Navigation signal generation device and method based on radio frequency sampling

Abstract

The invention discloses a navigation signal generation device and method based on radio frequency sampling, and belongs to the technical field of satellite navigation, the device comprises a time frequency maintaining module, a constant temperature phase locking module, a signal processing module and an output filter, the time frequency maintaining module generates a reference clock and a second pulse signal; the constant-temperature phase locking module generates a radio frequency sampling clock, and enables the phase relation output by the radio frequency sampling clock to be consistent with the second pulse signal by maintaining the temperature of the constant-temperature phase locking module to be stable; the signal processing module is driven by the reference clock and the second pulse signal to generate a small navigation signal by using a DAC module; and the output filter filters the small navigation signals to filter irrelevant signals. According to the method, a link for generating the navigation signal can be simplified, the quality of the navigation signal is improved, and the uncertainty error of the navigation signal is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation technology, and in particular relates to a device and method for generating a navigation signal based on radio frequency sampling. Background Art

[0002] The satellite navigation system provides accurate and continuous three-dimensional position, speed and time information to users around the world with corresponding receiving equipment through satellites. It has become a basic strategic facility that is closely related to national security and social and economic development.

[0003] The generation of navigation signals is an important part of the navigation satellite payload. The generation of navigation signals affects the quality, delay and other indicators of the navigation signals, thereby affecting the positioning, navigation and timing accuracy provided by the satellite navigation system.

[0004] There are two main methods for generating navigation signals in the existing technology. The first method is to generate navigation signals using the superheterodyne method. First, an intermediate frequency navigation signal is generated, and then the intermediate frequency is mixed to the radio frequency by a mixer, and then the image is filtered out by a filter to generate the navigation signal. This method is the most conservative solution, but after the navigation signal is frequency converted and filtered, the signal quality, delay stability and other indicators will deteriorate; the second method is to generate navigation signals using a radio frequency agile chip. The radio frequency agile chip integrates digital upsampling, filtering, local oscillation, mixing, filtering and other links. This solution has a greater impact on the signal quality, and the navigation signal delay parameters are not fixed after each power on and off. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a device and method for generating a navigation signal based on radio frequency sampling, which directly generates a navigation radio frequency signal, can greatly simplify the link of navigation signal generation, improve the quality of navigation signals, reduce the uncertainty error of navigation signals, thereby improving the accuracy of navigation signals and improving the positioning and timing accuracy of navigation systems.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A navigation signal generating device based on radio frequency sampling, the device comprising:

[0008] A time-frequency maintenance module, wherein the time-frequency maintenance module generates a reference clock and a second pulse signal;

[0009] A constant temperature phase-locked module, which generates a radio frequency sampling clock and makes the phase relationship of the radio frequency sampling clock output consistent with the pulse-per-second signal by maintaining its own temperature stability;

[0010] A signal processing module, wherein the signal processing module generates a small navigation signal using a DAC module under the drive of the reference clock and the second pulse signal;

[0011] An output filter is used to filter the small navigation signal to remove irrelevant signals.

[0012] Furthermore, the time-frequency maintaining module generates homologous and coherent reference clock and pulse-per-second signals based on the constant temperature phase-locking module.

[0013] Furthermore, the signal processing module generates a small navigation signal using a DAC module under the drive of the reference clock and the second pulse signal, specifically including:

[0014] The signal processing module samples the pulse-per-second signal in the clock domain of the reference clock, converts the pulse-per-second edge signal into a synchronization signal, and sends the synchronous signal to the DAC module;

[0015] When the DAC module receives the synchronization signal, it divides the RF sampling clock to generate a data processing sampling clock used by the signal processing module, thereby completing the synchronization of the reference clock, the second pulse signal and the DAC module;

[0016] The signal processing module directly generates a navigation signal using the reference clock, the pulse per second signal and the sampling clock of the DAC module, and the navigation signal is distributed in the first and second Nyquist intervals.

[0017] Furthermore, the output filter filters out useless signals in the first or second Nyquist interval according to the DAC module and the RF sampling clock, thereby completing the generation of the navigation signal.

[0018] On the other hand, the present invention further provides a method for generating a navigation signal based on radio frequency sampling, the method being implemented based on any of the aforementioned navigation signal generating devices based on radio frequency sampling, the method comprising:

[0019] Selecting an operating frequency of RF sampling, wherein the operating frequency of RF sampling is an integer multiple of a reference clock, and the data processing clock output by the DAC module is one quarter of the operating frequency of RF sampling;

[0020] Selecting an intermediate frequency working frequency, wherein the intermediate frequency working frequency is an integer multiple of the data processing clock, and performing integer multiple distribution after the second pulse signal is triggered, so that the phase relationship between the intermediate frequency and the second pulse signal is fixed;

[0021] Generate a navigation intermediate frequency signal by using the pulse-per-second signal and the divided clock of the radio frequency sampling;

[0022] The navigation intermediate frequency signal is sent to the DAC module, and the target frequency radio frequency signal is generated by using the second Quest interval.

[0023] Furthermore, before selecting the operating frequency of the RF sampling, the method further includes:

[0024] Select the DAC module that works in the second Quest interval and perform hardware configuration and synchronization.

[0025] The beneficial effects of the present invention are:

[0026] The device and method for generating a navigation signal based on RF sampling proposed in the present invention can generate a navigation signal, which can omit the links of local oscillation, frequency conversion, RF filtering, etc., and solve the problem of non-fixed delay parameters of the navigation signal, which will greatly simplify the generation of the navigation signal, improve the quality of the navigation signal, and improve the accuracy of navigation positioning and timing provided by the navigation satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a structural block diagram of a navigation signal generating device based on radio frequency sampling according to an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of a navigation signal generation method based on radio frequency sampling according to an embodiment of the present invention;

[0029] Figure 3 It is a schematic diagram of the test and verification environment of an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0032] There are two main methods for generating navigation signals in the existing technology. The first method is to generate navigation signals using the superheterodyne method. First, an intermediate frequency navigation signal is generated, and then the intermediate frequency is mixed to the radio frequency by a mixer, and then the image is filtered out by a filter to generate the navigation signal. This method is the most conservative solution, but after the navigation signal is frequency converted and filtered, the signal quality, delay stability and other indicators will deteriorate; the second method is to generate navigation signals using a radio frequency agile chip. The radio frequency agile chip integrates digital upsampling, filtering, local oscillation, mixing, filtering and other links. This solution has a greater impact on the signal quality, and the navigation signal delay parameters are not fixed after each power on and off.

[0033] In order to solve the above technical problems, the following embodiments of a device and method for generating a navigation signal based on radio frequency sampling are proposed in the present invention.

[0034] Example 1

[0035] Reference Figure 1 ,like Figure 1 The figure is a structural block diagram of the navigation signal generating device based on radio frequency sampling of this embodiment. The device is specifically composed of four parts, including a time-frequency maintaining module, a constant temperature phase locking module, a signal processing module and an output filter.

[0036] Specifically, in this implementation, the time-frequency maintaining module is used to generate a 10.23 MHz reference clock and a pulse-per-second signal.

[0037] The constant temperature phase-locked module is used to generate a stable RF sampling clock to ensure that the phase relationship of the sampling clock output remains consistent with the second pulse when the temperature changes.

[0038] Driven by the reference clock and second pulse signal of the time and frequency maintenance module, the signal processing module generates telegrams, frames, spreads the spectrum, and upsamples, and outputs them to the high-speed DAC chip to complete the digital-to-analog conversion and initially generate a small navigation signal.

[0039] The output filter filters the small signal output by the signal processing module and removes unnecessary signals.

[0040] The hardware configuration and synchronization method of the navigation signal generating device based on radio frequency sampling in this embodiment are as follows:

[0041] Step 1: Turn on the time-frequency maintenance module to generate a homologous and coherent 10.23MHz, second pulse 1PPS signal. After the time-frequency module works stably, start the next step.

[0042] Step 2: Turn on the constant temperature phase lock module and generate a radio frequency sampling clock under the 10.23MHz reference standard. The constant temperature phase lock module has built-in temperature control measures to maintain temperature stability by itself to avoid being affected by the external temperature environment. After the constant temperature phase lock module works stably, start the next step.

[0043] Step 3: Turn on the signal processing module and synchronize the high-speed DAC chip. The signal processing FPGA samples the pulse in the 10.23MHz clock domain, and converts the pulse-per-second edge signal into a synchronization signal and sends it to the high-speed DAC chip. When the synchronization signal comes, the high-speed DAC chip divides the RF sampling clock to generate a data processing sampling clock that can be used by the signal processing FPGA, completing the synchronization of 10.23MHz, pulse-per-second 1PPS and DAC sampling.

[0044] Step 4: Signal processing FPGA uses 10.23MHz, 1PPS pulse per second and DAC sampling clock to directly generate navigation signals. The navigation signals generated at this time are distributed in the first and second Nyquist intervals.

[0045] Step 5: By selecting different RF sampling clocks and high-speed DAC chips, unnecessary signals in the first or second Nyquist interval are filtered out to complete the generation of the navigation signal.

[0046] Example 2

[0047] This embodiment proposes a navigation signal generation method based on radio frequency sampling, referring to Figure 2 ,like Figure 2 The figure shows a schematic diagram of a navigation signal generation method based on radio frequency sampling in this embodiment. The method mainly utilizes the characteristic that a high-speed DAC can work in the second Quest interval to generate a navigation signal with a higher frequency under a low sampling rate. Specifically, the method includes the following steps:

[0048] Step 1: Select a high-speed DAC chip that can work in the second Quest interval, select a 4-way parallel data interface, increase the data rate, and complete the hardware configuration and synchronization according to the steps in the navigation signal generating device based on RF sampling.

[0049] Step 2: Select the RF sampling operating frequency Fs, which must be an integer multiple of 10.23MHz. The data processing clock output by the high-speed DAC is Fs / 4.

[0050] Step 3: Select a suitable intermediate frequency operating frequency IF so that IF and Fs / 4 are integer multiples, and the second pulse trigger is distributed in integer multiples so that the phase relationship between the intermediate frequency and the second pulse is in a fixed relationship.

[0051] Step 4: Use the second pulse and the divided clock to generate four intermediate frequency signals for navigation: S IF =Icos(2π*IF*t)+Qsin(2π*IF*t).

[0052] Step 5: Send the four-way intermediate frequency signals to the high-speed DAC and use the second Quest interval to generate the target frequency RF signal SRF =Icos(2π*(Fs-IF)*t)+Qsin(2π*(Fs-IF)*t).

[0053] Example 3

[0054] This embodiment verifies the apparatus and method for generating a navigation signal based on radio frequency sampling proposed in the previous embodiment, and takes direct generation of a navigation signal at a frequency of 1575.42 MHz as an implementation example.

[0055] Step 1: Build a verification environment, refer to Figure 3 ,like Figure 3 The figure is a schematic diagram of the test verification environment of this embodiment, where the pulse and navigation signals are simultaneously connected to a high-speed oscilloscope, and the navigation signal is connected to a spectrum analyzer.

[0056] Step 2: Turn on the time-frequency maintenance module to generate a homologous and coherent 10.23MHz, second pulse 1PPS signal. After the time-frequency module works stably, start the next step.

[0057] Step 3: Configure the constant temperature output RF sampling operating frequency Fs to 1718.64MHz, which is 168 times of 10.23MHz. The data processing clock output by the high-speed DAC is Fs / 4, which is 492.66MHz. The intermediate frequency operating frequency is selected to be 143.22MHz, which is 3 times of 492.66MHz. The target RF frequency output in the second Nyquist interval is 1575.42MHz.

[0058] Step 4: Turn on the constant temperature phase lock module. Under the reference standard of 10.23MHz, the RF sampling clock Fs is generated to be 1718.64MHz. After the constant temperature phase lock module works stably, start the next step.

[0059] Step 5: Turn on the signal processing module and download the FPGA configuration file.

[0060] Step 6: The signal processing FPGA synchronizes the high-speed DAC chip and directly generates the navigation signal using 10.23MHz, 1PPS pulse per second and DAC sampling clock.

[0061] Step 7: Filter out unnecessary signals in the first Nyquist interval to complete the generation of navigation signals.

[0062] Step 8: Use a high-speed oscilloscope to trigger the second pulse to observe the zero-crossing flip point position of the navigation signal and record the data once;

[0063] Step 8: Repeat steps 5 to 7 to verify the navigation signal delay parameters of the method proposed in this embodiment when the power is turned on and off ten times. The test results are shown in Table 1:

[0064] Table 1 Navigation signal delay parameter test results

[0065]

[0066] The test results show that the maximum value of the delay parameter minus the minimum value is 20 ps, ​​which proves that the method proposed in this embodiment can solve the problem of the navigation signal delay parameter being not fixed.

[0067] The present embodiment proposes a device and method for generating a navigation signal based on radio frequency sampling, which utilizes a high-speed DAC, a constant temperature phase-locked loop, and high-precision synchronization to solve the problem of non-fixed navigation signal delay caused when generating a radio frequency sampling navigation signal. In addition, the multi-channel characteristics of a high-speed DAC chip, an optional Nyquist operating range, and the selection of a suitable sampling frequency and intermediate frequency are utilized to directly generate a radio frequency navigation signal, thereby simplifying the navigation signal generation process and greatly improving the quality of the navigation signal, thereby improving the navigation positioning and timing accuracy of the navigation system.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A navigation signal generating device based on radio frequency sampling, characterized in that: The device comprises: A time-frequency maintenance module, wherein the time-frequency maintenance module generates a reference clock and a second pulse signal; A constant temperature phase-locked module, which generates a radio frequency sampling clock and makes the phase relationship of the radio frequency sampling clock output consistent with the pulse-per-second signal by maintaining its own temperature stability; A signal processing module, wherein the signal processing module generates a small navigation signal using a DAC module under the drive of the reference clock and the second pulse signal; An output filter is used to filter the small navigation signal to remove irrelevant signals.

2. The navigation signal generating device based on radio frequency sampling according to claim 1, characterized in that: The time-frequency maintaining module generates homologous and coherent reference clock and pulse-per-second signals based on the constant temperature phase-locking module.

3. The navigation signal generating device based on radio frequency sampling according to claim 1, characterized in that: The signal processing module generates a small navigation signal by using a DAC module under the drive of the reference clock and the second pulse signal, specifically comprising: The signal processing module samples the pulse-per-second signal in the clock domain of the reference clock, converts the pulse-per-second edge signal into a synchronization signal, and sends the synchronous signal to the DAC module; When the DAC module receives the synchronization signal, it divides the RF sampling clock to generate a data processing sampling clock used by the signal processing module, thereby completing the synchronization of the reference clock, the second pulse signal and the DAC module; The signal processing module directly generates a navigation signal using the reference clock, the pulse per second signal and the sampling clock of the DAC module, and the navigation signal is distributed in the first and second Nyquist intervals.

4. The navigation signal generating device based on radio frequency sampling as claimed in claim 3, characterized in that: The output filter filters out useless signals in the first or second Nyquist interval according to the DAC module and the radio frequency sampling clock, thereby completing the generation of the navigation signal.

5. A navigation signal generation method based on radio frequency sampling, characterized in that: The method is implemented based on the navigation signal generating device based on radio frequency sampling according to any one of claims 1 to 4, and the method comprises: Selecting an operating frequency of RF sampling, wherein the operating frequency of RF sampling is an integer multiple of a reference clock, and the data processing clock output by the DAC module is one quarter of the operating frequency of RF sampling; Selecting an intermediate frequency working frequency, wherein the intermediate frequency working frequency is an integer multiple of the data processing clock, and performing integer multiple distribution after the second pulse signal is triggered, so that the phase relationship between the intermediate frequency and the second pulse signal is fixed; Generate a navigation intermediate frequency signal using the second pulse signal and the divided clock of the radio frequency sampling clock; The navigation intermediate frequency signal is sent to the DAC module, and the target frequency radio frequency signal is generated by using the second Quest interval.

6. The navigation signal generation method based on radio frequency sampling according to claim 5, characterized in that: Before selecting the operating frequency of the RF sampling, the method further includes: Select the DAC module that works in the second Quest interval and perform hardware configuration and synchronization.

Images