Laser wind-finding radar signal processing device

Abstract

According to the laser wind-finding radar signal processing device provided by the invention, a heterogeneous pipeline structure is used for organically combining utilization of logic resources of a chip and utilization of processor resources, hardware area optimization and calculation acceleration are carried out by adopting a self-adaptive selection spectrum dynamic range and a circulating sliding window, the integration level of the device is improved, and the reliability of the device is improved. And the size and the weight of the device are reduced. Meanwhile, remote software version updating and remote parameter changing are achieved based on a multi-guiding mechanism, a plurality of distance doors which can customize the starting point distance and length in a fine-grained mode and can be overlapped with one another are arranged, the flexibility of the device is greatly improved, the requirements of various platforms can be met, and the application range of the device is expanded.

Description

Technical Field

[0001] The invention relates to the technical field of laser wind measurement, in particular to a signal acquisition and processing device for realizing the acquisition and real-time processing of echo signals of a coherent Doppler laser wind measurement radar. Background Art

[0002] Atmospheric wind field is an important parameter of weather dynamics. Accurate detection of atmospheric wind field is of great significance to flight safety and development of wind energy resources. Traditional direct detection methods, such as anemometers and wind vanes, measure wind speed by direct contact with the atmosphere, which makes it difficult to obtain high-resolution, large-scale, long-term and real-time wind field information. Compared with traditional detection methods, Doppler laser wind radar has simple spatial maintenance, high resolution and can perform long-term real-time high-precision measurements, so it has attracted people's attention.

[0003] Doppler laser wind radar is divided into incoherent detection and coherent detection. The former obtains the frequency of the incident light according to the transmittance of the incident light, obtains the Doppler frequency shift by the frequency difference between the transmitted laser and the received laser, and then calculates the wind field information; the latter performs heterodyne coherent mixing of the echo signal and the local oscillator light, and then extracts the difference frequency signal, namely the Doppler frequency shift. The signal-to-noise ratio of the received signal of the latter is significantly improved compared with the former, and the detection sensitivity is higher, which has obvious advantages.

[0004] Since the wind speed is positively correlated with the frequency shift of the Doppler laser wind radar echo, according to the Nyquist theorem, in order to meet the requirements of the wind speed measurement range, the signal processing system needs to have a very high data sampling rate. On the one hand, this leads to a sharp increase in the data rate after analog-to-digital conversion. On the other hand, in order to ensure the accuracy of frequency estimation, it is necessary to increase the number of Fourier transform points. At the same time, since the laser in laser wind measurement has a very high repetition frequency and a large number of range gates, the amount of calculation required by the processing system is very large. The processing speed using the CPU is slow and cannot achieve the purpose of real-time processing; while using FPGA for spectrum acquisition and then using the CPU to complete the wind speed calculation, the entire system has a low degree of integration, which is not conducive to miniaturization and cannot meet the needs of specific scenarios. At the same time, the parameter settings of the existing acquisition device are rigid and the code cannot be updated remotely, lacking flexibility and cannot adapt to a variety of scenarios. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a highly integrated remote coherent Doppler laser wind radar signal acquisition and processing device. The device uses a heterogeneous pipeline structure to organically combine the use of chip logic resources and processor resources, and realizes remote software version updates based on a multi-boot mechanism. It has the characteristics of high integration and high flexibility, and realizes real-time acquisition and processing of coherent Doppler laser wind radar signals. Specifically, the technical solution of the present invention relates to a laser wind radar signal processing device, comprising an external interface module (19) and a signal processing module (20), wherein the external interface module (19) is composed of a level conversion circuit (191), a bridge circuit (192), an ADC chip (193), a programmable clock chip (194) and a PHY chip (195); the signal processing module (20) is composed of a ZYNQ chip (201) and peripherals; wherein the peripherals include a FLASH chip (202) and a DDR SDRAM chip (203); the ZYNQ chip (201) includes two parts: a PL (2011) and a processing system PS (2012);

[0006] The PL (2011) comprises an interface module (20111), a data buffer module (20112), a parallel FFT calculation module (20113), a spectrum accumulation module (20114), a spectrum buffer module (20115), a base noise suppression module (20116) and a data transmission module (20117).

[0007] The PS (2012) implements a network port transceiver module (20121), a command parsing module (20122) and a wind speed calculation module (20123);

[0008] The interface module (20111) generates a switch signal (15) through the bridge circuit (192) to control the optical switch and complete the configuration of the programmable clock chip (194) and the ADC chip (193) in the ADC module, wherein the programmable clock chip (194) generates a sampling clock used by the ADC chip (193); then, in synchronization with the trigger signal (14) of the laser (11), the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar output by the photoelectric conversion module (12) and converted into a digital signal by the ADC module;

[0009] After the data signal is cached by the data cache module (20112), the data of a range gate is used as the minimum processing unit and the data is distributed to the parallel processing sub-units in the parallel FFT calculation module (20113) in sequence for zero padding, FFT calculation and modulus value taking; the spectrum obtained by calculating the signal of each echo is accumulated in the spectrum accumulation module (20114) and the accumulated result is cached in the spectrum cache module (20115); the base noise suppression module (20116) reads the cached accumulated spectrum of each range gate and subtracts it from the spectrum of the base noise in sequence;

[0010] The spectrum cache uses on-chip RAM, and the effective number and exponent use an independent true dual-port RAM cache respectively; when performing spectrum accumulation, the B port of the true dual-port RAM outputs the temporarily stored accumulated value, which is added to the spectrum calculated by the signal of the current echo, and the updated accumulated value is written to the A port of the true dual-port RAM;

[0011] When performing base noise suppression, port A outputs the spectrum of the base noise, and port B outputs the spectrum of each range gate; then the data transmission module (20117) controls the direct memory access (DMA) in the PS (2012) through the AXI4 protocol to write the spectrum after deducting the base noise into the DDR SDRAM (203) plug-in of the PS (2012) and outputs an interrupt signal (2013) according to the timer (20119); after receiving the interrupt signal (2013), the PS (2012) reads the spectrum data (2014) stored in the DDR SDRAM (203) and calculates the apparent wind speed, turbulence intensity and wind shear in turn, and finally sends the calculation results to the host computer (13) through the Gigabit Ethernet using the TCP protocol.

[0012] Furthermore, the conversion rate of the ADC chip (193) is 500MSPS, the sampling bit width is 12 bits, and the laser repetition frequency is 100KHz.

[0013] Furthermore, the parallel FFT calculation module (20113) performs a 512-point FFT transformation on each range gate, the number of the range gates is 30, the resolution of the range gate starting distance is 0.6m, the starting position can be adjusted, the range gate length is configured to be 15m, 30m, 60m and 90m, corresponding to 50, 100, 200 and 300 sampling points respectively, and adjacent range gates may not overlap or may have overlapping areas.

[0014] Furthermore, the starting position of the range gate can be adjusted according to the number of the range gates.

[0015] Furthermore, the technical solution of the present application also relates to a method for processing radar echo signals using a laser wind radar signal processing device, comprising the following steps:

[0016] (1) Load the program and perform self-test after power-on;

[0017] (2) After the program is loaded, all internal registers are cleared, and the programmable clock chip (194) and the ADC chip (193) in the ADC module are configured, and then the timer generates a pulse signal of a corresponding frequency according to the output frequency agreed upon by the system;

[0018] (3) After receiving the pulse signal from the timer, PL (2011) executes steps (4) to (11), and PS (2012) executes steps (12) to (14);

[0019] (4) After receiving the pulse signal from the timer, the PL (2011) starts a new processing cycle and sets the cumulative counter T to 0; the PS (2012) simultaneously receives the control instruction (17) sent by the host computer (13) through the Gigabit Ethernet, configures the PS (2012) parameters after parsing the instruction, and communicates with the parameter setting module (20118) on the PL (2011) through the on-chip RAM to complete the setting of the PL (2011) parameters;

[0020] (5) Under the synchronization of the trigger signal, the cumulative counter T is increased by 1, and at the same time, the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar output by the photoelectric conversion module (12) and converted into a digital signal by the ADC module; the interface module (20111) converts the input signal into two parallel signals and simultaneously reduces the clock frequency by half;

[0021] (6) The data cache module (20112) caches the input data through the on-chip RAM. After the data is cached by the data cache module (20112), the input signal is divided into a number of range gates according to the set range gate length and starting position parameters, and each group of data is distributed to the parallel processing sub-unit in the parallel FFT calculation module (20113) in sequence, with the data of one range gate length as a group;

[0022] (7) The parallel processing subunit first fills the range gate time sequence with zeros to make the sequence length equal to the number of FFT calculation points 2 n Equal; then perform FFT calculation on the data of each range gate and take the modulus value of the output spectrum. In order to save computing resources and adapt to long-distance detection, the spectrum adopts adaptive spectrum dynamic range;

[0023] (8) The spectrum accumulation module (20114), if the accumulation counter T=1, only writes the data transmitted by the parallel FFT calculation module (20113) into the port A of the true dual-port RAM; otherwise, reads the temporarily stored accumulation value from the port B of the true dual-port RAM and then adds it to the spectrum input by the parallel FFT calculation module (20113) at the corresponding point, and then writes the result into the port A of the true dual-port RAM;

[0024] (9) Repeat steps (5) to (8) until the value of the cumulative counter T is equal to the set cumulative number parameter N;

[0025] (10) The base noise suppression module (20116) reads the accumulated frequency spectra of each range gate from the cache and subtracts them from the frequency spectra of the base noise in turn, and uses the farthest range gate signal as the base noise; when performing base noise suppression, port A outputs the frequency spectra of the base noise, and port B outputs the frequency spectra of each range gate;

[0026] (11) The data transmission module (20117) controls the DMA in the PS (2012) through the AXI4 protocol to write the spectrum after deducting the base noise into the DDR SDRAM (203) external to the PS (2012);

[0027] (12) If the current cycle is the first cycle, PL (2011) has not prepared data, and PS (2012) does not perform any operation; otherwise, after receiving the pulse signal from the timer, PS (2012) reads out the spectrum data (2014) stored in DDR SDRAM (203), and then calculates the frequency f corresponding to the maximum peak of the spectrum for each range gate;

[0028] (13) PS (2012) uses the following formula to calculate the apparent wind speed v in the corresponding range gate:

[0029]

[0030] Where λ represents the laser wavelength and f represents the ADC sampling frequency;

[0031] Then, the wind shear and plane wind speed are calculated using the apparent wind speed of each range gate;

[0032] (14) The turbulence intensity is calculated using a cyclic sliding window method;

[0033] (15) Repeat steps (4) to (14) to perform a new signal processing of the laser wind radar.

[0034] Furthermore, step (1) further comprises the following steps:

[0035] (1-1) First, the version control program is loaded, and the program selects whether to update the program version and the running program version according to the instructions of the host computer (13);

[0036] (1-2) If the host computer (13) sends an instruction to select an updated program version after power-on, the updated program version is first specified, and then the binary file of the new program and the verification code are sent to the PS (2012) through the network port and stored in the DDR SDRAM (203) plug-in of the PS (2012);

[0037] (1-3) When all the data of the file has been sent, the PS (2012) erases the data at the address corresponding to the program to be updated in the FLASH (202), then writes the data to be updated into the FLASH (202), and performs verification;

[0038] (1-4) If the host computer (13) does not send a corresponding instruction after power-on, the multi-boot register is automatically modified to point to the default version program after a timer of 10 seconds, and then a soft reset is performed to load the corresponding version program.

[0039] Furthermore, the spectrum modulus value in step (7) is expressed as follows:

[0040] F=a×2 b

[0041] Where F represents the spectrum after modulo, a represents the effective number, and b represents the exponent. The spectrum data of each range gate uses the same exponent b.

[0042] Further, the step (14) of calculating the turbulence intensity by using a cyclic sliding window method includes:

[0043] set up but Store A, B, C, D and v, α of each time period in the time sliding window; and v, α are stored cyclically in the memory; when calculating, first read the data v0, α0 stored in the current address to be written, and set A, B, C, D of the previous time period as A N-1 , B N-1 , C N-1 , D N-1 , then the update formulas of A, B, C, and D are as follows:

[0044] A N =A N-1 -v0 2 α0+v N 2 α N

[0045] B N =B N-1-v0α0+v N α N

[0046] C N =C N-1 -α0+α N

[0047] D n =D 0-1 -|v0|α0+|v n |α N

[0048] According to A, B, C, D, calculate the turbulence intensity, and then v N , α N Deposit address.

[0049] Compared with the prior art, the beneficial effects of the present invention are: using a heterogeneous pipeline structure to organically combine the utilization of the logic resources and processor resources of the chip, using adaptive selection of the dynamic range of the spectrum and a cyclic sliding window to optimize the hardware area and accelerate the calculation, making it possible to complete the entire calculation process from radar echo signal acquisition to wind field inversion on the basis of a ZYNQ chip, simplifying the circuit and device structure, improving the device integration, reducing the size and weight of the device, and saving costs. In addition, based on the multi-boot mechanism, remote software version updates are realized, and remote parameter changes through the host computer are supported, including setting a number of fine-grained customizable starting point distances, lengths, and overlapping range gates, which greatly improves the flexibility of the device, can meet the needs of multiple platforms, and expands the scope of application of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic structural diagram of a highly integrated and highly flexible laser wind radar signal processing device of the present invention.

[0051] Figure 2 This is a block diagram of the internal structure of ZYNQ of the present invention.

[0052] Figure 3 Schematic diagram of heterogeneous pipeline processing of the present invention.

[0053] Figure 4 a is a schematic diagram of the DDR ping-pong operation of PL (2011) of the present invention in odd cycles.

[0054] Figure 4 b is a schematic diagram of the DDR ping-pong operation of PL (2011) of the present invention in an even cycle.

[0055] Figure 5 It is a schematic diagram of sliding window calculation of the present invention.

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0057] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0059] The present invention relates to a highly integrated long-range laser wind measurement radar signal processing device, comprising an external interface module (19) and a signal processing module (20), wherein the external interface module (19) mainly comprises a level conversion circuit (191), a bridge circuit (192), an analog to digital converter (ADC) chip (193), a programmable clock chip (194) and an Ethernet physical layer (PHY) chip (195). The signal processing module (20) is mainly composed of a ZYNQ chip (201) and peripherals, wherein the ZYNQ chip (201) comprises two parts: a programmable logic (PL) (2011) and a processing system (PS) (2012), and the PL (2011) comprises an interface module (20111), a data cache module (20112), a parallel FFT (Fast Fourier Transformation) chip (2013), and a signal processing module (2014). The device comprises a fast Fourier transform (FFT, fast Fourier transform) calculation module (20113), a spectrum accumulation module (20114), a spectrum cache module (20115), a base noise suppression module (20116), a data transmission module (20117) and a timer (20119). The PS implements a network port transceiver module (20121), a command parsing module (20122) and a wind speed calculation module (20123). The peripherals include a flash memory chip (202) and a double data rate synchronous dynamic random access memory (DDR SDRAM) chip (203). The connection relationship between the various parts of the device in signal processing is as follows:

[0060] The timer (20119) generates a pulse signal of a corresponding frequency according to the system agreement to start the calculation cycle of the PL (2011) and PS parts. The interface module (20111) controls the optical switch through the bridge circuit (192) and completes the configuration of the programmable clock chip (194) and the ADC chip (193) in the ADC module. Then, under the synchronization of the trigger signal (14) of the laser (11), the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar after being converted into a digital signal by the ADC module. After being cached by the data cache module (20112), the data is distributed to each parallel processing sub-unit in the parallel FFT calculation module (20113) in units of range gates for zero padding, FFT calculation and modulus value extraction. Among them, each two adjacent range gates may overlap or may not overlap. It is preferred to set the two adjacent range gates to overlap, so that the precision and accuracy of the wind field signal to be measured can be effectively improved. The calculated spectrum is accumulated in the spectrum accumulation module (20114) and cached in the spectrum cache module (20115). The base noise suppression module (20116) subtracts the spectrum of each accumulated range gate from the spectrum of the base noise in turn, and then the data transmission module (20117) writes the spectrum after deducting the base noise into the DDR of the PS plug-in. After receiving the interrupt signal (2013) of the timer (20119), the PS reads the spectrum data (2014) stored in the DDR SDRAM (203) and calculates the apparent wind speed, turbulence intensity, and wind shear, and finally sends the calculation result (18) to the host computer (13) via Gigabit Ethernet. At the same time, the PS receives the control instruction (17) sent by the host computer (13) via Gigabit Ethernet, configures the PS parameters after the instruction is parsed, and communicates with the parameter setting module (20118) on the PL (2011), transmits the PL configuration parameters (2015), and completes the setting of the PL (2011) parameters.

[0061] In order to improve the data processing speed of the device, a heterogeneous pipeline structure is adopted, and the PL (2011) and PS parts are used as two stages of the pipeline, and the pipeline method is adopted for acceleration. When the PS uses the spectrum data of the previous cycle for calculation, the PL (2011) collects the radar echo signal of the current cycle and performs Fourier transform. Correspondingly, the DDR SDRAM (203) spectrum storage area is divided into two areas, and a ping-pong operation is performed to avoid data reading and storage conflicts in different cycles.

[0062] In order to save computing resources and adapt to long-distance detection, the spectrum is set to use an adaptive spectrum dynamic range. The spectrum after modulo is expressed as follows:

[0063] F=a×2 b

[0064] Where F represents the spectrum after modulo, a represents the effective number, and b represents the exponent. The spectrum data of each range gate uses the same exponent b.

[0065] The turbulence intensity formula uses a sliding period smoothing calculation. The smoothing time period is long, the calculation amount is huge, it takes a lot of time, and it cannot meet the real-time requirements. Therefore, this device deforms the formula and uses a circular sliding window. Extra memory space is used to store the accumulated value (integral value) in the window and the speed of each time period, avoiding the summation of all values ​​in the time period each time, and exchanging memory space for calculation time for acceleration.

[0066] The device can also remotely update the software version and select the software version to be used through the network under the control of the host computer (13).

[0067] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with specific implementation methods.

[0068] Embodiment 1: Figure 1 Schematic diagram of the structure of the highly integrated remote laser wind radar signal processing device proposed by the present invention. Figure 1 As shown, the present invention comprises an external interface module (19) and a signal processing module (20). The external interface module (19) is composed of a level conversion circuit (191), a bridge circuit (192), an ADC chip (193), a programmable clock chip (194) and a PHY chip (195). The signal processing module (20) is mainly composed of a ZYNQ chip (201) and peripherals, wherein the peripherals include a FLASH chip (202) and a DDR SDRAM chip (203).

[0069] The internal structure diagram of ZYNQ is as follows Figure 2 As shown, the ZYNQ chip (201) includes two parts: PL (2011) and processing system PS (2012). PL (2011) includes interface module (20111), data cache module (20112), parallel FFT calculation module (20113), spectrum accumulation module (20114), spectrum cache module (20115), base noise suppression module (20116) and data transmission module (20117). PS (2012) implements network port transceiver module (20121), instruction parsing module (20122) and wind speed calculation module (20123). The connection relationship between the various parts of the device in signal processing is as follows:

[0070] The interface module (20111) generates a switch signal (15) through a bridge circuit (192) to control the optical switch and complete the configuration of the programmable clock chip (194) and the ADC chip (193) in the ADC module, wherein the programmable clock chip (194) generates a sampling clock used by the ADC chip (193). Then, under the synchronization of the trigger signal (14) of the laser (11), the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar output by the photoelectric conversion module (12) and converted into a digital signal by the ADC module. Since the peak instantaneous input data rate is higher than the data processing rate of the subsequent module, a true dual-port random access memory (Random Access Memory, abbreviated RAM) is used to cache data, and then the address corresponding to each range gate data is calculated according to the range gate position in the instruction of the host computer (13) for reading, which can support the overlap of the positions between the range gates, is more flexible, and the configuration of the center position of the range gate is more fine-grained.

[0071] After the data is cached by the data cache module (20112), the data is distributed to each parallel processing sub-unit in the parallel FFT calculation module (20113) in sequence with the data of one range gate as the minimum processing unit for zero padding, FFT calculation and modulus value taking. The spectrum obtained by calculating the signal of each echo is accumulated in the spectrum accumulation module (20114) and the accumulated result is cached in the spectrum cache module (20115). The base noise suppression module (20116) reads the cached accumulated spectrum of each range gate and subtracts it from the spectrum of the base noise in sequence. The spectrum cache uses an on-chip RAM, and the effective number and the exponent use an independent true dual-port RAM cache respectively. When performing spectrum accumulation, the B port of the true dual-port RAM outputs the temporarily stored accumulated value, and after adding the spectrum obtained by calculating the signal of the current echo, the updated accumulated value is written into the A port of the true dual-port RAM; when performing base noise suppression, the A port outputs the spectrum of the base noise, and the B port outputs the spectrum of each range gate. Then, the data transmission module (20117) controls the direct memory access (DMA) in the PS (2012) through the second version of the Advanced eXtensible Interface 4 (AXI4) protocol to write the spectrum after deducting the base noise into the DDR SDRAM (203) plug-in of the PS (2012) and output an interrupt signal (2013) according to the timer (20119). After receiving the interrupt signal (2013), the PS (2012) reads the spectrum data (2014) stored in the DDR SDRAM (203) and calculates the apparent wind speed, turbulence intensity, and wind shear in turn, and finally sends the calculation result (18) to the host computer (13) through the Gigabit Ethernet using the Transmission Control Protocol (TCP). The PS (2012) simultaneously receives control instructions (17) sent by the host computer (13) through Gigabit Ethernet, configures the PS (2012) parameters after parsing the instructions, and communicates with the parameter setting module (20118) on the PL (2011) through the on-chip RAM to complete the setting of the PL (2011) parameters.

[0072] The method for processing radar echo signals using the above-mentioned laser wind radar signal processing device comprises the following steps:

[0073] (1) After power-on, the version control program is first loaded. The program selects whether to update the program version and the version of the running program according to the instructions of the host computer (13).

[0074] (2) If the host computer (13) sends an instruction to select an updated program version after power-on, the updated program version is first specified, and then the binary file of the new program and the verification code are sent to the PS (2012) through the network port and stored in the DDR SDRAM (203) plug-in of the PS (2012).

[0075] (3) When all the data of the file are sent, PS (2012) erases the data at the address corresponding to the program to be updated in FLASH (202), and then writes the data into FLASH (202). After that, the data at the corresponding address in FLASH (202) is read back and verified with the checksum of the binary file sent by the host computer (13), and then the verification result is returned to the host computer (13).

[0076] (4) If the host computer (13) does not send a corresponding instruction after power-on, the multi-boot register is automatically modified to point to the default version program after a timer of 10 seconds, and then a soft reset is performed to load the corresponding version program.

[0077] (5) After the program is loaded, all internal registers are cleared, and the programmable clock chip (194) and the ADC chip (193) in the ADC module are configured. Then, the timer generates a pulse signal of a corresponding frequency according to the output frequency agreed upon by the system.

[0078] (6) Figure 3 As shown, PL (2011) and PS (2012) are two stages of the pipeline, and are accelerated in a pipeline manner. After receiving the pulse signal from the timer, PL (2011) executes steps (7) to (14), and PS (2012) executes steps (15) to (17). Correspondingly, Figure 4 As shown, the spectrum storage area of ​​DDR SDRAM (203) is divided into two areas for ping-pong operation. PL (2011) uses area A in odd cycles and area B in even cycles; while PS (2012) uses area B in odd cycles and area A in even cycles. This avoids conflicts in data reading and storage in different cycles.

[0079] (7) After receiving the pulse signal from the timer, PL (2011) starts a new processing cycle and sets the cumulative counter T to 0. PS (2012) simultaneously receives the control instruction (17) sent by the host computer (13) through Gigabit Ethernet, configures the PS (2012) parameters after parsing the instruction, and communicates with the parameter setting module (20118) on PL (2011) through the on-chip RAM to complete the setting of the PL (2011) parameters.

[0080] (8) Under the synchronization of the trigger signal, the cumulative counter T is increased by 1, and at the same time, the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar output by the photoelectric conversion module (12) and converted into a digital signal by the ADC module. The interface module (20111) converts the input signal into two parallel signals while halving the clock frequency.

[0081] (9) The data cache module (20112) caches the input data through the on-chip RAM. After the data is cached by the data cache module (20112), the input signal is divided into a number of range gates according to the set range gate starting position and length parameters. The data of one range gate length is grouped as a group and each group of data is distributed in turn to the parallel processing sub-unit in the parallel FFT calculation module (20113).

[0082] (10) The parallel processing subunit first fills the range gate time sequence with zeros to make the sequence length equal to the number of FFT calculation points 2 n Then, the data of each range gate is subjected to FFT calculation and the output spectrum is modulo. In order to improve the operation speed, only the spectrum values ​​of the K points corresponding to the speed range are passed to the spectrum accumulation module (20114).

[0083] (11) The spectrum accumulation module (20114), if the accumulation counter T = 1, only writes the data transmitted by the parallel FFT calculation module (20113) to the A port of the true dual-port RAM. Otherwise, read the temporarily stored accumulation value from the B port of the true dual-port RAM and then add it to the spectrum input by the parallel FFT calculation module (20113) at the corresponding point, and then write the result to the A port of the true dual-port RAM. Set the accumulation value Current spectrum value The updated cumulative value Among them, F represents the spectrum after modulo, a represents the effective number, b represents the index, and c represents the pre-carry value of the previous accumulation. The spectrum data of each range gate uses the same b and c. When adding, let M1 be the maximum value of the effective number range of the accumulated value, M2 be the maximum value of the effective number range of the spectrum, M3 be the maximum value of the spectrum index, and M4 be the maximum value of the effective number of all points after the spectrum of the range gate is accumulated. If The current accumulated pre-carry value is set to 1, otherwise it is set to 0.

[0084] (12) Repeat steps (8) to (11) until the value of the cumulative number counter T is equal to the set cumulative number parameter N.

[0085] (13) The base noise suppression module (20116) reads the accumulated frequency spectra of each range gate from the cache and subtracts them from the frequency spectra of the base noise in turn. The farther the range gate is, the lower the energy of the echo signal is. The energy of the echo signal of the range gate at the farthest distance is approximately zero, and it only contains the base noise. Therefore, the range gate signal is used as the base noise. When performing base noise suppression, port A outputs the frequency spectrum of the base noise, and port B outputs the frequency spectrum of each range gate.

[0086] (14) The data transmission module (20117) controls the DMA in the PS (2012) through the AXI4 protocol to write the spectrum after deducting the background noise into the DDR SDRAM (203) external to the PS (2012).

[0087] (15) If the current cycle is the first cycle, PL (2011) has not prepared data, and PS (2012) does not perform any operation. Otherwise, PS (2012) reads out the spectrum data (2014) stored in DDR SDRAM (203) after receiving the pulse signal from the timer. Then, the frequency f corresponding to the maximum peak of the spectrum is calculated for each range gate.

[0088] (16) PS (2012) uses the following formula to calculate the apparent wind speed v in the corresponding range gate:

[0089]

[0090] Among them, λ represents the laser wavelength. Then the wind shear, plane wind speed, etc. are calculated using the wind speed in each range gate direction.

[0091] (17) The calculation formula for turbulence intensity is:

[0092]

[0093] Where N represents the number of smoothing cycles, α i It represents whether the data of the ith period is valid according to the signal-to-noise ratio. Since the number of smoothing periods is large and the original formula has a large amount of calculation, PS (2012) cannot meet the real-time requirements by directly using the original formula. First, the formula is transformed:

[0094]

[0095] set up but like Figure 5As shown, the device uses a cyclic sliding window method to calculate and store A, B, C, D and v and α of each time period in the time sliding window. Among them, v and α are stored cyclically in the memory, that is, if the data of the current time period is stored at address N, the next data is stored at address 1. When calculating, first read the data v0 and α0 stored in the current address to be written, and set A, B, C, D of the previous time period as A N-1 , B n-1 , C n-1 , D N-1 , then the update formulas of A, B, C, and D are as follows:

[0096] A N =A N-1 -v0 2 α0+v n 2 α n

[0097] B n =B n-1 -v0α0+v N α N

[0098] C N =C N-1 -α0+α N

[0099] D N =D N-1 -|v0|α0+|v N |α N

[0100] According to A, B, C, D, calculate the turbulence intensity, and then v N , α N Deposit address.

[0101] (18) Repeat steps (7) to (17) to perform a new signal processing of the laser wind radar.

[0102] In the examples, see Figure 1 The conversion rate of the ADC chip (193) is 500 million samples per second (MSPS), the sampling bit width is 12 bits, and the laser repetition frequency is 100KHz. The processing chip used in the embodiment is XC7Z020-2CLG400I of the Zynq7000 series.

[0103] In the examples, see Figure 2The parallel FFT calculation module (20113) performs a 512-point FFT transformation on each range gate, supports 30 configurable range gates, and the resolution of the range gate starting distance is 0.6m. The range gate length can be configured to 15m, 30m, 60m and 90m, corresponding to 50, 100, 200 and 300 sampling points respectively.

[0104] According to the data rate to be processed, the parallel FFT calculation module (20113) instantiates 10 parallel processing sub-units, each of which calculates the spectrum of a range gate separately at a time. According to the measured wind speed range, in order to save computing resources and increase the computing speed, only 160 spectrum points near the intermediate frequency corresponding spectrum point are output to the subsequent stage for accumulation.

[0105] In the examples, see Figure 3 and Figure 4 The system accumulation times are set to 10000. After receiving 10000 echo data, PL (2011) accumulates the echo spectrum and subtracts the background noise, and then writes the result into DDR SDRAM (203) at PS (2012) via AXI4 bus.

[0106] In the embodiment, the dual-core ARM Cortex-A9 processor integrated in PS (2012) is used to calculate the wind speed, and the frequency of the output result is 8 Hz. The PL (2011) and PS (2012) parts are used as two stages of the pipeline, and the pipeline method is adopted for acceleration. All wind speed calculation related algorithms are performed in PS (2012), which simplifies the system design and shortens the development cycle.

[0107] See in the examples, see Figure 2 The device controls the optical switch under the control of the timer (20123) in a polling manner, switches the four beams, and adds a beam number identifier to the spectrum data (2014). The wind speed calculation module (20123) in the PS (2012) determines which beam the data belongs to based on the identifier during calculation.

[0108] Finally, the lightweight Internet Protocol (LWIP) stack is used, configured as a client, and the data is sent to the host computer via Gigabit Ethernet using the TCP protocol (13).

[0109] The comparison table of the size and weight of the device before integration is shown in Table 1. It can be seen that the volume of the device is reduced by 72.2% and the weight is reduced by 58.8% compared with the device before integration, saving a huge amount of space and load.

[0110] Table 1 Comparison of dimensions and weights of this device and the device before integration

[0111] Length(cm) Width (cm) Height(cm) <![CDATA[Volume (cm 3 )]]> Weight(g) This device 9.8 8.1 5.1 404.8 340 Integrated front device 16.1 11.0 8.2 1452.2 825 Savings compared to before integration 39.1％ 35.8％ 37.8％ 72.2％ 58.8％

[0112] A comparison table of resources occupied by spectrum-related calculations of whether the device uses adaptive spectrum dynamic range is shown in Table 2. It can be seen that using adaptive spectrum dynamic range can effectively reduce resource occupation.

[0113] Table 2 Comparison of resource occupancy when using adaptive spectrum dynamic range

[0114] DSP48 slice Block RAM Using Adaptive Spectral Dynamic Range 120 50 Without adaptive spectral dynamic range 180 60 Reduced resource usage 33.3％ 16.7％

[0115] The comparison table of the time for the PS end to calculate one frame of data when the device uses a circular sliding window is shown in Table 3. It can be seen that the use of a circular sliding window can greatly speed up the calculation speed.

[0116] Table 3 Comparison of calculation time using or not using circular sliding window

[0117] Computation time (ms) Using a circular sliding window 36.7 No circular sliding window 1779.5 Reduced calculation time 97.9％

[0118] Practical tests show that the present invention can meet the needs of collecting and real-time processing echo signals of coherent Doppler laser wind radar, can support software upgrades, and has the characteristics of high integration and high flexibility.

[0119] In this specification, each embodiment is described in a progressive, parallel, or progressive and parallel manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0120] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0121] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser wind radar signal processing device, characterized in that: The invention comprises an external interface module (19) and a signal processing module (20), wherein the external interface module (19) is composed of a level conversion circuit (191), a bridge circuit (192), an ADC chip (193), a programmable clock chip (194) and a PHY chip (195); the signal processing module (20) is composed of a ZYNQ chip (201) and peripherals; wherein the peripherals include a FLASH chip (202) and a DDR SDRAM chip (203); and the ZYNQ chip (201) includes two parts: a PL (2011) and a processing system PS (2012); The PL (2011) comprises an interface module (20111), a data buffer module (20112), a parallel FFT calculation module (20113), a spectrum accumulation module (20114), a spectrum buffer module (20115), a base noise suppression module (20116) and a data transmission module (20117). The PS (2012) implements a network port transceiver module (20121), a command parsing module (20122) and a wind speed calculation module (20123); The interface module (20111) generates a switch signal (15) through the bridge circuit (192) to control the optical switch and complete the configuration of the programmable clock chip (194) and the ADC chip (193) in the ADC module, wherein the programmable clock chip (194) generates a sampling clock used by the ADC chip (193); then, in synchronization with the trigger signal (14) of the laser (11), the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar output by the photoelectric conversion module (12) and converted into a digital signal by the ADC module; After the data signal is cached by the data cache module (20112), the data is distributed in sequence to each parallel processing sub-unit in the parallel FFT calculation module (20113) with the data of a range gate as the minimum processing unit for zero padding, FFT calculation and modulus value taking; the spectrum obtained by calculating the signal of each echo is accumulated in the spectrum accumulation module (20114) and the accumulated result is cached in the spectrum cache module (20115); The base noise suppression module (20116) reads the accumulated frequency spectra of each range gate from the cache and subtracts them from the frequency spectra of the base noise in turn; The spectrum cache uses on-chip RAM, and the effective number and exponent use an independent true dual-port RAM cache respectively; when performing spectrum accumulation, the B port of the true dual-port RAM outputs the temporarily stored accumulated value, which is added to the spectrum calculated by the signal of the current echo, and the updated accumulated value is written to the A port of the true dual-port RAM; When performing base noise suppression, port A outputs the spectrum of the base noise, and port B outputs the spectrum of each range gate; then the data transmission module (20117) controls the direct memory access (DMA) in the PS (2012) through the AXI4 protocol to write the spectrum after deducting the base noise into the DDR SDRAM (203) plug-in of the PS (2012) and outputs an interrupt signal (2013) according to the timer (20119); after receiving the interrupt signal (2013), the PS (2012) reads the spectrum data (2014) stored in the DDR SDRAM (203) and calculates the apparent wind speed, turbulence intensity and wind shear in turn, and finally sends the calculation results to the host computer (13) through the Gigabit Ethernet using the TCP protocol.

2. The laser wind radar signal processing device according to claim 1, characterized in that: The conversion rate of the ADC chip (193) is 500MSPS, the sampling bit width is 12 bits, and the laser repetition frequency is 100KHz.

3. The laser wind radar signal processing device according to claim 1, characterized in that: The parallel FFT calculation module (20113) performs a 512-point FFT transformation on each range gate, the number of the range gates is 30, the resolution of the range gate starting distance is 0.6m, the range gate lengths are configured to be 15m, 30m, 60m and 90m, corresponding to 50, 100, 200 and 300 sampling points respectively, and adjacent range gates include overlapping areas.

4. The laser wind radar signal processing device according to claim 3, characterized in that: The starting position of the range gate is adjusted according to the number of the range gates.

5. A method for processing radar echo signals using the laser wind radar signal processing device according to claim 1, characterized in that: The steps include: (1) Load the program and perform self-test after power-on; (2) After the program is loaded, all internal registers are cleared, and the programmable clock chip (194) and the ADC chip (193) in the ADC module are configured, and then the timer generates a pulse signal of a corresponding frequency according to the output frequency agreed upon by the system; (3) After receiving the pulse signal from the timer, PL (2011) executes steps (4) to (11), and PS (2012) executes steps (12) to (14); (4) After receiving the pulse signal from the timer, the PL (2011) starts a new processing cycle and sets the cumulative counter T to 0; the PS (2012) simultaneously receives the control instruction (17) sent by the host computer (13) through the Gigabit Ethernet, configures the PS (2012) parameters after parsing the instruction, and communicates with the parameter setting module (20118) on the PL (2011) through the on-chip RAM to complete the setting of the PL (2011) parameters; (5) Under the synchronization of the trigger signal, the cumulative counter T is increased by 1, and at the same time, the interface module (20111) receives the echo signal (16) of the coherent Doppler laser wind radar output by the photoelectric conversion module (12) and converted into a digital signal by the ADC module; the interface module (20111) converts the input signal into two parallel signals and simultaneously reduces the clock frequency by half; (6) The data cache module (20112) caches the input data by using the on-chip RAM using a ping-pong operation. After the input data is cached by the data cache module (20112), the input signal is divided into a number of range gates according to the set range gate length and the starting position. The data of one range gate length is used as a group, and each group of data is distributed in sequence to the parallel processing sub-unit in the parallel FFT calculation module (20113); (7) The parallel processing subunit first fills the range gate time sequence with zeros to make the sequence length equal to the number of FFT calculation points 2 n equal; then perform FFT calculation on the data of each range gate and take the modulus value of the output spectrum; (8) The spectrum accumulation module (20114), if the accumulation counter T=1, only writes the data transmitted by the parallel FFT calculation module (20113) into the port A of the true dual-port RAM; otherwise, reads the temporarily stored accumulation value from the port B of the true dual-port RAM and then adds it to the spectrum input by the parallel FFT calculation module (20113) at the corresponding point, and then writes the result into the port A of the true dual-port RAM; (9) Repeat steps (5) to (8) until the value of the cumulative counter T is equal to the set cumulative number parameter N; (10) The base noise suppression module (20116) reads the accumulated frequency spectra of each range gate from the cache and subtracts them from the frequency spectra of the base noise in turn, and uses the signal of the farthest range gate as the base noise; When performing base noise suppression, port A outputs the spectrum of base noise, and port B outputs the spectrum of each range gate; (11) The data transmission module (20117) controls the DMA in the PS (2012) through the AXI4 protocol to write the spectrum after deducting the base noise into the DDR SDRAM (203) external to the PS (2012); (12) If the current cycle is the first cycle, PL (2011) has not prepared data, and PS (2012) does not perform any operation; otherwise, after receiving the pulse signal from the timer, PS (2012) reads out the spectrum data (2014) stored in DDR SDRAM (203), and then calculates the frequency f corresponding to the maximum peak of the spectrum for each range gate; (13) PS (2012) uses the following formula to calculate the apparent wind speed v in the corresponding range gate: Where λ represents the laser wavelength; f is the frequency corresponding to the maximum peak of the spectrum; Then, the wind shear and plane wind speed are calculated using the apparent wind speed of each range gate; (14) The turbulence intensity is calculated using a cyclic sliding window method; (15) Repeat steps (4) to (14) to perform a new signal processing of the laser wind radar.

6. The method according to claim 5, characterized in that: The steps include: Step (1) further comprises the following steps: (1-1) First, the version control program is loaded, and the program selects whether to update the program version and the running program version according to the instructions of the host computer (13); (1-2) If the host computer (13) sends an instruction to select an updated program version after power-on, the updated program version is first specified, and then the binary file of the new program and the verification code are sent to the PS (2012) through the network port and stored in the DDR SDRAM (203) plug-in of the PS (2012); (1-3) When all the data of the file has been sent, the PS (2012) erases the data at the address corresponding to the program to be updated in the FLASH (202), then writes the data to be updated into the FLASH (202), and performs verification; (1-4) If the host computer (13) does not send a corresponding instruction after power-on, the multi-boot register is automatically modified to point to the default version program after a timer of 10 seconds, and then a soft reset is performed to load the corresponding version program.

7. The method according to claim 5, characterized in that: The calculation of turbulence intensity using a cyclic sliding window method in step (14) includes: set up but Store A, B, C, D and v, α of each time period in the time sliding window; and v, α are stored cyclically in the memory; when calculating, first read the data v0, α0 stored in the current address to be written, and set A, B, C, D of the previous time period as A N-1 , B N-1 , C N-1 , D N-1 , then the update formulas of A, B, C, and D are as follows: A N =A N-1 -v0 2 a0+v N 2 a N B N =B N-1 -v0α0+v N a N C N =C N-1 -α0+α N D N =D N-1 -|v0|α0+|v N |a N According to A, B, C, D, calculate the turbulence intensity, and then v N , α N Deposit address; N represents the number of smoothing cycles, α i It represents judging whether the data of the ith cycle is valid according to the signal-to-noise ratio.

8. The method according to claim 5, characterized in that: The spectrum is configured to adopt an adaptive spectrum dynamic range.

9. The method according to claim 8, characterized in that: The spectrum modulus value in step (7) is expressed by the following formula: F=a×2 b Wherein, F represents the modulus value of the spectrum, a represents the effective number, and b represents the exponent; the spectrum of each range gate uses the same exponent b.

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