CN107271967B

CN107271967B - Pulse coherent transponder same-frequency interference processing system

Info

Publication number: CN107271967B
Application number: CN201611057684.4A
Authority: CN
Inventors: 陈霞; 黄伟; 范义平
Original assignee: Southwest Electronic Technology Institute No 10 Institute of Cetc
Current assignee: Southwest Electronic Technology Institute No 10 Institute of Cetc
Priority date: 2016-11-26
Filing date: 2016-11-26
Publication date: 2020-03-31
Anticipated expiration: 2036-11-26
Also published as: CN107271967A

Abstract

The invention provides a same frequency interference processing system of a pulse coherent responder, which can solve the self-excitation problem of the same frequency interference of the pulse coherent responder and ensure the working stability of the responder. The invention is realized by the following technical scheme: after the pulse transponder antenna receives the radio frequency signal, the radio frequency signal F_RThe signal enters a field amplifier module through a circulator, the signal is filtered and amplified by the field amplifier module and then is controlled by a microwave switch, the controlled radio frequency signal and a local oscillator signal are mixed to output an intermediate frequency signal, the intermediate frequency signal is amplified and detected by the field amplifier module and then is transmitted to an analog/digital (A/D) acquisition module of a digital circuit module, the acquired signal is stored and forwarded through a digital delay line, the time sequence control of the digital delay line is controlled by a receiving and transmitting time sequence control circuit, the forwarded signal is transmitted to a D/A converter to output an intermediate frequency signal, the intermediate frequency signal is up-converted by a transmitting channel module and then is amplified by a power amplifier module, and the amplified signal_TAnd output through the circulator. The invention solves the self-excitation problem of pulse receiving and transmitting with the same frequency.

Description

Pulse coherent transponder same-frequency interference processing system

Technical Field

The invention relates to a co-frequency interference processing system of a pulse coherent transponder in a single pulse transponder of a pulse system measuring system.

Background

Monopulse radar is a type of precision tracking radar. The measurement accuracy is generally expressed in terms of the magnitude of the data error of the radar output. When a target is positioned on an antenna axis, the amplitude and the phase of each wave beam echo signal are equal, and the signal difference is zero; when the target is not on the antenna axis, the amplitude and phase of each wave beam echo signal are unequal, signal difference is generated, the antenna is driven to rotate to the target until the antenna axis is aligned with the target, so that the elevation angle and the azimuth angle of the target can be measured, the distance of the target can be measured from the sum of the signals received by each wave beam, and the target can be measured and tracked. The distance measuring system of the radar has a very important position in a single-pulse precision measuring radar, the function of the distance measuring system is to obtain the measurement tracking of the radial distance of the radar by processing the radar echo, and the servo system performs space angle position tracking on the basis, so that the distance measuring system and the servo system form the measurement basis of the single-pulse precision tracking measuring radar. A single pulse refers to information on the number of echo pulses on which a single pulse can extract target angular position information. The monopulse measurement radar belongs to the simultaneous lobe method angle measurement, and can obtain all information of a target by only comparing the same echo pulse received by each wave beam. However, due to the continuous characteristic of observation and measurement of the target, the radar needs to continuously receive the echo signal and continuous transmission pulse of the target, and after a series of target information is obtained, the information can be scientifically processed, so that the information with high precision and high authenticity on the target can be obtained. Early monopulse precision measurement radar ranging subsystems are independent subsystems, and tracking and measuring targets are usually 'pure targets' (namely high-altitude targets) without clutter interference. When facing complex electromagnetic environments such as ground clutter interference and the like, the modern distance measuring machine needs to adopt complex high-intensity real-time processing technologies such as coherent accumulation, clutter cancellation, constant false alarm detection, vernier distance measurement, broadband distance measurement and the like, the digital signal processing function of the modern distance measuring machine is more and more prominent, the boundary with a signal processing subsystem is more and more fuzzy, and the integrated design and processing of the two technologies is a development direction. Monopulse precision measurement radar ranging systems typically have the characteristics of …:1) high range measurement accuracy, which is affected by many factors, such as range zero settling, receiver delay, dynamic lag due to target motion, transponder delay, propagation errors, thermal noise errors, quantization errors, timing jitter, and the like. The errors can be divided into systematic errors and random errors, the systematic errors refer to errors that are measured with the change of the measurement time and the magnitude of the measurement amplitude is kept constant or slowly changes according to a certain rule, the predictability is realized, and proper proofreading and partial modification can be carried out on the technology before or after the measurement; the random error refers to an error whose measurement amplitude is uncertain or rapidly changes along with the change of time, such an error cannot be predicted before measurement, cannot be corrected and modified after measurement, and can be reduced only by some methods, and a commonly used method is a filtering technology. The system errors mainly comprise shafting errors, data transmission system errors, dynamic lag errors and atmospheric propagation errors. While random errors are mainly caused by thermal noise. Random errors are mainly caused by measurement noise caused by target flicker in the measurement process, and the noise mostly conforms to white Gaussian noise in a white process. Systematic errors need to be corrected to eliminate, and random errors can be suppressed by smooth filtering. In radar system errors, the influence caused by shafting errors and data transmission system errors is large. The errors of the radar in measuring the angular coordinate are angle tracking measurement errors, and the error sources are three types, namely tracking errors, conversion errors and propagation errors, so that the antenna axis of the radar deviates from a target angle, and the axis angle report is inaccurate, and the three error sources respectively contain respective system errors and random errors. Range tracking measurement errors can cause the centroid of the radar range gate or target gate pulse to deviate from the target echo pulse. Conversion errors associated with radar can result in false reports of delayed versions of the gate or strobe and affect tracking errors and propagation errors associated with the target.

The target to be detected by the radar is typically a moving object, such as an airborne aircraft, a vehicle on the ground of a marine vessel, etc. There are often various backgrounds around the target, such as various terrain, clouds, waves, and released wire disturbances. These backgrounds may be completely immobile, such as mountains and buildings, or may be slow moving, such as waves and wire disturbances in the presence of wind, and generally have much lower speeds than the target, and the echoes produced by these backgrounds are called clutter or passive disturbances. When clutter and moving target echoes are displayed simultaneously on the radar display, the observation of the target can be made difficult. If the target is within the clutter background, the weak target is annihilated in the strong clutter, especially when the strong clutter overloads the receiving system, finding the target is very difficult. When the target is not in the clutter background, it is not easy to quickly distinguish the moving target echo in the patch clutter. If the radar terminal employs an automatic detection and data processing system, the presence of a large amount of clutter may overload the chess terminal or unnecessarily increase the capacity and complexity of the system. Therefore, whether from the viewpoint of anti-interference or improving the radar tracking quality, selecting the moving target echo to suppress the fixed clutter background is an important problem. Modern radar signal processing Moving Target Detection (MTD) generally uses a digital processing technique, and performs digital processing after a/D conversion on an echo signal, that is, a clock signal with a specific frequency is used for driving, radar echoes are sampled from the beginning of a repetition period until the repetition period is finished, and each clock period corresponds to a range gate. The signal processor can process all or part of range gate data in the repetition period according to the radar working mode control instruction word. The processing mechanism has the defects that 1) the modern radar usually adopts linear frequency modulation signals, the video envelope of the signals is bell-shaped after matching and compression processing, the signals are not lost when the signals are sampled at the peak position of the bell-shaped envelope, and the signals are slightly lost when the signals are sampled at other positions. If the sampling clock frequency is high enough, the sampling loss is negligible, but this results in a large amount of processed data and cannot be applied in engineering practice. So this method has a problem of slight loss of signal-to-noise ratio. Modern radar signal processing Moving Target Detection (MTD) usually adopts resident inter-repetition frequency parameter difference, if an echo signal falls on a clear filter unit of FFT during processing of a certain resident MTD, repetition frequency is not changed, otherwise, repetition frequency needs to be changed, and a control mode generally adopts a cyclic recursion in sequence according to [ repetition frequency l, repetition frequency 2, …, repetition frequency. By adopting the method, the problem of 'blind speed' is basically solved under the condition of small target acceleration, and the measurement precision is not influenced when the occasionally occurring individual dwell period signal falls on an unclear filter unit of the FFT. The method has the advantage of not requiring accurate target velocity measurement information, and works especially when target velocity measurements are difficult under low signal-to-noise ratio conditions. The method has the disadvantages that the echo signals of the individual residual repetition frequencies fall on the FFT unclear filter, and improvement is needed for the precision measurement requirements that each echo can be effectively detected and the like.

In the conventional working process of the distance measuring system, when a distance measuring machine searches a target, a signal processing subsystem searches in a specified detection range by taking a gate as a center, a primary threshold and a secondary threshold are set, after the target is found according to a set threshold detection criterion, information such as a distance value between a detection unit where the target is located and the center of the gate, an effective mark and the like is sent to the distance measuring machine, the distance measuring machine adjusts the position of the gate according to detection information, then the wide gate tracking (namely, broadband tracking) is carried out, and after a loop is adjusted stably, the narrow band tracking is carried out. After the distance measuring machine performs tracking, the signal processing subsystem detects the echo within the range of the wave gate and extracts the distance error for the distance measuring machine to perform closed-loop filtering. If the detection criterion is met in the memory tracking process, the memory tracking mark is cleared and the normal tracking is changed. In the tracking process, ranging requires disambiguation, blindness avoidance, counter-switching, and multi-station operation … as needed.

The radar anti-interference problem is a very important problem in an intricate and complex electromagnetic environment. In order to complete the tracking measurement of the whole task segment, a plurality of same-frequency radars are often needed to perform relay tracking measurement on the same target. In order to increase the redundancy of measurement, in actual work, a multi-station working mode is often adopted, which brings about a problem that the multi-station co-channel interference is caused. When the interference is serious, the radar tracking target is easy to lose. The same-frequency interference refers to the interference caused by the receiver which receives the same-frequency useful signal, wherein the carrier frequency of the useless signal is the same as that of the useful signal. Usually, the task segments of the radars have cross overlapping parts, that is, the condition that a plurality of radars simultaneously track the same target occurs in the task process, so that relay and redundancy of measured data are realized. Because the multiple stations of radars work at the same frequency and share the same set of transponder, and the transponder can only respond to one trigger signal at the same time, when the multiple sets of radar trigger signals reach the transponder at the same time, only one signal is responded, and other radars can lose targets. Co-channel interference has become a key factor affecting normal tracking measurement, and many single-pulse measurement and control devices have identified co-channel interference phenomena in the tracking process as a major risk. However, the mechanism for resisting co-channel interference is not improved correspondingly, and at present, a guard gate area is mainly adopted to be arranged in front of a wave gate, and co-channel interference is avoided by detecting interference signals in the guard gate area and combining phase shifting. Because the existing monopulse radar can not directly distinguish the interference signal of other stations from the coherent signal of the station generallyDuring the answering type tracking, the position of the aircraft carrier reflection signal must be deducted, and a dead zone of a satellite gate is caused. . The existing anti-co-frequency interference mechanism can generate larger influence on the tracking measurement process due to the co-frequency interference problem, and the existing anti-co-frequency interference mechanism mainly adopts the mode that a guard detection area is arranged in front of a gatekeeper to reduce the risk of co-frequency interference. The blind avoidance process causes the same frequency interference to be in a condition that the radar of the station B does not track the target, the front guard gate does not work at the moment, and when the signal of the station B is close to the signal normally tracked by the station A from the rear, the signal of the station B can slowly enter the wave gate of the station A, so that the error of the measured data is increased. The radar can not distinguish other station interference signals from the local station coherent signals, so that the local station coherent reflection signals are mistakenly taken as the other station interference signals during the guard gate detection, or the other station interference signals falling into the blind area of the guard gate are considered as the local station coherent signals, so that the phase shifting action is started when the phase shifting is not needed, and the phase shifting action is not started correctly when the phase shifting is needed. Therefore, the inability of the radar to distinguish between signal coherence is the source of the problem. If the radar can identify whether the signal in the guard gate area is sent by the station, the guard gate blind area is not needed, so that the reliability of resisting same frequency interference is improved, and the emission pulse of each radar is required to have self uniqueness. Co-channel interference is a condition often encountered when the same type of radar works at a short distance, which causes the radar to find that the frequency of a received signal of a pulse coherent transponder is f_RThe frequency of the transmitted signal being f_TLocal oscillator frequency of f_oReceiving an intermediate frequency signal having a frequency f_IRAt a frequency f of the transmitted intermediate frequency signal_IT。

The design scheme according to the frequency relation of the pulse transponder comprises the following steps:

f_R＝f_IR+f_o(1)

f_T＝f_IT+f_o(2)

when required f_R＝f_TWhen the formula (1) is equal to the formula (2), f can be easily deduced_IR＝f_IT. Therefore, according to the calculation, only the coherent forwarding characteristic of the intermediate frequency signal needs to be ensured in order to ensure the coherent forwarding characteristic of the pulse responder, and the coherent forwarding characteristic is irrelevant to the local oscillator signal.

The enemy target is subjected to strong same frequency interference of own radar before, and the detection performance of the radar is sharply reduced and even completely paralyzed. At present, the suppression of the same frequency interference is mainly to find out the difference between the interference and the real echo from the aspects of time domain, frequency domain, space domain, polarization domain and the like, and take measures to eliminate the interference.

How to solve the problem of co-channel interference becomes a core problem of coherent forwarding design of the pulse responder. Especially, after the transmitted signal is amplified by power, the signal energy is large, and the signal energy can directly enter a receiving channel in the pulse responder, so that the pulse responder can automatically receive and generate self-excitation problems. In the prior art, a processing scheme of transmitting and receiving time-sharing work is generally adopted for the self-excitation problem of the pulse responder. However, the pulse transponder of the conventional analog system adopts an analog circuit scheme based on a microwave switch, is limited by isolation indexes of analog circuits such as a circulator and the microwave switch, and still interferes a receiving channel when the power of a transmitted signal is high, so that the pulse transponder transmits spontaneous pulses, and the work is abnormal.

In summary, in a monopulse radar measurement system, in order to ensure the distance resolution and the ranging accuracy of the measurement system, it is generally required that the narrower the pulse width of a pulse signal is, the better the pulse width is, and that the forwarding delay of a pulse transponder is stable; in order to ensure the speed measurement precision, the carrier frequency of a downlink signal forwarded by the pulse transponder is required to be equal to the carrier frequency of an uplink signal of the radar and coherent, which is equivalent to a coherent forwarding ratio, the signal receiving and transmitting of the pulse transponder has the same frequency, and the problem of same frequency interference must be considered in the design. Meanwhile, after coherent forwarding processing of the pulse responder, the stability of forwarding time delay can be improved, and the pulse power of the forwarded signal is improved, so that the quality of an echo signal received by the ground station is improved, and finally the working distance and the measurement precision of the ground radar are improved.

Disclosure of Invention

The invention provides a simple, reliable, flexible and expandable co-frequency interference processing system of a pulse coherent transponder, which aims to solve the problem of co-frequency interference of the transmitting and receiving signals of the single pulse transponder in a pulse radar measurement system, improve the reliability of resisting co-frequency interference, ensure the reliable work of the single pulse transponder and avoid the self-excitation problem of the single pulse transponder.

The above object of the present invention can be achieved by the following means. A pulse coherent transponder co-channel interference processing system, comprising: circulator, received signal module, power amplifier module, transmission channel module, local oscillator and digital circuit module, its characterized in that: the pulse transponder selects the radio frequency signal F with the same frequency of the receiving frequency and the transmitting frequency_RThe intermediate frequency signal is amplified and detected by the intermediate amplifier module and then divided into two paths, one path is sent to the digital circuit module for A/D acquisition and conversion into a digital signal, the digital signal is subjected to time delay storage in the FPGA circuit, the other path of pulse detection signal output by the intermediate amplifier module is subjected to time sequence processing of completely closed received signals in the FPGA circuit by a transceiving time sequence control circuit by taking the leading edge pulse of a reference pulse as a reference, a time delay forwarding control pulse, a microwave switch pulse delay and a power amplifier detection pulse are generated, the received pulse detection signal is subjected to time sequence control by adopting pulse time sequence control, a regenerated detection reference pulse is generated to control a delay storage circuit to realize a digital delay line, and the A/D digital signal acquisition signal is stored and forwarded by the digital delay line, the forwarded signal is sent to a D/A converter, converted into an analog intermediate frequency signal through D/A, and the analog intermediate frequency signal is sent to a power amplification module for amplification through up-conversion of a transmitting channel module; when the power amplifier detection pulse is at high level, the power amplifier module amplifies the radio frequency signal F_TThe pulse modulated signal is output through the circulator.

Compared with the prior art, the invention has the following beneficial effects:

is simple and reliable. After the pulse responder receives a signal, the received signal is filtered and amplified through the field amplifier module, the amplified signal is mixed with the mixer down, the intermediate frequency signal obtained by mixing is amplified and detected through the intermediate amplifier module and is sent to the A/D converter for sampling and conversion into a digital signal, the digital signal is delayed and stored for a certain time (the delay time is programmable) in the FPGA circuit, the delayed signal is converted into an analog intermediate frequency signal through the D/A converter, and the analog intermediate frequency signal is amplified and output through the power amplifier module after being up-converted through a transmitting channel. And the channel design of the pulse responder is simplified through the same-frequency coherent forwarding design.

Has flexibility and expansibility. After the antenna of the pulse transponder receives the radio frequency signal, the radio frequency signal F_RThe signal enters the field amplifier module through the circulator, after the signal is filtered and amplified by the field amplifier module, the signal is controlled by the microwave switch, the controlled radio frequency signal and the local oscillator signal are mixed to output an intermediate frequency signal, after the intermediate frequency signal is amplified and detected by the field amplifier module, the intermediate frequency signal is transmitted to the A/D acquisition of the digital circuit module in a digital storage mode, the acquired signal is stored and forwarded through a digital delay line, the forwarded signal is transmitted to the D/A converter to output the intermediate frequency signal, after the intermediate frequency signal is up-converted by the transmitting channel module, the intermediate frequency signal is amplified by the power amplifier module, and the amplified signal F is transmitted to the transmitter module_TAnd output through the circulator. The time delay of the pulse responder is programmable, and the flexibility and the expansibility of the pulse responder are enhanced.

The self-excitation problem of the pulse responder is solved. On the basis of the analog circuit scheme based on the microwave switch, the invention adds the pulse time sequence control based on the digital circuit to realize the time-sharing work of the receiving and sending of the pulse responder, namely when the power amplifier works, the time sequence processing of completely closed received signals is generated in the FPGA circuit. In the digital circuit module, a receiving and transmitting time sequence control circuit receives a pulse detection signal output by a middle amplifier module, and the signal is subjected to time sequence control by adopting a pulse time sequence control method to generate a microwave switch pulse, a delay forwarding control pulse and a power amplifier detection pulse, so that the problems of pulse answering machine of the traditional analog system, namely, the pulse answering machine of the traditional analog system is limited by a circulator by adopting an analog circuit isolation index based on a microwave switch, and when the power of a transmitted signal is high, the receiving channel is interfered, the pulse answering machine forwards a spontaneous pulse, self-excitation of same frequency interference and abnormal pulse answering machine during working are caused are fundamentally solved. The invention shields the self-excitation detection pulse generated by the interference of the power amplifier transmitting signal with the receiving channel on the reference signal through the regenerative pulse time sequence control, thereby effectively solving the self-excitation problem of pulse receiving and transmitting with the same frequency.

Drawings

The invention is further described with reference to the following figures and examples.

FIG. 1 is a schematic circuit diagram of a coherent transponder co-channel interference processing system according to the present invention.

Fig. 2 is a pulse timing control waveform diagram for the pulse coherent transponder of fig. 1.

Fig. 3 is a schematic diagram of the pulse measurement principle of the pulse transponder.

Detailed Description

See fig. 1. In the following embodiments, an impulse coherent transponder co-channel interference processing system includes: circulator, received signal module, power amplifier module, transmission channel module, local oscillator and digital circuit module. Firstly, in order to ensure coherent forwarding of the pulse transponder, the frequency relation of the pulse transponder selects the same frequency of the receiving frequency and the transmitting frequency, and the coherent forwarding ratio. Meanwhile, for the miniaturization design of the transponder, the pulse transponder receives and transmits signals by adopting a one-time frequency conversion scheme and shares a local oscillator. The pulse transponder selects the radio frequency signal F with the same frequency of the receiving frequency and the transmitting frequency_RThe intermediate frequency signal is amplified and detected by the intermediate amplifier module and then divided into two paths, one path is sent to the digital circuit module for A/D acquisition and conversion into a digital signal, the digital signal is subjected to time delay storage in the FPGA circuit, the pulse detection signal output by the intermediate amplifier module in the digital circuit module is subjected to time sequence control on the received pulse detection signal by a transceiving time sequence control circuit by taking the leading edge pulse of a reference pulse as a reference, a delay forwarding control pulse, a microwave switch pulse delay and a power amplifier detection pulse are generated in the FPGA circuit, the time sequence processing of a completely closed received signal is generated, the pulse time sequence control is adopted to carry out time sequence control on the received pulse detection signal, the regenerated detection reference pulse controls the delay storage circuit to realize a digital delay line, and the A/D digital signal acquisition signal is stored and forwarded through the digital delay line, the forwarded signal is sent to a D/A converter, converted into an analog intermediate frequency signal through D/A, and the output analog intermediate frequency signal is sent to a power amplification module for amplification through up-conversion of a transmitting channel module; power amplifierWhen the power amplifier detects the pulse to be high level, the module amplifies the radio frequency signal F_TThe pulse modulated signal is output through the circulator.

Let the frequency of the received signal of the pulse coherent transponder be f_RThe frequency of the transmitted signal being f_TLocal oscillator frequency of f_oReceiving an intermediate frequency signal having a frequency f_IRAt a frequency f of the transmitted intermediate frequency signal_IT°

f_R＝f_IR+f_o(1)

f_T＝f_IT+f_o(2)

The receiving channel module includes: the field amplifier module, the microwave switch and the mixer are sequentially connected in series, and after the radio-frequency signal is received by the frequency pulse transponder antenna, the radio-frequency signal F_REntering the field discharge module through a circulator, a radio frequency signal F_RAfter the intermediate frequency signal is amplified and detected by the intermediate amplifier module, the intermediate frequency signal is sent to a receiving and transmitting time sequence control circuit to carry out regeneration processing on a pulse detection signal output by the intermediate amplifier detection, after the pulse signal is inverted, the inverted pulse signal is compared with an inverted pulse phase of a microwave switch pulse to obtain a new reference detection pulse, a leading edge pulse of the reference pulse is taken as a reference to generate a delay forwarding control pulse, an acquisition signal is stored and forwarded by a digital delay line, and the forwarded signal outputs the intermediate frequency signal through a D/A converter.

The intermediate frequency signal is up-converted by the transmitting channel module, amplified by the power amplifier module, and the amplified signal F_TAnd output through the circulator. Meanwhile, in the digital circuit module, the receiving and transmitting time sequence control circuit receives the pulse detection signal output by the intermediate amplifier module and adopts the pulseThe sequence control method carries out time sequence control on the signal to generate microwave switch pulse, delay forwarding control pulse and power amplifier detection pulse. The microwave switch sends the pulse to the microwave switch control end of the receiving channel module, and the receiving channel is closed in time when the power amplifier works. The receiving and transmitting time sequence control circuit transmits the delay forwarding control pulse to the digital delay line, the delay time is programmed in the FPGA, the power amplifier detection pulse generated by the delay forwarding control of the pulse coherent responder is transmitted to the power amplifier module, and only when the power amplifier detection pulse is in a high level state, the power amplifier module outputs a pulse modulation signal.

According to the waveform diagram of fig. 2, the pulse detection signal is a negative pulse signal with a pulse width of 0.6us, which is detected and output by the intermediate amplifier module. The microwave switch pulse is a control pulse signal for controlling the on-off of a microwave switch of the receiving channel module, the control pulse signal is a positive pulse signal with the pulse width of 35.7us, and when the control pulse signal is at a high level, the control pulse signal indicates that the receiving channel is closed. After the pulse detection signal output by the intermediate amplifier module is inverted by the regenerative detection pulse of the transceiving time sequence control circuit, the regenerative detection pulse of the transceiving time sequence control circuit is compared with the inverted pulse phase of the microwave switch pulse to obtain a new reference detection pulse; the power amplifier detects the switching signal of the work of the power amplifier when the pulse, the signal is the positive pulse with the pulse width of 3.3us, the delay forwarding control pulse is the control pulse of the delay forwarding precision of the control pulse coherent responder, the pulse is the positive pulse with the pulse width of 0.6us, and the time difference between the leading edge of the pulse and the falling edge of the pulse detection signal is the forwarding delay value of the pulse responder, and is set to 16.4us in the figure, and the time can be set by the software of the receiving and transmitting time sequence control circuit and can be programmed and controlled at will.

See fig. 3. The single-pulse radar measuring system repeatedly transmits an uplink pulse modulation signal through a pulse radar ground station, a pulse transponder on the aircraft receives the signal and transmits the signal to the ground in a coherent mode, and the ground station measures the time delay difference of the transmitted and received signal, so that the radial distance of the aircraft target can be calculated; the ground station measures the Doppler frequency value of the carrier signal modulated in the downlink pulse signal forwarded by the pulse transponder, and then the radial velocity of the aircraft target can be obtained through calculation.

If the pulse repetition period is T, the pulse width delta, the propagation delay tau,

the uplink pulse modulation signal:

s(t)＝Ac(t)cos(2πf_ot+θ)

downlink pulse modulation signal:

s(t-τ)＝Ac(t-τ)cos[2πf_o(t-τ)+θ]

then there are:

target distance:

maximum detection target distance:

distance resolution:

will be provided with

Substituting the downlink pulse modulation signal to obtain:

wherein the Doppler frequency

According to the expressions (3) and (6), the distance and velocity values can be measured. By analyzing the formulas (4) and (5), it can be known that: the narrower the transmission pulse is, the higher the distance resolution is, and the higher the distance measurement precision is; the longer the repetition period, the larger the maximum detection range, but the larger the repetition period, the lower the average power of its pulses, which in turn limits the range.

What has been described above is merely a preferred embodiment of the invention. It should be noted that, for those skilled in the art, variations and modifications can be made without departing from the principle of the present invention, for example, it can be seen from the above description that parameters such as pulse width, delay forwarding time, etc. are changed according to the system use requirements to realize a pulse coherent transponder with different delay forwarding time requirements. Such modifications and variations are considered to be within the scope of the invention.

Claims

1. A pulse coherent transponder co-channel interference processing system, comprising: circulator, received signal module, power amplifier module, transmission channel module, local oscillator and digital circuit module, its characterized in that: receiving frequency f selected by pulse responder_RWith a transmission frequency f_TRadio frequency signal F of same frequency_RThe intermediate frequency signal is amplified and detected by the intermediate amplifier module and then is divided into two paths, one path of the intermediate frequency signal is sent to the digital circuit module for A/D acquisition and conversion into a digital signal, the digital signal is subjected to time delay storage in an FPGA circuit, the other path of the pulse detection signal output by the intermediate amplifier module is sent to the transceiving time sequence control circuit in the digital circuit module, the intermediate frequency signal is amplified and detected by the intermediate amplifier module through the transceiving time sequence control circuit, the pulse detection signal output by the intermediate amplifier is subjected to regeneration processing by the transceiving time sequence control circuit, the pulse signal is subjected to inversion and then is subjected to AND operation with the inversion pulse of the microwave switch pulse to obtain a new reference detection pulse, the leading edge pulse of the reference detection pulse is taken as a reference to generate a time delay forwarding control pulse, a microwave switch pulse and a power amplifier detection pulse, and the time sequence processing of completely closed received signals is generated in the FPGA circuit, the method comprises the steps that pulse time sequence control is adopted to carry out time sequence control on received pulse detection signals, a reference detection pulse is utilized to control a delay storage circuit to realize a digital delay line, A/D digital signal acquisition signals are stored and forwarded through the digital delay line, the forwarded signals are sent to a D/A converter and converted into analog intermediate frequency signals through D/A, and the analog intermediate frequency signals are sent to a power amplification module through an up-conversion of a transmitting channel module to be amplified; when the power amplifier detection pulse is at high level, the power amplifier module amplifies the radio frequency signal F_TOutput pulses through a circulatorThe modulated signal is pulsed.

2. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: the frequency relation of the pulse answering machine selects the same frequency of the receiving frequency and the transmitting frequency, and the coherent forwarding ratio.

3. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: the pulse answering machine adopts a one-time frequency conversion scheme for transmitting and receiving signals and shares a local oscillator.

4. The impulse coherent transponder co-channel interference processing system of claim 2, wherein: the design scheme according to the frequency relation of the pulse transponder comprises the following steps:

f_R＝f_IR+f_o(1)

f_T＝f_IT+f_o(2)

when required f_R＝f_TWhen (1) and (2) are equal, f_IR＝f_IT，

In the formula (f)_RFor receiving signal frequency, f, of pulse coherent transponder_TTo transmit signal frequency, f_oIs the local oscillator frequency, f_IRFor receiving intermediate frequency signal frequency, f_ITTo transmit intermediate frequency signal frequencies.

5. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: the receiving channel module includes: the field amplifier module, the microwave switch and the frequency mixer are sequentially connected in series, and after the pulse transponder antenna receives the radio-frequency signal, the radio-frequency signal F_REntering the field discharge module through a circulator, a radio frequency signal F_RAfter the intermediate frequency signal is amplified and detected by the intermediate amplifier module, the intermediate frequency signal is sent to a receiving and transmitting time sequence control circuit to carry out regeneration processing on a pulse detection signal output by the intermediate detection, and after the pulse signal is inverted, the intermediate frequency signal and an inverted pulse of a microwave switch pulse are subjected to inversionAnd obtaining a new reference detection pulse, generating a delay forwarding control pulse by taking a leading edge pulse of the reference detection pulse as a reference, storing and forwarding the acquired signal through a digital delay line, and outputting an intermediate frequency signal by the forwarded signal through a D/A converter.

6. The impulse coherent transponder co-channel interference processing system of claim 5, wherein: the microwave switch sends microwave switch pulse to the microwave switch control end of the receiving channel module, and the receiving channel is closed in time when the power amplifier works.

7. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: the receiving and transmitting time sequence control circuit transmits the delay forwarding control pulse to the digital delay line, the delay time is programmed in the FPGA, the power amplifier detection pulse generated by the delay forwarding control of the pulse coherent responder is transmitted to the power amplifier module, and only when the power amplifier detection pulse is in a high level state, the power amplifier module outputs a pulse modulation signal.

8. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: the pulse detection signal is a negative pulse signal with the pulse width of 0.6us, which is detected and output by the intermediate amplifier module.

9. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: the microwave switch pulse is a control pulse signal for controlling the on-off of a microwave switch of the receiving channel module, the control pulse signal is a positive pulse signal with the pulse width of 35.7us, and when the control pulse signal is at a high level, the control pulse signal indicates that the receiving channel is closed.

10. The impulse coherent transponder co-channel interference processing system of claim 1, wherein: after the pulse detection signal output by the intermediate amplifier module is inverted by the regenerative detection pulse of the transceiving time sequence control circuit, the regenerative detection pulse of the transceiving time sequence control circuit is compared with the inverted pulse phase of the microwave switch pulse to obtain a new reference detection pulse; the power amplifier detects the switching signal that the pulse controlled power amplifier worked, this switching signal is the positive pulse of 3.3us of pulse width, delay and forward the control pulse of the delay and forward precision of the control pulse coherent answering machine, this control pulse is the positive pulse of 0.6us of pulse width, and the time difference between this positive pulse leading edge and pulse detection signal falling edge is the forward delay value of the pulse answering machine.