65 results about "Instantaneous frequency measurement" patented technology

The invention discloses a device and a method for realizing instantaneous frequency measurement using a lithium niobate phase modulator. The device and the method relate to the technical field of microwave and the technical field of optical communication, and are mainly applied to the field of electronic reconnaissance. The device comprises a laser, a polarization controller, a phase modulator, a standard single-mode optical fiber, an optical divider, a polarizer and an optical receiver, as shown in the appended drawings. By using the polarization sensitive property of the lithium niobate phase modulator and reasonably adjusting the polarization controller, phase modulation and intensity modulation can be realized at the same time. Based on the dispersion characteristic of the optical fiber, two frequency response functions opposite in change trend can be constructed. Thus, an amplitude comparison function obtained changes more quickly in a large band. By calculating the power ratio of upper and lower branches, the frequency of a to-be-measured microwave signal can be estimated. The measurement error of the device within the range from 1.6GHz to 24.6GHz is less than + / -0.3GHz.

The invention discloses a large-dynamic ultra-wideband digital instantaneous frequency measurement method. The method adopts a radio frequency division technology and is combined with a channelized digital frequency measurement method, so that the covered frequency band is wide, the interception probability is high, and the high frequency resolution can be kept. The method selects 32 paths of digital channelization, so that the frequency measurement delay is ensured not to exceed 1 microsecond and the frequency measurement precision is within the range of 1 MHz. A radio frequency division module carries out three-stage amplification and equalization on an input 1-18 GHz radio frequency signal firstly, so that the input amplitude dynamic range is compressed through the design, and the dynamic range of the input signal is -45 dBm to 0 dBm, and the dynamic range is compressed to -5 dBm to 0 dBm after multi-stage amplification and equalization; and meanwhile, the deterioration of a signal-to-noise ratio is reduced; and furthermore, the amplitude flatness of 1 to 18 GHz of an ultra-wideband signal is ensured, so that the power of full-band signals sent to a frequency divider is within the normal working range of the frequency divider.

The invention discloses a ultrasonic positioning method. The method comprises that a ultrasonic wave emitting device generates a ultrasonic signal according to a preset device code and a time code, and transmits the ultrasonic signal; that a client acquires the ultrasonic signal emitted by the ultrasonic wave emitting device; that the client decodes the acquired ultrasonic signal in order to generate the device code and the time code, and transmits the device code and the time code to a server; that the server positions the real-time position of the client according to the device code; that whether the ultrasonic signal is normal is determined according to the time code, and the positional information is forwarded to the client if yes. The invention also discloses a ultrasonic positioning system. The ultrasonic positioning system accurately acquires the ultrasonic signal with a instantaneous frequency measurement algorithm, converts the ultrasonic signal into a frequency domain signal with fast Fourier transform, restores the ultrasonic signal high efficiently, extracts the device code, and achieves the accurate positioning of the client.

The present invention relates to a device and method that digitally replicates the analog processing that is normally associated with an instantaneous frequency measurement device. Specifically, the present relates to a digital frequency measurement device comprising: a filter, where the filter receives an input RF signal and transmits an output signal centered around a desired frequency; a limiting amplifier downstream of the filter, where the amplifier receives and amplifies the output signal; a deserializer downstream of the amplifier that continuously samples the output signal from the limiting amplifier; and a digital frequency measurement processor (DFM), where the DFM receives data at a rate of 1 / 16 of the deserializer sample rate. The DFM transforms the data into multiples stages that are combined in order to produce an estimate of the input signal, where the DFM is implemented through a digital processing device.

The invention, which relates to the field of the microwave photonics, provides a bias-voltage-control-based adjustable instantaneous frequency measure system. A first continuous wave laser (11) and a second continuous wave laser (12) are respectively connected with a first polarization controller (21) and a second polarization controller (22); the first polarization controller (21) and the second polarization controller (22) are respectively connected with a polarization beam splitter (3); the polarization beam splitter (3) is connected with a third polarization controller (23); the third polarization controller (23), a radio frequency signal source (5) and a bias voltage source (6) are connected to a light input terminal (41), a radio frequency input terminal (42), and a bias input terminal (43) of a polarization modulator (4); the output of the polarization modulator (4) is connected with a fourth polarization controller (24) connected with a wire grid polarizer (7); and the wire grid polarizer (7) is connected with a single-mode fiber (8) and a wavelength division multiplexing device (9) is used for carrying out shunting. A first photoelectric detector and a second photoelectric detector (101 and 102) respectively detect separated two paths of signals and output the signals to a first input terminal and a second input terminal (131 and 132) of an electric treatment module (13), thereby obtaining an amplitude comparison function.

The invention discloses an instantaneous frequency measurement method based on an FPGA and a digital receiver thereof. The method comprises the following steps of: delaying the original data stream byb clock cycles, forming two real sequences with the current data stream, wherein the two real sequences are respectively used as a real part and an imaginary part to obtain complex original data stream signals; inputting the plurality of original data stream signals into an FFT (Fast Fourier Transform) operation module according to the bit width, performing butterfly operation for the output of the FFT module operation module, and inputting the output into a decomposition circuit to obtain frequency spectrums corresponding to two real sequences respectively; calculating a noise threshold according to the two complex frequency spectrums; according to the noise threshold and a set signal-to-noise ratio margin, performing searching by adopting an extreme value to obtain a coarse frequency measurement signal; demodulating and outputting the pulse synchronous signal according to the noise threshold, the signal-to-noise ratio margin and the coarse frequency measurement signal; obtaining a real part value and an imaginary part value corresponding to the coarse frequency measurement signal according to the coarse frequency measurement signal and the complex frequency spectrums; measuringthe frequency by adopting a phase difference method; and finally, fusing data to output a frequency measurement result. The digital receiver includes the FPGA implementation that integrates the above-described method.

The invention discloses an instantaneous frequency measuring device based on optical power monitoring, and relates to the field of optoelectronic devices and microwave photonics. The device comprises a continuous wave laser (1), a polarization controller (2), a signal generator (3), an electric power divider (4), an electric delay line (5), an optical power divider (6), an electric power divider (7), an electric power divider (8), an I / Q modulator (9), an I / Q modulator (10), an optical power meter (11) and an optical power meter (12). By monitoring the power values of the two optical power meters, the frequency of the radio frequency signal can be calculated. By changing the delay amount of the electric delay line (5), the measurement range and measurement error of the instantaneous frequency measurement can be adjusted.

The invention discloses a silicon-based integrated microwave frequency measuring instrument, which comprises an electro-optical intensity modulator, a frequency classification unit, a frequency selection unit, an instantaneous frequency measurement unit and a Y branch; the electro-optical intensity modulator is used for loading a microwave signal to be measured to an optical carrier to form an optical carrier microwave signal; the Y branch divides the optical carrier microwave signal into two paths with equal intensity, the two paths of the optical carrier microwave signal are respectively sent to the frequency classification unit and the frequency selection unit, the frequency classification unit is used for judging the frequency component and the frequency type of the optical carrier microwave signal, and the frequency selection unit is used for shaping the frequency spectrum and sending the selected frequency band to the instantaneous frequency measurement unit; the instantaneous frequency measurement unit provides two independent linear frequency responses, maps the frequency of the optical carrier microwave signal to the power through the two linear frequency responses, and determines the frequency of the microwave signal to be measured by measuring the power. Therefore, different types of unknown signals can be identified during instantaneous measurement, and the capability of distinguishing complex signals in a complex environment is greatly improved.