CN-122017739-A - Complex modulation signal generation method based on multiphase fitting modeling

CN122017739ACN 122017739 ACN122017739 ACN 122017739ACN-122017739-A

Abstract

The invention particularly relates to a complex modulation signal generation method based on multiphase fitting modeling, belongs to the field of radars, and is applied to a radar frequency synthesizer. The method comprises the steps of taking an FPGA and a DAC as core hardware, firstly generating an n-phase increment sequence through multiphase fitting modeling according to the phase change characteristics of CW, LFM, NLFM signals and the IP instantiation quantity of FPGA phase amplitude conversion, then outputting amplitude codes through multiple paths of IP, and transmitting the amplitude codes to the DAC through an LVDS or JESD204B/C high-speed interface after cross sequencing according to the phase relation, so as to generate a target signal. The method is aimed at fitting signal phase characteristics, the LFM signal generation can calculate phase increment in real time, no extra memory is occupied, the three signal processing flows are consistent, the universality is strong, the transplanting is easy, and high-stability and high-precision complex modulation signals can be generated efficiently.

Inventors

ZHU KANGSHENG
WANG DAIBIN
SHI ZHIRONG
LI HONG
Fang Xinkuo
ZHU QIFAN

Assignees

西安电子工程研究所

Dates

Publication Date: 20260512
Application Date: 20260108

Claims (9)

1. The complex modulation signal generation method based on multiphase fitting modeling is characterized in that a circuit composition main body comprises an FPGA and a DAC, and the method comprises the following specific implementation steps: step 1, generating an n-phase increment sequence through multiphase fitting modeling according to the phase change characteristics of signal forms and the phase amplitude conversion IP instantiation number n in the FPGA, wherein the signal forms comprise a CW signal, an LFM signal and a NLFM signal; Step 2, outputting amplitude codes by multiple paths of IP; Step 3, cross ordering the amplitude codes according to the phase change relation to obtain a signal amplitude change sequence; and 4, sending the sequenced amplitude codes to a DAC, and generating complex modulation signals with expected frequencies by the DAC, wherein the complex modulation signals comprise continuous wave CW, linear frequency modulation signals LFM and nonlinear frequency modulation signals NLFM.
2. The complex modulation signal generation method based on multiphase fitting modeling according to claim 1, wherein the determination principle of the number n of IP instantiations is that the rate of the IP clock clk is less than or equal to 250MHz.
3. The complex modulated signal generation method based on multi-phase fitting modeling of claim 1, wherein the phase delta quantization is: Wherein, the Depending on the signal form, either as a constant value or as a sequence over time.
4. A complex modulated signal generating method based on multiphase fitting modeling as claimed in claim 3, wherein for CW signal generation, the specific implementation manner is: the 1 st path of initial phase is 0, the phase increment is a fixed value, and the fixed value is input as IP 1; The 2 nd path of initial phase is a specific value, the phase increment is a specific value, and the specific value is input as IP 2; by analogy, the nth path of initial phase is a corresponding specific value, the phase increment is a fixed value, the fixed value is used as IPn input, and the time axis is based on a preset reference; After the IP 1 ～IP n outputs amplitude data and carries out cross sequencing according to the corresponding phase sequencing, the amplitude data is output to the DAC at the n multiplied by clk data rate, and the DAC generates a CW signal with corresponding output frequency.
5. The complex modulated signal generating method based on multiphase fitting modeling according to claim 3, wherein for LFM signal generation, the phase increment change has a constant acceleration characteristic, and the specific implementation manner is as follows: taking n phases as an example, the 1 st path of initial phase is 0, and the phase increment is in a corresponding change form and is used as IP1 input; the 2 nd path of initial phase is a specific value, the phase increment is a corresponding change form, and the specific value is used as IP2 input; And so on, the nth path of initial phase is a corresponding specific value, the phase increment is a corresponding change form, the phase increment is input as an IP n , and the time axis is based on a preset reference; After the IP 1 ～IP n outputs the amplitude data and carries out cross sequencing according to the corresponding phase sequencing, the amplitude data is output to the DAC at the n multiplied by clk data rate, and the DAC generates an LFM signal with corresponding output frequency.
6. The complex modulated signal generating method based on multiphase fitting modeling as set forth in claim 3, wherein for NLFM signal generation, the phase change has a nonlinear characteristic, and the specific implementation manner is as follows: pre-calculating a phase sequence in MATLAB, and then grouping; The 1 st path adopts the corresponding phase sequence after grouping as IP 1 input; The 2 nd path adopts the corresponding phase sequence after grouping as IP 2 input; And so on, the nth path adopts the grouped corresponding phase sequence as IPn input; After the IP 1 ～IP n outputs amplitude data to be subjected to cross sequencing according to the corresponding phase sequencing, the amplitude data is output to the DAC at the n multiplied by clk data rate, and the DAC generates NLFM signals with corresponding output frequencies.
7. The complex modulated signal generating method based on multi-phase fitting modeling according to claim 1, wherein the ordered amplitude codes are sent to the DAC via LVDS or JESD204B/C high-speed interface.
8. The complex modulation signal generation method based on multi-phase fitting modeling of claim 7, wherein the DAC comprises a parallel DAC based on an LVDS interface and a serial DAC based on a JESD204B/C interface.
9. The complex modulated signal generating method based on multi-phase fitting modeling according to claim 1, wherein the expression of the desired frequency is: Wherein, the Is an IP working clock.

Description

Complex modulation signal generation method based on multiphase fitting modeling Technical Field The invention relates to the technical field of radars, in particular to a complex modulation signal generation method based on multiphase fitting modeling. Background In a radar system, a frequency synthesizer occupies a core position, and the core function of the frequency synthesizer is to generate a high-stability, high-precision and flexible and controllable radio frequency signal, and the performance of the signal directly determines the overall performance index of the radar system. The generation of complex modulation signals (such as a linear frequency modulation signal LFM, a nonlinear frequency modulation signal NLFM, a continuous wave CW, etc.) is one of the key tasks of the frequency synthesizer, and is of great importance to the detection accuracy, the anti-interference capability, etc. of the radar. Currently, hardware schemes based on DAC (digital-to-analog converter), DDS (direct digital frequency synthesizer), VCO (voltage controlled oscillator), PLL (phase locked loop) and the like have become a mainstream way of generating complex modulation signals. With the rapid development of integrated semiconductor technology, FPGA (field programmable gate array) and DAC devices have made breakthrough progress, which have flexible IP cores, rich high-speed interfaces (such as LVDS, JESD 204B/C) and continuously improved data transmission rates, thus providing a wide space for innovation of complex modulation signal generation technology and promoting continuous widening of related technology routes. However, in the complex modulation signal generation process in the prior art, the problems of poor adaptability of part of schemes to different types of signals, extra memory space occupation during LFM signal generation, poor portability and the like still exist, so that the wide application of the complex modulation signal generation method in radar systems and the improvement of performance are limited. It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the invention and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a complex modulation signal generation method based on multiphase fitting modeling, which takes general hardware (FPGA, DAC) and rich resources (IP core, high-speed interface and the like) as a platform, realizes the efficient generation of various complex modulation signals such as CW, LFM, NLFM and the like in a phase fitting modeling mode, and solves the problems of poor generality, large memory occupation, difficult transplanting and the like in the prior art. Other features and advantages of the invention will be apparent from the following detailed description, or may be learned by the practice of the invention. According to a first aspect of the invention, a complex modulation signal generation method based on multiphase fitting modeling is provided, a circuit composition main body comprises an FPGA and a DAC, and the specific implementation steps are as follows: step 1, generating an n-phase increment sequence through multiphase fitting modeling according to the phase change characteristics of signal forms and the phase amplitude conversion IP instantiation number n in the FPGA, wherein the signal forms comprise a CW signal, an LFM signal and a NLFM signal; Step 2, outputting amplitude codes by multiple paths of IP; Step 3, cross ordering the amplitude codes according to the phase change relation to obtain a signal amplitude change sequence; and 4, sending the sequenced amplitude codes to a DAC, and generating complex modulation signals with expected frequencies by the DAC, wherein the complex modulation signals comprise continuous wave CW, linear frequency modulation signals LFM and nonlinear frequency modulation signals NLFM. In some exemplary embodiments, the determination principle of the IP instantiation number n is that the IP clock clk rate is less than or equal to 250MHz. In some exemplary embodiments, the phase delta is quantized to: Wherein, the Depending on the signal form, either as a constant value or as a sequence over time. In some exemplary embodiments, for CW signal generation, the specific implementation is: the 1 st path of initial phase is 0, the phase increment is a fixed value, and the fixed value is input as IP 1; The 2 nd path of initial phase is a specific value, the phase increment is a specific value, and the specific value is input as IP 2; by analogy, the nth path of initial phase is a corresponding specific value, the phase increment is a fixed value, the fixed value is used as IPn input, and the time axis is based on a preset reference; After the IP 1-IPn output amplitude data are subjected to c