to as "Modification 2-3").

[0093] In the receiving section 21, the receiving-side optical detector 214 detects a frequency f Ｌｏ The local oscillator electrical signal is output.

[0094] The measuring unit 31 uses the frequency 4f instead of the double-type harmonic mixer 312. ＲＦ The electrical signal to be measured and the frequency f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) and an octupling type harmonic mixer 322 that outputs an intermediate frequency signal.

[0095] The measuring unit 31 also measures the frequency f of the second receiving-side electrical signal output from the receiving-side distributor 216. Ｌｏ is doubled to a frequency of 2f Ｌｏ The input side multiplier 321 generates an input signal of

[0096] The reference signal generating fundamental wave mixer 318 generates the reference signal at the frequency f ＲＦ and the second transmitting electrical signal of frequency 2f Ｌｏ The input signal and the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ), and the output side multiplier 319 generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ) frequency of the reference signal is multiplied by four to obtain a frequency 4 (f ＲＦ -2f Ｌｏ ), i.e., 4f ＩＦ１ A reference signal is generated.

[0097] The lock-in detector 320 detects the frequency 4f ＩＦ１ The reference signal and the difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0098] FIG. 12 is a sequence diagram of the attenuation characteristic measuring method according to the second-third modified example.

[0099] In the receiver 21, the receiver optical detector 214 receives the receiver optical signal from the receiver optical intensity modulator 212 and detects the frequency f Ｌｏand transmits it to the octupling harmonic mixer 322.

[0100] In the measurement unit 31, the second receiving-side electrical signal output from the receiving-side distributor 216 is received by the input-side multiplier 321, and the frequency f of the second receiving-side electrical signal is Ｌｏ is doubled to a frequency of 2f Ｌｏ Generate an input signal.

[0101] The reference signal generating fundamental wave mixer 318 generates the reference signal at the frequency f ＲＦ and receives the second transmission-side electrical signal of the frequency 2f received from the input-side multiplier 321. Ｌｏ and receives an input signal of difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ) reference signal.

[0102] On the other hand, the octupling harmonic mixer 322 receives the frequency f Ｌｏ The local oscillation electrical signal of the frequency 4f received from the receiving device unit 311 is ＲＦ From the measured electrical signal, the difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) intermediate frequency signal.

[0103] The lock-in detector 320 receives the frequency 4f from the output multiplier 319. ＩＦ１ The reference signal and the difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal to be measured are measured. ＩＦ２ (4f ＲＦ -8f Ｌｏ ) is 4(f ＲＦ -2f Ｌｏ ), so the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ) is a reference signal of f ＩＦ２ = 4f ＩＦ１ This becomes:

[0104] <Fourth Modification of Second Embodiment> FIG. 13 is a configuration diagram of a damping characteristic measuring device according to a fourth modification of the second embodiment (hereinafter referred to as "Modification 2-4").

[0105] In the second-third modification, the electrical signal to be measured in the transmitting section 11 has a frequency f ＲＦ In the second-fourth modification, the frequency modulation laser radar 118 generates a signal having a frequency f ＦＭＣＷ The measured electrical signal is output.

[0106] In the receiving section 21, the receiving-side optical intensity modulation section 212 receives the laser light from the laser oscillator section, and the receiving-side optical detection section receives the laser light at a frequency 2f obtained by doubling the frequency of the local oscillation electrical signal. Ｌｏ The local oscillator electrical signal is output.

[0107] The octupling harmonic mixer 322 multiplies the frequency f received by the receiving device section 311. ＦＭＣＷ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 16f is generated by multiplying the local oscillation electrical signal by 8. Ｌｏ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -16f Ｌｏ ) intermediate frequency signal.

[0108] The reference signal generating fundamental wave mixer 33 receives the frequency f ＲＦ and the frequency f received from the receiving side distributor 216. Ｌｏ and the second receiving side electrical signal, ＩＦ１ (f ＲＦ -f Ｌｏ ) reference signal.

[0109] The output side multiplier 319 multiplies the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ A reference signal is generated.

[0110] The lock-in detection unit 320 detects the frequency f ＬＡ_ｒｅｆ The reference signal and the difference frequency f ＩＦ２ (f ＦＭＣＷ -16f Ｌｏ ) and an intermediate frequency signal of frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0111] FIG. 14 is a sequence diagram of the attenuation characteristic measuring method according to the second-fourth modified example.

[0112] In the transmitter 11, a frequency modulation laser radar 118 transmits a frequency f ＦＭＣＷ The signal is output as an electrical signal to be measured and transmitted to the receiving device section 311.

[0113] In the receiver 21, the receiver-side optical intensity modulator 212 receives the laser light directly from the laser oscillator 112 and outputs a receiver-side optical signal to the receiver-side optical detector 214. The receiver-side optical detector 214 receives the receiver-side optical signal and outputs it at a frequency 2f, which is twice the frequency of the local oscillator electrical signal. Ｌｏ The local oscillation electrical signal is sent to the octupling harmonic mixer 322 .

[0114] In the measurement unit 31, an octupling type harmonic mixer 322 mixes the frequency f received by the receiving device unit 311. ＦＭＣＷ The electrical signal to be measured and the frequency 2f Ｌｏ The frequency 16f is generated by multiplying the local oscillation electrical signal by 8. Ｌｏ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -16f Ｌｏ ) to the lock-in detector 320.

[0115] On the other hand, the reference signal generating fundamental wave mixer 318 receives the frequency f ＲＦ and the frequency f received from the receiving side distributor 216. Ｌｏ and the second receiving side electrical signal, ＩＦ１ (f ＲＦ -f Ｌｏ ) reference signal.

[0116] The output side multiplier 319 receives the difference frequency f from the reference signal generating fundamental wave mixer 318. ＩＦ１ (f ＲＦ -f Ｌｏ ) and multiplies the frequency by two or four to produce a frequency f ＬＡ_ｒｅｆ A reference signal is generated.

[0117] The lock-in detector 320 receives the frequency f ＬＡ_ｒｅｆ and receives a reference signal of the difference frequency f ＩＦ２ (f ＦＭＣＷ -16f Ｌｏ ) and receives an intermediate frequency signal of the frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0118] <Fifth Modification of Second Embodiment> FIG. 15 is a configuration diagram of a damping characteristic measuring device according to a fifth modification of the second embodiment (hereinafter referred to as "Modification 2-5").

[0119] In the second to fifth variant, for example, it is possible to measure the vector radiation pattern of a moving object such as an automobile or a mobile terminal that has a built-in frequency modulation radar while it is moving.

[0120] In the transmitting unit 11, as in the second-fourth modified example, the frequency-modulated laser radar 118 outputs a non-measurement signal, but the frequency-modulated laser radar 8 is fixedly installed on a pedestal 121 (Azimuth Turn table) that can rotate forward and backward in all directions, at a position facing the receiving device unit 311.

[0121] The receiving unit 21 receives the signal from the receiving-side optical detector 214 at a frequency f Ｌｏ The local oscillator electrical signal is output.

[0122] The measuring unit 31 measures the frequency f received by the receiving device unit 311 using the octupling type harmonic mixer 322. ＦＭＣＷ The electrical signal to be measured and the frequency f Ｌｏ The frequency 8f is generated by multiplying the local oscillation electrical signal by 8. Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ) intermediate frequency signal.

[0123] The measurement unit 31 also includes a measurement-side optical intensity modulation unit 325 that receives the second receiving-side electrical signal from the receiving-side distribution unit 216, a measurement-side laser oscillation unit 329 that oscillates laser light to the measurement-side optical intensity modulation unit 325, and a frequency f Ｌｏ The second receiving side electrical signal of frequency f Ｌｏ_ref and a measurement-side optical detector 316 that outputs a local oscillation electrical signal.

[0124] The measurement unit 31 is mounted on the base 121 at a predetermined distance from the frequency modulation laser radar 118, and receives a frequency f ＲＦ The reference signal receiving device 327 is fixedly installed to receive the reference signal. That is, in the 2-4th modification, the reference signal is generated by the reference signal generating fundamental wave mixer 318, but in the 2-5th modification, the reference signal is generated by the reference signal generating double-type harmonic mixer 324.

[0125] The reference signal generating double-harmonic mixer 324 generates a reference signal having a frequency f Ｌｏ_ref The local oscillator electrical signal and frequency f ＲＦ and the reference signal, the difference frequency f ＩＦ１_ref (f ＲＦ -2f Ｌｏ_ref ) intermediate frequency signal.

[0126] The measurement unit 31 measures the difference frequency f ＩＦ１_ref (f ＲＦ -2f Ｌｏ_ref ) and the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) and the frequency f ＦＭＣＷThe waveform analyzer 332 measures the amplitude and phase of the signal attenuation of the electrical signal under test. The waveform analyzer 332 is preferably, for example, an oscilloscope. In Variation 2-4, the lock-in detector 320 measures the amplitude and phase of the signal attenuation. However, in Variation 2-5, a chirp signal is measured, so a necessary time constant must be set for the lock-in detector 320. Furthermore, while the lock-in detector 320 is advantageous for measuring single-frequency signals, when measuring a chirp signal as in Variation 2-5, it is necessary to synchronize the timing of the output signal for each chirp. Therefore, in Variation 2-5, an oscilloscope capable of real-time measurement, i.e., the waveform analyzer 332, is preferred.

[0127] FIG. 16 is a sequence diagram of the attenuation characteristic measuring method according to the second-fifth modified example.

[0128] In the transmitting unit 11, a frequency modulation laser radar 118 fixedly installed on a base 121 transmits a frequency f ＦＭＣＷ The signal is output as an electrical signal to be measured and transmitted to the receiving device section 311.

[0129] In the receiver 21, the receiver-side optical intensity modulator 212 receives the laser light directly from the laser oscillator 112 and outputs a receiver-side optical signal to the receiver-side optical detector 214. The receiver-side optical detector 214 receives the receiver-side optical signal and outputs a frequency f Ｌｏ The local oscillation electrical signal is sent to the octupling harmonic mixer 322 .

[0130] In the measurement unit 31, an octupling type harmonic mixer 322 mixes the frequency f received by the receiving device unit 311. ＦＭＣＷ The electrical signal to be measured and the frequency f Ｌｏ The frequency 8f is generated by multiplying the local oscillation electrical signal by 8. Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) to the waveform analysis unit 332.

[0131] Meanwhile, the receiving-side distributor 216 of the receiver 21 transmits the second receiving-side electrical signal to the measurement-side optical intensity modulator 325 of the measurement unit 31. The measurement-side optical intensity modulator 325 receives the laser light from the measurement-side laser oscillator 326 and outputs the measurement-side optical signal to the measurement-side optical detector 316. The measurement-side optical detector 316 that has received the measurement-side optical signal outputs a signal having a frequency f Ｌｏ_ref (=4f Ｌｏ ) to a double-harmonic mixer 324 for generating a reference signal.

[0132] A reference signal receiving device 327 fixedly installed on the base 121 from the frequency modulation laser radar 118 at a predetermined distance from the frequency modulation laser radar 118 receives a frequency f ＲＦ Receive a reference signal.

[0133] The reference signal generating double-harmonic mixer 324 generates a reference signal having a frequency f Ｌｏ_ref and the local oscillation electrical signal of frequency f ＲＦ and the reference signal, the difference frequency f ＩＦ１_ref (f ＲＦ -2f Ｌｏ_ref ) intermediate frequency signal.

[0134] In addition, the frequency f ＦＭＣＷ The electrical signal to be measured is used as a trigger signal because the frequency modulation laser radar 118 and the reference signal generating double-type harmonic mixer 324 are fixedly mounted on the base 121 and the base 121 is rotated for measurement.

[0135] The waveform analysis unit 332 calculates the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) and the difference frequency f ＩＦ１_ref (f ＲＦ -2f Ｌｏ_ref ) and the frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0136] <Sixth Modification of Second Embodiment> FIG. 17 is a configuration diagram of a damping characteristic measuring device according to a sixth modification of the second embodiment (hereinafter referred to as "Modification 2-6").

[0137] In the second embodiment, the transmitter 11 receives a frequency 4f ＲＦ In the second-sixth modification, the frequency of the transmission-side optical signal is doubled to a frequency of 2f ＲＦ The measured electrical signal is output.

[0138] In the second embodiment, the measuring unit 31 has a double-type harmonic mixer 312, but in this fifth modification, ＲＦ and the frequency 2f output from the receiving side optical detection unit 214. Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ) and outputs an intermediate frequency signal.

[0139] As described above, in the present Modification 2-6, the lock-in detection unit 320 detects the difference frequency f generated by the reference signal generating fundamental wave mixer 318. ＩＦ１ (f ＲＦ -f Ｌｏ ) and the difference frequency f generated by the fundamental wave mixer 323 for generating an intermediate frequency signal. ＩＦ２ (2f ＲＦ -2f Ｌｏ ) and the frequency 2f output from the transmitting side optical detection unit 116 ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0140] FIG. 18 is a sequence diagram of the attenuation characteristic measuring method according to the second-sixth modified example.

[0141] In the transmitter 11, the transmitter optical detector 116 receives the transmission-side optical signal from the transmission-side optical intensity modulator 114 and doubles the frequency to obtain a frequency 2f ＲＦ The electrical signal under test is output and transmitted to the receiving device section 311.

[0142] In the measurement unit 31, the fundamental wave mixer 323 for generating an intermediate frequency signal mixes the frequency 2f transmitted from the receiving-side optical detection unit 214. Ｌｏ and receives the local oscillation electrical signal of frequency 2f output from the receiving device section 311. ＲＦand receiving the electrical signal to be measured, and ＩＦ２ (2f ＲＦ -2f Ｌｏ ) intermediate frequency signal.

[0143] The lock-in detector 320 detects the difference frequency f output from the reference signal generating fundamental wave mixer 318. ＩＦ１ (f ＲＦ -f Ｌｏ ) and the difference frequency f output from the fundamental wave mixer 323 for generating an intermediate frequency signal. ＩＦ２ (2f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 2f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0144] <Seventh Modification of Second Embodiment> FIG. 19 is a configuration diagram of a damping characteristic measuring device according to a seventh modification of the second embodiment (hereinafter referred to as "Modification 2-7").

[0145] In the second-seventh modified example, the transmitter 11 receives a frequency 2f ＲＦ In the second-seventh modification, the frequency f is calculated from the transmission-side optical signal. ＲＦ The measured electrical signal is output.

[0146] In the second-seventh modified example, the receiving section 21 has a receiving-side optical detecting section 214 that detects a frequency 2f Ｌｏ In the second-seventh modification, the receiving-side optical detector 214 outputs a local oscillation electrical signal of frequency f Ｌｏ The output is a local oscillator electrical signal.

[0147] In the second-sixth modified example, the measuring unit 31 determines whether the fundamental wave mixer 323 for generating an intermediate frequency signal is equal to or greater than the difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ), but in the second-seventh modification, the intermediate frequency signal generating fundamental wave mixer 323 outputs an intermediate frequency signal of the frequency f ＲＦ The electrical signal to be measured and the frequency f Ｌｏ The difference frequency f ＩＦ２(f ＲＦ -f Ｌｏ ) intermediate frequency signal.

[0148] As described above, in the second-seventh modification, the lock-in detection unit 320 detects the difference frequency f generated by the reference signal generating fundamental wave mixer 318. ＩＦ１ (f ＲＦ -f Ｌｏ ) and the difference frequency f generated by the fundamental wave mixer 323 for generating an intermediate frequency signal. ＩＦ２ (f ＲＦ -f Ｌｏ ) and the intermediate frequency signal of the frequency f ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0149] FIG. 20 is a sequence diagram of the attenuation characteristic measuring method according to the second-seventh modified example.

[0150] In the transmitter 11, the transmitter optical detector 116 detects a frequency f ＲＦ The electrical signal under test is output and transmitted to the receiving device section 311.

[0151] In the receiver 21, the receiver optical detector 214 converts the receiver optical signal received from the receiver optical intensity modulator 212 into a signal having a frequency f Ｌｏ The locally oscillated electrical signal is output and sent to a fundamental wave mixer 323 for generating an intermediate frequency signal.

[0152] In the measurement unit 31, the fundamental wave mixer 323 for generating an intermediate frequency signal receives the frequency f ＲＦ and the frequency f received from the receiving-side optical detection unit 214. Ｌｏ The difference frequency f ＩＦ２ (f ＲＦ -f Ｌｏ ) intermediate frequency signal.

[0153] The lock-in detector 320 detects the difference frequency f output from the reference signal generating fundamental wave mixer 318. ＩＦ１ (f ＲＦ -f Ｌｏ) and the difference frequency f output from the fundamental wave mixer 323 for generating an intermediate frequency signal. ＩＦ２ (f ＲＦ -f Ｌｏ ) and the intermediate frequency signal of the frequency f ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0154] 21 is a configuration diagram of an attenuation characteristics measuring device according to an eighth modification of the second embodiment (hereinafter referred to as "Modification 2-8"). Specific differences between Modification 2-8 and Modification 2-6 will be described.

[0155] In the second-sixth modified example, the transmitter 11 receives a frequency 2f ＲＦ In the second-eighth modification, the frequency modulation laser radar 118 outputs a measured electrical signal having a frequency f ＦＭＣＷ As described above, the signal output from the frequency modulation laser radar 118 is a frequency sweep signal within a predetermined range.

[0156] In the second-sixth modified example, the receiving unit 21 receives a signal at a frequency of 2f Ｌｏ In the second-eighth modification, the receiving-side optical intensity modulation unit 212 receives the laser light directly from the laser oscillator 112, and the receiving-side optical detection unit 214 outputs a frequency 4f, which is four times the frequency of the local oscillation electrical signal. Ｌｏ The local oscillator electrical signal is output.

[0157] In the second-sixth modified example, the measuring unit 31 measures the difference frequency f ＩＦ２ (f ＲＦ -f Ｌｏ ), but in the second-eighth modification, the intermediate frequency signal generating fundamental wave mixer 323 outputs an intermediate frequency signal of the frequency f ＦＭＣＷ The electrical signal to be measured and the frequency 4f Ｌｏ The frequency of the local oscillation electrical signal is doubled to 8f Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) intermediate frequency signal.

[0158] In addition, in the second-sixth modified example, the reference signal generated by the reference signal generating fundamental wave mixer 318 has the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) and outputs it to the lock-in detection unit 320. In the second-eighth modification, the reference signal generating fundamental wave mixer 318 generates a reference signal of the frequency f ＲＦ and the second local oscillator electrical signal, ＩＦ１ (f ＲＦ -f Ｌｏ ) and generate a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ The reference signal is generated by an output multiplier 319.

[0159] The lock-in detector 320 detects the frequency f ＬＡ_ｒｅｆ The reference signal and the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) and an intermediate frequency signal of frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0160] FIG. 22 is a sequence diagram of the attenuation characteristic measuring method according to the second-eighth modified example.

[0161] In the transmitter 11, a frequency modulation laser radar 118 transmits a signal having a predetermined frequency f ＦＭＣＷ The electrical signal under test is output and transmitted to the receiving device section 311.

[0162] In the receiver 21, the receiver-side optical intensity modulator 212 receives the laser light from the laser oscillator 112 and outputs a receiver-side optical signal to the receiver-side optical detector 214. The receiver-side optical detector 214 receives the receiver-side optical signal and outputs a frequency 4f, which is four times the frequency of the local oscillator electrical signal. Ｌｏ The local oscillator electrical signal is output.

[0163] The measurement unit 31 measures the frequency f received from the receiving device unit 311 by the fundamental wave mixer 323 for generating an intermediate frequency signal. ＦＭＣＷ and the electrical signal to be measured of frequency 4f received from the receiving-side optical detection unit 214. Ｌｏ The frequency of the local oscillation electrical signal is doubled to 8f Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) intermediate frequency signal.

[0164] The reference signal generating fundamental wave mixer 318 mixes the frequency f ＲＦ and the second receiving-side electrical signal, ＩＦ１ (f ＲＦ -f Ｌｏ ) reference signal.

[0165] The difference frequency f output from the reference signal generating fundamental wave mixer 318 ＩＦ１ (f ＲＦ -f Ｌｏ ) is received by the output side multiplier 319 and multiplied by two or four to produce a reference signal of frequency f ＬＡ_ｒｅｆ A reference signal is generated.

[0166] The lock-in detector 320 receives the frequency f ＬＡ_ｒｅｆ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) and receives an intermediate frequency signal of the frequency f ＦＭＣＷ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0167] <Third Embodiment> Fig. 23 is a configuration diagram of an attenuation characteristic measuring device according to a third embodiment. While the second embodiment is configured with two signal generating units (a transmitting-side signal generating unit 111 and a receiving-side signal generating unit 211), the third embodiment is basically configured with a single signal generating unit. Furthermore, the third embodiment is characterized in that it does not have a fundamental wave mixer 318 for generating a reference signal in the measuring unit 31, but has an up-conversion mixer 217 in the receiving unit 21. Differences from the second embodiment will be described below.

[0168] In the receiving unit 21, the receiving side optical intensity modulation unit 212 generates a receiving side optical signal from the second transmitting side electrical signal output from the transmitting side signal generating unit 111 via the transmitting side distribution unit 119 and the second laser light output from the optical power distribution unit 113.

[0169] The receiving-side optical detector 214 doubles the frequency of the receiving-side optical signal to a frequency 2f ＲＦ The receiving side outputs the electrical signal.

[0170] In the third embodiment, unlike the second embodiment, the lock-in detector 320 detects a frequency f ＩＦ１ An output reference signal of the frequency f ＩＦ１ and the output reference signal of frequency 2f ＲＦ The difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) local oscillation electrical signal.

[0171] The measuring unit 31 detects the frequency 4f output from the transmitting side optical detector 116 by the double-harmonic mixer 312. ＲＦ The electrical signal to be measured and the difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) frequency 2f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) intermediate frequency signal.

[0172] The lock-in detector 320 detects the frequency f ＩＦ１and the difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0173] The difference frequency f output from the up-conversion mixer 217 is Ｌｏ (2f ＲＦ -f ＩＦ１ ) the difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) from the local oscillation electrical signal of frequency 2f ＲＦ A filter unit 221 may be provided to remove frequency components that are present in the receiving-side electrical signal of the up-conversion mixer 217. By providing the filter unit 221, the signal is not dependent on the characteristics of the up-conversion mixer 217, and therefore the dynamic range can be expanded in the measurement by the lock-in detection unit 320. The same applies to the modifications of the third embodiment described later.

[0174] Furthermore, the difference frequency f output from the double-harmonic mixer 312 ＩＦ２ (4f ＲＦ -2f Ｌｏ ) may be input to the lock-in detector 320 via a coaxial cable. In the third embodiment, however, the first electro-optical converter 328 converts the intermediate frequency signal of the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) into a first measurement-side optical modulated signal, and the first measurement-side optical detector 329 converts the first measurement-side optical modulated signal into an electrical signal via an optical fiber and outputs the electrical signal to the lock-in detector 320.

[0175] Furthermore, the frequency f output from the lock-in detection unit 320 ＩＦ１ The output reference signal of the second electro-optical converter 218 may be input to the up-conversion mixer 217 via a coaxial cable. Ｌｏ (2f ＲＦ -fＩＦ１ ) into a second measurement-side optical modulated signal, and the second measurement-side optical detector 219 converts the second measurement-side optical modulated signal into an electrical signal via an optical fiber and outputs the electrical signal to the up-conversion mixer 217.

[0176] The above-described configuration allows the attenuation characteristics measuring device to have a simpler overall structure and a wider dynamic range, thereby enabling more accurate measurements. In the modified examples of this embodiment described later, similarly, intermediate frequency signals output by various mixers from the electrical signal under measurement and the local oscillation signal can be output to the lock-in detector 320 via a coaxial cable, or alternatively, the first electro-optical converter 328 and the first measurement-side optical detector 329 can output the signal to the lock-in detector 320 via an optical fiber. Furthermore, the output reference signal output from the lock-in detector 320 can be output to the up-conversion mixer 217 via a coaxial cable, or alternatively, the second electro-optical converter 218 and the second measurement-side optical detector 219 can output the signal to the up-conversion mixer 217 via an optical fiber. In the modified example of this embodiment described later, the specific functions of the first electro-optical converter 328, the first measurement side light detector 329, the second electro-optical converter 218, and the second measurement side light detector 219 will not be described.

[0177] In this embodiment, a third measurement amplifier 220 is interposed between the lock-in detector 320 and the up-conversion mixer 217 to amplify the output reference signal.

[0178] FIG. 24 is a sequence diagram of the attenuation characteristic measuring method according to the third embodiment.

[0179] In the receiver 21 , the receiver optical intensity modulator 212 receives the second transmitter electrical signal output from the transmitter signal generator 111 via the transmitter distributor 119 and transmitted.

[0180] The receiving-side optical intensity modulation unit 212 generates the receiving-side optical signal from the received second transmitting-side electrical signal and the second laser light received from the optical power distribution unit 113. The receiving-side optical detection unit 214 receives the receiving-side optical signal from the receiving-side optical intensity modulation unit 212, doubles the frequency, and generates a frequency 2f ＲＦ The receiving side outputs the electrical signal.

[0181] The up-conversion mixer 217 converts the frequency 2f output from the receiving-side optical detector 214 into ＲＦ Furthermore, the up-conversion mixer 217 receives the receiving-side electrical signal of frequency f ＩＦ１ The output reference signal is received.

[0182] The up-conversion mixer 217 receives the frequency f ＩＦ１ and the output reference signal of frequency 2f ＲＦ The difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) to a double-harmonic mixer 312.

[0183] In the measuring unit 31, a double-harmonic mixer 312 mixes the frequency 4f output from the transmitting-side optical detector 116 and received via the receiving device unit 311. ＲＦ and the difference frequency f received from the up-conversion mixer 217. Ｌｏ (2f ＲＦ -f ＩＦ１ ) frequency 2f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) intermediate frequency signal.

[0184] The lock-in detector 320 detects the frequency f transmitted to the up-conversion mixer 217. ＩＦ１ and the difference frequency f received from the double-harmonic mixer 312. ＩＦ２ (4f ＲＦ -2f Ｌｏ) and the intermediate frequency signal of the frequency 4f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0185] <First Modification of Third Embodiment> FIG. 25 is a configuration diagram of a damping characteristic measuring device according to a first modification of the third embodiment (hereinafter referred to as "Modification 3-1").

[0186] In the third embodiment, the transmission-side optical detector 116 of the transmitter 11 multiplies the frequency of the transmission-side optical signal by four to obtain a frequency of 4f ＲＦ In the third modification, the frequency of the transmission-side optical signal is doubled to a frequency of 2f ＲＦ The measured electrical signal is output.

[0187] In the third embodiment, the measuring unit 31 detects that the double-harmonic mixer 312 is ＲＦ The electrical signal to be measured and the difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) frequency 2f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) is output, but in the 3-1 modification, the intermediate frequency signal generating fundamental wave mixer 323 outputs the intermediate frequency signal of the frequency 2f ＲＦ The electrical signal to be measured and the difference frequency f Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -f Ｌｏ ) intermediate frequency signal.

[0188] FIG. 26 is a sequence diagram of the attenuation characteristic measuring method according to the 3-1 modification.

[0189] In the transmitter 11, the transmitter optical detector 116 doubles the frequency of the transmitter optical signal received from the transmitter optical intensity modulator 114 to obtain a frequency 2f ＲＦ The electrical signal under test is output and transmitted to the receiving device section 311.

[0190] In the measurement unit 31, the fundamental wave mixer 323 for generating an intermediate frequency signal receives the frequency 2f from the receiving device unit 311. ＲＦ and receives the electrical signal to be measured at the difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) local oscillator electrical signal.

[0191] The fundamental wave mixer 323 for generating an intermediate frequency signal is ＲＦ The electrical signal to be measured and the difference frequency f Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -f Ｌｏ ) to the lock-in detector 320.

[0192] The lock-in detector 320 detects the frequency f transmitted to the up-conversion mixer 217. ＩＦ１ and the difference frequency f received from the fundamental wave mixer 323 for generating an intermediate frequency signal. ＩＦ２ (2f ＲＦ -f Ｌｏ ) and the intermediate frequency signal of the frequency 2f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0193] 27 is a configuration diagram of a damping characteristics measuring device according to a second modification of the third embodiment (hereinafter referred to as "Modification 3-2"). Modification 3-2 explains the differences from Modification 3-1.

[0194] In the 3-1 modified example, the first laser light is output from the laser oscillator 112 to the transmitting-side optical intensity modulator 114 via the optical power distributor 113, and the second laser light is transmitted to the receiving-side optical intensity modulator 212 of the receiver 21. In contrast, in the 3-2 modified example, the transmitting-side optical intensity modulator 114 receives the transmitting-side electrical signal output from the transmitting-side signal generator 111 and the laser light output from the laser oscillator 112, and generates the transmitting-side optical signal. Furthermore, the optical power distributor 113 receives the generated transmitting-side optical signal and outputs it to the transmitting-side optical detector 116, and also outputs it to the receiving-side optical detector 214 as a receiving-side optical signal.

[0195] FIG. 28 is a sequence diagram of the attenuation characteristic measuring method according to the third modified example.

[0196] In the transmitter 11, the transmitter optical intensity modulator 114 receives the frequency f ＲＦ and a bias voltage from the transmitting-side bias control unit 115 , and also receives the laser light from the laser oscillator unit 112 , and outputs the transmitting-side optical signal to the optical power distributor 113 .

[0197] The optical power distribution unit 113 receives the transmission-side optical signal and outputs it to the transmission-side optical detection unit 116 , and also transmits it to the reception-side optical detection unit 214 as a reception-side optical signal.

[0198] The lock-in detector 320 detects the frequency f transmitted to the up-conversion mixer 217. ＩＦ１ and the difference frequency f received from the fundamental wave mixer 323 for generating an intermediate frequency signal. ＩＦ２ (2f ＲＦ -f Ｌｏ ) and the intermediate frequency signal of the frequency 2f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0199] <Third Modification of Third Embodiment> FIG. 29 is a configuration diagram of an attenuation characteristic measuring device according to a third modification of the third embodiment (hereinafter referred to as "Modification 3-3").

[0200] In the transmitter 11, the transmission-side optical detector 116 multiplies the frequency of the transmission-side optical signal by eight to produce a frequency 8f ＲＦ The measured electrical signal is output.

[0201] In the receiving unit 21, the receiving-side optical detector 214 detects a frequency f ＲＦ The up-conversion mixer 217 outputs the receiving side electrical signal of the frequency f ＩＦ１ and the output reference signal of frequency f ＲＦ The difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal.

[0202] The measuring unit 31 detects that the octal harmonic mixer 322 is ＲＦ The electrical signal to be measured and the difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal is multiplied by 8 to generate frequency 8f Ｌｏ The difference frequency f ＩＦ２ (8f ＲＦ -8f Ｌｏ ) intermediate frequency signal.

[0203] The difference frequency f ＩＦ２ (8f ＲＦ -8f Ｌｏ ) is converted into a difference frequency f ＩＦ1 (f ＲＦ -f Ｌｏ ) or difference frequency 2f ＩＦ1 (2f ＲＦ -2f Ｌｏ ) to an intermediate frequency signal.

[0204] The lock-in detector 320 detects the frequency f ＩＦ１ and the difference frequency f ＩＦ1 (f ＲＦ -f Ｌｏ ) or difference frequency 2f ＩＦ1 (2f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 8f output from the transmitting side optical detection unit. ＲＦThe amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0205] FIG. 30 is a sequence diagram of the attenuation characteristic measuring method according to the third modified example.

[0206] In the transmitter 11, the transmitter optical detector 116 receives the transmission-side optical signal from the transmission-side optical intensity modulator 114 and multiplies the frequency of the transmission-side optical signal by eight to obtain a frequency 8f. ＲＦ The electrical signal under test is output and transmitted to the receiving device section 311.

[0207] In the receiving unit 21, the receiving-side optical detection unit 214 receives the receiving-side optical signal from the receiving-side optical intensity modulation unit 212 and detects a frequency f ＲＦ The up-conversion mixer 217 outputs the receiving-side electrical signal of the frequency f ＩＦ１ and the output reference signal of frequency f ＲＦ The difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal.

[0208] The octupling harmonic mixer 322 receives the frequency 8f from the receiving device section 311. ＲＦ and receives the electrical signal under test of the difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal is multiplied by 8 to generate frequency 8f Ｌｏ The difference frequency f ＩＦ２ (8f ＲＦ -8f Ｌｏ ) intermediate frequency signal.

[0209] The lock-in detector 320 detects the frequency f ＩＦ１ and the difference frequency f ＩＦ1 (f ＲＦ -f Ｌｏ ) or difference frequency 2f ＩＦ1 (2f ＲＦ -2f Ｌｏ) and the intermediate frequency signal of the frequency 8f output from the transmitting side optical detection unit. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0210] 31 is a configuration diagram of a damping characteristic measuring device according to a fourth modification of the third embodiment (hereinafter referred to as "Modification 3-4"). Modification 3-4 explains the differences from Modification 3-3.

[0211] The measurement unit 31 measures the frequency f ＩＦ１ a measurement side signal generating unit 331 that generates a reference signal of the frequency f ＩＦ１ receives a reference signal of frequency f ＩＦ１ and a first reference signal of frequency f ＩＦ１ a measurement-side distributor 332 that outputs a second reference signal of the frequency f ＩＦ１ The first reference signal is multiplied by 4 or 8 to obtain a frequency of 4f ＩＦ１ or frequency 8f ＩＦ１ and a reference signal generating multiplier 333 that outputs the reference signal.

[0212] The receiver 21 includes an up-conversion mixer 217 that converts the frequency f ＩＦ１ and the second reference signal of frequency f ＲＦ and the difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal.

[0213] The lock-in detector 320 detects the frequency 4f ＩＦ１ or frequency 8f ＩＦ１ and the reference signal of frequency f ＩＦ２ and the intermediate frequency signal of the frequency 8f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0214] FIG. 32 is a sequence diagram of the attenuation characteristic measuring method according to the third-fourth modified example.

[0215] In the measurement unit 31, the measurement side signal generating unit 331 generates the frequency f ＩＦ１The measurement-side distributor 332 receives the reference signal of frequency f from the measurement-side signal generator 331. ＩＦ１ and receives a reference signal of frequency f ＩＦ１ The measurement-side distributor 332 outputs the first reference signal of frequency f ＩＦ１ , and transmits the second reference signal to the up-conversion mixer 217.

[0216] The frequency f ＩＦ１ The reference signal generating multiplier 333 receives the first reference signal of the frequency 4f ＩＦ１ or frequency 8f ＩＦ１ The reference signal of the frequency f ＩＦ１ The up-conversion mixer 217 receives the second reference signal of the difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillator electrical signal.

[0217] The lock-in detector 320 detects the frequency 4f ＩＦ１ or frequency 8f ＩＦ１ and the reference signal of frequency f ＩＦ２ and the intermediate frequency signal of the frequency 8f output from the transmitting side optical detection unit 116. ＲＦ The amplitude and phase of the signal attenuation of the electrical signal under test are measured.

[0218] The technology disclosed in this specification is not limited to the above-described embodiments. That is, it includes the embodiments shown as examples and modifications made by those skilled in the art based on them. It also includes the substitution or combination of parts or elements between one embodiment and another embodiment. Furthermore, the disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope is defined by the claims and includes all modifications within the meaning and scope equivalent to the claims.

Claims

1. Frequency f ＲＦ a laser oscillator that outputs a laser beam via an optical fiber cable; an optical power distributor that receives the laser beam and outputs a first laser beam and a second laser beam; a transmission-side optical intensity modulator that receives the first laser beam and the transmission-side electrical signal and generates a transmission-side optical signal; a transmission-side bias controller that inputs a DC voltage to the transmission-side optical intensity modulator; ＲＦ is multiplied by 4 to get frequency 4f ＲＦ a transmitter section including a transmission-side optical detector section for outputting an electrical signal to be measured of frequency f Ｌｏ a receiving-side optical intensity modulation section that receives the second laser light and the receiving-side electrical signal to generate a receiving-side optical signal; a receiving-side bias control section that inputs a DC voltage to the receiving-side optical intensity modulation section; and a frequency f of the receiving-side optical signal via an optical fiber cable. Ｌｏ is multiplied by two to get frequency 2f Ｌｏ a receiving section including a receiving-side optical detector that outputs a local oscillation electrical signal of the frequency 4f ＲＦ a receiving device unit for receiving an electrical signal to be measured of frequency 4f received by the receiving device unit; ＲＦ The measured electrical signal of frequency 2f Ｌｏ The frequency 4f is generated by doubling the local oscillation electrical signal. Ｌｏ The difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) an intermediate frequency signal of the difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) by measuring the amplitude of the intermediate frequency signal of the frequency 4f ＲＦ and a measurement unit comprising: a spectrum analysis unit that measures the amount of signal attenuation of an electrical signal under test.

2. The transmitting unit transmits a signal having a predetermined frequency range f ＦＭＣＷ The receiving unit includes a frequency modulation laser radar that outputs a measured electrical signal of a frequency f, the receiving side optical intensity modulation unit receiving the laser light and the receiving side electrical signal from the laser oscillator unit to generate the receiving side optical signal, and the measurement unit includes a frequency modulation unit that receives the laser light and the receiving side electrical signal from the laser oscillator unit to generate the receiving side optical signal, ＦＭＣＷ The measured electrical signal of frequency 4f Ｌｏ and the difference frequency f ＩＦ (f ＦＭＣＷ -4f Lo 2. The attenuation characteristic measuring device according to claim 1, wherein said attenuation characteristic measuring device outputs an intermediate frequency signal of 3. The transmitting unit receives the frequency f from the transmitting side signal generating unit. ＲＦ and a transmitting-side distribution unit that receives a transmitting-side electrical signal of frequency f and outputs a first transmitting-side electrical signal and a second transmitting-side electrical signal, the transmitting-side optical signal being generated from the first transmitting-side electrical signal and the first laser light by the transmitting-side optical intensity modulation unit, and the receiving unit receives the frequency f from the receiving-side signal generation unit. Ｌｏ and outputting a first receiving-side electrical signal and a second receiving-side electrical signal, the receiving-side optical signal being generated from the first receiving-side electrical signal and the second laser light by the receiving-side optical intensity modulation unit, and the measurement unit deriving a difference frequency f from the second transmitting-side electrical signal received from the transmitting-side distribution unit and the second receiving-side electrical signal received from the receiving-side distribution unit. ＩＦ１ (f ＲＦ -f Ｌｏ ) a reference signal generating fundamental mixer for generating a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) frequency of the reference signal is multiplied by 2 or 4 to obtain a frequency of 2f ＩＦ１ Or frequency 4f ＩＦ１ an output side multiplier unit for generating a reference signal of the frequency 4f received by the receiving device unit; ＲＦ The measured electrical signal of frequency 2f Ｌｏ The frequency 4f is generated by doubling the local oscillation electrical signal. Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ a doubling type harmonic mixer for outputting an intermediate frequency signal of said frequency 2f ＩＦ１ Or frequency 4f ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmission side optical detection unit. ＲＦ 2. The attenuation characteristic measuring device according to claim 1, further comprising a lock-in detector for measuring the amplitude and phase of the signal attenuation of the electrical signal to be measured.

4. The transmitting unit transmits a signal having a predetermined frequency range f ＦＭＣＷ The receiver has a frequency modulation laser radar that outputs a measured electrical signal of a frequency f, the receiver side optical intensity modulation unit receives the laser light from the laser oscillator and the receiver side electrical signal to generate the receiver side optical signal, and the measurement unit has a frequency modulation unit that receives the laser light from the laser oscillator and the receiver side electrical signal to generate the receiver side optical signal, ＦＭＣＷ The measured electrical signal of frequency 2f Ｌｏ The frequency 4f generated by doubling Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Ｌｏ ), and the reference signal generating fundamental wave mixer outputs an intermediate frequency signal of the frequency f ＲＦ and receiving the transmitting side electrical signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ), and the output side multiplier generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ The lock-in detection unit generates a reference signal of the frequency f ＬＡ_ｒｅｆ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Ｌｏ ) and an intermediate frequency signal of the frequency f ＦＭＣＷ 4. The attenuation characteristic measuring device according to claim 3, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

5. The receiving unit has a receiving-side optical detection unit that multiplies the frequency of the receiving-side optical signal by four to a frequency of 4f Ｌｏ The measuring unit outputs a local oscillation electrical signal of frequency f ＦＭＣＷ The measured electrical signal of frequency 4f Ｌｏ The frequency 8f is generated by doubling the local oscillation electrical signal. Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ 5. The attenuation characteristic measuring device according to claim 4, wherein said attenuation characteristic measuring device outputs an intermediate frequency signal of 6. The receiving unit detects a frequency f from the receiving optical signal by the receiving optical detection unit. Ｌｏ The measurement unit outputs a local oscillation electrical signal having a frequency f of the second receiving electrical signal. Ｌｏ is multiplied by 2 to get frequency 2f Ｌｏ an input side multiplier for generating an input signal of frequency 4f ＲＦ The measured electrical signal and the frequency f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ and an octupling type harmonic mixer that outputs an intermediate frequency signal of the frequency f ＲＦ and the second transmitting electrical signal of frequency 2f Ｌｏ The input signal and the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ), and the output side multiplier generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ) is multiplied by four to produce a frequency of 4f ＩＦ１ The lock-in detection unit generates a reference signal of the frequency 4f ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmission side optical detection unit. ＲＦ 4. The attenuation characteristic measuring device according to claim 3, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

7. The transmitting unit transmits a signal having a predetermined frequency range f ＦＭＣＷ The receiving unit includes a frequency modulation laser radar that receives the laser light from the laser oscillator and outputs a frequency 2f obtained by doubling the frequency of the local oscillator electrical signal. Ｌｏ The measuring unit outputs a local oscillation electrical signal of the frequency f received by the octupling type harmonic mixer at the receiving device unit. ＦＭＣＷ The measured electrical signal of frequency 2f Ｌｏ The frequency 16f is generated by multiplying the local oscillation electrical signal by 8. Ｌｏ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -16f Ｌｏ ) an intermediate frequency signal of frequency f ＲＦ and the frequency f received from the receiving side distribution unit. Ｌｏ and the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ), and the output side multiplier generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ The lock-in detection unit generates a reference signal of the frequency f ＬＡ_ｒｅｆ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -16f Ｌｏ ) and an intermediate frequency signal of frequency f ＦＭＣＷ 7. The attenuation characteristic measuring device according to claim 6, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

8. The transmitting unit has a base part on which the frequency modulation laser radar is fixedly installed at a position facing the receiving device unit and can rotate forward and backward in all directions from the facing position, and the receiving unit has a receiving side optical detection unit that detects a frequency f Ｌｏ The measurement unit includes a measurement-side light intensity modulation unit that receives a second receiving-side electric signal from the receiving-side distribution unit, a measurement-side laser transmission unit that oscillates a laser beam to the measurement-side light intensity modulation unit, and a frequency f Ｌｏ The second receiving side electrical signal of frequency f Ｌｏ_ref A measurement side optical detection unit that outputs a local oscillation electric signal of frequency f from the frequency modulation laser radar is provided on the base unit at a predetermined distance from the frequency modulation laser radar. ＲＦ A reference signal receiving device unit fixedly installed to receive a reference signal of a difference frequency f ＩＦ１_ref (f ＲＦ -2f Ｌｏ_ref a reference signal generating double-multiplier type harmonic mixer that outputs an intermediate frequency signal of the frequency f ＦＭＣＷ The measured electrical signal and the frequency f Ｌｏ The frequency 8f is generated by multiplying the local oscillation electrical signal by 8. Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ), and generating the difference frequency f ＩＦ１_ref (f ＲＦ -2f Ｌｏ_ref ) and the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) from the frequency f ＦＭＣＷ 8. The attenuation characteristic measuring device according to claim 7, further comprising: a waveform analyzing section for measuring the amplitude and phase of the signal attenuation of the electric signal to be measured.

9. The transmitter doubles the frequency of the transmission-side optical signal to a frequency of 2f ＲＦ The measurement unit outputs a measured electrical signal of frequency 2f ＲＦ and the frequency 2f output from the receiving side optical detection unit. Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ), and the lock-in detection unit detects the difference frequency f generated by the fundamental mixer for generating a reference signal. ＩＦ１ (f ＲＦ -f Ｌｏ ) and the difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 2f output from the transmission side optical detection unit. ＲＦ 4. The attenuation characteristic measuring device according to claim 3, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

10. The transmitting section detects the frequency of the transmitting optical signal by the transmitting optical detection section. ＲＦ The receiving section outputs the measured electrical signal at a frequency f Ｌｏ The measurement unit outputs a local oscillation electric signal of frequency f ＲＦ The measured electrical signal and the frequency f Ｌｏ The difference frequency f ＩＦ２ (f ＲＦ -f Ｌｏ 10. The attenuation characteristic measuring device according to claim 9, wherein said attenuation characteristic measuring device outputs an intermediate frequency signal of 11. The transmitter unit transmits a signal having a predetermined frequency range f ＦＭＣＷ The receiving unit includes a frequency modulation laser radar that receives the laser light from the laser oscillator and outputs a frequency 4f obtained by multiplying the frequency of the local oscillator electrical signal by four. Ｌｏ The measurement unit outputs a local oscillation electrical signal of frequency f ＦＭＣＷ The measured electrical signal of frequency 4f Ｌｏ The frequency of the local oscillator electrical signal is doubled to 8f. Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) and the reference signal generating fundamental wave mixer outputs an intermediate frequency signal of frequency f ＲＦ and the second receiving side electrical signal, ＩＦ１ (f ＲＦ -f Ｌｏ ) and generating a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ The lock-in detection unit has an output side multiplier unit that generates a reference signal of the frequency f ＬＡ_ｒｅｆ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -8f Ｌｏ ) and an intermediate frequency signal of frequency f ＦＭＣＷ 10. The attenuation characteristic measuring device according to claim 9, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

12. The receiving unit is configured such that the receiving-side optical intensity modulation unit generates the receiving-side optical signal from the second transmitting-side electrical signal output from the transmitting-side signal generation unit via the transmitting-side distribution unit and the second laser light, and the receiving-side optical detection unit doubles the frequency of the receiving-side optical signal to a frequency of 2f ＲＦ and outputs a receiving side electrical signal of frequency f ＩＦ１ and the output reference signal of frequency 2f ＲＦ The difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ The measurement unit has an up-conversion mixer that outputs a local oscillation electrical signal of the frequency 4f output from the transmission side optical detection unit, ＲＦ The measured electrical signal and the difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) local oscillation electrical signal is multiplied by 2 to generate a frequency 2f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ), and the lock-in detection unit outputs an intermediate frequency signal of the frequency f ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmission side optical detection unit. ＲＦ 4. The attenuation characteristic measuring device according to claim 3, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

13. The transmitting section, the transmitting-side optical detection section, doubles the frequency of the transmitting-side optical signal to a frequency of 2f ＲＦ The measurement unit outputs an electric signal to be measured having a frequency of 2f. ＲＦ The measured electrical signal and the difference frequency f Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -f Ｌｏ 13. The attenuation characteristic measuring device according to claim 12, wherein said attenuation characteristic measuring device outputs an intermediate frequency signal of 14. An attenuation characteristic measuring device as described in claim 13, wherein the transmitting section has a transmitting side optical intensity modulation section that receives the transmitting side electrical signal from the transmitting side signal generating section and the laser light output from the laser oscillator section to generate the transmitting side optical signal, and the optical power distribution section that receives the generated transmitting side optical signal and outputs it to the transmitting side optical detection section, as well as outputting it to the receiving side optical detection section as the receiving side optical signal.

15. The transmitting section, the transmitting-side optical detection section, multiplies the frequency of the transmitting-side optical signal by 8 to obtain a frequency of 8f ＲＦ The receiving section outputs a measured electrical signal of frequency f ＲＦ and the up-conversion mixer outputs a receiving side electrical signal of the frequency f ＩＦ１ and the output reference signal of frequency f ＲＦ The difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal, and the measurement unit outputs the local oscillation electrical signal of the frequency 8f ＲＦ The measured electrical signal and the difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal is multiplied by 8 to generate frequency 8f Ｌｏ The difference frequency f ＩＦ２ (8f ＲＦ -8f Ｌｏ ) an 8-multiplier type harmonic mixer that outputs an intermediate frequency signal of the difference frequency f ＩＦ２ (8f ＲＦ -8f Ｌｏ ) intermediate frequency signal with difference frequency f ＩＦ1 (f ＲＦ -f Ｌｏ ) or the difference frequency 2f ＩＦ1 (2f ＲＦ -2f Ｌｏ ), and the lock-in detection unit converts the frequency f ＩＦ１ and the difference frequency f ＩＦ1 (f ＲＦ -f Ｌｏ ) or the difference frequency 2f ＩＦ1 (2f ＲＦ -2f Ｌｏ ) and the frequency 8f output from the transmission side optical detection unit. ＲＦ 13. The attenuation characteristic measuring device according to claim 12, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

16. The measurement unit measures the frequency f ＩＦ１ a measurement unit side signal generating unit that generates a reference signal of frequency f ＩＦ１ Receive a reference signal of frequency f ＩＦ１ and a first reference signal of frequency f ＩＦ１ a measurement-side distribution unit that outputs a second reference signal of the frequency f ＩＦ１ The first reference signal is multiplied by 4 or 8 to obtain a frequency of 4f ＩＦ１ Or frequency 8f ＩＦ１ and a reference signal generating multiplication unit that outputs a reference signal of frequency f ＩＦ１ and the second reference signal of frequency f ＲＦ and the difference frequency f Ｌｏ (f ＲＦ -f ＩＦ１ ) local oscillation electrical signal, and the lock-in detection unit outputs the local oscillation electrical signal of the frequency 4f ＩＦ１ Or frequency 8f ＩＦ１ and the reference signal of frequency f ＩＦ２ and the intermediate frequency signal of the frequency 8f output from the transmission side optical detection unit. ＲＦ 16. The attenuation characteristic measuring device according to claim 15, wherein the amplitude and phase of the signal attenuation of the electric signal to be measured are measured.

17. An attenuation characteristic measuring device according to any one of claims 12 to 16, further comprising a filter section for removing frequency components present in the receiving side electrical signal from the locally oscillated electrical signal output from the up-conversion mixer.

18. An attenuation characteristic measuring device as claimed in any one of claims 3, 4 and 5, further comprising: an electro-optical converter that converts the signal output from the double-type harmonic mixer into a measurement-side optical modulated signal; and a measurement-side optical detector that is interposed between the electro-optical converter and the lock-in detector and converts the measurement-side optical modulated signal transmitted via an optical fiber into an electrical signal.

19. An attenuation characteristic measuring device as claimed in any one of claims 6, 7 and 8, further comprising: an electro-optical converter for converting a signal output from said octal harmonic mixer into a measurement-side optical modulated signal; and a measurement-side optical detector interposed between said electro-optical converter and said lock-in detector for converting said measurement-side optical modulated signal transmitted via an optical fiber into an electrical signal.

20. An attenuation characteristic measuring device as claimed in any one of claims 9, 10 and 11, comprising an electro-optical converter for converting a signal output from the fundamental wave mixer for generating an intermediate frequency signal into a measurement-side optical modulated signal, and a measurement-side optical detector interposed between the electro-optical converter and the lock-in detector and for converting the measurement-side optical modulated signal transmitted via an optical fiber into an electrical signal.

21. An attenuation characteristic measuring device as described in claim 12, comprising: a first electro-optical converter for converting a signal output from said double-type harmonic mixer into a first measurement-side optical modulated signal; a first measurement-side optical detector interposed between said first electro-optical converter and said lock-in detector for converting said first measurement-side optical modulated signal transmitted through an optical fiber into an electrical signal; a second electro-optical converter for converting said output reference signal output from said lock-in detector into a second measurement-side optical modulated signal; and a second measurement-side optical detector interposed between said second electro-optical converter and said up-conversion mixer for converting said second measurement-side optical modulated signal transmitted through an optical fiber into an electrical signal.

22. An attenuation characteristic measuring device as claimed in any one of claims 13 and 14, comprising: a first electro-optical converter which converts a signal output from the fundamental wave mixer for generating an intermediate frequency signal into a first measurement side optical modulated signal; a first measurement side optical detector which is interposed between the first electro-optical converter and the lock-in detector and which converts the first measurement side optical modulated signal transmitted through an optical fiber into an electrical signal; a second electro-optical converter which converts the output reference signal output from the lock-in detector into a second measurement side optical modulated signal; and a second measurement side optical detector which is interposed between the second electro-optical converter and the up-conversion mixer and which converts the second measurement side optical modulated signal transmitted through an optical fiber into an electrical signal.

23. An attenuation characteristic measuring device as claimed in any one of claims 15 or 16, comprising: a first electro-optical converter which converts a signal output from said octupling harmonic mixer into a first measurement-side optical modulated signal; a first measurement-side optical detector which is interposed between said first electro-optical converter and said lock-in detector and which converts said first measurement-side optical modulated signal transmitted through an optical fiber into an electrical signal; a second electro-optical converter which converts said output reference signal output from said lock-in detector into a second measurement-side optical modulated signal; and a second measurement-side optical detector which is interposed between said second electro-optical converter and said up-conversion mixer and which converts said second measurement-side optical modulated signal transmitted through an optical fiber into an electrical signal.

24. In the transmitting section, the transmitting side signal generating section outputs a frequency f ＲＦ a transmission-side electrical signal of frequency f, an optical power distribution unit receives a laser beam output from a laser oscillator unit via an optical fiber cable and outputs a first laser beam and a second laser beam, a transmission-side optical intensity modulation unit receives the first laser beam and the transmission-side electrical signal to generate a transmission-side optical signal, and receives an input of a DC voltage from a transmission-side bias control unit and generates a transmission-side optical signal of frequency f via the optical fiber cable at a transmission-side optical detection unit. ＲＦ is multiplied by 4 to get frequency 4f ＲＦ The receiving section outputs a measured electrical signal of frequency f Ｌｏ a receiving-side optical intensity modulation unit receives the second laser light and the receiving-side electric signal to generate a receiving-side optical signal, and receives an input of a DC voltage from a receiving-side bias control unit, and a receiving-side optical detection unit detects a frequency of the receiving-side optical signal at a frequency f Ｌｏ is multiplied by two to get frequency 2f Ｌｏ In the measurement section, a double-harmonic mixer outputs a local oscillation electrical signal of the frequency 4f received by the receiving device section. ＲＦ The measured electrical signal of frequency 2f Ｌｏ The frequency 4f is generated by doubling the local oscillation electrical signal. Ｌｏ The difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) an intermediate frequency signal, and the spectrum analyzer outputs the difference frequency f ＩＦ (4f ＲＦ -4f Ｌｏ ) by measuring the amplitude of the intermediate frequency signal of the frequency 4f ＲＦ The attenuation characteristic measuring method measures the amount of signal attenuation of an electrical signal under test.

25. In the transmitting unit, a transmitting-side distribution unit receives the transmitting-side electrical signal from the transmitting-side signal generating unit and outputs a first transmitting-side electrical signal and a second transmitting-side electrical signal, and the transmitting-side optical signal is generated from the first transmitting-side electrical signal and the first laser light by the transmitting-side optical intensity modulation unit; in the receiving unit, a receiving-side distribution unit receives the receiving-side electrical signal from the receiving-side signal generating unit and outputs a first receiving-side electrical signal and a second receiving-side electrical signal, and the receiving-side optical signal is generated from the first receiving-side electrical signal and the second laser light by the receiving-side optical intensity modulation unit; and in the measuring unit, a reference signal generating fundamental wave mixer derives a difference frequency f from the second transmitting-side electrical signal received from the transmitting-side distribution unit and the second receiving-side electrical signal received from the receiving-side distribution unit. ＩＦ１ (f ＲＦ -f Ｌｏ ), and the output side multiplier generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) frequency of the reference signal is multiplied by 2 or 4 to obtain a frequency of 2f ＩＦ１ Or frequency 4f ＩＦ１ The frequency doubler type harmonic mixer generates a reference signal of the frequency 4f received by the receiving device section. ＲＦ The measured electrical signal of frequency 2f Ｌｏ The frequency 4f is generated by doubling the local oscillation electrical signal. Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) an intermediate frequency signal of the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) is converted into a measurement-side optical modulation signal, a measurement-side optical detection unit converts the measurement-side optical modulation signal transmitted through an optical fiber into an electrical signal, and a lock-in detection unit converts the measurement-side optical modulation signal into an electrical signal. ＩＦ１ Or frequency 4f ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -4f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmission side optical detection unit. ＲＦ 25. The attenuation characteristic measuring method according to claim 24, further comprising measuring the amplitude and phase of the signal attenuation of the electrical signal to be measured.

26. The transmitter is a frequency-modulated laser radar that transmits a frequency f ＦＭＣＷ The receiving unit outputs a measured electrical signal of frequency f, the receiving-side optical intensity modulation unit receives the laser light from the laser oscillator unit and the receiving-side electrical signal to generate the receiving-side optical signal, and the measuring unit outputs a measured electrical signal of frequency f ＦＭＣＷ The measured electrical signal of frequency 2f Ｌｏ The frequency 4f generated by doubling Ｌｏ The difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Ｌｏ ) an intermediate frequency signal of the difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Ｌｏ ) is converted into a measurement-side optical modulated signal, the measurement-side optical detection unit converts the measurement-side optical modulated signal transmitted through the optical fiber into an electrical signal, and the reference signal generating fundamental wave mixer converts the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ), and the output side multiplier generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) is doubled or quadrupled to obtain a frequency f ＬＡ_ｒｅｆ The lock-in detection unit generates a reference signal of the frequency f ＬＡ_ｒｅｆ and the difference frequency f ＩＦ２ (f ＦＭＣＷ -4f Ｌｏ ) and an intermediate frequency signal of frequency f ＦＭＣＷ 26. The attenuation characteristic measuring method according to claim 25, further comprising measuring the amplitude and phase of the signal attenuation of the electrical signal to be measured.

27. The receiving section detects a frequency f Ｌｏ The measurement unit outputs a local oscillation electrical signal having a frequency f of the second receiving electrical signal, Ｌｏ is multiplied by 2 to get frequency 2f Ｌｏ and an octupling harmonic mixer generates an input signal of said frequency 4f ＲＦ The measured electrical signal and the frequency f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) an intermediate frequency signal of the difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) to a measurement-side optical modulated signal, the measurement-side optical detector converts the measurement-side optical modulated signal transmitted through an optical fiber into an electrical signal, and the reference signal generating fundamental wave mixer converts the intermediate frequency signal of the frequency f ＲＦ and the second transmitting electrical signal of frequency 2f Ｌｏ The input signal and the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ), and the output side multiplier generates a reference signal of the difference frequency f ＩＦ１ (f ＲＦ -2f Ｌｏ ) is multiplied by four to produce a frequency of 4f ＩＦ１ and the lock-in detection unit generates a reference signal of the frequency 4f ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -8f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmission side optical detection unit. ＲＦ 26. The attenuation characteristic measuring method according to claim 25, further comprising measuring the amplitude and phase of the signal attenuation of the electrical signal to be measured.

28. The transmitter doubles the frequency of the optical signal on the transmission side to a frequency of 2f ＲＦ The measurement unit outputs an electric signal to be measured having a frequency of 2f. ＲＦ and the frequency 2f output from the receiving side optical detection unit. Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ) an intermediate frequency signal of the difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ) is converted into a measurement-side optical modulated signal, a measurement-side optical detection unit converts the measurement-side optical modulated signal transmitted through an optical fiber into an electrical signal, and the lock-in detection unit converts the difference frequency f ＩＦ１ (f ＲＦ -f Ｌｏ ) and the difference frequency f ＩＦ２ (2f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 2f output from the transmission side optical detection unit. ＲＦ 26. The attenuation characteristic measuring method according to claim 25, further comprising measuring the amplitude and phase of the signal attenuation of the electrical signal to be measured.

29. In the receiving section, the receiving-side optical intensity modulation section generates the receiving-side optical signal from the second transmitting-side electrical signal output from the transmitting-side signal generation section via the transmitting-side distribution section and the second laser light, and the receiving-side optical detection section doubles the frequency of the receiving-side optical signal to a frequency of 2f ＲＦ The up-conversion mixer outputs a receiving side electrical signal of frequency f ＩＦ１ and the output reference signal of frequency 2f ＲＦ The difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ), and the filter section outputs a local oscillation electrical signal of the difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) from the local oscillation electrical signal of frequency 2f ＲＦ The measuring unit removes a frequency component of the receiving side electrical signal of the frequency 4f output from the transmitting side optical detection unit by the double-harmonic mixer. ＲＦ The measured electrical signal of frequency 2f ＲＦ The difference frequency f Ｌｏ (2f ＲＦ -f ＩＦ１ ) local oscillation electrical signal is multiplied by 2 to generate a frequency 2f Ｌｏ The difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) an intermediate frequency signal of the difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) an intermediate frequency signal of the frequency f 1 is converted into a measurement-side optical modulation signal, and a measurement-side optical detection unit converts the measurement-side optical modulation signal transmitted through an optical fiber into an electrical signal, and the lock-in detection unit converts the measurement-side optical modulation signal of the frequency f 1 into an electrical signal. ＩＦ１ and the difference frequency f ＩＦ２ (4f ＲＦ -2f Ｌｏ ) and the intermediate frequency signal of the frequency 4f output from the transmission side optical detection unit. ＲＦ 26. The attenuation characteristic measuring method according to claim 25, further comprising measuring the amplitude and phase of the signal attenuation of the electrical signal to be measured.

30. The transmitting section, the transmitting-side optical detection section, doubles the frequency of the transmitting-side optical signal to a frequency of 2f ＲＦ The measurement unit outputs an electric signal to be measured having a frequency of 2f. ＲＦ The measured electrical signal and the difference frequency f Ｌｏ The difference frequency f ＩＦ２ (2f ＲＦ -f Ｌｏ 30. The attenuation characteristic measuring method according to claim 29, wherein the intermediate frequency signal output is an intermediate frequency signal of

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