Frequency Converter

Abstract

To generate an unmodulated signal from a modulated signal without changing configuration of existing frequency converter.SOLUTION: A frequency converter 1 includes distributes 10, 11, 13, BPFs 12, 15, an LPF 17 and mixers 14, 16 in addition to a circuit of a conventional frequency converter 90. The mixer 16 mixes a signal of frequency (f1-LO1) performed filtering process by the BPF 12 and a signal of frequency (f1-LO2) performed filtering process by the BPF 15, and generates a signal of frequency (LO1-LO2) and a signal of frequency (2f1-(LO1+LO2)). The LPF 17 eliminates unwanted signals from those signals by performing filtering process for passing a signal of a predetermined low frequency bandwidth (a bandwidth including the frequency (LO1-LO2)). As a result, an unmodulated signal which is CW for measurement of frequency (LO1-LO2) can be obtained.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technical field relating to satellite broadcast receiving devices that receive satellite broadcast waves, and more particularly to a frequency conversion device that converts a radio frequency into an intermediate frequency. [Background technology]

[0002] Current satellite broadcasting uses right-handed and left-handed circularly polarized waves, and the frequencies for satellite broadcasting are 11.7 to 12.75 GHz (12 GHz band). Also, since coaxial cables cannot transmit received signals of satellite broadcast waves in the 12 GHz band, frequency converters are used to convert the 12 GHz band RF (radio frequency) to 1.0 to 3.2 GHz IF (intermediate frequency).

[0003] A frequency converter designed for receiving satellite broadcast waves converts the RF of right-handed circularly polarized waves of satellite broadcast waves into an IF of 1032 to 2071 MHz, and converts the RF of left-handed circularly polarized waves into an IF of 2224 to 3224 MHz (see, for example, Non-Patent Document 1).

[0004] These IFs are defined in the standard of the aforementioned Non-Patent Document 1, and the local oscillation frequencies used for frequency conversion are LO1=10.678 GHz for right-handed circularly polarized waves and LO2=9.505 GHz for left-handed circularly polarized waves.

[0005] 4 is a block diagram showing an example of the configuration of a conventional frequency conversion device 90. This frequency conversion device 90 is configured to include BPFs (band pass filters) 100 and 103, mixers 101 and 104, and LPFs (low pass filters) 102 and 105.

[0006] The frequency conversion device 90 has an input section for right-handed circularly polarized waves and an input section for left-handed circularly polarized waves, and inputs RF right-handed circularly polarized signals and left-handed circularly polarized signals, which are modulated signals of polarization-separated 12 GHz band satellite broadcast waves.

[0007] BPF 100, mixer 101, and LPF 102 of frequency converter 90 convert the RF right-handed circularly polarized signal into an IF right-handed circularly polarized signal and output the IF right-handed circularly polarized signal. Also, BPF 103, mixer 104, and LPF 105 of frequency converter 90 convert the RF left-handed circularly polarized signal into an IF left-handed circularly polarized signal and output the IF left-handed circularly polarized signal.

[0008] A signal with a local oscillation frequency LO1=10.678 GHz for right-handed circular polarization is input to mixer 101, and a signal with a local oscillation frequency LO2=9.505 GHz for left-handed circular polarization is input to mixer 104.

[0009] Meanwhile, a power measuring device that uses a mixer to measure power in a satellite broadcast receiving device that receives satellite broadcast waves is known (see, for example, Patent Document 1). This power measuring device uses a mixer to measure weak power leaking from the receiving equipment based on an intermediate frequency signal converted by a frequency conversion device. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2019-39843 [Non-patent literature]

[0011] [Non-Patent Document 1] ARIB Standard STD-B63, "Advanced Wideband Satellite Digital Broadcasting Receiver (Desired Specifications)" Summary of the Invention [Problem to be solved by the invention]

[0012] As mentioned above, satellite broadcasting uses radio waves in the 12 GHz band. Because the power of satellite broadcasting is attenuated by rainfall, rain attenuation characteristics of satellite broadcasting waves are measured. In recent years, the pattern of rainfall has changed due to the occurrence of linear rain bands, so it is necessary to continuously evaluate the rain attenuation characteristics of satellite broadcasting waves.

[0013] The rain attenuation characteristics of satellite broadcasting waves are measured by measuring the received power of the satellite broadcasting. Since the satellite broadcasting is still in operation when the rain attenuation characteristics are measured, the received power of the satellite broadcasting waves is measured using the modulated signal of the received signal.

[0014] To improve the accuracy of rain attenuation measurement, it is necessary to measure a larger amount of attenuation. In other words, it is necessary to measure the received power of satellite broadcasting with the noise floor as low as possible. When measuring power using a general spectrum analyzer, the noise floor can be lowered by narrowing the measurement bandwidth. For example, theoretically, narrowing the bandwidth to 1 / 10 can lower the noise floor by 10 dB.

[0015] However, when using the frequency conversion device described in Non-Patent Document 1, the power of the signal is spread over a 34.5 MHz bandwidth due to modulation, making it difficult to narrow the measurement bandwidth and measure the power.

[0016] Furthermore, the power measuring device using a mixer described in the aforementioned Patent Document 1 is intended for intermediate frequency signals that have already undergone frequency conversion. This power measuring device measures leakage power, not the received power of 12 GHz band satellite broadcasts.

[0017] Thus, in order to measure the rain attenuation characteristics of satellite broadcasting waves, it is necessary to measure the received power of the satellite broadcasting. However, the method of narrowing the measurement bandwidth to lower the noise floor is not practical because the power of the received signal is spread over a 34.5 MHz bandwidth, making it impossible to perform accurate measurements.

[0018] One way to measure the received power of satellite broadcasting with high accuracy is to increase the aperture diameter of the receiving antenna. This increases the signal-to-noise ratio (C / N) of the received signal and widens the dynamic range when measuring rain attenuation characteristics. For example, by increasing the aperture diameter of the receiving antenna from 45 cm to 90 cm, the area of ​​the aperture surface becomes four times larger, which increases the received power by 6 dB and increases the C / N by 6 dB.

[0019] However, this method has the drawback of requiring large measurement equipment. Also, even with this method, the power of the received signal is spread over a 34.5 MHz bandwidth, so even if the measurement bandwidth is narrowed to lower the noise floor, it is difficult to measure the received power of satellite broadcasts with high accuracy.

[0020] Another method for improving the accuracy of received power of satellite broadcasting is to reduce noise by averaging the measured power values ​​over time.

[0021] However, because the received power fluctuates instantaneously due to rainfall, this method has the problem of insufficient time resolution to measure rain attenuation characteristics.

[0022] Since rain attenuation characteristics usually vary depending on the region, it is desirable that the rain attenuation measurement equipment be small and inexpensive in order to realize measurements at multiple locations. For example, if it is possible to measure the received power of satellite broadcasting by using an existing frequency conversion device as is and adding a circuit that utilizes the signal within the frequency conversion device, it is expected that the measurement equipment will be small and inexpensive.

[0023] Therefore, the present invention has been made to solve the above-mentioned problems, and its object is to provide a frequency conversion device that generates an unmodulated signal from a modulated signal without changing the configuration of an existing frequency conversion device. [Means for solving the problem]

[0024] In order to solve the above problem, a frequency conversion device according to claim 1 is a frequency conversion device that converts the radio frequencies of the right-handed circularly polarized waves and the left-handed circularly polarized waves to intermediate frequencies by mixing a right-handed circularly polarized signal of a satellite broadcast including a plurality of channels with a signal of a first local oscillation frequency LO1 and mixing the left-handed circularly polarized signal of the satellite broadcast with a signal of a second local oscillation frequency LO2, the frequency conversion device comprising: a first BPF (band pass filter) that performs filtering on the signal obtained by mixing the right-handed circularly polarized signal with the signal of the first local oscillation frequency LO1 to pass signals of a predetermined band including a frequency (f1-LO1) obtained by subtracting the first local oscillation frequency LO1 from a center frequency f1 of a desired channel; and a filter that mixes the right-handed circularly polarized signal with the signal of the second local oscillation frequency LO2. a first mixer that outputs a first signal; a second BPF that applies filtering to the first signal output by the first mixer to pass signals of a predetermined band including a frequency (f1-LO2) obtained by subtracting the second local oscillation frequency LO2 from the center frequency f1; a second mixer that mixes the signal that has been filtered by the first BPF with the signal that has been filtered by the second BPF and outputs a second signal; and a first LPF (low pass filter) that applies filtering to the second signal output by the second mixer to pass signals of a predetermined low frequency band including a frequency (LO1-LO2) obtained by subtracting the second local oscillation frequency LO2 from the first local oscillation frequency LO1, and outputs an unmodulated signal.

[0025] The frequency converter of claim 2 converts the radio frequencies of the right-handed circularly polarized waves and the left-handed circularly polarized waves to intermediate frequencies by mixing a right-handed circularly polarized signal of a satellite broadcast including a plurality of channels with a signal of a first local oscillation frequency LO1 and mixing the left-handed circularly polarized signal of the satellite broadcast with a signal of a second local oscillation frequency LO2. The frequency converter further comprises a third BPF (band pass filter) that performs filtering on the signal obtained by mixing the left-handed circularly polarized signal with the signal of the second local oscillation frequency LO2 to pass signals of a predetermined band including a frequency (f1-LO2) obtained by subtracting the second local oscillation frequency LO2 from the center frequency f1 of a desired channel, and a third BPF that mixes the left-handed circularly polarized signal with the signal of the first local oscillation frequency LO1 and a fourth BPF that filters the third signal output by the third mixer to pass signals of a predetermined band including a frequency (f1-LO1) obtained by subtracting the first local oscillation frequency LO1 from the center frequency f1; a fourth mixer that mixes the signal filtered by the third BPF with the signal filtered by the fourth BPF to output a fourth signal; and a second LPF (low pass filter) that filters the fourth signal output by the fourth mixer to pass signals of a predetermined low frequency band including a frequency (LO1-LO2) obtained by subtracting the second local oscillation frequency LO2 from the first local oscillation frequency LO1, and outputs an unmodulated signal.

[0026] Furthermore, a frequency conversion device according to claim 3 is the frequency conversion device according to claim 1 or 2, characterized in that the unmodulated signal is a signal used to measure the reception power of the satellite broadcast. [Effects of the Invention]

[0027] As described above, according to the present invention, an unmodulated signal can be generated from a modulated signal without changing the configuration of an existing frequency conversion device. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a block diagram showing an example of the configuration of a frequency conversion device according to an embodiment of the present invention; [Figure 2] FIG. 10 is a block diagram showing an example of the configuration of a frequency conversion device according to another embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing an example of the overall configuration of a rain attenuation measurement system. [Figure 4] FIG. 1 is a block diagram showing an example of the configuration of a conventional frequency conversion device. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention is characterized in that it is configured by adding a circuit such as a mixer to the circuit of an existing frequency conversion device that converts the RF of a modulated signal of a satellite broadcast wave to IF, converts the modulated signal of a satellite broadcast wave to signals of two different frequencies, and generates an unmodulated signal whose frequency is the difference between two different local oscillation frequencies LO1 and LO2.

[0030] [Frequency conversion device] First, a frequency conversion device according to an embodiment of the present invention will be described. Fig. 1 is a block diagram showing an example of the configuration of a frequency conversion device according to an embodiment of the present invention.

[0031] This frequency conversion device 1 is configured to include BPFs 100, 103, 12, and 15, dividers 10, 11, and 13, mixers 101, 104, 14, and 16, and LPFs 102, 105, and 17. The frequency conversion device 1 is a device that performs frequency conversion from RF to IF and generates an unmodulated signal from an RF right-handed circularly polarized signal.

[0032] The frequency converter 1 is a device that adds three dividers 10, 11, and 13, three filters, namely BPFs 12 and 15 and an LPF 17, and two mixers 14 and 16, to the circuit of the conventional frequency converter 90 shown in Fig. 4 that performs frequency conversion. The added circuits generate an unmodulated signal from an RF right-hand circularly polarized signal.

[0033] It should be noted that amplifiers necessary for level adjustment are omitted from Fig. 1. The same applies to Fig. 4 described above and Fig. 2 described below.

[0034] The frequency converter 1 receives RF right-handed circularly polarized signals and left-handed circularly polarized signals, which are modulated signals of polarization-separated satellite broadcast waves. Then, the frequency converter 1 converts the RF to IF using a signal with a local oscillation frequency LO1 for right-handed circularly polarized waves and a signal with a local oscillation frequency LO2 for left-handed circularly polarized waves using an existing circuit, and outputs the IF right-handed circularly polarized signals and left-handed circularly polarized signals.

[0035] Furthermore, the frequency conversion device 1 uses an added circuit to convert the RF right-handed circularly polarized signal into signals of two different frequencies f1-LO1 and f1-LO2 using a signal of a local oscillation frequency LO1 for right-handed circularly polarized waves and a signal of a local oscillation frequency LO2 for left-handed circularly polarized waves, and generates and outputs an unmodulated signal, which is a CW signal for measurement of frequency (LO1-LO2), from these signals.

[0036] The frequency f1 is the center frequency of the satellite broadcast wave whose power is to be measured (the center frequency of one channel whose power is to be measured among the multiple channels of the satellite broadcast wave), and f1>LO1>LO2.

[0037] (Circuit that converts right-hand circularly polarized RF signals to IF signals) First, a circuit for converting a right-handed circularly polarized RF signal into a right-handed circularly polarized IF signal will be described.

[0038] BPF 100 receives a right-handed circularly polarized RF signal and filters it to pass signals in a predetermined band (here, the 12 GHz band), thereby eliminating unwanted waves. As a result, signals outside the 12 GHz band are removed as unwanted waves. The right-handed circularly polarized RF signal (multiple channel signals in the 12 GHz band) filtered by BPF 100 is output to distributor 10.

[0039] Divider 10 receives the filtered RF right-handed circularly polarized signal from BPF 100 and divides the RF right-handed circularly polarized signal. The right-handed circularly polarized RF signals divided by divider 10 are output to mixers 101 and 14, respectively.

[0040] Mixer 101 receives an RF right-handed circularly polarized signal from distributor 10 and also receives a signal of local oscillation frequency LO1 for right-handed circularly polarized waves from a local oscillator (not shown), and mixes these signals. The right-handed circularly polarized signal mixed with the signal of local oscillation frequency LO1 by mixer 101 is output to distributor 11.

[0041] Here, mixer 101 is a high-frequency device used for frequency conversion. If the frequencies of two different input signals (input frequencies) are F1 and F2 (F1>F2), the frequencies of the output signal (output frequency) are the frequency F1 plus the frequency F2 (F1+F2) and the frequency F1 minus the frequency F2 (F1-F2). The same applies to mixers 104, 14, and 16 described below and mixers 24 and 26 shown in FIG. 2.

[0042] The right-handed circularly polarized signal mixed with the signal of local oscillation frequency LO1 is input from mixer 101 to distributor 11, and distributor 11 distributes the signal. The right-handed circularly polarized signal mixed with the signal of local oscillation frequency LO1 distributed by distributor 11 is output to LPF 102 and BPF 12, respectively.

[0043] LPF 102 receives the right-handed circularly polarized signal mixed with the signal of local oscillation frequency LO1 from distributor 11 and performs filtering on the signal to pass signals in a predetermined low frequency band, thereby removing unwanted waves. The signal filtered by LPF 102 is then output as an IF right-handed circularly polarized signal.

[0044] In this way, BPF 100, mixer 101 and LPF 102 (and distributors 10 and 11) convert the RF right-handed circularly polarized signal in the modulated signal of the 12 GHz band satellite broadcast wave into an IF right-handed circularly polarized signal of 1032 to 2071 MHz.

[0045] (A circuit that converts left-handed circularly polarized RF signals to IF signals) Next, a circuit for converting a left-handed circularly polarized RF signal into a left-handed circularly polarized IF signal will be described.

[0046] BPF 103 receives a left-handed circularly polarized RF signal and applies filtering to the RF left-handed circularly polarized signal to pass signals in a predetermined band (here, the 12 GHz band), thereby removing unwanted waves. As a result, signals outside the 12 GHz band are removed as unwanted waves. The left-handed circularly polarized RF signal (multiple channel signals in the 12 GHz band) filtered by BPF 103 is output to mixer 104.

[0047] Divider 13 receives a signal of local oscillation frequency LO2 for left-handed circular polarization from a local oscillator (not shown) and divides the signal of local oscillation frequency LO2 for left-handed circular polarization. The signal of local oscillation frequency LO2 for left-handed circular polarization divided by divider 13 is output to mixers 104 and 14, respectively.

[0048] Mixer 104 receives the RF left-handed circularly polarized signal from BPF 103 and also receives the signal of local oscillation frequency LO2 for left-handed circularly polarized waves from distributor 13, and mixes these signals. The left-handed circularly polarized signal mixed with the signal of local oscillation frequency LO2 by mixer 104 is output to LPF 105.

[0049] LPF 105 receives the left-handed circularly polarized signal mixed with the signal of local oscillation frequency LO2 from mixer 104 and performs filtering on the signal to pass signals in a predetermined low frequency band, thereby removing unwanted waves. The signal filtered by LPF 105 is then output as an IF left-handed circularly polarized signal.

[0050] In this way, BPF 103, mixer 104 and LPF 105 convert the RF left-handed circularly polarized signal in the modulated signal of the 12 GHz band satellite broadcast wave into an IF left-handed circularly polarized signal of 2224 to 3224 MHz.

[0051] (Circuit that converts RF right-handed circularly polarized signals into unmodulated signals) Next, we will explain the circuit that converts the RF right-handed circularly polarized signal into an unmodulated CW signal for measurement.

[0052] This conversion circuit is made up of dividers 10, 11, and 13, BPFs 12 and 15, an LPF 17, and mixers 14 and 16. The dividers 10, 11, and 13 have already been explained.

[0053] The BPF 12 receives a right-hand circularly polarized signal mixed with a signal of local oscillation frequency LO1 from the distributor 11, and applies filtering to the signal to pass signals in a predetermined band (a band (a predetermined width equal to or greater than a bandwidth of 34.5 MHz) centered on the frequency (f1-LO1) corresponding to one channel for which power is to be measured)), thereby removing unwanted waves.

[0054] This allows signals in a predetermined band centered on the frequency (f1-LO1) corresponding to the one channel whose power is to be measured (one channel signal centered on the frequency (f1-LO1) among the signals of multiple channels of satellite broadcast waves) to pass. In addition, signals outside the predetermined band centered on the frequency (f1-LO1) (such as signals of multiple channels not targeted for power measurement) are removed as unwanted waves. As mentioned above, frequency f1 is the center frequency of the satellite broadcast waves whose power is to be measured.

[0055] The signal in a predetermined band centered on the frequency (f1-LO1) that has been filtered by the BPF 12 is output to the mixer 16.

[0056] Mixer 14 receives the RF right-handed circularly polarized signal from distributor 10 and the left-handed circularly polarized local oscillation frequency LO2 signal from distributor 13, and mixes these signals. The right-handed circularly polarized signal mixed with the local oscillation frequency LO2 signal by mixer 14 is output to BPF 15.

[0057] The BPF 15 receives a right-handed circularly polarized signal mixed with a signal of local oscillation frequency LO2 from the mixer 14, and applies filtering to the signal to pass signals in a predetermined band (a band (a predetermined width equal to or greater than a bandwidth of 34.5 MHz) centered on the frequency (f1-LO2) corresponding to one channel for which power is to be measured)), thereby removing unwanted waves.

[0058] This allows signals in a predetermined band centered on the frequency (f1-LO2) corresponding to one channel for which power is to be measured (one channel signal centered on the frequency (f1-LO2) among multiple channel signals of satellite broadcast waves) to pass through. Also, signals outside the predetermined band centered on the frequency (f1-LO2) (such as signals of multiple channels not for which power is to be measured) are removed as unnecessary waves.

[0059] The signal in a predetermined band centered on a frequency (f1-LO2) that has been filtered by the BPF 15 is output to the mixer 16.

[0060] The mixer 16 receives the filtered signal of a predetermined band centered on the frequency (f1-LO1) from the BPF 12 and the filtered signal of a predetermined band centered on the frequency (f1-LO2) from the BPF 15, and mixes these signals. The signal mixed by the mixer 16 is output to the LPF 17.

[0061] As a result, a signal of a single frequency (LO1-LO2) and a signal of a predetermined band centered on the frequency (2f1-(LO1+LO2)) are generated and output to the LPF 17, as shown in the following equations. [Number 1] (f1-LO2)-(f1-LO1)=LO1-LO2...(1) [Number 2] (f1-LO2)+(f1-LO1)=2f1-(LO1+LO2) ···(2)

[0062] The LPF 17 receives signals of frequency (LO1-LO2) and signals of a predetermined band centered on frequency (2f1-(LO1+LO2)) from the mixer 16, and performs filtering on these signals to pass signals of a predetermined low frequency band (a band including frequency (LO1-LO2)), thereby removing unwanted waves.

[0063] As a result, signals of frequency (LO1-LO2) pass through, and signals in a predetermined band centered on frequency (2f1-(LO1+LO2)) are removed as unnecessary waves.

[0064] Here, as described above, since f1>LO1, the following magnitude relationship holds when the above formula (1) is subtracted from the above formula (2). [Number 3] 2f1-2LO1=2×(f1-LO1)>0 ···(3)

[0065] Therefore, the frequency (2f1-(LO1+LO2)) shown in the above formula (2) is higher than the frequency (LO1-LO2) shown in the above formula (1) ((2)>(1)).

[0066] In other words, the LPF 17 removes signals in a predetermined band centered on the frequency (2f1-(LO1+LO2)) shown in equation (2), and obtains a signal of frequency (LO1-LO2), which is a single frequency signal shown in equation (1), that is not affected by the frequency components of the satellite broadcast wave whose center frequency is frequency f1 and whose power is to be measured.

[0067] The signal filtered by the LPF 17 is then output as an unmodulated CW signal for measurement.

[0068] As described above, according to the frequency conversion device 1 of the embodiment of the present invention, the BPFs 100 and 103, the mixers 101 and 104, and the LPFs 102 and 105, which correspond to the circuits of the conventional frequency conversion device 90 shown in FIG. 4, convert the frequencies of the RF right-handed circularly polarized signal and the left-handed circularly polarized signal, which are the modulated signals of the satellite broadcast wave, and output the IF right-handed circularly polarized signal and the left-handed circularly polarized signal.

[0069] Furthermore, dividers 10, 11, and 13, BPFs 12 and 15, LPF 17, and mixers 14 and 16, which correspond to circuits added to the conventional frequency conversion device 90 shown in Figure 4, convert the RF right-handed circularly polarized signal into an unmodulated CW signal for measurement and output it.

[0070] Specifically, the mixer 16 mixes a signal of a predetermined band centered on the frequency (f1-LO1) that has been filtered by the BPF 12 with a signal of a predetermined band centered on the frequency (f1-LO2) that has been filtered by the BPF 15, to generate a signal of the frequency (LO1-LO2) and a signal of a predetermined band centered on the frequency (2f1-(LO1+LO2)).

[0071] The LPF 17 removes unwanted waves by performing filtering on the signal of frequency (LO1-LO2) generated by the mixer 16 and the signal of a predetermined band centered on frequency (2f1-(LO1+LO2)) to pass signals of a predetermined low frequency band (a band including frequency (LO1-LO2)).

[0072] This allows signals of frequency (LO1-LO2) to pass, signals in a specified band centered on frequency (2f1-(LO1+LO2)) are removed as unnecessary waves, and a measurement CW of single frequency (LO1-LO2) is output as an unmodulated signal.

[0073] In other words, by adding circuits such as a mixer 14 to the circuitry of an existing frequency conversion device 90, the modulated signal of the satellite broadcast wave is converted into signals of two different frequencies ((f1-LO1), (f1-LO2)), and an unmodulated signal is generated that is a single-frequency CW signal for measurement, whose frequency is the difference (LO1-LO2) between the two different local oscillation frequencies.

[0074] As will be described later, the amplitude of this measurement CW is proportional to the square of the amplitude of the signal at center frequency f1 in the satellite broadcast wave whose power is to be measured. This relationship makes it possible to obtain the received power of the satellite broadcast whose power is to be measured from the measurement CW.

[0075] Therefore, the configuration of an existing frequency conversion device can be used as is without changing it to perform frequency conversion, and by adding a mixer 14 or the like, an unmodulated signal can be generated from a modulated signal.

[0076] Furthermore, an unmodulated signal can be obtained from the received satellite broadcast signal (the modulated satellite broadcast wave signal) without changing the transmitted satellite broadcast signal. By using this unmodulated signal, it is possible to measure the received power with high accuracy to measure the rain attenuation characteristics without affecting the satellite broadcast service.

[0077] The measurement results of rain attenuation characteristics can be utilized for future system design, such as rain margin considerations for satellite broadcasting.

[0078] Furthermore, the frequency converter 1 of the embodiment of the present invention utilizes the local oscillators (local oscillation frequency LO1 for right-handed circularly polarized waves = 10.678 GHz, local oscillation frequency LO2 for left-handed circularly polarized waves = 9.505 GHz) that are provided in current satellite broadcast receiving converters. Therefore, it is possible to generate an unmodulated signal without using a separate special oscillator, thereby reducing the circuit size and cost.

[0079] [Frequency conversion device / other examples] Next, a frequency conversion device according to another embodiment of the present invention will be described below. Fig. 2 is a block diagram showing an example of the configuration of a frequency conversion device according to another embodiment of the present invention.

[0080] This frequency conversion device 2 is configured to include BPFs 100, 103, 22, and 25, dividers 20, 21, and 23, mixers 101, 104, 24, and 26, and LPFs 102, 105, and 27. The frequency conversion device 2 performs frequency conversion from RF to IF and generates an unmodulated signal from an RF left-handed circularly polarized signal.

[0081] The frequency converter 2 is a device that adds three dividers 20, 21, and 23, three filters, namely BPFs 22 and 25 and an LPF 27, and two mixers 24 and 26, to the circuit of the conventional frequency converter 90 shown in Fig. 4 that performs frequency conversion. The added circuits generate an unmodulated signal from an RF left-handed circularly polarized signal.

[0082] Comparing the frequency converter 1 shown in FIG. 1 with this frequency converter 2, both frequency converters 1 and 2 have in common the fact that they are equipped with BPFs 100 and 103, mixers 101 and 104, and LPFs 102 and 105, which correspond to the circuits of the conventional frequency converter 90.

[0083] On the other hand, frequency conversion device 2 differs from frequency conversion device 1, which generates an unmodulated signal from a right-handed circularly polarized RF signal, in that frequency conversion device 2 generates an unmodulated signal from a left-handed circularly polarized RF signal. For this reason, frequency conversion device 2 is equipped with dividers 20, 21, 23, BPFs 22, 25, LPF 27, and mixers 24, 26, which correspond to dividers 10, 11, 13, BPFs 12, 15, LPF 17, and mixers 14, 16 provided in frequency conversion device 1. In Fig. 2, the same parts as those in Fig. 1 are designated by the same reference numerals, and duplicated explanations will be omitted.

[0084] The frequency converter 2 receives RF right-handed circularly polarized signals and left-handed circularly polarized signals, which are modulated signals of polarization-separated satellite broadcast waves. Then, the frequency converter 2 converts the RF to IF using a signal with a local oscillation frequency LO1 for right-handed circularly polarized waves and a signal with a local oscillation frequency LO2 for left-handed circularly polarized waves using an existing circuit, and outputs the IF right-handed circularly polarized signals and left-handed circularly polarized signals.

[0085] Furthermore, the frequency conversion device 2 uses an added circuit to convert the RF left-handed circularly polarized signal into signals of two different frequencies f1-LO1 and f1-LO2 using a signal of local oscillation frequency LO1 for right-handed circularly polarized waves and a signal of local oscillation frequency LO2 for left-handed circularly polarized waves, and generates and outputs an unmodulated signal, which is a CW signal for measurement of frequency (LO1-LO2), from these signals.

[0086] As in the frequency conversion device 1 shown in FIG. 1, frequency f1 is the center frequency of the satellite broadcast wave whose power is to be measured, and f1>LO1>LO2.

[0087] (Circuit that converts right-hand circularly polarized RF signals to IF signals) The circuit that converts the RF right-handed circularly polarized signal into the IF right-handed circularly polarized signal is the BPF 100, mixer 101, and LPF 102 (as well as distributors 10 and 11) provided in the frequency conversion device 1 shown in Figure 1, so a detailed description will be omitted.

[0088] Divider 23 receives a signal of local oscillation frequency LO1 for right-handed circular polarization from a local oscillator (not shown) and divides the signal of local oscillation frequency LO1 for right-handed circular polarization. The signal of local oscillation frequency LO1 for right-handed circular polarization divided by divider 23 is output to mixers 101 and 24, respectively.

[0089] Mixer 101 receives a signal of local oscillation frequency LO1 for right-handed circularly polarized waves from distributor 23 and performs the above-mentioned mixing.

[0090] In this way, BPF 100, mixer 101, and LPF 102 convert the RF right-handed circularly polarized signal in the modulated signal of the 12 GHz band satellite broadcast wave into an IF right-handed circularly polarized signal of 1032 to 2071 MHz.

[0091] (A circuit that converts left-handed circularly polarized RF signals to IF signals) The circuit that converts the RF left-handed circularly polarized signal into the IF left-handed circularly polarized signal is a circuit in which distributors 20 and 21 are added to BPF 103, mixer 104, and LPF 105 provided in frequency conversion device 1 shown in Fig. 1. Description of BPF 103, mixer 104, and LPF 105 will be omitted.

[0092] Here, distributor 20 receives the filtered RF left-handed circularly polarized signal from BPF 103 and distributes the RF left-handed circularly polarized signal. The RF left-handed circularly polarized signals distributed by distributor 20 are output to mixers 104 and 24, respectively.

[0093] Mixer 104 receives the RF left-handed circularly polarized signal from distributor 20 and performs the mixing described above. The left-handed circularly polarized signal mixed with the signal of local oscillation frequency LO2 by mixer 104 is output to distributor 21.

[0094] The distributor 21 receives the left-handed circularly polarized signal mixed with the signal of the local oscillation frequency LO2 from the mixer 104 and distributes the signal. The left-handed circularly polarized signal mixed with the signal of the local oscillation frequency LO2 distributed by the distributor 21 is output to the LPF 105 and the BPF 22, respectively.

[0095] The LPF 105 receives the left-handed circularly polarized signal mixed with the signal of the local oscillation frequency LO2 from the distributor 21 and performs the above-mentioned filtering process.

[0096] In this way, BPF 103, mixer 104 and LPF 105 (and distributors 20 and 21) convert the RF left-handed circularly polarized signal in the modulated signal of the 12 GHz band satellite broadcast wave into an IF left-handed circularly polarized signal of 2224 to 3224 MHz.

[0097] (Circuit that converts RF left-handed circularly polarized signals into unmodulated signals) Next, we will explain the circuit that converts the RF left-handed circularly polarized signal into an unmodulated CW signal for measurement.

[0098] This conversion circuit is made up of dividers 20, 21, and 23, BPFs 22 and 25, an LPF 27, and mixers 24 and 26. The dividers 20, 21, and 23 have already been explained.

[0099] The BPF 22 receives a left-handed circularly polarized signal mixed with a signal of local oscillation frequency LO2 from the distributor 21, and applies filtering to the signal to pass signals in a predetermined band (a band (a predetermined width equal to or greater than a bandwidth of 34.5 MHz) centered on the frequency (f1-LO2) corresponding to one channel for which power is to be measured)), thereby removing unwanted waves.

[0100] This allows signals in a predetermined band centered on the frequency (f1-LO2) corresponding to one channel for which power is to be measured (one channel signal centered on the frequency (f1-LO2) among multiple channel signals of satellite broadcast waves) to pass through. Also, signals outside the predetermined band centered on the frequency (f1-LO2) (such as signals of multiple channels not for which power is to be measured) are removed as unnecessary waves.

[0101] The signal in a predetermined band centered on the frequency (f1-LO2) that has been filtered by the BPF 22 is output to the mixer .

[0102] Mixer 24 receives the RF left-handed circularly polarized signal from distributor 20 and the right-handed circularly polarized local oscillation frequency LO1 signal from distributor 23, and mixes these signals. The left-handed circularly polarized signal mixed with the local oscillation frequency LO1 signal by mixer 24 is output to BPF 25.

[0103] The BPF 25 receives a left-handed circularly polarized signal mixed with a signal of local oscillation frequency LO1 from the mixer 24, and applies filtering to the signal to pass signals in a predetermined band (a band (a predetermined width equal to or greater than a bandwidth of 34.5 MHz) centered on the frequency (f1-LO1) corresponding to one channel for which power is to be measured)), thereby removing unwanted waves.

[0104] This allows signals in a predetermined band centered on the frequency (f1-LO1) corresponding to one channel for which power is to be measured (a signal on one channel centered on the frequency (f1-LO1) among signals on multiple channels of satellite broadcast waves) to pass through. Also, signals outside the predetermined band centered on the frequency (f1-LO1) (such as signals on multiple channels not for which power is to be measured) are removed as unnecessary waves.

[0105] The signal in a predetermined band centered on the frequency (f1-LO1) that has been filtered by the BPF 25 is output to the mixer .

[0106] Mixer 26 receives a signal of a predetermined band centered on a frequency (f1-LO1) that has been subjected to filtering from BPF 25, and also receives a signal of a predetermined band centered on a frequency (f1-LO2) that has been subjected to filtering from BPF 22. Mixer 26 performs the same processing as mixer 16 shown in FIG. 1. The signal mixed by mixer 26 is output to LPF 27.

[0107] The LPF 27 receives the signal of frequency (LO1-LO2) and the signal of a predetermined band centered on frequency (2f1-(LO1+LO2)) from the mixer 26. The LPF 27 then performs the same processing as the LPF 17 shown in FIG. 1. The signal filtered by the LPF 27 becomes a CW signal for measurement of a single frequency (LO1-LO2), and is output as an unmodulated signal.

[0108] As described above, according to the frequency conversion device 2 of another embodiment of the present invention, similar to the frequency conversion device 1, the frequency of the RF right-handed circularly polarized signal and the left-handed circularly polarized signal, which are modulated signals of satellite broadcast waves, is converted, and the IF right-handed circularly polarized signal and the left-handed circularly polarized signal are output.

[0109] Furthermore, dividers 20, 21, 23, BPFs 22, 25, LPF 27, and mixers 24, 26, which correspond to circuits added to the conventional frequency conversion device 90 shown in Figure 4, convert the RF left-handed circularly polarized signal into an unmodulated CW signal for measurement and output it.

[0110] This achieves the same effect as the frequency conversion device 1 shown in Figure 1, and frequency conversion can be performed by using the existing frequency conversion device as is without changing its configuration, and by adding a mixer 24 or the like, an unmodulated signal can be generated from a modulated signal.

[0111] [Rain Attenuation Measurement System] Next, a rain attenuation measurement system using the frequency conversion devices 1 and 2 (frequency conversion device 1 or frequency conversion device 2) shown in Figures 1 and 2 will be described. Figure 3 is a schematic diagram showing an example of the overall configuration of the rain attenuation measurement system.

[0112] This rain attenuation measurement system 30 comprises a satellite broadcast receiving antenna 3, a polarization separator 4, frequency converters 1 and 2, a multiplexer 5, a receiver 6, a spectrum analyzer 7, a rain gauge 8, and a data collection device 9. The frequency converters 1 and 2 and the spectrum analyzer 7 make up a power measurement system 31. The rain attenuation measurement system 30 is a system that measures the amount of attenuation of the received power of one channel centered on the frequency f1 that is the object of power measurement.

[0113] The satellite broadcast receiving antenna 3 receives satellite broadcast waves in the 12 GHz band. The polarization separator 4 inputs the received signal of the 12 GHz band satellite broadcast waves received by the satellite broadcast receiving antenna 3 and separates the received signal into a right-handed circularly polarized RF signal and a left-handed circularly polarized RF signal. The right-handed circularly polarized RF signal and the left-handed circularly polarized RF signal separated by the polarization separator 4 are output to the frequency converters 1 and 2.

[0114] Frequency converters 1 and 2 receive RF right-handed circularly polarized signals and left-handed circularly polarized signals from polarization separator 4. Then, through processing by the components shown in Figures 1 and 2, frequency converters 1 and 2 generate IF right-handed circularly polarized signals and left-handed circularly polarized signals using a signal with a local oscillation frequency LO1 of 10.678 GHz for right-handed circularly polarized waves and a signal with a local oscillation frequency LO2 of 9.505 GHz for left-handed circularly polarized waves. Frequency converters 1 and 2 output these signals to combiner 5.

[0115] In addition, the frequency conversion devices 1 and 2 generate a measurement CW for one channel centered on the frequency f1 of the desired power measurement target among the multiple channels of the satellite broadcast wave, and output an unmodulated signal that is the measurement CW of this frequency (LO1-LO2) to the spectrum analyzer 7.

[0116] The multiplexer 5 receives the IF right-handed circularly polarized signal and the IF left-handed circularly polarized signal from the frequency converters 1 and 2, multiplexes these signals, and outputs the multiplexed signal to the receiver 6. The receiver 6 receives the multiplexed signal from the multiplexer 5 and performs satellite broadcast reception processing.

[0117] The spectrum analyzer 7 receives the unmodulated signal, which is a measurement CW of frequency (LO1-LO2), from the frequency converters 1 and 2, and measures the power of the measurement CW at the measurement frequency (LO1-LO2=1.173 GHz). The power of the measurement CW measured by the spectrum analyzer 7 is output to the data collector 9 as the measurement power.

[0118] The rain gauge 8 is a sensor that measures the amount of rainfall, and outputs the amount of rainfall to the data collection device 9 .

[0119] The data collection device 9 receives the measurement power (power of the measurement CW) from the spectrum analyzer 7 and also receives the rainfall amount from the rain gauge 8. The data collection device 9 then calculates the power of the signal of frequency f1 based on the power of the measurement CW, utilizing the relationship that the amplitude of the measurement CW is proportional to the square of the amplitude of the signal of frequency f1 in the satellite broadcast wave whose power is to be measured.

[0120] The data collection device 9 collects data that associates the amount of rainfall with the power of the signal of frequency f1, and records the amount of rainfall and the power of the signal of frequency f1.

[0121] Here, the relationship between the amplitude of the measurement CW and the amplitude of the signal at frequency f1 will be explained. Generally, the amplitude of the output signal from mixer 101, etc. is proportional to the product of the amplitudes of the two input signals. Furthermore, the amplitudes of the signal at local oscillation frequency LO1 for right-handed circular polarization and the signal at local oscillation frequency LO2 for left-handed circular polarization are constant. Therefore, the amplitude of the output signal from mixers 101, 104, 14, and 24 is proportional to the amplitude of the signal at frequency f1.

[0122] Therefore, since the input signals to the mixers 16 and 26 are signals of frequency (f1-LO1) and frequency (f1-LO2), the amplitude of the output signals from the mixers 16 and 26 is proportional to the square of the amplitude of the signal of frequency f1. In other words, the amplitude of the measurement CW of frequency (LO1-LO2) is proportional to the square of the amplitude of the signal of frequency f1. Using this relationship, the power of the signal of frequency f1 can be found based on the power of the measurement CW.

[0123] Then, using the data set of rainfall amount and power of the signal of frequency f1 collected by the data collection device 9, the attenuation amount is calculated from the relative value of power for the received power of the desired channel that is the power measurement target, and the rain attenuation characteristics of the satellite broadcast wave can be obtained.

[0124] As described above, according to the rain attenuation measurement system 30 using the frequency conversion device 1 of an embodiment of the present invention or the frequency conversion device 2 of another embodiment of the present invention, the power measurement system 31 composed of the frequency conversion devices 1, 2 and the spectrum analyzer 7 generates an unmodulated signal of the measurement CW and measures the power of the measurement CW from the signal.

[0125] The data collection device 9 calculates the received power of the satellite broadcasting signal of the power measurement target, which is the power of the signal at frequency f1, based on the power of the measurement CW signal measured by the power measurement system 31, and collects data that corresponds the amount of rainfall measured by the rain gauge 8 with the received power of the satellite broadcasting signal of the power measurement target.

[0126] This allows the received power of the satellite broadcast signal to be measured using the unmodulated measurement CW signal generated from the modulated signal of the satellite broadcast wave. In other words, since the measurement CW does not have a frequency bandwidth, the measurement bandwidth of the spectrum analyzer 7 can be narrowed to lower the noise floor, allowing the rain attenuation characteristics of the satellite broadcast wave to be measured with high accuracy while the satellite broadcast is continued.

[0127] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the technical concept thereof. [Explanation of symbols]

[0128] 1,2,90 Frequency converter 3 Satellite broadcast receiving antenna 4 Polarization separator 5 Multiplexer 6 Receiver 7. Spectrum Analyzer 8 Rain gauge 9 Data Collection Equipment 12, 15, 22, 25, 100, 103 BPF (Band Pass Filter) 17,27,102,105 LPF (Low Pass Filter) 14,16,24,26,101,104 Mixer 10,11,13,20,21,23 distributor 30 Rain Attenuation Measurement System 31 Power Measurement System LO1, LO2 local oscillation frequency f1 frequency (center frequency of the satellite broadcast signal to be measured)

Claims

1. A right-handed circularly polarized signal of a satellite broadcast including multiple channels and a first local oscillation frequency LO 1 and mixes the left-handed circularly polarized signal of the satellite broadcast with the second local oscillation frequency LO. 2 a frequency conversion device for converting the radio frequencies of the right-handed circularly polarized wave and the left-handed circularly polarized wave into an intermediate frequency by mixing the signals of The right-handed circularly polarized signal and the first local oscillation frequency LO 1 The signal obtained by mixing the signal with the center frequency f of the desired channel is added. 1 to the first local oscillation frequency LO 1 The frequency (f 1 -LO 1 a first BPF (band pass filter) that performs filtering to pass signals in a predetermined band including The right-handed circularly polarized signal and the second local oscillation frequency LO 2 a first mixer that mixes the first signal with the second signal and outputs a first signal; The first signal output by the first mixer is mixed with the center frequency f 1 to the second local oscillation frequency LO 2 The frequency (f 1 -LO 2 a second BPF that performs filtering to pass signals in a predetermined band including the a second mixer that mixes the signal filtered by the first BPF and the signal filtered by the second BPF to output a second signal; The second signal output by the second mixer is mixed with the first local oscillation frequency LO. 1 to the second local oscillation frequency LO 2 The frequency (LO 1 -LO 2 a first LPF (low pass filter) that performs filtering to pass signals in a predetermined low frequency band including the first LPF and outputs an unmodulated signal; A frequency conversion device comprising:

2. A right-handed circularly polarized signal of a satellite broadcast including multiple channels and a first local oscillation frequency LO 1 and mixes the left-handed circularly polarized signal of the satellite broadcast with the second local oscillation frequency LO. 2 a frequency conversion device for converting the radio frequencies of the right-handed circularly polarized wave and the left-handed circularly polarized wave into an intermediate frequency by mixing the signals of The left-handed circularly polarized signal and the second local oscillation frequency LO 2 The signal obtained by mixing the signal with the center frequency f of the desired channel is added. 1 to the second local oscillation frequency LO 2 The frequency (f 1 -LO 2 a third BPF (band pass filter) that performs filtering to pass signals in a predetermined band including the first and second bands; The left-handed circularly polarized signal and the first local oscillation frequency LO 1 a third mixer that mixes the first signal with the second signal and outputs a third signal; The third signal output by the third mixer is mixed with the center frequency f 1 to the first local oscillation frequency LO 1 The frequency (f 1 -LO 1 a fourth BPF that performs filtering to pass signals in a predetermined band including the a fourth mixer that mixes the signal filtered by the third BPF and the signal filtered by the fourth BPF to output a fourth signal; The fourth signal output by the fourth mixer is mixed with the first local oscillation frequency LO. 1 to the second local oscillation frequency LO 2 The frequency (LO 1 -LO 2 a second LPF (low pass filter) that performs filtering to pass signals in a predetermined low frequency band including the first LPF and outputs an unmodulated signal; A frequency conversion device comprising:

3. 3. The frequency conversion device according to claim 1, A frequency conversion device, characterized in that the unmodulated signal is a signal used to measure the reception power of the satellite broadcast.

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