A multi-reference synchronization method for radar echo superposition of intermediate frequency analog data

Abstract

The present invention relates to the field of radar, and in particular to a high-real-time asynchronous optical fiber data multi-reference switching synchronization method for radar echo superimposed on intermediate frequency analog data, including: (1) using the first data frame header mark combined with the data unique synchronization mark as a reference to measure the delay difference of the later data; (2) using the frame end mark as a reference to reset the FIFO synchronization to cache the complete message data; (3) using the maximum delay difference as a reference to achieve synchronous reading; (4) using the main data as a reference to adjust the zero distance and amplitude of the simulated echo; (5) using the main data as a reference to cache its message parameters and set the abnormal value superposition protection of IQ data. The method solves the problem that it is difficult to achieve synchronous superposition of radar echo and intermediate frequency analog data due to different clock sources, nanosecond delay difference is difficult to measure, echo amplitude distance does not match, etc.

Description

Technical Field

[0001] The present invention relates to the field of radar technology. Background Art

[0002] With the continuous development of phased array radar technology, higher requirements are placed on the completeness of equipment performance. Phased array radar target echo simulation technology solves the problem of verifying the functions of the radar back-end subsystems in the early stage of radar development without the launch front end, and can also evaluate and analyze its overall performance, saving a lot of costs for the research, design and verification of radar systems, speeding up the development process, and becoming an important technical means in all aspects of radar system analysis, design, testing, and evaluation.

[0003] However, in the traditional radar working state, radar echo and simulated echo data are sent to the radar back-end for processing separately. It is difficult to synchronously superimpose radar echo and simulated echo fiber data, and realize the function of setting superimposed simulated targets and setting clutter / interference simulation sectors based on echo. The main difficulties are: (1) different clock sources; (2) high-precision nanosecond-level optical fiber transmission delay difference is difficult to determine; (3) echo zero distance / amplitude does not match; (4) lack of means to achieve synchronous superposition output of two asynchronous data channels of echo and simulated echo. Summary of the invention

[0004] The present invention provides a multi-reference synchronization method for radar echo superimposed with intermediate frequency analog data. Radar echo data and intermediate frequency analog echo data are initially controlled by the same radar wave control parameter trigger. The wave control parameters are obtained under the condition of uncertainty of delay in uplink transmission (including inherent delay of radar timing, TR phase shift, D / A, up-conversion, power amplification, radiation), downlink reception (T / R reception, low noise amplifier, down-conversion, filtering, A / D, amplitude and phase correction, DBF synthesis), and data transmission. The wave control parameters are obtained after simulated target data generation, clutter generation, interference generation, echo superposition, and data transmission to obtain radar intermediate frequency analog echo data. If radar echo IQ data is superimposed with intermediate frequency analog echo IQ data, it is necessary to synchronize the data of two asynchronous optical fiber links, set a unique synchronization reference to complete the high-precision delay difference test of asynchronous data across clock domains, and realize the comprehensive output of IQ data under high real-time asynchronous data conditions based on multi-synchronous reference switching.

[0005] The technical solution adopted by the present invention is:

[0006] A multi-reference synchronization method for radar echo superposition of intermediate frequency simulation data includes an optical fiber link super-delay test method, a high-real-time asynchronous data synchronization reference, and a superposition protection function for abnormal data based on the main data. The steps are as follows:

[0007] S1, receives two channels of asynchronous optical fiber data and performs clock homology processing through FIFO;

[0008] S2, based on the first arrival reference, the timing is cleared to zero and the timing of the later arrival reference is latched, and the maximum delay of the link transmission is measured multiple times;

[0009] S3, using the end of the frame as the synchronization reference to enable the synchronous reset of the FIFO buffer to ensure the integrity of the stored optical fiber data message; the first arriving data uses the maximum delay of S2 as the synchronization reference to achieve synchronous reading of the FIFO of the two optical fiber data;

[0010] S4, taking the echo data as the priority synchronization reference, the IQ data of the intermediate frequency analog echo data is adjusted in zero distance and amplitude;

[0011] S5, considering data saturation, idle codewords, virtual connection and disconnection, etc., performs signal comprehensive output under abnormal value protection.

[0012] Furthermore, the step S1 includes:

[0013] (1) Receive optical fiber IQ data of one radar echo and one intermediate frequency analog echo. The clocks of the two optical fiber data are from different sources, but the message formats are consistent. They are both composed of message parameters and IQ data, which are recorded as A1 and B1;

[0014] (2) Setting message parameter flags and data unique synchronization references, including message start flag flag_start, message end flag flag_end, and data unique synchronization reference flag_same;

[0015] (3) The data of A1 and B1 are simultaneously fed into the same FIFO1 for clock homology processing, and after output, A2 and B2 are obtained.

[0016] Furthermore, the step S2 comprises:

[0017] (1) Based on the first-arrived benchmark B2 data, parse flag_start, detect flag_same and reset the count to zero;

[0018] (2) Based on the later-arrived reference A2 data, flag_start is parsed and flag_same is detected, then the counter latches and triggers a latch pulse, and the ChipScope software is used to trigger this pulse, and the delay difference is collected, which is timed as T1;

[0019] (3) Perform M delay tests under different working conditions such as radar orientation or rotation. The test results are as follows: If A2 is slower than B2, this assumption is maintained in the following. The measured delay difference is {T1, T2, …T M};

[0020] (4) Set the maximum delay difference to Timedelay_max = max{T1, T2, ... T M}.

[0021] Furthermore, the step S3 includes:

[0022] (1) The A2 and B2 data are simultaneously fed into the same FIFO2, and their reset references are set to flag_end to ensure that the fiber data in each cycle is a complete message;

[0023] (2) Set the storage depth of FIFO2 to Fifo_depth = N*Timedelay_max, where N is an integer greater than 2, to ensure that the cache size can maintain data synchronization conditions;

[0024] (3) Set the synchronous read flag, taking B2 as the reference. When the number of data stored in B2 reaches (N-1)*Timedelay_max, the read enable of the two FIFO2s is valid.

[0025] (4) Synchronous reading: synchronously read FIFO2 to obtain data A3 and B3 respectively.

[0026] Furthermore, the step S4 comprises:

[0027] (1) Message parameters and IQ data are stored separately: the message parameters of B3 are stored as Head, and the IQ data of A3 and B3 are stored as A4 and B4 respectively;

[0028] (2) Zero distance / amplitude adjustment: Take A4 as the reference and correct B4 for distance / amplitude correction;

[0029] (3) IQ data alignment: A4 and B4 are aligned according to the distance unit.

[0030] Furthermore, the step S5 comprises:

[0031] (1) Abnormal value protection: If A4 or B4 is detected to be abnormal in some distance units, it belongs to one of the following situations: ① the data after superposition is saturated; ② the data is idle K code; ③ the B fiber link is virtual connection and disconnected; then it will not participate in the subsequent superposition and will be directly output based on A4;

[0032] (2) IQ data superposition: A4 and B4 are synchronously superimposed to obtain Data_out;

[0033] (3) Integrated output: Align the timing of Head and Data_out and splice them for integrated output.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Adopting outlier superposition protection settings to overcome the asymmetry of asynchronous optical fiber transmission links;

[0036] (2) Using echo distance / amplitude correction to achieve the echo and intermediate frequency simulation echo position / amplitude match;

[0037] (3) The FIFO synchronous reset is combined with the synchronous reference reading to ensure the integrity and synchronization of the FIFO stored message data;

[0038] (4) A high-real-time asynchronous fiber optic data synchronization method based on multi-synchronous reference switching is proposed, including: ① using the first data frame header mark combined with the data unique synchronization mark as the reference to measure the delay difference of the subsequent reference data; ② using the frame end mark as the reference to reset the FIFO synchronization to cache the complete message data; ③ using the maximum delay difference as the reference to synchronize reading to ensure that the IQ data can be synchronously superimposed; ④ adjusting the zero distance and amplitude of the simulated echo based on the main data; ⑤ caching its message parameters based on the main data and setting the abnormal value superposition protection of the IQ data.

[0039] (5) Based on the radar echo background, the invention can realize the function of adding intermediate frequency simulated targets in different posture environments, different interference simulation sectors and clutter simulation sectors, which has important application value for the realization of phased array radar echo superposition simulation data.

[0040] The present invention proposes a multi-reference synchronization method for radar echo superposition of intermediate frequency analog data, which can meet the requirements of the two-way IQ data of the echo and the intermediate frequency analog echo under the conditions of unknown nanosecond fiber delay, asynchronous clock, different zero distance, and mismatched amplitude, and realize the synchronous superposition function of asynchronous signals across clock domains. The present invention is further explained below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Attached Figure 1 It is the system implementation block diagram.

[0042] Attached Figure 2 It is a schematic diagram of the system implementation.

[0043] Attached Figure 3 It is a specific flow chart for system implementation. DETAILED DESCRIPTION

[0044] The present invention proposes a multi-reference synchronization method for radar echo superposition intermediate frequency analog data, the system implementation frame is as shown in the attached figure. Figure 1 The system implementation diagram is shown in the attached Figure 2 The implementation steps are shown in the attached Figure 3 As shown, the specific embodiment can be described as the following process:

[0045] Step 1, receiving two channels of asynchronous optical fiber data across clock domains, including echo IQ data and intermediate frequency analog IQ data, denoted as A1 and B1.

[0046] Step 2, set the message parameter flags and synchronization reference, including the message start flag flag_start, the message end flag flag_end, and the data unique synchronization reference flag_same.

[0047] Step 3, the data of A1 and B1 are simultaneously fed into the same FIFO for clock homology processing to obtain A2 and B2.

[0048] Step 4, based on the first-arrived benchmark B2 data, parse flag_start, detect flag_same and reset the count to 0; based on the later-arrived benchmark A2 data, parse flag_start, detect flag_same, then trigger the counter latch pulse, use ChipScope software to trigger this pulse, collect the delay difference, and count as T1; use flag_same as the only data synchronization benchmark to perform M delay tests in radar orientation or different speed rotation scenarios. The test results are as follows: If A2 is slower than B2, the following assumptions are maintained, and the measured delay difference is {T1, T2, …T M}; Set the maximum delay difference to Timedelay_max = max{T1, T2, ... T M}.

[0049] Step 5, the A2 and B2 data enter the same FIFO2 at the same time, and set the reset reference to flag_end to ensure that the optical fiber data in each cycle is a complete message.

[0050] Step 6, set the storage depth of FIFO2 to Fifo_depth = N*Timedelay_max, where N is an integer greater than 2, to ensure that the cache size can maintain data synchronization conditions.

[0051] Step 7, synchronous reading. ① Set the synchronous reading flag, taking B2 as the reference, when the number of data stored in B2 reaches (N-1)*Timedelay_max, the reading enable of the two FIFO2s is valid. ② Synchronous reading. Synchronously read FIFO2 to obtain data A3 and B3 respectively.

[0052] Step 8, the message parameters and IQ data are stored separately, the message parameters of B3 are stored as Head; the IQ data of A3 and B3 are stored as A4 and B4 respectively.

[0053] Step 9, zero distance / amplitude adjustment. Using A4 as the reference, correct B4 for distance correction and IQ amplitude correction.

[0054] Step 10, IQ data alignment. Align A4 and B4 according to the distance unit.

[0055] Step 11, abnormal value protection. If an abnormality is detected in some units of A4 or B4, it belongs to one of the following situations: ① the data after superposition is saturated; ② the data is idle K code; ③ the B optical fiber link is disconnected. Then it will not participate in the subsequent superposition and directly output based on A4.

[0056] Step 12, IQ data superposition. A4 and B4 are superimposed synchronously to obtain Data_out.

[0057] Step 13, signal synthesis output. Align the timing of Head and Data_out and splice them for integrated output.

Claims

1. A multi-reference synchronization method for radar echo superposition intermediate frequency analog data, characterized in that: S1, receives two channels of asynchronous optical fiber data and performs clock homology processing through FIFO; S2, based on the first arrived benchmark data, parse the message start flag, detect the unique synchronization benchmark of the data and reset the count to zero; Based on the late arrival reference data, the message start flag is parsed and the unique synchronization reference of the data is detected, which triggers the counter latch pulse. The ChipScope software is used to trigger this pulse and collect the delay difference. Using the unique data synchronization benchmark, the delay test is performed in radar orientation or different rotation speed scenarios to obtain the maximum delay difference; S3, the data processed by the same source enter the same FIFO2 at the same time, and the reset reference is set to the message end mark to ensure that the optical fiber data in each cycle is a complete message; the synchronous reading mark is set based on the maximum delay difference obtained in S2, and FIFO2 is read synchronously; S4, taking the echo data as the priority synchronization reference, the IQ data of the intermediate frequency analog echo data is adjusted for zero distance / amplitude; S5, signal integrated output.

2. The multi-reference synchronization method of radar echo superimposed intermediate frequency analog data according to claim 1, characterized in that: The step S1 comprises: (1) Receive optical fiber IQ data of one radar echo and one intermediate frequency analog echo. The clocks of the two optical fiber data are from different sources, but the message formats are consistent. They are both composed of message parameters and IQ data, which are recorded as A1 and B1; (2) Setting message parameter flags and data unique synchronization references, including message start flag flag_start, message end flag flag_end, and data unique synchronization reference flag_same; (3) The data of A1 and B1 are simultaneously fed into the same FIFO1 for clock homology processing, and after output, A2 and B2 are obtained.

3. The multi-reference synchronization method of radar echo superimposed intermediate frequency analog data according to claim 2, characterized in that: The step S2 comprises: (1) Based on the first-arrived benchmark B2 data, parse flag_start, detect flag_same and reset the count to zero; (2) Based on the later-arrived reference A2 data, flag_start is parsed and flag_same is detected, then the counter latches and triggers a latch pulse, and the ChipScope software is used to trigger this pulse, and the delay difference is collected, which is timed as T1; (3) Perform M delay tests in different working conditions of radar orientation or rotation. The test results are as follows: If A2 is slower than B2, this assumption is maintained in the following. The measured delay difference is {T1, T2, ..., T M }; (4) Set the maximum delay difference to Timedelay_max = max{T1, T2, ..., T M }.

4. The multi-reference synchronization method of radar echo superimposed intermediate frequency analog data according to claim 3, characterized in that: The step S3 comprises: (1) The A2 and B2 data are simultaneously fed into the same FIFO2, and their reset references are set to flag_end to ensure that the fiber data in each cycle is a complete message; (2) Set the storage depth of FIFO2 to Fifo_depth = N*Timedelay_max, where N is an integer greater than 2, to ensure that the cache size can maintain data synchronization conditions; (3) Set the synchronous read flag, taking B2 as the reference. When the number of data stored in B2 reaches (N-1)*Timedelay_max, the read enable of the two FIFO2s is valid. (4) Synchronous reading: synchronously read FIFO2 to obtain data A3 and B3 respectively.

5. The multi-reference synchronization method of radar echo superimposed intermediate frequency analog data according to claim 4, characterized in that: The step S4 comprises: (1) Message parameters and IQ data are stored separately: the message parameters of B3 are stored as Head, and the IQ data of A3 and B3 are stored as A4 and B4 respectively; (2) Zero distance / amplitude adjustment: Take A4 as the reference and correct B4 for distance / amplitude correction; (3) IQ data alignment: A4 and B4 are aligned according to the distance unit.

6. The multi-reference synchronization method of radar echo superimposed intermediate frequency analog data according to claim 5, characterized in that: The step S5 comprises: (1) Abnormal value protection: If A4 or B4 is detected to be abnormal in some distance units, it belongs to one of the following situations: ① the data after superposition is saturated; ② the data is idle K code; ③ the B fiber link is virtual connection and disconnected; then it will not participate in the subsequent superposition and will be directly output based on A4; (2) IQ data superposition: A4 and B4 are synchronously superimposed to obtain Data_out; (3) Integrated output: Align the timing of Head and Data_out and splice them for integrated output.

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