VHF and UHF navigation signal processing method and device based on ZYNQ

Abstract

The application discloses a VHF and UHF navigation signal processing method and device based on ZYNQ, relates to the technical field of signal processing, and has the technical scheme as follows: the application uses a single ZYNQ chip to replace the 'FPGA+DSP' double-chip architecture of the digital processing part of a traditional aviation navigation signal receiver, increases the system integration, makes the design more compact, the circuit design simpler, and is beneficial to the lightweight design of the airborne equipment; in addition, with the aid of the powerful processing performance of the PL part of the ZYNQ chip and the high-speed analog-digital conversion chip (ADC) developing rapidly, the reception of VHF and UHF navigation signals can be realized through radio frequency direct sampling technology, and complete digitalization of analog down-conversion is realized, the advantage is that the leakage, frequency deviation and the generation of more harmonics and spurious of the analog local oscillator can be solved, and the electromagnetic interference of the equipment is significantly reduced.

Description

Technical Field

[0001] The present invention relates to the field of signal processing technology, and more particularly, to a ZYNQ-based VHF and UHF navigation signal processing method and device. Background Art

[0002] To improve airspace operational efficiency and ensure flight safety, the international civil aviation sector has vigorously promoted the development of Performance-Based Navigation (PBN) technology, which emphasizes navigation performance rather than focusing on specific navigation sources. This allows aircraft to obtain their latitude and longitude position information with optimal accuracy and integrity using multiple navigation signals within the coverage of the navigation system signal or within the operating capabilities of the onboard navigation equipment, and then fly along any desired path.

[0003] like Figure 1 As shown in the figure, large civil airliners are equipped with integrated radio navigation equipment for receiving and processing navigation signals from instrument landing systems (ILS), very high frequency omnidirectional range (VOR), satellite navigation systems (GNSS), and satellite landing systems (GLS) to calculate the aircraft's position. The ILS calculates the depth difference of modulation (DDM) between the 150Hz and 90Hz amplitude modulated signals in the LOC and GS signals, respectively, to obtain lateral and vertical deviation indicators from the intended approach path. The VOR calculates the phase difference between the 30Hz amplitude modulated signal and the frequency modulated signal to obtain the aircraft's azimuth relative to the ground station. The GLS demodulates and decodes the VDB message, extracting GNSS augmentation information and the intended approach path. The GNSS augmentation information is used to correct the aircraft's latitude and longitude altitude position obtained by the GNSS system and compares it with the intended approach path to obtain lateral and vertical deviation indicators.

[0004] However, the signal demodulation and processing within current airborne navigation equipment is typically implemented using purely analog circuits or a partially digital "FPGA + DSP" architecture. This involves downconverting the RF signal to an intermediate frequency (IF) using an analog local oscillator and mixer. After sampling and digitizing the IF signal, the FPGA chip performs digital downconversion from IF to baseband, while the DSP chip performs baseband digital signal processing. This configuration offers the advantage that later functional and algorithm upgrades require only modifications to the DSP software, without altering the hardware logic design. However, this architecture avoids the issues of analog local oscillator leakage, frequency deviation, and the generation of significant harmonics and spurious signals. Summary of the Invention

[0005] To address the deficiencies in the prior art, the present invention aims to provide a ZYNQ-based VHF and UHF navigation signal processing method and apparatus, replacing the "FPGA+DSP" dual-chip architecture of the digital processing portion of a traditional aviation navigation signal receiver with a single ZYNQ chip. This increases system integration, makes the design more compact, and simplifies the circuit design, which is conducive to the lightweight design of airborne equipment.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] In a first aspect, a ZYNQ-based VHF and UHF navigation signal processing method is provided, comprising the following steps:

[0008] The received VHF signal and UHF signal are respectively subjected to RF direct sampling to obtain corresponding sampling signals, wherein the VHF signal includes VOR, LOC and VDB baseband signals, and the UHF signal includes GS baseband signals;

[0009] The PS part of the ZYNQ chip converts the received tuning frequency instruction into an NCO frequency word and sends it to the digital down-conversion module of the PL part of the ZYNQ chip;

[0010] The VHF and UHF RF signals on the channel corresponding to the tuning frequency command in the sampled signal are down-converted to zero frequency through the digital down-conversion module to obtain the in-phase and quadrature components of the three baseband signals of VOR, VHF-xLS and GS. The VHF-xLS is LOC or VDB.

[0011] The aircraft's azimuth is calculated from the VOR baseband signal through the PS part of the ZYNQ chip, and the xLS function is switched according to the input mode selection command: if it is ILS, the DDM of LOC and GS are calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is D8PSK demodulated and the VDB message is output.

[0012] Furthermore, the digital baseband signal processed and output by the PL part is transmitted to the PS part through direct memory access.

[0013] Furthermore, the data exchange between the PS part and the outside is completed through the UART bus;

[0014] The data interaction includes the input of tuning frequency instructions and mode selection instructions and the output of navigation measurement data and VDB messages.

[0015] Furthermore, the lower frequency limit of the VHF signal is 108 MHz, and the upper frequency limit is 118 MHz, and the VOR and VHF-xLS are received simultaneously through an analog and sampling circuit.

[0016] Furthermore, the sampling rate expression of the RF direct sampling is:

[0017]

[0018] Among them, f s is the sampling rate; f L is the lower frequency limit of the signal; f H Take it as the upper limit of the signal frequency; m is the frequency that can satisfy natural number.

[0019] Furthermore, the method further comprises:

[0020] Generate multiple sampling clocks through a mixed-mode clock manager or phase-locked loop and output them to the ADC to sample UHF and VHF RF signals;

[0021] The sampling rate of VHF radio frequency signal is set to an integer multiple of 10.5kHz, and the sampling rate of UHF radio frequency signal is set to 2 K ×M×5Hz, where K and M are both integers.

[0022] Furthermore, the digital down-conversion module is configured with three digital down-conversion channels: a VOR channel, a VHF-xLS channel, and a UHF-GS channel;

[0023] The VOR channel and VHF-xLS channel are of the same origin and structure, process VHF radio frequency signals simultaneously, and use the same digital down-conversion structure.

[0024] Furthermore, the signal processing process of the VOR channel and / or VHF-xLS channel is specifically as follows:

[0025] The I / Q signals are filtered out by comb-integrator cascade filters to remove the frequency multiplication components during mixing, and the baseband signals are downsampled at the same time.

[0026] Then they are downsampled by three-stage half-band filters respectively;

[0027] Finally, they are processed by frequency-selective finite impulse response filters to output baseband signals with a symbol rate suitable for the PS part operation.

[0028] Furthermore, the signal processing process of the UHF-GS channel is specifically as follows:

[0029] The I / Q signals are filtered out by comb-integrator cascade filters to remove the frequency multiplication components during mixing, and the baseband signals are downsampled at the same time.

[0030] Then they are processed by frequency-selective finite impulse response filters respectively;

[0031] Finally, they are down-sampled through three-stage half-band filters to output baseband signals with a symbol rate suitable for the PS part operation.

[0032] Secondly, a ZYNQ-based VHF and UHF navigation signal processing device is provided, including:

[0033] The signal sampling module is used to directly sample the received VHF signal and UHF signal to obtain corresponding sampling signals. The VHF signal includes VOR, LOC and VDB baseband signals, and the UHF signal includes GS baseband signal.

[0034] The NCO conversion module is used to convert the received tuning frequency instruction into an NCO frequency word through the PS part of the ZYNQ chip and send it to the digital down-conversion module of the PL part of the ZYNQ chip;

[0035] The digital down-conversion module is used to down-convert the VHF and UHF radio frequency signals on the channel corresponding to the tuning frequency command in the sampling signal to zero frequency, and obtain the in-phase and quadrature components of the three baseband signals of VOR, VHF-xLS and GS. The VHF-xLS is LOC or VDB.

[0036] The baseband signal processing module is used to calculate the aircraft's azimuth from the VOR baseband signal through the PS part of the ZYNQ chip, and switch the xLS function according to the input mode selection command: if it is ILS, the DDM of LOC and GS is calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is demodulated by D8PSK and outputs the VDB message.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The ZYNQ-based VHF and UHF navigation signal processing device provided by the present invention replaces the "FPGA+DSP" dual-chip architecture of the digital processing part of the traditional aviation navigation signal receiver with a single ZYNQ chip, increasing system integration, making the design more compact and the circuit design simpler, which is conducive to the lightweight design of airborne equipment.

[0039] 2. With the help of the powerful processing performance of the PL part of the ZYNQ chip and the rapidly developing high-speed analog-to-digital conversion chip (ADC), the present invention can receive VHF and UHF navigation signals through RF direct sampling technology and realize the complete digitalization of analog down-conversion. Its advantage is that it can solve the problems of leakage, frequency deviation and the generation of more harmonics and spurious waves of the analog local oscillator, and significantly reduce the electromagnetic interference of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0041] Figure 1 It is an architectural diagram of an airborne integrated radio navigation device in the prior art.

[0042] Figure 2 is a schematic diagram of signal processing in Example 1 of the present invention;

[0043] Figure 3 is a processing flow chart of digital down conversion in embodiment 1 of the present invention;

[0044] Figure 4 is a flowchart of baseband signal processing in embodiment 1 of the present invention;

[0045] Figure 5 This is a system block diagram in Example 2 of the present invention. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0047] The Zynq system-on-chip consists of two parts: a programmable logic array (PL) and a processing system (PS). The PL can be programmed using a hardware description language to create hardware circuits; the PS is a dual-core ARM Cortex-A9 processor that can be software-programmed. The PL and PS are interconnected via an AXI bus.

[0048] Example 1: VHF and UHF navigation signal processing method based on ZYNQ, such as Figure 2 shown.

[0049] (1) The received VHF signals in the 108-118 MHz frequency band and the UHF signals in the 329-335 MHz frequency band are sampled directly by RF to obtain the corresponding sampling signals.

[0050] VHF signals include the ILS system's localizer (LOC), VOR signal, and GLS system's VHF data broadcast (VDB) signal. UHF signals include the ILS system's glide slope (GS) signal. Typically, the VOR function is always enabled, while the xLS function (a general term for both ILS and GLS) is enabled either during approach or landing.

[0051] (2) The PS part of the ZYNQ chip converts the received tuning frequency instruction into an NCO frequency word and sends it to the digital down-conversion module of the PL part of the ZYNQ chip.

[0052] (3) The VHF and UHF RF signals on the channel corresponding to the tuning frequency instruction in the sampled signal are down-converted to zero frequency through the digital down-conversion module to obtain the in-phase and quadrature components of the three baseband signals of VOR, VHF-xLS and GS. VHF-xLS is LOC or VDB.

[0053] (4) The aircraft's azimuth is calculated from the VOR baseband signal through the PS part of the ZYNQ chip, and the xLS function is switched according to the input mode selection command: if it is ILS, the DDM of LOC and GS are calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is D8PSK demodulated and the VDB message is output.

[0054] In this embodiment, the digital baseband signal processed and output by the PL is transferred to the PS via direct memory access (DMA).

[0055] In this embodiment, data exchange between the PS and the outside world is accomplished via the UART bus, including the input of tuning frequency commands and mode selection commands, as well as the output of navigation measurement data and VDB messages. Because the input of tuning frequency and mode selection is random and sudden, they are processed by the interrupt controller of the UART bus on the PS side of the ZYNQ chip. The main program of the PS is baseband signal processing and continuously outputs navigation data. When the tuning frequency or mode selection is input to the PS side via the UART bus, an interrupt service is initiated to run the NCO frequency word calculation program or mode switching program. The calculated NCO frequency word is transmitted to the digital down-conversion module of the PL part via the AXI general-purpose input and output interface (GPIO), or the operating mode is switched.

[0056] The analog-to-digital converter (ADC) directly samples the RF signal. According to the bandpass sampling theorem, when the signal spectrum is limited to (f L ,f H ) within , can Sampling it will not cause spectrum aliasing, where m is the number that can satisfy In this example, m=3, f s The value should be as close as possible to This allows the sampled digital signal spectrum to be located near the center of the first Nyquist zone, reducing the design requirements of the front-end analog frequency selection filter and leaving more transition band margin. LTake 108 MHz, f H Choose 118MHz, so that only one analog and sampling circuit can be used to receive the VOR signal and the xLS VHF signal at the same time.

[0057] The present invention can generate multi-channel sampling clocks through a mixed mode clock manager / phase locked loop (MMCM / PLL), and output the clocks to an ADC for sampling UHF and VHF radio frequency signals.

[0058] Considering that the symbol rate of GLS-VDB transmission is 10.5ksps, in order to facilitate the symbol timing and synchronization of D8PSK digital demodulation, the sampling rate of the VHF RF signal is set to an integer multiple of 10.5kHz.

[0059] In order to facilitate the spectrum analysis of the 90Hz and 150Hz modulation waves in the UHF signal using discrete Fourier transform (DFT), the sampling rate of the UHF radio frequency signal is set to 2 K ×M×5Hz, where K and M are both integers. In this example, the VHF sampling rate is set to fsv=84MHz, and the UHF sampling rate is set to fsu=256MHz.

[0060] The sampled carrier frequency f c The corresponding digital angular frequency is The numerically controlled oscillator (NCO) outputs the same phase branch I [n]=sin(w c n), and output s to the orthogonal branch Q [n]=cos(w c n), and mix them with the sampling signal respectively, so that the carrier frequency f c The digital RF signal is down-converted to zero.

[0061] like Figure 3 As shown in the figure, the digital down-conversion module has three digital down-conversion channels, namely VOR, VHF-xLS and UHF-GS. The VOR and VHF-xLS channels are homologous and isomorphic, that is, they process VHF digital RF signals simultaneously and use the same digital down-conversion structure.

[0062] For both the I / Q channels, a comb-integrator cascade (CIC) filter is used to remove the frequency-multiplied components generated during mixing, while also downsampling the baseband signals. In this example, the VHF first in-phase and quadrature signals are downsampled by a factor of 50, while the UHF first in-phase and quadrature signals are downsampled by a factor of 625.

[0063] Subsequently, the I / Q signals of the VOR and VHF-xLS channels are first downsampled by a three-stage half-band filter (HB), and then respectively passed through a frequency-selective finite impulse response filter (FIR), and finally output a baseband signal with a symbol rate suitable for efficient operation of the PS. The frequency-selective FIR suppresses adjacent frequency (fc±50kHz) interference, which can be achieved through a low-complexity polyphase filtering structure, and at the same time, the baseband signal is downsampled by a D factor. The passband cutoff frequency of the frequency-selective FIR is not less than 10440Hz, and the stopband start frequency is not higher than The minimum value of the two, f FIR is the sampling rate of the frequency-selective FIR. In this example, the frequency-selective FIR performs 5x downsampling, with a stopband start frequency of 21 kHz, and ultimately outputs a baseband signal with a symbol rate of 42 kHz.

[0064] The I / Q signals of the UHF-GS channel first pass through the frequency-selective FIR, then pass through three-stage HB for downsampling, and finally output a baseband signal with a symbol rate suitable for efficient operation of the PS. The frequency-selective FIR suppresses adjacent frequency (fc±150kHz) interference, which can be achieved through a low-complexity polyphase filter structure, and at the same time, the baseband signal is downsampled by a D factor. The passband cutoff frequency of the frequency-selective FIR is not less than 1020Hz, and the stopband start frequency is not higher than The minimum value of the two, f FIR is the sampling rate of the frequency-selective FIR. In this example, the frequency-selective FIR performs 5x downsampling, with the stopband start frequency at 40.96 kHz, and ultimately outputs a baseband signal with a symbol rate of 10.24 kHz.

[0065] like Figure 4 As shown in the figure, the mode frequency frame input via the UART contains the operating mode control field and the tuning frequency field. The mode control field includes the VOR mode control word and the xLS mode control word. The VOR mode control word controls the VOR function on and off, while the xLS mode control word switches the landing guidance function between off, ILS, and GLS states. The main program of the PS is baseband signal processing. After initializing the AXI GPIO driver, AXIDMA driver, UART driver, and UART interrupt controller, it begins continuously loading digital baseband signals from the DMA and then performs the following processing (main program):

[0066] First read the mode control register;

[0067] Then determine the VOR mode. If it is on, the aircraft's azimuth is calculated from the VOR baseband signal. If it is off, the VOR baseband signal is not processed and is skipped.

[0068] Then judge the xLS mode: in the off state (such as when the aircraft is cruising at high altitude, not during approach and landing), the VHF-xLS and GS baseband signals are not processed and are skipped; if it is ILS, the DDM of LOC and GS are calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is D8PSK demodulated and the VDB message is output.

[0069] After the interrupt controller is configured, the UART interrupt routine can run independently of the main program and concurrently with it. The UART interrupt controller operates as follows: when a mode frequency frame containing the mode control field and the tuning frequency field is input to the PS via the UART port, an interrupt is triggered, calling the interrupt routine, which executes until it completes and then exits to continue executing the main program.

[0070] After the interrupt program is triggered, the mode control register is updated according to the mode control field, and then the NCO frequency word is calculated according to the tuning frequency and sent to the PL through the AXI GPIO. The NCO frequency word is Round to the nearest integer, where f c is the carrier frequency of the VOR signal, f s is the ADC sampling rate, and N is the NCO frequency word width.

[0071] Example 2: A ZYNQ-based VHF and UHF navigation signal processing device, which is used to implement the ZYNQ-based VHF and UHF navigation signal processing method as described in Example 1. Figure 5 As shown, it includes a signal sampling module, an NCO conversion module, a digital down-conversion module and a baseband signal processing module.

[0072] Among them, the signal sampling module is used to directly sample the received VHF signal and UHF signal respectively to obtain the corresponding sampling signal. The VHF signal includes VOR, LOC and VDB baseband signals, and the UHF signal includes GS baseband signal; the NCO conversion module is used to convert the received tuning frequency instruction into NCO frequency word through the PS part of the ZYNQ chip, and send it to the digital down-conversion module of the PL part of the ZYNQ chip; the digital down-conversion module is used to convert the VHF and UHF radio frequency signals on the channel corresponding to the tuning frequency instruction in the sampling signal Down-convert to zero frequency to obtain the in-phase and quadrature components of the three baseband signals of VOR, VHF-xLS and GS. VHF-xLS is LOC or VDB. The baseband signal processing module is used to calculate the aircraft's azimuth from the VOR baseband signal through the PS part in the ZYNQ chip, and switch the xLS function according to the input mode selection instruction: if it is ILS, the DDM of LOC and GS is calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is D8PSK demodulated and the VDB telegram is output.

[0073] Working Principle: The present invention replaces the "FPGA+DSP" dual-chip architecture of the digital processing part of the traditional aviation navigation signal receiver with a single-chip ZYNQ chip, which increases the system integration, makes the design more compact, and simplifies the circuit design, which is conducive to the lightweight design of airborne equipment. In addition, with the help of the powerful processing performance of the PL part of the ZYNQ chip and the rapidly developing high-speed analog-to-digital conversion chip (ADC), the reception of VHF and UHF navigation signals can be achieved through RF direct sampling technology, and the analog down-conversion can be fully digitized. Its advantage is that it can solve the problems of leakage, frequency deviation, and the generation of more harmonics and spurious signals of the analog local oscillator, and significantly reduce the electromagnetic interference of the equipment.

[0074] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0075] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0076] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0078] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The VHF and UHF navigation signal processing method based on ZYNQ is characterized by: The following steps are involved: The received VHF signal and UHF signal are respectively subjected to RF direct sampling to obtain corresponding sampling signals, wherein the VHF signal includes VOR, LOC and VDB baseband signals, and the UHF signal includes GS baseband signals; The PS part of the ZYNQ chip converts the received tuning frequency instruction into an NCO frequency word and sends it to the digital down-conversion module of the PL part of the ZYNQ chip; The VHF and UHF RF signals on the channel corresponding to the tuning frequency command in the sampled signal are down-converted to zero frequency through the digital down-conversion module to obtain the in-phase and quadrature components of the three baseband signals of VOR, VHF-xLS and GS. The VHF-xLS is LOC or VDB. The aircraft's azimuth is calculated from the VOR baseband signal through the PS part of the ZYNQ chip, and the xLS function is switched according to the input mode selection command: if it is ILS, the DDM of LOC and GS are calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is D8PSK demodulated and the VDB message is output.

2. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 1, characterized in that: The digital baseband signal processed and outputted by the PL part is transmitted to the PS part through direct memory access.

3. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 1, wherein: The data exchange between the PS part and the outside is completed through the UART bus; The data interaction includes the input of tuning frequency instructions and mode selection instructions and the output of navigation measurement data and VDB messages.

4. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 1, wherein: The lower frequency limit of the VHF signal is 108 MHz, and the upper frequency limit is 118 MHz, and the VOR and VHF-xLS are received simultaneously through an analog and sampling circuit.

5. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 1, wherein: The sampling rate expression of the RF direct sampling is: Among them, f s is the sampling rate; f L is the lower frequency limit of the signal; f H Take it as the upper limit of the signal frequency; m is the frequency that can satisfy natural number.

6. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 1, characterized in that: The method further includes: Generate multiple sampling clocks through a mixed-mode clock manager or phase-locked loop and output them to the ADC to sample UHF and VHF RF signals; The sampling rate of VHF radio frequency signal is set to an integer multiple of 10.5kHz, and the sampling rate of UHF radio frequency signal is set to 2 K ×M×5Hz, where K and M are both integers.

7. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 1, wherein: The digital down-conversion module is equipped with three digital down-conversion channels: a VOR channel, a VHF-xLS channel, and a UHF-GS channel; The VOR channel and VHF-xLS channel are of the same origin and structure, process VHF radio frequency signals simultaneously, and use the same digital down-conversion structure.

8. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 7, wherein: The signal processing process of the VOR channel and / or VHF-xLS channel is specifically as follows: The I / Q signals are filtered out by comb-integrator cascade filters to remove the frequency multiplication components during mixing, and the baseband signals are downsampled at the same time. Then they are downsampled by three-stage half-band filters respectively; Finally, they are processed by frequency-selective finite impulse response filters to output baseband signals with a symbol rate suitable for the PS part operation.

9. The ZYNQ-based VHF and UHF navigation signal processing method according to claim 7, characterized in that: The signal processing process of the UHF-GS channel is specifically as follows: The I / Q signals are filtered out by comb-integrator cascade filters to remove the frequency multiplication components during mixing, and the baseband signals are downsampled at the same time. Then they are processed by frequency-selective finite impulse response filters respectively; Finally, they are down-sampled through three-stage half-band filters to output baseband signals with a symbol rate suitable for the PS part operation.

10. The VHF and UHF navigation signal processing device based on ZYNQ is characterized by: include: The signal sampling module is used to directly sample the received VHF signal and UHF signal to obtain corresponding sampling signals. The VHF signal includes VOR, LOC and VDB baseband signals, and the UHF signal includes GS baseband signal. The NCO conversion module is used to convert the received tuning frequency instruction into an NCO frequency word through the PS part of the ZYNQ chip and send it to the digital down-conversion module of the PL part of the ZYNQ chip; The digital down-conversion module is used to down-convert the VHF and UHF radio frequency signals on the channel corresponding to the tuning frequency command in the sampling signal to zero frequency, and obtain the in-phase and quadrature components of the three baseband signals of VOR, VHF-xLS and GS. The VHF-xLS is LOC or VDB. The baseband signal processing module is used to calculate the aircraft's azimuth from the VOR baseband signal through the PS part of the ZYNQ chip, and switch the xLS function according to the input mode selection command: if it is ILS, the DDM of LOC and GS is calculated from the VHF-xLS and GS baseband signals respectively; if it is GLS, the VHF-xLS baseband signal is demodulated by D8PSK and outputs the VDB message.

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