A primary and secondary combined radar electromagnetic compatibility method based on timing synchronization

Abstract

The application discloses a primary and secondary combined radar electromagnetic compatibility method based on timing synchronization, and steps include: unified time reference design: including unified timing of primary radar and secondary radar receiving and unified radar control; transmission trigger synchronization design: the trigger of the secondary radar is at the front t0 moment when the primary radar is triggered, each trigger signal triggers the secondary radar to emit two pulse signals, and the interval of the trigger is consistent with the primary radar; working timing synchronization design. In the working mode, the primary radar and the secondary radar are considered and designed compatibly, so that the frequency mutual interference can be obviously inhibited when the primary and secondary radars work simultaneously, and the equipment use degree is improved.

Description

Technical Field

[0001] This invention relates to radar system technology, and in particular to an electromagnetic compatibility method for primary and secondary integrated radar based on time synchronization. Background Technology

[0002] A radar transmits electromagnetic signals into space, receives echoes from targets within its coverage area, and extracts the target's location and other information from the echo signals.

[0003] The secondary radar transmits interrogation pulses into space. Once the transponder on the target aircraft receives a valid interrogation, it transmits a reply signal to the radar containing aircraft information (such as identification code, altitude, etc.).

[0004] Primary and secondary radars are indispensable partners in modern air traffic control and air defense early warning systems. Currently, more and more air traffic control or air defense early warning systems are adopting integrated primary and secondary radars, which are structurally integrated into a single design. The primary and secondary radars can be turned on and operate simultaneously, allowing the system to acquire both primary and secondary air situation data at the same time, and can also fuse primary and secondary air situation data as needed.

[0005] Due to differences in operating principles and signal characteristics, integrated primary and secondary radar systems face severe electromagnetic compatibility (EMC) problems, particularly interference from the secondary radar to the primary radar. Primary radars used for air defense and early warning typically operate in the L, S, and C bands, while secondary radars operate in the L band. The fundamental frequency of the secondary radar can directly interfere with the L-band primary radar; harmonics or spurious signals from the secondary radar may fall into the operating frequency band of the primary radar, interfering with the S and C band primary radars. For example, if the secondary radar transmits at a frequency of 1030MHz, its third harmonic signal frequency is 3090MHz, which may be received by the S-band primary radar and mistaken for a target echo, creating false targets and affecting normal target detection.

[0006] Currently, the main electromagnetic compatibility (EMC) measures for primary and secondary radar systems include: First, suppressing out-of-band emissions, with strict standards limiting out-of-band radiation and harmonic levels of radar transmitters (especially the high power of primary radars and the purity of the emission spectrum of secondary radars / transponders). Second, receiver selectivity, equipping primary radar receivers with high-performance filters (such as cavity filters) to ensure that only signals within the operating frequency band are received, thus suppressing out-of-band interference as much as possible. Third, minimizing the antenna sidelobe level of the primary radar.

[0007] All of the above measures place stringent requirements on the performance of radar system hardware, leading to difficulties in cost and manufacturing, and thus have certain limitations in application.

[0008] In traditional integrated primary and secondary radar systems, the primary radar's transmission triggering is controlled by the primary radar's time and space management board, while the secondary radar's transmission triggering is controlled by the secondary radar's main unit; the two are independent of each other. For example... Figure 1 As shown, there is no definite relationship between the primary radar's transmission trigger and the secondary radar's transmission trigger. Therefore, the transmitted signals from the primary and secondary radars are not synchronized. The transmitted signal from the secondary radar (fundamental signal, harmonics, or spurious signals) may fall into the primary radar's receiving gate, causing frequency interference, such as... Figure 2 As shown. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides an electromagnetic compatibility method for primary and secondary radars based on time synchronization. This method integrates the primary and secondary radars in a coordinated and compatible design, significantly suppressing frequency interference and improving equipment usability when the primary and secondary radars are installed and operating simultaneously.

[0010] The objective of this invention is achieved through the following technical solutions.

[0011] An electromagnetic compatibility method for primary and secondary assembled radar based on time synchronization, comprising the following steps:

[0012] 10) Unified time reference design: including unified time system for primary and secondary radar reception and unified radar control;

[0013] 20) Transmission trigger synchronization design: The secondary radar is triggered at the lead time t0 before the primary radar is triggered. Each trigger signal triggers the secondary radar to transmit two pulse signals, and the trigger interval is consistent with that of the primary radar.

[0014] 30) Synchronous Design of Operating Timing: After receiving the transmit trigger signal from the time-space management board, the primary radar transceiver component and the primary radar frequency source send the local oscillator signal to the primary radar transceiver component according to the agreed timing. The primary radar transceiver component generates an intermediate frequency signal according to the agreed timing, mixes it with the local oscillator signal to generate an radio frequency signal, and then radiates a signal with a set pulse width according to the time specified in the operating timing. After transmission, the transceiver component switches to the receiving state according to the time specified in the operating timing to receive the target echo signal. After receiving the transmit trigger signal from the time-space management board, the secondary radar host sends the radio frequency signal to the secondary radar wave control component according to the agreed timing, and then radiates a signal with a set pulse width according to the time specified in the operating timing. After transmission, the secondary radar host switches to the receiving state according to the time specified in the operating timing to receive the target response signal.

[0015] Step 10) specifically includes:

[0016] The time synchronization equipment receives a unified time reference and then simultaneously transmits the time information to the primary radar time and space management board and the secondary radar host, so that the primary radar and the secondary radar have a unified time reference.

[0017] The operating timing of the primary radar transceiver equipment is controlled by the primary radar time and space management board, and the transmitted local oscillator signal is provided by the primary radar signal source. The primary radar time and space management board is simultaneously connected to the secondary radar host and the secondary radar wave control component, thereby controlling the operating timing of the secondary radar, so that the primary radar and the secondary radar are controlled to a unified operating timing.

[0018] Step 20) includes:

[0019] Each radar transmission signal is controlled by a trigger signal from the radar time and space management board. Each trigger signal triggers the radar to transmit a pulse signal once, and the trigger interval depends on the radar waveform design.

[0020] Based on the primary and secondary integrated radar RF control architecture, the secondary radar's transmission signal is also controlled by the trigger signal of the primary radar's time and space management board. The secondary radar is triggered at the lead time t0 before the primary radar is triggered. Each trigger signal triggers the secondary radar to transmit two pulse signals, and the trigger interval is consistent with that of the primary radar.

[0021] In step 30), the working timing signal of the primary radar is sent by the time-space management board to the primary radar transceiver component and the primary radar frequency source. The signal includes transmit trigger, TR switch, receive gate start, receive gate end, frame start, and frame end signals.

[0022] The primary radar detects non-cooperative targets, while the secondary radar detects cooperative targets. The primary radar has a longer transmission pulse width than the secondary radar.

[0023] The duration and repetition period of a single radar pulse signal transmission are variable, depending on the radar's operating mode, and range from tens of microseconds to thousands of microseconds.

[0024] The time width of the secondary radar transmission pulse signal is 0.8 microseconds, and the interval between the two pulses is 8 microseconds or 21 microseconds.

[0025] Compared with the prior art, the advantages of this invention are:

[0026] 1. Triggered at the source of frequency interference, actively cutting off leakage paths, resulting in high isolation.

[0027] This invention adopts an electromagnetic compatibility design for primary and secondary integrated radar based on timing synchronization. By comprehensively designing the transmission and reception timing, it eliminates the possibility of spatial interference signals leaking into the receiver from the source, resulting in high isolation.

[0028] 2. Wide applicability and high work efficiency.

[0029] This invention employs a time-synchronized electromagnetic compatibility design for primary and secondary radars, using a time-domain design method. Therefore, it is applicable to the combined operation of secondary radars and primary radars of different frequency bands, and has a wide range of applications. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the independent triggering of the primary and secondary combined radar launch.

[0031] Figure 2 This is an independent schematic diagram of the operating timing of the primary and secondary combined radar.

[0032] Figure 3 This invention relates to a time-synchronized primary and secondary combined radar radio frequency control architecture.

[0033] Figure 4 This is a schematic diagram of the primary and secondary combined radar transmission triggering synchronization of the present invention.

[0034] Figure 5 This is a schematic diagram of the timing synchronization of the primary and secondary combined radar of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0036] An electromagnetic compatibility method for primary and secondary assembled radar based on time synchronization includes the following:

[0037] (10) Unified time reference design: unified time system, unified radar control; Figure 3 A primary and secondary combined radar radio frequency control architecture is presented.

[0038] Time synchronization equipment (such as the BeiDou Navigation Satellite System and the Global Navigation Satellite System) receives a unified time reference and then simultaneously transmits the time information to the primary radar time and space management board and the secondary radar host, so that the primary radar and the secondary radar have a unified time reference.

[0039] The primary radar's transceiver equipment operates on a timing control system controlled by the primary radar's time-space management board, with the transmitted local oscillator signal provided by the primary radar's signal source. In traditional designs, the secondary radar's timing is triggered independently of the primary radar. In this invention, the primary radar's time-space management board is simultaneously connected to both the secondary radar's main unit and its beam control components, thereby controlling the secondary radar's timing and ensuring that both radars are controlled within a unified timing framework.

[0040] (20) Launch trigger synchronization design;

[0041] Figure 4 This is a schematic diagram illustrating the synchronization of the trigger signal for the primary and secondary combined radar.

[0042] Each radar transmission signal is controlled by a trigger signal from the radar time and space management board. Each trigger signal triggers the radar to transmit a pulse signal once, and the trigger interval depends on the radar waveform design.

[0043] based on Figure 3 The primary and secondary radar RF control architecture shown in the diagram is such that the secondary radar's transmission signal is also controlled by the trigger signal of the primary radar's time and space management board. The secondary radar is triggered at the lead time t0 before the primary radar is triggered. Each trigger signal triggers the secondary radar to transmit two pulse signals, and the trigger interval is consistent with that of the primary radar.

[0044] (30) Synchronization design of working sequence; Figure 5 This is a schematic diagram of the timing synchronization of the primary and secondary combined radar systems.

[0045] The timing signals for the operation of the primary radar are sent from the time-space management board to the primary radar transceiver components and the primary radar frequency source. These signals include transmit trigger, TR switch, receive gate start, receive gate end, frame start, and frame end signals.

[0046] After receiving the transmit trigger signal from the time and space management board, the primary radar transceiver component and the primary radar frequency source send a local oscillator signal to the primary radar transceiver component according to the agreed-upon rhythm. The primary radar transceiver component generates an intermediate frequency signal according to the agreed-upon rhythm, mixes it with the local oscillator signal to generate a radio frequency signal, and then radiates a signal with a set pulse width according to the time specified in the working sequence. After the transmission is completed, the transceiver component switches to the receiving state according to the time specified in the working sequence to receive the target echo signal.

[0047] After receiving the transmission trigger signal from the time and space management board, the secondary radar host and the secondary radar beam control component send radio frequency signals to the secondary radar beam control component according to the agreed rhythm, and then radiate signals with a set pulse width according to the time specified in the working sequence. After the transmission is completed, the secondary radar host switches to the receiving state according to the time specified in the working sequence to receive the target response signal.

[0048] Primary radar detects non-cooperative targets, while secondary radar detects cooperative targets. Generally, the pulse width of primary radar is greater than that of secondary radar. The duration and repetition period of the pulse signal transmitted by primary radar are variable, depending on the radar's operating mode, and are typically in the range of tens to thousands of microseconds. According to the International Civil Aviation Organization (ICAO), the duration of the pulse signal transmitted by secondary radar is 0.8 microseconds, and the interval between two pulses is 8 microseconds (Mode A) or 21 microseconds (Mode C).

[0049] Since the transmission trigger signals of the primary and secondary combined radars are synchronized and known, the transmission signal of the secondary radar will not enter the receiving gate of the primary radar, thus avoiding frequency interference.

Claims

1. A method for electromagnetic compatibility of primary and secondary assembled radar based on time synchronization, characterized by the following steps: include: 10) Unified time reference design: including unified time system for primary and secondary radar reception and unified radar control; 20) Transmission trigger synchronization design: The secondary radar is triggered at the lead time t0 before the primary radar is triggered. Each trigger signal triggers the secondary radar to transmit two pulse signals, and the trigger interval is consistent with that of the primary radar. 30) Synchronization design of working sequence: After the primary radar transceiver component and the primary radar frequency source receive the transmit trigger signal from the time and space management board, the frequency source sends the local oscillator signal to the primary radar transceiver component according to the agreed sequence. The primary radar transceiver component generates the intermediate frequency signal according to the agreed sequence, and mixes it with the local oscillator signal to generate the radio frequency signal. Then, it radiates the signal with the set pulse width outward according to the time specified in the working sequence. After the launch is completed, the transceiver unit switches to the receiving state according to the time specified in the working sequence and receives the target echo signal. After the secondary radar host and the secondary radar beam control component receive the launch trigger signal from the time and space management board, the secondary radar host sends radio frequency signals to the secondary radar beam control component according to the agreed time sequence, and then radiates a signal with a set pulse width outward according to the time specified in the working sequence. After the launch, according to the time specified in the work sequence, the secondary radar main unit switches to receiving mode to receive the target response signal; Step 10) specifically includes: The time synchronization equipment receives a unified time reference and then simultaneously transmits the time information to the primary radar time and space management board and the secondary radar host, so that the primary radar and the secondary radar have a unified time reference. The operating timing of the primary radar transceiver equipment is controlled by the primary radar time and space management board, and the transmitted local oscillator signal is provided by the primary radar signal source. The primary radar time and space management board is simultaneously connected to the secondary radar host and the secondary radar wave control component, thereby controlling the operating timing of the secondary radar, so that the primary radar and the secondary radar are controlled under the same operating timing. Step 20) includes: Each radar transmission signal is controlled by a trigger signal from the radar time and space management board. Each trigger signal triggers the radar to transmit a pulse signal once, and the trigger interval depends on the radar waveform design. Based on the primary and secondary radar RF control architecture, the secondary radar's transmission signal is also controlled by the trigger signal of the primary radar's time and space management board. The secondary radar is triggered at the lead time t0 before the primary radar is triggered. Each trigger signal triggers the secondary radar to transmit two pulse signals, and the trigger interval is consistent with that of the primary radar. In step 30), the working timing signal of the primary radar is sent by the time-space management board to the primary radar transceiver component and the primary radar frequency source. The signal includes transmit trigger, TR switch, receive gate start, receive gate end, frame start, and frame end signals.

2. The electromagnetic compatibility method for primary and secondary assembled radar based on time synchronization according to claim 1, characterized in that, The primary radar detects non-cooperative targets, while the secondary radar detects cooperative targets. The primary radar has a longer transmission pulse width than the secondary radar.

3. The electromagnetic compatibility method for primary and secondary assembled radar based on time synchronization according to claim 2, characterized in that, The duration and repetition period of a single radar pulse signal transmission are variable, depending on the radar's operating mode, and range from tens of microseconds to thousands of microseconds.

4. The electromagnetic compatibility method for primary and secondary assembled radar based on time synchronization according to claim 3, characterized in that, The time width of the secondary radar transmission pulse signal is 0.8 microseconds, and the interval between the two pulses is 8 microseconds or 21 microseconds.

Images