Frequency-adaptive dual-frequency low-orbit navigation enhanced signal receiving system

Abstract

The invention provides a frequency-adaptive dual-frequency low-orbit navigation enhanced signal receiving system, and relates to the technical field of signal processing. The device specifically comprises an antenna module, a signal amplification module, a shunt module, a frequency mixing module, a self-adaptive intermediate frequency filtering module, a gain amplification module, an anti-aliasing filtering module, a combining module and an analog-to-digital conversion module. And the adaptive intermediate frequency filtering module is used for determining a corresponding target filter according to the input intermediate frequency signal, filtering the intermediate frequency signal by using the target filter and inputting the intermediate frequency signal into the gain amplification module. According to the invention, the adaptive intermediate-frequency filtering module selects the corresponding target filter according to the frequency of the intermediate-frequency signal, thereby achieving the flexible filtering of the signal, effectively avoiding the frequency offset phenomenon of the radio-frequency signal received by the receiver, guaranteeing the compatibility of the receiver to a large extent, improving the signal processing performance of two or more frequency bands, and improving the signal processing efficiency. And the navigation efficiency is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of signal processing technology, and in particular to a frequency-adaptive dual-frequency low-orbit navigation enhanced signal receiving system. Background Art

[0002] It is difficult for the Global Navigation Satellite System (GNSS) navigation enhancement to achieve decimeter, centimeter or even millimeter-level positioning performance. In recent years, due to the advantages of low-orbit constellations such as fast geometric changes, strong landing signal power and global space-based detection coverage, they can complement the GNSS system and comprehensively improve the accuracy, integrity, availability and anti-interference capabilities of satellite navigation and positioning services. For positioning and navigation systems that only use a single frequency, dual-frequency navigation technology is sometimes able to effectively eliminate ionospheric errors, improve carrier recovery capabilities, and achieve instantaneous carrier ambiguity resolution. The observation values ​​of the two frequencies can be combined to perform ionospheric delay correction.

[0003] In related technologies, with the development of low-orbit navigation enhancement, navigation enhancement receivers are required to simultaneously support signals from two or more frequency bands. Currently, receivers have poor signal processing performance for two or more frequency bands, which reduces navigation efficiency. Summary of the invention

[0004] The present disclosure provides a frequency-adaptive dual-frequency low-orbit navigation enhanced signal receiving system to at least solve the problem of poor signal processing performance of two or more frequency bands in the related art. The technical solution of the present disclosure is as follows:

[0005] According to a first aspect of an embodiment of the present disclosure, there is provided a frequency-adaptive dual-frequency low-orbit navigation enhanced signal receiving system, comprising: an antenna module, a signal amplification module, a branching module, a mixing module, an adaptive intermediate frequency filtering module, a gain amplification module, an anti-aliasing filtering module, a combining module and an analog-to-digital conversion module;

[0006] The antenna module is used to receive radio frequency signals and send the radio frequency signals to the signal amplification module;

[0007] The signal amplification module is used to amplify the radio frequency signal and send it to the branching module;

[0008] The branching module is used to divide the radio frequency signal into a plurality of radio frequency band signals of different frequency bands;

[0009] The frequency mixing module is used to perform frequency reduction processing on the multiple radio frequency band signals to obtain corresponding multiple intermediate frequency signals and output them to the adaptive intermediate frequency filtering module;

[0010] The adaptive intermediate frequency filtering module is used to determine the corresponding target filter according to the input intermediate frequency signal, and use the target filter to filter the intermediate frequency signal and input the signal into the gain amplification module;

[0011] The gain amplification module is used to perform channel signal gain on the intermediate frequency signal;

[0012] The anti-aliasing filtering module is used to perform anti-aliasing filtering on the intermediate frequency signal;

[0013] The combining module is used for combining the plurality of intermediate frequency signals to obtain a dual-band intermediate frequency signal and output it to the analog-to-digital conversion module;

[0014] The analog-to-digital conversion module is used to convert the dual-band intermediate frequency signal into a dual-band intermediate frequency digital signal.

[0015] Optionally, the adaptive intermediate frequency filtering module specifically includes: a frequency detection module, a control module, a first switch module, a second switch module, and at least two to-be-determined filters;

[0016] The frequency detection module is used to detect the frequency of the intermediate frequency signal and generate a detection result signal;

[0017] The control module is used to determine the target filter in the to-be-determined filter according to the frequency of the intermediate frequency signal, and generate a control signal to send to the first switch module and the second switch module;

[0018] The first switch module and the second switch module are used to open the signal path corresponding to the target filter according to the control signal.

[0019] Optionally, the control module includes:

[0020] A frequency comparison unit, used for comparing the frequency of the intermediate frequency signal with the center frequency of each of the to-be-determined filters to obtain a comparison result;

[0021] A first control unit, if the center frequency of the filter to be determined is the same as the frequency of the intermediate frequency signal, determines that the filter to be determined is the target filter;

[0022] The second control unit calculates the absolute value of the frequency difference between the center frequency of each of the to-be-determined filters and the intermediate frequency signal if the center frequency of each of the to-be-determined filters is different from the frequency of the intermediate frequency signal, and selects the to-be-determined filter with the smallest absolute value of the difference as the target filter.

[0023] Optionally, the signal amplification module is a low noise amplifier.

[0024] Optionally, the branching module is a balun splitter.

[0025] Optionally, the gain amplification module is a variable gain amplifier.

[0026] Optionally, the combining module is a balun combiner.

[0027] Optionally, the analog-to-digital conversion module is a digital-to-analog converter.

[0028] The technical solution provided by the embodiments of the present disclosure brings at least the following beneficial effects:

[0029] This system uses an adaptive IF filter module to select the corresponding target filter according to the frequency of the IF signal, thereby achieving flexible filtering of the signal. This can effectively avoid the frequency deviation of the RF signal received by the receiver, greatly ensure the compatibility of the receiver, improve the signal processing performance of two or more frequency bands, and improve the efficiency of navigation.

[0030] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the description are used to explain the principles of the present disclosure, and do not constitute improper limitations on the present disclosure.

[0032] Figure 1 is a structural diagram of a dual-channel receiving circuit according to an exemplary embodiment.

[0033] Figure 2 is a structural diagram of a common channel receiving circuit according to an exemplary embodiment.

[0034] Figure 3 It is a structural diagram of a frequency adaptive dual-frequency low-orbit navigation enhanced signal receiving system according to an exemplary embodiment.

[0035] Figure 4 is a structural diagram of an adaptive intermediate frequency filtering module according to an exemplary embodiment.

[0036] Figure 5 It is a structural diagram of a frequency-adaptive dual-frequency low-orbit navigation enhanced signal receiving system according to an exemplary embodiment. DETAILED DESCRIPTION

[0037] In order to enable ordinary persons in the art to better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0039] It should be noted that the user information involved in this disclosure (including but not limited to user device information, user personal information, etc.) is all information authorized by the user or fully authorized by all parties.

[0040] It is difficult for the GNSS navigation enhancement to achieve decimeter, centimeter or even millimeter-level positioning performance. In recent years, due to the advantages of low-orbit constellations such as fast geometric changes, strong landing signal power and global space-based detection coverage, they can complement the GNSS system and comprehensively improve the accuracy, integrity, availability and anti-interference capabilities of satellite navigation and positioning services. For positioning and navigation systems that only use a single frequency, dual-frequency navigation technology is sometimes able to effectively eliminate ionospheric errors, improve carrier recovery capabilities, and achieve instantaneous carrier ambiguity resolution. The observation values ​​of the two frequencies can be combined to perform ionospheric delay correction.

[0041] With the development of low-orbit navigation enhancement, navigation enhancement receivers are required to support signals of two or more frequency bands at the same time, which places very high demands on the circuit performance of the receiver. For signals of two frequency bands with two non-continuous bandwidths, the existing navigation receivers usually adopt the following two solutions in the design of the receiving circuit:

[0042] Figure 1 FIG. 1 is a structural diagram of a dual-channel receiving circuit according to an exemplary embodiment. Figure 1As shown, in a possible embodiment, the antenna 101 receives a signal containing multiple frequency bands, separates the signals of the two frequency bands f1 and f2 in the signal, and inputs them into two channels for processing respectively. The signals of the two frequency bands f1 and f2 are filtered by the corresponding bandpass filters 102 respectively, amplified by the low noise amplifier 103 (Low Noise Amplifier, LNA), and the amplified signals are filtered again by the bandpass filter 103, and the filtered signals are down-converted by the mixer 104. The intermediate frequency signal output by the mixer is down-converted and output by the intermediate frequency filter 105, leaving the corresponding intermediate frequency signals f1 and f2. The intermediate frequency signal is amplified by the amplifier 106, and then filtered by the anti-aliasing filter circuit 107. Finally, the analog to digital converter (ADC) 108 implements sampling conversion of the intermediate frequency signals f1 and f2.

[0043] Figure 2 is a structural diagram of a common channel receiving circuit according to an exemplary embodiment. Figure 2 As shown, in a possible embodiment, a common channel method is used to process a signal containing multiple frequency bands, and the process is as follows:

[0044] The antenna receives signals of frequency bands f1 and f2, and firstly performs low-noise amplification on the received signals through a signal low-noise amplifier 109, and respectively uses a filter 110a with a center frequency of f1 and a filter 110b with a center frequency of f2 to filter the signals of the f1 frequency band and the f2 frequency band, and combines the filtered signals into one channel, performs frequency reduction processing through a mixer 111, and obtains intermediate frequency signals of f1 and f2, and then filters and amplifies the intermediate frequency signals of f1 and f2 through a filter 112 and an amplifier 113, and finally collects and converts the intermediate frequency signals of f1 and f2 through an analog-to-digital converter ADC114.

[0045] Both of the above solutions have some defects. Figure 1 The embodiment of the present invention occupies too much area on the circuit board and is costly; Figure 2 In the embodiment, it is difficult to effectively suppress spurious signals while combining two signals at the intermediate frequency. In addition, the above two solutions have the problem of low frequency adaptability for the following reasons: at the intermediate frequency, the filter is set to a fixed center frequency and a fixed receiving bandwidth to receive the desired signal and remove interference. In actual applications, due to objective factors such as different manufacturers and processes of receiver communications, the frequency deviation of the RF and intermediate frequency signals of the receiver is inevitable. To meet communication requirements, it is necessary to ensure that the bandwidth of the receiving circuit is sufficient. Too large a bandwidth will increase the risk of adjacent channel interference, thereby causing instability.

[0046] Figure 3FIG. 1 is a structural diagram of a frequency adaptive dual-frequency low-orbit navigation enhanced signal receiving system according to an exemplary embodiment. Figure 3 As shown, the frequency adaptive dual-frequency low-orbit navigation enhanced signal receiving system 300 includes: an antenna module 310, a signal amplification module 320, a branching module 330, a mixing module 340, an adaptive intermediate frequency filtering module 350, a gain amplification module 360, an anti-aliasing filtering module 370, a combining module 390 and an analog-to-digital conversion module 390;

[0047] The antenna module 310 is used to receive radio frequency signals and send the radio frequency signals to the signal amplification module 320;

[0048] The signal amplification module 320 is used to amplify the radio frequency signal and send it to the branching module 330;

[0049] The branching module 330 is used to divide the radio frequency signal into a plurality of radio frequency band signals of different frequency bands;

[0050] The mixing module 340 is used to perform frequency reduction processing on the multiple RF frequency band signals to obtain corresponding multiple intermediate frequency signals and output them to the adaptive intermediate frequency filtering module 350;

[0051] The adaptive intermediate frequency filtering module 350 is used to determine the corresponding target filter according to the input intermediate frequency signal, and use the target filter to filter the intermediate frequency signal and input the signal into the gain amplification module;

[0052] The gain amplification module 360 ​​is used to perform channel signal gain on the intermediate frequency signal;

[0053] The anti-aliasing filter module 370 is used to perform anti-aliasing filtering on the intermediate frequency signal;

[0054] The combining module 380 is used for combining the plurality of intermediate frequency signals to obtain a dual-band intermediate frequency signal and output it to the analog-to-digital conversion module 390;

[0055] The analog-to-digital conversion module 390 is used to convert the dual-band intermediate frequency signal into a dual-band intermediate frequency digital signal.

[0056] The signal amplification module 320 uses a low noise amplifier, which is an amplifier with a very low noise coefficient. It is used as a high-frequency or intermediate-frequency preamplifier for various radio receivers, and an amplification circuit for high-sensitivity electronic detection equipment. When amplifying weak signals, the noise of the amplifier itself may seriously interfere with the signal. The low noise amplifier is used to reduce this noise to improve the output signal-to-noise ratio.

[0057] The branching module 330 receives the dual-band RF signal from the signal amplifying module 320 and divides it into a plurality of RF frequency band signals of different frequency bands.

[0058] In a possible embodiment, the signal sent by the signal amplification module 320 is divided into a first radio frequency band signal and a second radio frequency band signal by the branching module 330 .

[0059] The frequency mixing module 340 is used to implement frequency down-conversion processing of two RF signals, thereby reducing the signal frequency and obtaining corresponding intermediate frequency signals.

[0060] In a possible embodiment, the frequency mixing module 340 down-converts the first radio frequency band signal to obtain a first intermediate frequency signal, and down-converts the second radio frequency band signal to obtain a second intermediate frequency signal.

[0061] The adaptive intermediate frequency filter module 350 is an intermediate frequency filter circuit with frequency adaptation, which switches the filter path to ensure that the receiver is better adapted to and compatible with communication objects with different frequency offsets. The gain amplifier module 360 ​​is used to achieve channel signal gain.

[0062] The anti-aliasing filter module 370 performs anti-aliasing filtering on the signal output by the gain amplifier module 360. When sampling the signal, it is sufficient to set the sampling rate to more than twice the highest frequency of the useful signal. However, the frequency range of the signal in the real world is very wide. At room temperature, we can determine the maximum rate of temperature change, but we cannot rule out the existence of interference signals. Interference frequencies on the wires and even signals from local radio stations may be aliased into the required frequency range. The only way to truly limit the input frequency range is to add a low-pass filter before sampling. This filter is called an anti-aliasing filter.

[0063] The combining module 380 combines the first intermediate frequency signal and the second intermediate frequency signal processed by the previous module to obtain a dual-band intermediate frequency signal. The analog-to-digital conversion module 390 performs analog-to-digital conversion on the dual-band intermediate frequency signal to obtain a dual-band intermediate frequency digital signal, and divides the Nyquist zone according to the sampling frequency, and can sample f1 and f2 in different Nyquist zones.

[0064] Figure 4 FIG. 1 is a structural diagram of an adaptive intermediate frequency filter module according to an exemplary embodiment. Figure 4 As shown, optionally, the adaptive intermediate frequency filtering module 350 specifically includes: a frequency detection module 351, a control module 352, a first switch module 353, a second switch module 354, and at least two to-be-determined filters 355;

[0065] The frequency detection module 351 is used to detect the frequency of the intermediate frequency signal and generate a detection result signal;

[0066] The control module 352 is used to determine the target filter in the undetermined filter 355 according to the frequency of the intermediate frequency signal, and generate a control signal to send to the first switch module 353 and the second switch module 354;

[0067] The first switch module 353 and the second switch module 354 are used to open the signal path corresponding to the target filter according to the control signal.

[0068] In this embodiment, the adaptive intermediate frequency filter can automatically switch filter circuits with different center frequencies by detecting and judging the input signal frequency, thereby ensuring the compatibility of the receiver without sacrificing communication stability and anti-interference capability.

[0069] The frequency detection module 351 performs frequency detection on the input signal and generates a detection result signal, and the output terminal contacts the control module 352 to input the detection result signal. The control module 352 determines which pending filter 355 to use for filtering according to the detection result signal output by the frequency detection module. The pending filter 355 with the same center frequency as the intermediate frequency signal is preferentially used as the target filter for filtering; if there is no pending filter 355 that meets the conditions, the pending filter 355 with the smallest absolute value of the frequency difference between the center frequency and the intermediate frequency signal is selected as the target filter.

[0070] After determining the target filter, the control module 352 generates a control signal to the first switch module 353 and the second switch module 354. The first switch module 353 and the second switch module 354 are multi-way switches, and the switch state is controlled by the signal output by the control module 352. Each of the undetermined filters 355 corresponds to one switch in the first switch module 353 and the second switch module 354. By controlling each switch in the first switch module 353 and the second switch module 354, the filter array signal path can be switched.

[0071] In a possible embodiment, 355a of the pending filter 355 is determined as the target filter, and the corresponding switch is closed, which is shown as a solid line in the figure; the switches of other paths are opened, which are shown as dotted lines in the figure.

[0072] Optionally, the control module 352 includes:

[0073] A frequency comparison unit, used for comparing the frequency of the intermediate frequency signal with the center frequency of each of the to-be-determined filters to obtain a comparison result;

[0074] A first control unit, if the center frequency of the filter to be determined is the same as the frequency of the intermediate frequency signal, determines that the filter to be determined is the target filter;

[0075] The second control unit calculates the absolute value of the frequency difference between the center frequency of each of the to-be-determined filters and the intermediate frequency signal if the center frequency of each of the to-be-determined filters is different from the frequency of the intermediate frequency signal, and selects the to-be-determined filter with the smallest absolute value of the difference as the target filter.

[0076] Optionally, the signal amplification module is a low noise amplifier.

[0077] Optionally, the branching module is a balun splitter.

[0078] Optionally, the gain amplification module is a variable gain amplifier.

[0079] Optionally, the combining module is a balun combiner.

[0080] Optionally, the analog-to-digital conversion module is a digital-to-analog converter.

[0081] Figure 5 FIG. 1 is a structural diagram of a frequency adaptive dual-frequency low-orbit navigation enhanced signal receiving system according to an exemplary embodiment. Figure 5 As shown, the system is used to process dual-frequency signals, so the mixing module 340, the adaptive intermediate frequency filter module 350, the gain amplifier module 360, and the anti-aliasing filter module 370 each include two submodules. The signal amplification module 320 is a low noise amplifier, the branch module 330 is a balun brancher, and the filter module 331 therein adopts active filtering or acoustic surface filtering; the first mixing submodule and the second mixing submodule in the mixing module 340 respectively down-convert the signals of the f1 and f2 radio frequency bands; the first gain amplifier submodule 361 and the second gain amplifier submodule 362 in the gain amplifier module 360 ​​adopt variable gain amplifiers; the anti-aliasing filter module 370 adopts an anti-aliasing filter; the combining module 390 adopts a balun combiner; and the analog-to-digital conversion module 390 adopts an analog-to-digital converter.

[0082] When receiving radio frequency signals, a certain frequency deviation of the radio frequency signal will be generated. To ensure normal passage, the traditional method is to increase the receiving bandwidth, which also introduces the risk of increased interference from the leader due to excessive receiving bandwidth, resulting in unstable communication. The intermediate frequency filter of this low-orbit navigation signal receiver automatically adjusts the center frequency, which can effectively avoid the frequency deviation of the radio frequency signal received by the receiver, thereby ensuring the compatibility of the receiver to a large extent.

[0083] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0084] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A frequency adaptive dual-frequency low-orbit navigation enhanced signal receiving system, characterized in that: include: Antenna module, signal amplification module, branching module, mixing module, adaptive intermediate frequency filtering module, gain amplification module, anti-aliasing filtering module, combining module and analog-to-digital conversion module; The antenna module is used to receive radio frequency signals and send the radio frequency signals to the signal amplification module; The signal amplification module is used to amplify the radio frequency signal and send it to the branching module; The branching module is used to divide the radio frequency signal into a plurality of radio frequency band signals of different frequency bands; The frequency mixing module is used to perform frequency reduction processing on the multiple radio frequency band signals to obtain corresponding multiple intermediate frequency signals and output them to the adaptive intermediate frequency filtering module; The adaptive intermediate frequency filtering module is used to determine the corresponding target filter according to the input intermediate frequency signal, and use the target filter to filter the intermediate frequency signal and input the signal into the gain amplification module; The gain amplification module is used to perform channel signal gain on the intermediate frequency signal; The anti-aliasing filtering module is used to perform anti-aliasing filtering on the intermediate frequency signal; The combining module is used for combining the plurality of intermediate frequency signals to obtain a dual-band intermediate frequency signal and output it to the analog-to-digital conversion module; The analog-to-digital conversion module is used to convert the dual-band intermediate frequency signal into a dual-band intermediate frequency digital signal.

2. The system according to claim 1, characterized in that The adaptive intermediate frequency filtering module specifically includes: a frequency detection module, a control module, a first switch module, a second switch module, and at least two to-be-determined filters; The frequency detection module is used to detect the frequency of the intermediate frequency signal and generate a detection result signal; The control module is used to determine the target filter in the to-be-determined filter according to the frequency of the intermediate frequency signal, and generate a control signal to send to the first switch module and the second switch module; The first switch module and the second switch module are used to open the signal path corresponding to the target filter according to the control signal.

3. The system according to claim 2, characterized in that The control module comprises: A frequency comparison unit, used for comparing the frequency of the intermediate frequency signal with the center frequency of each of the to-be-determined filters to obtain a comparison result; A first control unit, if the center frequency of the filter to be determined is the same as the frequency of the intermediate frequency signal, determines that the filter to be determined is the target filter; The second control unit calculates the absolute value of the frequency difference between the center frequency of each of the to-be-determined filters and the intermediate frequency signal if the center frequency of each of the to-be-determined filters is different from the frequency of the intermediate frequency signal, and selects the to-be-determined filter with the smallest absolute value of the difference as the target filter.

4. The system according to any one of claims 1 to 3, characterized in that: The signal amplification module is a low noise amplifier.

5. The system according to any one of claims 1 to 3, characterized in that: The branching module is a balun splitter.

6. The system according to any one of claims 1 to 3, characterized in that: The gain amplifier module is a variable gain amplifier.

7. The system according to any one of claims 1 to 3, characterized in that: The combining module is a balun combiner.

8. The system according to any one of claims 1 to 3, characterized in that: The analog-to-digital conversion module is a digital-to-analog converter.

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