A method for improving the matching degree between the broadening line and the compression line of a Chirp transform spectrum analyzer system

Abstract

The present invention belongs to the technical field of deep space exploration. Specifically, it relates to a method for improving the matching degree between the broadening line and the compression line of a Chirp transform spectrum analyzer system. The method includes: Step 1) Build a Chirp transform spectrum analyzer system; Step 2) Obtain the relationship diagram between two key parameters of the compression pulse and the frequency modulation slope of the broadening line; Step 3) According to the relationship diagram between the two key parameters of the compression pulse and the frequency modulation slope of the broadening line, determine the frequency modulation slope of the broadening line with the optimal match for a single frequency point within the full frequency band in the Chirp transform spectrum analyzer system; The two key parameters of the compression pulse are the main lobe bandwidth and the peak sidelobe ratio of the compression pulse; Step 4) Select a preset frequency interval step size, change the frequency of the signal under test, and repeat the above Step 2) - Step 3) until the frequency modulation slope of the broadening line with the optimal match for each single frequency point is determined; Step 5) According to the frequency modulation slopes of the broadening lines with the optimal match for each single frequency point, determine the optimal matching slope within the full frequency band of the system.

Description

Technical Field

[0001] The present invention belongs to the technical fields of deep space exploration, fine spectrum detection, and Chirp transform spectrum analyzer, and specifically relates to a method for improving the matching degree between the broadening line and the compression line of a Chirp transform spectrum analyzer system. Background Art

[0002] The spectrum analyzer system based on Chirp transform can analyze signals with an instantaneous large bandwidth, and this system has high sensitivity and can resolve signals with very small frequency intervals. Moreover, the spectrum analyzer system based on Chirp transform also has advantages such as low power consumption, small size, light weight, strong anti-interference ability, and high stability, and has comprehensive advantages in fields such as deep space exploration and radio astronomy. In 2004, the detection satellite Rosetta launched by the European Space Agency carried the Chirp transform spectrometer MIRO (Microwave Instrument ROSETTA Orbiter, MIRO) to study the structure of Comet 67P, and successfully analyzed H2O, N2, and several water isotopes. In 2010, the SOFIA (Stratospheric Observatory For Infrared Astronomy, SOFIA) project jointly carried out by the National Aeronautics and Space Administration of the United States and the German Space Agency used a Boeing 747 aircraft equipped with a Chirp transform spectrometer to measure the molecular spectral lines at high altitudes, and further explored and studied the composition of the planetary surface and atmosphere, interstellar matter, etc. It is expected that the Jupiter Icy Moon Explorer JUICE to be launched in 2022 will also use a Chirp transform spectrometer to conduct precise spectrum detection on substances such as SO2, NaCl, and SO. The existing Chirp transform spectrometer with a bandwidth of 40 MHz and a resolution of 40 kHz is applied to the observation of water maser sources of 13.7 m radio telescopes and 25 m radio telescopes. In recent years, due to the outstanding advantages of the Chirp transform spectrometer in the field of deep space exploration, it has received extensive attention from researchers. However, there is still a large gap between the key performance parameters such as the resolution and the main side lobe level ratio of the existing Chirp transform spectrum analyzer system and the theoretical values, which cannot meet the requirements of deep space exploration applications.

[0003] Currently, the spectrum analyzer system based on Chirp transform mainly consists of two parts: a broadening line and a compression line. The broadening line is a device that generates the first multiplied Chirp signal, which is commonly generated by digital methods; the device for convolution is the compression line, which is generally composed of a SAW linear frequency modulation dispersion delay line. The slopes of the broadening line and the compression line must be the same in magnitude and opposite in direction to correctly generate a compressed pulse signal containing the spectral information of the measured signal. The time node of this pulse signal is related to the frequency information of the input signal, and the spectrum analysis of the measured signal is completed by measuring the distribution of the pulse signal on the time axis.

[0004] In the prior art, it is difficult to accurately match the stretching line and the compression line, resulting in an overly wide main lobe of the compression pulse waveform and a high side lobe level, which causes significant differences in key performance parameters such as the system frequency resolution and dynamic range.

[0005] The reasons for the difficulty in accurately matching the stretching line and the compression line are mainly the following two points:

[0006] 1. Problems with SAW (Surface Acoustic Wave) compression line devices; as a SAW device for the compression line, the dispersion slope K is not a standard reference value and is not constantly equal to a specific value, and it is not equal everywhere within the bandwidth. The phase deviation caused by the SAW filter results in the situation where when the slopes of the stretching line and the compression line are "equal", it is not the optimal compression result of the system.

[0007] 2. Problems with the RF conditioning circuit; in the generation of the stretching line, since the power, bandwidth, etc. of the Chirp signal directly generated by the DAC (Digital to analog converter) do not meet the system design requirements, analog devices need to be added to improve the Chirp signal, but at the same time, more variables will be introduced, making the system more complex. On the one hand, the phase mismatch of the analog devices will cause the dispersion slope of the stretching line to be the same as that of the compression line, that is, it is not the same everywhere within the bandwidth, making the matching between the stretching line and the compression line more difficult. On the other hand, the inconsistent responses of the analog devices at different frequencies lead to a large deviation in the dispersion slope of the stretching line in different frequency bands, and there will be a large difference in the compression results in different frequency bands. Summary of the Invention

[0008] To solve the above-mentioned defects existing in the prior art, the present invention proposes a method for improving the matching degree between the stretching line and the compression line of a Chirp transform spectrum analyzer system, and the method includes:

[0009] Step 1) Build a Chirp transform spectrum analyzer system;

[0010] Step 2) Obtain a relationship diagram between two key parameters of the compression pulse and the frequency modulation slope of the stretching line;

[0011] Step 3) According to the relationship diagram between the two key parameters of the compression pulse and the frequency modulation slope of the stretching line, determine the frequency modulation slope of the stretching line with the optimal single-frequency point matching within the full frequency band of the Chirp transform spectrum analyzer system; wherein, the two key parameters of the compression pulse are the main lobe bandwidth and the peak side lobe ratio of the compression pulse.

[0012] Step 4) Select a preset frequency interval step size, change the frequency of the measured signal, and repeat the above Step 2)-Step 3) until the frequency modulation slope of the stretching line with the optimal single-frequency point matching is determined for each single frequency point;

[0013] Step 5) Determine the optimal matching slope within the full frequency band of the system according to the chirp rate of the optimal matching for each single frequency point.

[0014] As an improvement to the above technical solution, the Chirp transform spectrum analyzer system includes: a chirp line, a multiplier, and a compression line;

[0015] The chirp line is used to generate a Chirp signal and input it to the multiplier;

[0016] The multiplier is used to multiply the signal to be tested and the Chirp signal, and input the product signal to the compression line;

[0017] The compression line is used to perform a convolution operation on the product signal to achieve pulse compression and obtain the spectrum of the signal to be tested; the duration of the impulse response of the compression line is half of the duration of the Chirp signal.

[0018] As an improvement to the above technical solution, the bandwidth of the signal to be tested is less than or equal to 400 MHz.

[0019] As an improvement to the above technical solution, the chirp line is a circuit composed of a signal generator, a filter, a mixer, a first filter bank, an attenuator, an amplifier, and a second filter bank connected in series; among them,

[0020] The signal generator is used to generate a Chirp signal with a frequency of 0.6 - 1.4 GHz;

[0021] The filter is used to filter out the harmonic signals generated by the signal generator and connect the output signal to the RF terminal of the mixer;

[0022] The mixer is used to perform up-conversion on the output signal of the filter and the local oscillator signal of 1.4 GHz input to the local oscillator terminal, and the output signal frequency is 2.0 - 2.8 GHz;

[0023] The first filter bank includes a high-pass filter and a low-pass filter, and this first filter bank is used to filter out other mixed frequency signals and the input signal at its input end in the output signal of the mixer;

[0024] The attenuator is used to attenuate the output signal after passing through the first filter bank and input it to the amplifier;

[0025] The amplifier is used to amplify the output signal of the attenuator and does not exceed the 1 dB compression point, so that the amplification process does not enter the non-linear region;

[0026] The second filter bank includes a high-pass filter and a low-pass filter, and is used to filter out clutter from the signal output by the amplifier to obtain a Chirp signal with a bandwidth of 800 MHz.

[0027] As an improvement to the above technical solution, the signal generator is an analog-to-digital converter.

[0028] As an improvement to the above technical solution, the compression line is a surface acoustic wave filter with a bandwidth of 400 MHz and a dispersion time of 10 μs, preferably a SAW linear frequency modulation dispersion delay line.

[0029] As an improvement to the above technical solution, the center frequency range of the Chirp transform spectrum analyzer system is 500 MHz to 5 GHz, and the bandwidth is 100 MHz to 2 GHz.

[0030] As an improvement to the above technical solution, step 2) specifically includes:

[0031] Input a specific frequency signal, continuously change the chirp slope of the stretching line, record multiple chirp slope values of the stretching line, and record two key parameter values of the main lobe -4 dB bandwidth and peak sidelobe ratio of the corresponding compression pulse, to obtain two key parameters of multiple compression pulses and the chirp slope value of the stretching line. According to the obtained two key parameters of multiple compression pulses and the chirp slope value of the stretching line, draw a relationship diagram of the two key parameters of the compression pulse and the chirp slope of the stretching line, that is, a relationship diagram between the main lobe bandwidth of the compression pulse and the chirp slope value of the stretching line and a relationship diagram between the peak sidelobe ratio of the compression pulse and the chirp slope value of the stretching line.

[0032] As an improvement to the above technical solution, step 3) specifically includes:

[0033] According to the relationship diagram of the two key parameters of the compression pulse and the chirp slope of the stretching line, based on the relationship between the two key parameters changing with the chirp slope of the stretching line, find the chirp slope of the stretching line corresponding to the point where the width of the main lobe -4 dB bandwidth in the compression result is the smallest and the peak sidelobe ratio is the largest, and use this chirp slope as the chirp slope of the optimal matching of a single frequency point within the full frequency band in this Chirp transform spectrum analyzer system; where the two key parameters of the compression pulse are the main lobe bandwidth and peak sidelobe ratio of the compression pulse.

[0034] As an improvement to the above technical solution, step 5) specifically includes:

[0035] Accumulate the chirp slopes of the optimal matching of each frequency point found, and then take the average to obtain the optimal matching slope μ within the full frequency band of this system opt :

[0036]

[0037] Among them, μ i is the broadened linear frequency modulation slope optimally matched for the i-th single frequency point.

[0038] The beneficial effects of the present invention compared with the prior art are as follows:

[0039] 1. The method of the present invention is based on two key parameters of pulse compression. By adjusting the broadened linear frequency modulation slope, slope matching is performed. The method is simple and easy to operate. Only the frequency modulation slope of the Chirp signal generated by the DAC needs to be changed, without changing the circuit structure and improving the SAW linear frequency modulation dispersion filter. It is very suitable for the design of a Chirp transform spectrum analyzer system with a large bandwidth and high frequency.

[0040] 2. This method obtains the optimal value of the broadened line dispersion slope, adjusts the broadened line dispersion slope, so as to improve the matching degree between the broadened line and the compressed line, and improve the performance of the Chirp transform spectrum analyzer system. Description of the Drawings

[0041] Figure 1 is a flowchart of a method for improving the matching degree between the broadened line and the compressed line of a Chirp transform spectrum analyzer system according to the present invention;

[0042] Figure 2 is the circuit structure diagram of the Chirp transform spectrum analyzer system;

[0043] Figure 3 is a schematic diagram of two key parameters of the compressed pulse;

[0044] Figure 4 is a relationship diagram of the -4dB main lobe width and peak sidelobe ratio of the compressed pulse varying with the broadened line dispersion slope when the measured signal is 2GHz;

[0045] Figure 5 is the optimal broadened line dispersion slope diagram of each frequency point in the Chirp transform spectrum analyzer system. Detailed Embodiment

[0046] The present invention will be further described in conjunction with the accompanying drawings.

[0047] The present invention provides a method for improving the matching degree between the stretching line and the compression line of a Chirp transform spectrum analyzer system. In the Chirp transform spectrum analyzer system, the matching degree between the stretching line and the compression line is directly related to the performance parameters of the spectrum analyzer system. The method of the present invention is based on a Chirp transform spectrum analyzer system with a large bandwidth and high frequency. The larger bandwidth makes the original analog method for generating the stretching line no longer applicable, and a digital method needs to be used to generate the stretching line, making the original matching method between the stretching line and the compression line no longer applicable. The method of the present invention aims to maximize the matching between the stretching line and the compression line and improve the frequency resolution and dynamic range of the Chirp transform spectrum analyzer system.

[0048] The method includes:

[0049] Build a Chirp transform spectrum analyzer system;

[0050] Within the full frequency band, determine the stretching line frequency modulation slope of each single frequency point, and match the optimal stretching line frequency modulation slope for each single frequency point;

[0051] According to the optimal stretching line frequency modulation slopes matched by each single frequency point in the full frequency band within the band, obtain the optimal matching frequency modulation slope value of the Chirp transform spectrum analyzer system.

[0052] As Figure 1 shown, the method specifically includes:

[0053] Step 101) Build a Chirp transform spectrum analyzer system;

[0054] Specifically, as Figure 2 shown, the Chirp transform spectrum analyzer system includes: a stretching line, a multiplier, and a compression line;

[0055] The stretching line is used to generate a Chirp signal and input it into the multiplier;

[0056] The multiplier is used to multiply the signal to be tested and the Chirp signal, and input the product signal into the compression line;

[0057] The compression line is used to perform a convolution operation on the product signal to achieve pulse compression and obtain the spectrum of the signal to be tested; the duration of the impulse response of the compression line is half of the duration of the Chirp signal.

[0058] Among them, the bandwidth of the signal to be tested is less than or equal to 400 MHz.

[0059] Among them, the stretching line is a circuit composed of a signal generator, a filter, a mixer, a first filter bank, an attenuator, an amplifier, and a second filter bank connected in series; among them,

[0060] The signal generator is used to generate a Chirp signal with a frequency ranging from 0.6 GHz to 1.4 GHz;

[0061] The filter is used to filter out the harmonic signals generated by the signal generator and connect the output signal to the RF terminal of the mixer;

[0062] The mixer is used to up-convert the output signal of the filter and the local oscillator signal of 1.4 GHz input at the local oscillator terminal, and the output signal frequency is 2.0 GHz to 2.8 GHz;

[0063] The first filter bank includes a high-pass filter and a low-pass filter, and this first filter bank is used to filter out other mixed frequency signals and the signals at its input terminal in the output signal of the mixer;

[0064] The attenuator is used to attenuate the output signal after passing through the first filter bank and input it to the amplifier;

[0065] The amplifier is used to amplify the output signal of the attenuator and does not exceed the 1 dB compression point, so that the amplification process does not enter the non-linear region;

[0066] The second filter bank includes a high-pass filter and a low-pass filter, and this second filter bank is used to filter out clutter from the signal output by the amplifier to obtain a Chirp signal with a bandwidth of 800 MHz.

[0067] Among them, the signal generator is an analog-to-digital converter.

[0068] Among them, the compression line is a surface acoustic wave filter with a bandwidth of 400 MHz and a dispersion time of 10 μs, preferably a SAW linear frequency modulation dispersion delay line.

[0069] Among them, the center frequency range of the Chirp transform spectrum analyzer system is from 500 MHz to 5 GHz, and the bandwidth is from 100 MHz to 2 GHz.

[0070] Step 102) Obtain a relationship diagram between two key parameters of the compression pulse and the chirp slope of the stretching line;

[0071] Specifically, as Figure 3 shown, the two key parameters of the compression pulse are the -4 dB bandwidth of the main lobe of the compression pulse and the peak sidelobe ratio; the -4 dB width of the main lobe is: within one compression period, obtain the peak value of the main lobe of the compression pulse and calculate the pulse duration τ at its -4 dB; peak sidelobe ratio: within one compression period, obtain the peak value of the main lobe of the compression pulse and obtain the maximum sidelobe peak value near the main lobe, and calculate the ratio of the main lobe peak value to the maximum sidelobe peak value.

[0072] Input a specific frequency signal, continuously change the broadening linear frequency modulation slope, record multiple broadening linear frequency modulation slope values, and record the two key parameter values of the main lobe -4dB bandwidth and peak sidelobe ratio of the corresponding compressed pulse, obtain the two key parameters of the compressed pulse and the broadening linear frequency modulation slope value for multiple groups, and based on the obtained two key parameters of the compressed pulse and the broadening linear frequency modulation slope value for multiple groups, plot the relationship diagram between the two key parameters of the compressed pulse and the broadening linear frequency modulation slope, that is, the relationship diagram between the main lobe bandwidth of the compressed pulse and the broadening linear frequency modulation slope value and the relationship diagram between the peak sidelobe ratio of the compressed pulse and the broadening linear frequency modulation slope value, as Figure 4 shown.

[0073] Step 103) Determine the broadening linear frequency modulation slope with the best match for a single frequency point within the full frequency band in the Chirp transform spectrum analyzer system according to the relationship diagram between the two key parameters of the compressed pulse and the broadening linear frequency modulation slope; wherein, the two key parameters of the compressed pulse are the main lobe bandwidth and peak sidelobe ratio of the compressed pulse;

[0074] Specifically, according to the relationship diagram between the two key parameters of the compressed pulse and the broadening linear frequency modulation slope, based on the relationship between the two key parameters changing with the broadening linear frequency modulation slope, find the broadening linear frequency modulation slope corresponding to the point where the width of the main lobe -4dB bandwidth in the compression result is the smallest and the peak sidelobe ratio is the largest, and use this broadening linear frequency modulation slope as the broadening linear frequency modulation slope with the best match for a single frequency point within the full frequency band in the Chirp transform spectrum analyzer system; wherein, the two key parameters of the compressed pulse are the main lobe bandwidth and peak sidelobe ratio of the compressed pulse. Step 104) Select a preset frequency interval step size, change the frequency of the measured signal, and repeat the above steps 2)-3) until the broadening linear frequency modulation slope with the best match for each single frequency point is determined; wherein, in this embodiment, the bandwidth of the chirp transform spectrum analyzer system is 400 MHz, and the selected frequency interval step size is 50 MHz.

[0075] Step 105) Determine the best matching slope within the full frequency band of the system according to the broadening linear frequency modulation slope with the best match for each single frequency point.

[0076] Specifically, the best broadening linear dispersion slope diagram for each frequency point of the system is as Figure 5 shown, and the best slope within the full frequency band of the system is the average value of the best frequency modulation slopes for each frequency point.

[0077] Specifically, add up the best matching broadening linear frequency modulation slopes for each frequency point found, and then take the average to obtain the best matching slope μ opt :

[0078]

[0079] wherein, μ iThe widened linear frequency modulation slope that is optimally matched for the i-th single frequency point.

[0080] Embodiment 1.

[0081] Use Matlab to generate initial waveform data, transmit the data to the FPGA through the serial port, the FPGA controls the data transmission to the signal generator DAC to generate a Chirp signal, and through the amplification, filtering, frequency multiplication and amplification analog circuits, meet the requirements of the local oscillator end of the mixer, form a widened line, and input it into the multiplier; the multiplier multiplies the signal to be tested and the Chirp signal, and inputs the product signal into the compression line (SAW linear frequency modulation dispersion filter); the compression line performs a convolution operation on the product signal to achieve pulse compression and obtain the spectrum of the signal to be tested; the duration of the pulse response of the compression line is half of the duration of the Chirp signal.

[0082] Among them, the bandwidth of the Chirp transform spectrum analyzer system is 400 MHz, the center frequency is 2 GHz, input a 2 GHz signal to be measured, use the ADC acquisition system to compress the pulse, calculate the main lobe -4 dB bandwidth and peak sidelobe ratio of the compressed pulse through Matlab, and record the widened linear frequency modulation slope and the values of the above two key parameters at this time. Change the widened linear frequency modulation slope, with an interval of 0.001 MHz / μs, repeat the acquisition of the compressed pulse, calculate the two key parameters, and generate a relationship diagram of the two key parameters respectively with the widened linear frequency modulation slope, as Figure 4 shown.

[0083] According to the relationship diagram of the two key parameters and the widened linear frequency modulation slope, find the point with the smallest main lobe -4 dB and the highest peak sidelobe ratio, and determine that the nearby points are also close to the optimum. Determine that the widened linear frequency modulation slope of the signal to be measured at 2 GHz is near 39.95 MHz / μs. In this example, the frequency modulation slope of 39.950 MHz / μs is selected.

[0084] In this embodiment, the bandwidth of the Chirp transform spectrum analyzer system is 400 MHz, with a 50 MHz frequency interval, measure the optimal frequency modulation slope of the system at each frequency point, and make a diagram of the optimal widened linear frequency modulation slope at each frequency point, as Figure 5 shown. The average value of the optimal frequency modulation slopes at each frequency point is used as the optimal frequency modulation slope value within the frequency band of this system. In this example, the frequency modulation slope of 39.943 MHz / μs is selected as the optimal slope matching of the system.

[0085] The method of the present invention is based on the relationship between the widened linear frequency modulation slope and the compression result, and improves the matching degree of the system by adjusting the widened linear frequency modulation slope. The method is simple and easy to operate. It only needs to change the frequency modulation slope of the Chirp signal generated by the DAC, without changing the circuit structure and improving the SAW linear frequency modulation dispersion filter, and is very suitable for the design of a Chirp transform spectrum analyzer with a large bandwidth and high frequency.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for improving the matching degree between the broadening line and the compression line of a Chirp transform spectrum analyzer system, the method comprising: Step 1) Build a Chirp transform spectrum analyzer system; Step 2) Obtain a relationship diagram between two key parameters of the compression pulse and the frequency modulation slope of the broadening line; Step 3) According to the relationship diagram between the two key parameters of the compression pulse and the frequency modulation slope of the broadening line, determine the frequency modulation slope of the broadening line with the optimal single-frequency point matching within the full frequency band of the Chirp transform spectrum analyzer system; wherein, the two key parameters of the compression pulse are the main lobe bandwidth and the peak sidelobe ratio of the compression pulse; Step 4) Select a preset frequency interval step size, change the frequency of the signal to be measured, and repeat the above Step 2)-Step 3) until the frequency modulation slope of the broadening line with the optimal single-frequency point matching is determined for each single-frequency point; Step 5) According to the frequency modulation slopes of the broadening lines with the optimal single-frequency point matching, determine the optimal matching slope within the full frequency band of the system.

2. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 1, characterized in that, The Chirp transform spectrum analyzer system includes: a broadening line, a multiplier, and a compression line; The broadening line is used to generate a Chirp signal and input it to the multiplier; The multiplier is used to multiply the signal to be tested and the Chirp signal, and input the product signal to the compression line; The compression line is used to perform a convolution operation on the product signal to achieve pulse compression and obtain the spectrum of the signal to be tested; the duration of the pulse response of the compression line is half of the duration of the Chirp signal.

3. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 2, characterized in that The bandwidth of the signal to be tested is less than or equal to 400 MHz.

4. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 2, wherein The broadening line is a circuit composed of a signal generator, a filter, a mixer, a first filter bank, an attenuator, an amplifier, and a second filter bank connected in series; wherein, The signal generator is used to generate a Chirp signal with a frequency of 0.6 - 1.4 GHz; The filter is used to filter out the harmonic signals generated by the signal generator and connect the output signal to the RF terminal of the mixer; The mixer is used to perform up-conversion on the output signal of the filter and the local oscillator signal of 1.4 GHz input to the local oscillator terminal, and the output signal frequency is 2.0 - 2.8 GHz; The first filter bank includes a high-pass filter and a low-pass filter, and this first filter bank is used to filter out other frequency-converted signals and the signals at its input terminal mixed in the output signal of the mixer; The attenuator is used to attenuate the output signal after passing through the first filter bank and input it to the amplifier; The amplifier is used to amplify the output signal of the attenuator and does not exceed the 1 dB compression point, so that the amplification process does not enter the non-linear region; The second filter bank includes a high-pass filter and a low-pass filter, and this second filter bank is used to filter out clutter from the signal output by the amplifier and obtain a Chirp signal with a bandwidth of 800 MHz.

5. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 4, characterized in that The signal generator is an analog-to-digital converter.

6. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 2, wherein The compression line is a surface acoustic wave filter with a bandwidth of 400 MHz and a dispersion time of 10 μs, preferably a SAW linear frequency modulation dispersion delay line.

7. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 1, characterized in that The center frequency range of the Chirp transform spectrum analyzer system is from 500 MHz to 5 GHz, and the bandwidth is from 100 MHz to 2 GHz.

8. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 1, characterized in that The specific content of Step 2) includes: Input a specific frequency signal, continuously change the broadening linear frequency modulation slope, record multiple broadening linear frequency modulation slope values, and record the two key parameter values of the main lobe -4dB bandwidth and peak sidelobe ratio of the corresponding compressed pulse, obtain the two key parameters of multiple compressed pulses and the broadening linear frequency modulation slope values, and draw a relationship diagram of the two key parameters of the compressed pulse and the broadening linear frequency modulation slope, that is, a relationship diagram between the main lobe bandwidth of the compressed pulse and the broadening linear frequency modulation slope value and a relationship diagram between the peak sidelobe ratio of the compressed pulse and the broadening linear frequency modulation slope value.

9. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 1, characterized in that The specific content of step 3) includes: According to the relationship diagram of the two key parameters of the compressed pulse and the broadening linear frequency modulation slope, based on the relationship between the two key parameters changing with the broadening linear frequency modulation slope, find the broadening linear frequency modulation slope corresponding to the point where the width of the main lobe -4dB bandwidth in the compression result is the smallest and the peak sidelobe ratio is the largest, and use this broadening linear frequency modulation slope as the broadening linear frequency modulation slope with the best single-frequency point matching within the full frequency band in the Chirp transform spectrum analyzer system; among them, the two key parameters of the compressed pulse are the main lobe bandwidth and peak sidelobe ratio of the compressed pulse.

10. The method for improving the matching degree between the broadening line and the compression line of the Chirp transform spectrum analyzer system according to claim 1, characterized in that, The specific content of step 5) includes: Accumulate the spread linear frequency modulation slopes of the optimal matches at each found frequency point, and then calculate the average to obtain the optimal matching slope μ within the full frequency band of the system. opt : Among them, μ i is the chirp rate of the spread FM for the optimal match of the i-th single frequency point.

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