Radar communication machine based on EBPSK / MPPSK modulation

Abstract

The invention discloses a radar communication machine based on EBPSK / MPPSK modulation, which comprises a transmitter power amplifier, a receiver intermediate frequency amplifier, a transceiving switch and an antenna / feeder line, and further comprises a data frame memory, an EBPSK / MPPSK signal modulator, an impact filter, a matched filter, two time gating gates and a radar signal detector, and a communication data demodulator. The data frame memory processes the randomized communication data code stream, and sends the randomized communication data code stream to the matched filter; and the EBPSK / MPPSK signal modulator processes a carrier signal of the radar transmitter by using the data in the data frame memory, and sends the carrier signal to the transmitter power amplifier. Under different combinations of the framework, the single-path EBPSK / MPPSK signal modem and the matched filter, the radar communication integrated equipment function can be obtained by using the same system.

Description

Technical Field

[0001] This invention relates to the field of communication and radar engineering technology, and in particular to a radar communication device based on EBPSK / MPPSK modulation. Background Technology

[0002] Current technological status of radar communication equipment: With the development of electronic technology and the needs of information warfare, many engineering application platforms are equipped with more and more complex electronic systems. This has led to increasing pressure on aspects such as size, weight, energy, complexity, installation space, spectrum resources, electromagnetic compatibility (EMC), and the aerodynamic characteristics of the aircraft. Therefore, effectively integrating and combining different electronic devices to achieve multi-functionality and multi-tasking within limited platform payload, available frequency band, and aperture resources presents a formidable challenge in terms of fundamental principles, significant socio-economic benefits, and far-reaching and far-reaching technological advancements.

[0003] Therefore, existing technologies essentially utilize the multi-beam antennas of phased array radar systems to achieve spatial division. On the one hand, this consumes the radar system's beam resources; on the other hand, it is neither applicable nor universal for the numerous single-antenna non-phased array radar systems that exist. To avoid frequent switching of radar antennas or antenna beams, the University of Electronic Science and Technology of China proposed starting from signal integration, multiplying the communication signal with the linear frequency modulation (LFM) radar signal after direct sequence spread spectrum and binary phase shift keying (BPSK) modulation before transmission. However, this is still essentially a co-channel transmission of two signal systems. The receiving end must first perform nonlinear homomorphic filtering to convert the multiplicative signal into an additive signal, and then perform complex blind source separation to distinguish the radar target echo from the communication signal, resulting in a loss of signal-to-noise ratio, directly affecting the radar's detection of small targets or weak signals. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a radar communication device based on EBPSK / MPPSK modulation that overcomes or at least partially solves the above problems.

[0005] According to one aspect of the present invention, a radar communication device based on EBPSK / MPPSK modulation is provided, comprising a transmitter power amplifier, a receiver intermediate frequency amplifier, a transceiver switch, and an antenna / feeder, wherein the radar communication device includes: One data frame memory, one EBPSK / MPPSK signal modulator, one impulse filter, one matched filter, two time gating gates, one radar signal detector, and one communication data demodulator; The data frame storage processes the randomized communication data stream and sends it to the matched filter respectively; The EBPSK / MPPSK signal modulator uses the data in the data frame memory to process the radar transmitter carrier signal and sends it to the transmitter power amplifier. Pulse Code Modulated Signal After being amplified by the transmitter, the signal is radiated into the air through the antenna during the transmit / receive switch's transmit time slot. The impulse filter uses the steep slope of the amplitude-frequency characteristic to convert the EBPSK / MPPSK phase-modulated signal into an amplitude-modulated signal, and tolerates the Doppler frequency shift of the signal carrier between the valley and peak of its amplitude-frequency characteristic. The radar-communication hybrid signal, amplified by the intermediate frequency amplifier, is divided into two outputs, utilizing a first gating gate and a second gating gate with the same time width but different opening times. The first gating gate is used to select the target radar echo signal with time delay, and at the same time isolate the data communication signal sent by the target radar communication device to our radar communication device; The second gating gate is used to select the data communication signals sent by the target radar transmitter to our radar transmitter with time delay, while isolating the strong radar echo signals of close-range targets.

[0006] Optionally, the data frame memory processes the randomized communication data stream, specifically including: according to the radar pulse width. It is truncated into a single communication frame, and the frames are arranged according to the repetition period of the radar pulse. Perform burst transmissions and data updates.

[0007] Optionally, the processing of the radar transmitter carrier signal specifically includes: performing binary EBPSK modulation or multi-level MPPSK modulation on the radar transmitter carrier signal.

[0008] Optionally, the first gating gate is used to select the target radar echo signal with time delay, and at the same time isolate the data communication signals sent by the target radar receiver to our radar receiver, specifically including: The radar signal detector includes a matched filter and a peak detector. Within the time width of the first gating gate, it uses a copy of the data frame in the data frame memory to perform matched filtering and threshold decision with the radar echo signal to estimate the target distance.

[0009] Optionally, the second gating gate is used to select the data communication signals sent by the target radar receiver to our radar receiver with time delay, while isolating strong radar echo signals from nearby targets. Specifically, this includes: The communication data demodulator, within the time width of the second gate, demodulates an EBPSK / MPPSK communication data frame from the output signal of the impulse filter and buffers it, then transmits it during the radar pulse repetition period. The data frame is then broken down into a continuous bitstream.

[0010] Optionally, the data frame memory can also store fixed pseudo-random sequence codewords and reuse them. In this case, the radar communication device is a conventional phase-coded pulse compression radar. The impulse filter includes an analog filter and a digital filter; The first gating gate and the second gating gate are adjacent but do not overlap, and their widths are both the radar pulse width. Furthermore, the first gate precedes the second gate; The data frame memory works in conjunction with the data frame splitting function in the communication data demodulator to convert half-duplex burst communication in units of frames into full-duplex communication of continuous code streams.

[0011] This invention provides a radar communication device based on EBPSK / MPPSK modulation, comprising a transmitter power amplifier, a receiver intermediate frequency amplifier, a transceiver switch, and an antenna / feeder. The radar communication device includes: a data frame memory, an EBPSK / MPPSK signal modulator, an impulse filter, a matched filter, two time-selective gates, a radar signal detector, and a communication data demodulator. The data frame memory processes randomized communication data streams and sends them to the matched filter. The EBPSK / MPPSK signal modulator uses the data in the data frame memory to process the radar transmitter carrier signal and sends it to the transmitter power amplifier. The pulse-code modulated signal... After power amplification by the transmitter, the signal is radiated into the air via the antenna during the transmit / receive switch's transmit time slot. The impulse filter utilizes the steep slope of the amplitude-frequency characteristic to convert the EBPSK / MPPSK phase-modulated signal into an amplitude-modulated signal, tolerating the Doppler frequency shift of the signal carrier between its amplitude-frequency characteristic valley and peak. The radar-communication hybrid signal, amplified by the intermediate frequency amplifier, is divided into two outputs, using a first gating gate and a second gating gate with the same time width but different turn-on times. The first gating gate is used to select the target radar echo signal with time delay, while isolating the data communication signal sent from the target radar receiver to our radar receiver. The second gating gate is used to select the data communication signal sent from the target radar receiver to our radar receiver with time delay, while isolating the strong radar echo signal from close-range targets. Through different combinations of the single-channel EBPSK / MPPSK signal modem and matched filter, this invention achieves integrated radar and communication equipment functionality using a single system.

[0012] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A block diagram of a radar communication system based on EBPSK / MPPSK modulation provided in an embodiment of the present invention; Figure 2 A schematic diagram illustrating the interaction between ground (radar) bases and aircraft / mobile platforms; Figure 3 This is the impulse filtering result of the EBPSK modulated signal, where Figure 3 (a) shows the impulse filter response waveform of the EBPSK modulated signal. Figure 3 (b) is Figure 3 (a) The absolute value of the waveform. Figure 3 (c) is Figure 3 (b) The result of low-pass filtering on the signal waveform; Figure 4 Simulation results of the constant false alarm rate (CFAR) detection performance of LFM, EBPSK, and MPPSK modulated signals for a target with the same radar pulse amplitude, width, energy, and number of pulses, and a target velocity of 400 m / s; Figure 5 Simulation results of the constant false alarm rate (CFAR) detection performance of LFM, EBPSK, and MPPSK modulated signals for a target with the same radar pulse amplitude, width, energy, and number of pulses, and a target velocity of 750 m / s; Figure 6 Simulation results of the constant false alarm rate (CFAR) detection performance of LFM, EBPSK, and MPPSK modulated signals for a target with the same radar pulse amplitude, width, energy, and number of pulses, and a target velocity of 2000 m / s; Figure 7 Simulation results of the constant false alarm rate (CFAR) detection performance of LFM, EBPSK, and MPPSK modulated signals for a target with the same radar pulse amplitude, width, energy, and number of pulses, and a target velocity of 3400 m / s. Detailed Implementation

[0015] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0016] The terms "comprising" and "having," and any variations thereof, in the specification, embodiments, claims, and drawings of this invention are intended to cover non-exclusive inclusion, such as including a series of steps or units.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] The transmitted signals of current pulse radar / pulse code radar are actually special cases of EBPSK / MPPSK modulated signals defined by equations (4) and (6); and EBPSK / MPPSK modulated signals and EBPSK / MPPSK signal demodulators based on impulse filters are used in high-efficiency digital communication systems.

[0019] 1. Transmitter 1) Within the pulse width of the radar system, the radar sub-pulse train is directly modulated with EBPSK / MPPSK using the already randomized communication data frames to be transmitted, which is completely consistent with the pulse compression radar system and pulse radar transmitter system of phase-coded modulation type. 2) Data frames are transmitted in bursts according to the radar's pulse repetition cycle.

[0020] 2. Receiving end 1) Use the locally backed-up copy of the data frame just sent (i.e. the current range scan) as the radar's pseudo-random (PN) pulse code to perform matched filtering or correlation processing on the received signal, thereby achieving conventional pulse compression, consistent with the pulse compression radar system and pulse radar receiver system of phase-coded modulation type. 2) After the received signal is enhanced by an impulse filter, it is sent to a conventional EBPSK / MPPSK signal demodulator to demodulate the communication data; 3) Since the impulse filter is implemented analogally, the radar echo signal is first amplified by the impulse filter before conventional pulse compression. This allows it to share the same impulse filter as the communication signal. Furthermore, if the impulse filter is implemented analogally, the intermediate frequency bandpass filter in a conventional radar receiver can be omitted. Figure 1 As shown.

[0021] Figure 2This is a schematic diagram of the ground-to-air operation process of the radar communication device based on EBPSK / MPPSK modulation proposed in this invention patent. Of course, the radar communication device can also be used in other operating modes, such as air-to-air and ground-to-ground. Figure 1 This is a block diagram of a radar communication device based on EBPSK / MPPSK modulation proposed in this patent. The invention will now be described in detail with reference to other accompanying drawings and embodiments.

[0022] 1. EBPSK / MPPSK modulated signal transmitter The EBPSK / MPPSK modulated signal transmitter uses all the functions of existing pulse radar transmitters, and its main working process is as follows: 1) It is common knowledge in this field to scramble the data stream used for communication with a PN sequence to make it randomized and to make the probability of data "0" and data "1" appearing equal. 2) such as Figure 1 As shown, according to the radar pulse width The scrambled communication stream is truncated into a single communication frame, and the frames are processed according to the repetition period of the radar pulses. Periodic burst transmissions are performed at this time. Period of internal communication data bits This is also the repetition period of the radar sub-pulse; 3) Using the data frame, the sinusoidal signal generated by the oscillator is processed. EBPSK modulation as defined by equation (4) or MPPSK modulation as defined by equation (5) is performed. This is the conventional modulation technique of pulse radar or pulse code radar, which is common knowledge in this field. 4) Signal after pulse code modulation (EBPSK / MPPSK) After being amplified by the transmitter, the signal is radiated into the air through the antenna during the transmit / receive switch's transmit time slot. This is common knowledge in the field. 5) The frame memory always stores the transmission data of the current frame, and in... Updated periodically.

[0023] 2. EBPSK / MPPSK modulated signal receiver The EBPSK / MPPSK modulated signal receiver retains all the functions of existing radar receivers before matched filtering. Its main operating process is as follows: 1) Within the receive time slot of the transceiver switch, there is a received signal containing both the target echo and the communication signal transmitted by the target. The signal is amplified by the preamplifier of the radar receiver via the transmit / receive switch, and then down-converted to an intermediate frequency (IF) signal by the mixer before being amplified by the IF amplifier. This is exactly the same as a typical radar receiver. However, the IF bandpass filter in the IF amplifier unit of a typical radar receiver can be replaced by the analog impulse filter specified in this application, which saves one IF bandpass filter.

[0024] 2) The radar-communication hybrid signal, amplified by the intermediate frequency amplifier, is divided into two outputs. Two gating gates, 1 and 2, with the same time width but different opening times, are used to separate the radar target echo from the communication signal. The time lag between the opening time of gating gate 2 and gating gate 1 is the width of the radar pulse. At this point, the time width of both gates can also be selected as [value missing]. .

[0025] 3. Detection and decision-making of radar echo signals 1) The gating gate 1 mentioned above is the range gating gate (or simply range gate) in classical radar. In this application, in addition to its usual function of selecting signals at a certain range (time delay) for processing, it also isolates the communication data sent by the target carrier to our radar transmitter using EBPSK / MPPSK radar transmitters. Since this communication data is equivalent to a "secondary radar" signal, its energy is much stronger than the target echo signal (the primary radar received signal). (For this invention, because the communication transmitter is also a radar transmitter, and the communication signal is also a radar signal, its energy is even stronger). Various radar transmitter technical solutions must find ways to separate these two signals. Because this invention uses communication data frames as units, according to the radar pulse repetition period... and in the radar pulse width Transmission occurs in bursts within the radar; therefore, as long as the radar transmitters of both parties send communication data frames after one radar target reflection signal, they can avoid mutual interference in time, especially the interference of the strong communication signal on the weak radar echo. Since the target's metallic outer shell reflects incident radar waves immediately, theoretically, after a certain time... Therefore, both radar receivers can easily avoid interference from the other's data transmission by using time separation, as long as they receive and process a complete data frame before sending their own. The minimum time to receive and process a complete data frame is the radar's pulse width. .

[0026] 2) The radar echo signal from the gating gate 1 enters the matched filter and undergoes autocorrelation processing on the entire frame data with the "copy" of the current frame transmission data stored in the frame memory (this processing can be either analog or digital, and is not specifically limited in this application). This completes the matched filtering and pulse compression of the EBPSK / MPPSK modulated signal of the communication data, which is common knowledge in the art. The impulse filter preceding the gating gate 1 also performs two functions for the radar signal: ① The weak radar echo signal was enhanced and filtered, improving the SNR. The effect of signal enhancement is illustrated in the diagram below. Figure 3 (a) The effect of noise filtering is... Figure 3 (a) is reflected by the overall amplitude-frequency bandpass characteristics; ② The ability to adapt to the unavoidable Doppler frequency shift in radar echo signals due to target motion is the adaptability (or tolerance) of the radar transducer of this invention to the maximum Doppler frequency shift of the echo signal (i.e., the maximum radial velocity of the target detected by the radar). Classical radar systems, on the other hand, require multiple matched filters with different center frequencies to adapt to different Doppler frequency shifts, which are called Doppler filter banks.

[0027] 3) Peak detection and threshold decision are performed on the output of the autocorrelation operation. By measuring the time delay of the peak value of the autocorrelation function relative to its transmission time, the distance between the target and the radar can be estimated. The CFAR target detector of the traditional radar receiver can still be used for this, which is common knowledge in the field. It is worth noting that the influence of the Doppler frequency shift of the target motion has been eliminated by the impulse filter.

[0028] 4) Once the matched filtering is complete, the frame memory can be cleared to prepare for the next frame of communication data.

[0029] 4. Demodulation of EBPSK / MPPSK modulated signals 1) As mentioned above, when the time widths of both gating gates are both Furthermore, the opening time of gate 2 is delayed compared to gate 1. Therefore, the two gating gates do not overlap in time, so even strong radar echoes from close-range targets will not affect the demodulation of EBPSK / MPPSK modulated signals by the radar receiver; at the same time, since data communication is performed in bursts of frames, it only affects the frame length (i.e., pulse width). Performing signal processing and demodulation within the time domain also helps to remove noise and interference as much as possible, which is why the width is... The function of gate 2 is essentially the same as that of the range gate in a radar receiver.

[0030] 2) Since the communication data is carried by radar subpulses, the demodulation of the EBPSK / MPPSK modulated signal is performed bit by bit on a subpulse basis. Although it is impossible to obtain the processing gain (pulse compression factor) of radar processing by frame, the signal-to-noise ratio of the communication signal is much higher than that of the radar echo signal. Therefore, after using an impulse filter to highlight the phase change of the EBPSK / MPPSK modulated signal bit by bit, it is directly sent to the demodulator to demodulate the digital communication information bit by bit.

[0031] The impulse filter itself can be digital or analog; and a digital impulse filter can be either finite impulse response (FIR) or infinite impulse response (IIR). This embodiment uses a frequency response digital impulse filter, whose transfer function is as follows: (8) The values ​​of each coefficient are as follows: , , , , , , , , , .

[0032] This filter converts the phase transition of the EBPSK modulated signal into a transition like... Figure 3 The parasitic amplitude modulation waveform shown in (a) is obtained by taking the absolute value and low-pass filtering as follows: Figure 3 (b) and Figure 3 The signal waveform shown in (c) can be used to detect the signal using a threshold detector. Figure 3 (c) shows the signal envelope, which is used to make "0" and "1" information decisions. Therefore, impulse filtering is actually matched filtering for phase change signals. Although it is not strictly speaking, it is very simple to implement because the order of the IIR digital impulse filter is very low, as shown in equation (8).

[0033] Please note again: within a certain frequency range, Figure 3 The transition portion of the signal waveform shown is invariant, thus the detection performance of the radar detector is robust to the target's movement speed.

[0034] 3) If data framing corresponding to data framing in the modulator is performed within the repetition period of the radar pulse, the half-duplex high-speed burst data transmission can be transformed into full-duplex low-speed continuous code stream communication.

[0035] 5. Simulation 1) Parameter settings ①Application Scenarios and Environment Taking helicopter applications as an example, the maximum transmission distance of the radar is 35km, using an additive white Gaussian noise channel.

[0036] ② Transmitter The modulator transmits carrier frequencies of 1000 and 1000 respectively. The LFM signal, EBPSK modulated signal, and MPPSK modulated signal are all at 10GHz, with a bandwidth of 50MHz and a pulse width of [missing information]. The pulse repetition period is (Pulse repetition frequency is 5kHz), and simulation is performed using a sampling frequency of 100GHz.

[0037] ③ Receiver 10GHz The frequency was down-converted to a 100MHz intermediate frequency, and simulation was performed using a 1GHz sampling frequency. Figure 2 The impulse filter is implemented using a digital IIR filter, and the parameter design of equation (8) ensures that the intermediate frequency of the signal is at the center of the slope of the filter's amplitude-frequency response. In order to ensure that the bandwidth of the EBPSK / MPPSK modulated signal is also 50MHz, K=2 is kept constant for various combinations of EBPSK / MPPSK modulation parameters at an intermediate frequency of 100MHz. If the radar transmits an LFM signal, the receiver uses classic matched filtering detection.

[0038] 2) Improvement in signal-to-noise ratio With a fixed input signal-to-noise ratio (SNR) of 1dB, this application compares classic LFM signal radar systems with those described in this paper. Figure 1 The signal-to-noise ratio improvement of the EBPSK encoded modulated signal after matched filtering, wherein: ① The EBPSK signal uses 1024-bit M-sequence encoding, and the modulation parameters are N=8, 7, and 6 respectively; ②Doppler frequency shift At 10GHz The ratio of the frequency generated to the carrier frequency. That is, the relative value of the Doppler frequency shift is independent of the frequency conversion.

[0039] Therefore, the improvement in signal-to-noise ratio at the output of the matched filter for both LFM and EBPSK systems under different target velocities and radial Doppler frequency shifts is listed in Table 1.

[0040] Table 1 Comparison of output signal-to-noise ratio improvement between the two radar systems As shown in Table 1, the simulation results indicate that, considering only the improvement in the radar receiver's output signal-to-noise ratio (SNR), the EBPSK-coded modulation scheme is inferior to the traditional LFM scheme for low-speed targets (approximately 0.5 dB lower). However, this gap narrows as the target speed increases, with the turning point occurring when the target speed reaches 750 m / s (the maximum speed of the US F-22 fighter jet). When the target speed reaches Mach 10 (approximately 3400 m / s), the EBPSK-coded modulation scheme improves the output SNR by approximately 1.5 dB compared to the traditional LFM scheme. It should be noted that if the radar platform is mobile, the maximum relative speed of the target can reach twice the values ​​shown in Table 1 (e.g., two aircraft approaching head-on). Therefore, the improvement in the output SNR of the EBPSK-coded modulation scheme compared to the traditional LFM scheme will be even more significant.

[0041] 3) Constant false alarm rate target detection performance Keeping the simulation conditions in Table 1 unchanged, for EBPSK modulation, only the case with N=7 is simulated; while for MPPSK modulation, only the case with N=7 and M=3 is simulated. The pulse accumulation count of the signal is set to 10, and the false alarm probability is... Target detection probability .

[0042] Figure 4 For target speed A comparison of constant false alarm detection probabilities (CFAR) of LFM and EBPSK / MPPSK echo signals after pulse compression at a speed of 400 m / s. The figure shows that for non-fluctuating targets, the detection performance of the EBPSK coded modulation signal is approximately 2.1 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 0.2 dB better than the LFM signal. However, for targets fluctuating according to Swerling 1 model, the detection performance of the EBPSK coded modulation signal is approximately 2.5 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 0.3 dB better than the LFM signal.

[0043] Figure 5 For target speed A comparison of constant false alarm detection probabilities (CFAR) of LFM and EBPSK / MPPSK echo signals after pulse compression at a speed of 750 m / s. The figure shows that for non-fluctuating targets, the detection performance of the EBPSK coded modulation signal is approximately 2.5 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 0.4 dB better than the LFM signal. For the Swerin 1 target, the detection performance of the EBPSK coded modulation signal is approximately 2.3 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 0.5 dB better than the LFM signal.

[0044] Figure 6 For target speed A comparison of constant false alarm detection probabilities (CFAR) of LFM and EBPSK / MPPSK echo signals after pulse compression at a speed of 2000 m / s. The figure shows that for non-fluctuating targets, the detection performance of the EBPSK coded modulation signal is approximately 3 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 1 dB better than the LFM signal. For the Swerin 1 target, the detection performance of the EBPSK coded modulation signal is approximately 3.1 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 1 dB better than the LFM signal.

[0045] Figure 7 For target speed A comparison of constant false alarm detection probabilities (CFAR) of LFM and EBPSK / MPPSK echo signals after pulse compression at a velocity of 3400 m / s. The figure shows that for non-fluctuating targets, the detection performance of the EBPSK coded modulation signal is approximately 3.5 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 1.4 dB better than the LFM signal. For the Swerin 1 target, the detection performance of the EBPSK coded modulation signal is approximately 3.5 dB better than the LFM signal, and the MPPSK coded modulation signal is approximately 1.5 dB better than the LFM signal.

[0046] It is evident that the higher the target speed, the greater the detection performance advantage of the EBPSK / MPPSK encoded modulation radar described in this application.

[0047] 4) Communication Applications The radar application described above stores fixed pseudo-random sequence codewords in the data frame memory and reuses them, resulting in a conventional phase-coded pulse compression radar. For communication applications, however, truly random data to be transmitted needs to be stored in the data frame memory. As can be seen from equation (7), the transmission code rate of EBPSK / MPPSK modulation is proportional to the carrier frequency. This is inversely proportional to N. Since the receiver needs to perform down-conversion, the carrier frequency can only be calculated based on an intermediate frequency of 100MHz, and N is taken as the maximum value of 8 from Table 1. Therefore: ① For EBPSK modulation, the burst transmission bit rate is 100 / 8 = 12.5 Mbps. Considering the radar's 20 / 200 signal duty cycle, the equivalent continuous transmission bit rate is 1.25 Mbps. ② For MPPSK modulation, if M=4, the burst transmission bit rate is 2*100 / 8=25Mbps, and the equivalent continuous transmission bit rate is 2.5Mbps.

[0048] So in Within the radar pulse width, EBPSK and MPPSK modulation can transmit 2000 bits and 4000 bits of data, respectively. This means that if pulse compression is used to encode radar pulses, MPPSK modulation can achieve a longer PN code length than EBPSK modulation, resulting in higher range resolution and ranging accuracy. (Based on:) Data volume of one beam = bit rate Pulse width Number of pulses (9) It can be seen that if a single radar beam can transmit and receive 20 radar pulses, then within one beam, EBPSK and MPPSK modulation can transmit 20*2000 / 8=5kB and 20*4000 / 8=10kB of data respectively. If the radar beam locks onto the target and is in a tracking state, then both parties can communicate continuously at an average rate of 1.25Mbps or 2.5Mbps. Therefore, for communication applications, the transmission code rate of MPPSK modulation is at least twice that of EBPSK modulation.

[0049] Because the communication signal of the cooperative target (e.g., a friendly aircraft) using the aforementioned radar is much stronger than its own radar echo (i.e., the difference between primary and secondary radar, as is well known in the art), therefore, according to Figure 3 By using an impulse filter to highlight the phase change of the EBPSK / MPPSK modulated signal bit by bit, a similar effect can be obtained. Figure 5 After obtaining the amplitude modulation waveform shown, it can be directly sent to the demodulator for bit synchronization and amplitude determination. Alternatively, it can be... Figure 5 Waveform matched filtering followed by threshold decision is common knowledge in the field of communications and will not be elaborated upon here. I will only point out one thing: Figure 3 It is evident that the data frame memory at the transmitting end, in conjunction with the data frame splitting function in the communication data demodulator at the receiving end, can convert half-duplex burst communication in units of frames into full-duplex communication in continuous code streams, presenting it to both users.

[0050] In summary, within this basic technical framework and through different combinations of single-channel EBPSK / MPPSK signal modulators and matched filters, this invention achieves integrated radar and communication device functionality using a single system. This embodiment demonstrates that the EBPSK / MPPSK-based radar communication device exhibits good ranging performance and can operate in different modes as needed, demonstrating excellent flexibility.

[0051] Although from Figures 4-7Simulation results show that, for radar applications, the constant false alarm rate (CFAR) detection performance of MPPSK modulated signals is not as good as that of EBPSK modulated signals (but it is still better than LFM radar for high-speed targets). However, MPPSK signals have higher range resolution and higher spectrum utilization and transmission code rate when used for communication.

[0052] Depending on the different radar ranging and data communication requirements, either EBPSK or MPPSK signals can be transmitted. Therefore, the aforementioned radar communication device is expected to achieve higher system cost-effectiveness and comprehensive integration benefits in various future integrated electronic systems centered on radar and communication.

[0053] Beneficial effects: 1. It possesses all the intuitive advantages of the radar transceiver already mentioned in the "Background Art" section of this application: 1) The high pulse power of the radar transmitter, the high sensitivity of the radar receiver, and the high gain of the radar antenna greatly increase the communication distance; 2) Utilize the large bandwidth of the radar system to improve the data transmission rate of the communication system; 3) Utilize the strong directivity of radar antennas to enhance the confidentiality and anti-interference capabilities of communication signals.

[0054] 2. Compared to existing radar detector technology, the radar detector described in this application: 1) High adaptability: It is equally applicable to multi-beam phased array radar and single-beam conventional radar; 2) High energy efficiency: The same EBPSK / MPPSK modulation signal is used to be compatible with radar ranging and digital communication, and there is no signal power distribution problem between radar and communication; 3) Subsystem decoupling: Digital communication and radar ranging are performed simultaneously, and the radar echo returns before the communication signal. The two do not affect each other, and the receiver does not need to separate the mixed signal, resulting in better EMC performance. 4) Good time and space utilization: In addition to the existing transmit and receive switches of the radar system, the system does not need to switch between radar and communication when it is working, and does not affect the transmission time utilization and beam space utilization of the existing radar system. 5) Full functionality: The same radar transmitter on the same carrier frequency can perform multiple functions, including ranging / speed measurement, primary radar / secondary radar, simplex / half-duplex / full-duplex communication, and target identification; 6) High communication code rate: Effectively utilizes the entire pulse width duration and full signal bandwidth of the radar; 7) Radar system performance can be flexibly optimized: ①For moving targets, the target detection performance of the EBPSK / MPPSK modulated signals is better than that of the LFM signal, and the higher the target speed, the more obvious the performance advantage. ② The EBPSK system has better detection performance, while the MPPSK system has higher distance resolution. Therefore, EBPSK or MPPSK signals can be sent according to different ranging requirements. ③ The radar system based on PN-coded phase modulation does not have range-velocity coupling. The communication data transmitted simultaneously by the EBPSK / MPPSK radar transmitter (especially after source coding compression) is itself random and generally different for each frame. After being scrambled by the pseudo-random sequence that is essential in the communication modulator, it is closer to a true random code than the pulse-coded radar using a fixed PN code. Moreover, the wider the pulse width, the larger the communication frame, and the longer the random code, which is closer to the noise radar. The range ambiguity function of the noise radar is an ideal "tack" shape. ④ Due to this randomness, the sub-pulse form within each radar pulse is different, which can be further used to improve the radar's anti-jamming performance.

[0055] 8) Good compatibility: It is completely consistent with the pulse compression radar system and signal processing method of phase-coded modulation, so it can make the most of the existing pulse radar system hardware.

[0056] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A radar communication device based on EBPSK / MPPSK modulation, comprising a transmitter power amplifier, a receiver intermediate frequency amplifier, a transceiver switch, and an antenna / feeder, characterized in that, The radar communication device includes: One data frame memory, one EBPSK / MPPSK signal modulator, one impulse filter, one matched filter, two time gating gates, one radar signal detector, and one communication data demodulator; The data frame storage processes the randomized communication data stream and sends it to the matched filter respectively; The EBPSK / MPPSK signal modulator uses the data in the data frame memory to process the radar transmitter carrier signal and sends it to the transmitter power amplifier. Pulse Code Modulated Signal After being amplified by the transmitter, the signal is radiated into the air through the antenna during the transmit / receive switch's transmit time slot. The impulse filter uses the steep slope of the amplitude-frequency characteristic to convert the EBPSK / MPPSK phase-modulated signal into an amplitude-modulated signal, and tolerates the Doppler frequency shift of the signal carrier between the valley and peak of its amplitude-frequency characteristic. The radar-communication hybrid signal, amplified by the intermediate frequency amplifier, is divided into two outputs, utilizing a first gating gate and a second gating gate with the same time width but different opening times. The first gating gate is used to select the target radar echo signal with time delay, and at the same time isolate the data communication signal sent by the target radar communication device to our radar communication device; The second gating gate is used to select the data communication signals sent by the target radar transmitter to our radar transmitter with time delay, while isolating the strong radar echo signals of close-range targets.

2. A radar communication device based on EBPSK / MPPSK modulation according to claim 1, characterized in that, The data frame memory processes the randomized communication data stream, specifically including: according to the radar pulse width. It is truncated into a single communication frame, and the frames are arranged according to the repetition period of the radar pulse. Perform burst transmissions and data updates.

3. A radar communication device based on EBPSK / MPPSK modulation according to claim 1, characterized in that, The processing of the radar transmitter carrier signal specifically includes: performing binary EBPSK modulation or multi-level MPPSK modulation on the radar transmitter carrier signal.

4. A radar communication device based on EBPSK / MPPSK modulation according to claim 1, characterized in that, The first gating gate is used to select the target radar echo signal with time delay, and at the same time isolate the data communication signals sent by the target radar receiver to our radar receiver. Specifically, it includes: The radar signal detector includes a matched filter and a peak detector. Within the time width of the first gating gate, it uses a copy of the data frame in the data frame memory to perform matched filtering and threshold decision with the radar echo signal to estimate the target distance.

5. A radar communication device based on EBPSK / MPPSK modulation according to claim 1, characterized in that, The second gating gate is used to select data communication signals sent from the target radar receiver to our radar receiver with time delay, while isolating strong radar echo signals from nearby targets. Specifically, it includes: The communication data demodulator, within the time width of the second gate, demodulates an EBPSK / MPPSK communication data frame from the output signal of the impulse filter and buffers it, then transmits it during the radar pulse repetition period. The data frame is then broken down into a continuous bitstream.

6. The radar communication device based on EBPSK / MPPSK modulation according to claim 1, characterized in that, The data frame memory can also store fixed pseudo-random sequence codewords and reuse them. In this case, the radar communication device is a conventional phase-coded pulse compression radar. The impulse filter includes an analog filter and a digital filter; The first gating gate and the second gating gate are adjacent but do not overlap, and their widths are both the radar pulse width. Furthermore, the first gate precedes the second gate; The data frame memory works in conjunction with the data frame splitting function in the communication data demodulator to convert half-duplex burst communication in units of frames into full-duplex communication of continuous code streams.

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