CN107390236B

CN107390236B - Satellite signal receiving device and method for processing received satellite signal

Info

Publication number: CN107390236B
Application number: CN201710369505.9A
Authority: CN
Inventors: 陈香雷; 张庭伟; 郭保龙
Original assignee: Hisense Mobile Communications Technology Co Ltd
Current assignee: Hisense Mobile Communications Technology Co Ltd
Priority date: 2017-05-23
Filing date: 2017-05-23
Publication date: 2023-03-31
Anticipated expiration: 2037-05-23
Also published as: CN107390236A

Abstract

The invention discloses a satellite signal receiving device and a method for processing received satellite signals. The satellite signal receiving device comprises a radio frequency front end, a baseband circuit and a programmable gain amplifier connected in series between digital filters in the radio frequency front end and the baseband circuit, and the method comprises the following steps: when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the IQ amplitude of a target satellite signal filtered by the digital filter is smaller than a preset amplitude, adjusting the gain value of the programmable gain amplifier to enable the IQ amplitude to reach the preset amplitude; otherwise, the gain value of the programmable gain amplifier is set to be 0, so that the interference in the satellite signal can be automatically detected on the premise of reducing the cost of manpower and material resources, and the influence of the interference on the positioning performance is eliminated by adjusting the gain value of the programmable gain amplifier, thereby improving the anti-interference performance and the working stability of the satellite signal receiving device.

Description

Satellite signal receiving device and method for processing received satellite signal

Technical Field

The invention relates to the technical field of navigation, in particular to a satellite signal receiving device and a method for processing received satellite signals.

Background

At present, the Beidou navigation system is widely applied to consumer electronics, and sequentially supports Beidou positioning in most electronic products such as smart phones, vehicle-mounted navigation equipment, child watches and the like. However, when the conventional Beidou receiver and other modules work together, the EMI (Electromagnetic Interference) noise of the other modules inevitably radiates to the antenna of the Beidou receiver, and then enters the Beidou receiver, so that the normal work of the Beidou receiver is influenced finally.

As shown in fig. 1, the beidou receiver includes an RF (Radio Frequency) front end, a baseband circuit, an antenna, an LNA (Low Noise Amplifier), and a Saw (Surface Acoustic Wave). The RF front end includes a VGA (Variable Gain Amplifier), an AGC (Automatic Gain Control), a mixer, and an ADC (Analog-to-Digital Converter), and the baseband circuit includes a Digital filter and a baseband processor.

In a specific application scenario, an antenna receives a satellite signal in space, and most of the interference signals are also coupled into a receiver through the antenna. The LNA amplifies satellite signals received by the antenna, introduces low noise, and amplifies effective satellite signals and interference signals simultaneously due to the wide operating bandwidth. Saw filters the LNA amplified satellite signal, passes the in-band signal, and attenuates the out-of-band signal. The VGA is matched with the AGC to use, satellite signals entering the RF front end after Saw filtering are further amplified, so that the output signal strength of the VGA meets the input level requirement of the ADC in the later stage, the VGA has a wider gain range due to the fact that the power value change range of the satellite signals (which may also contain interference signals) input to the RF front end is very large, and the gain value of the VGA can be automatically adjusted according to the feedback of the AGC. The AGC is matched with the VGA to automatically adjust the gain value of the VGA along with the signal intensity, the AGC detects the radio-frequency signal which enters the ADC after being amplified by the VGA, if the signal is overlarge, the signal is fed back to the VGA to reduce the gain value, and if the signal is too weak, the signal is fed back to the VGA to improve the gain value, so that the signal input to the ADC meets the standard level requirement of the ADC. The frequency mixer carries out frequency conversion processing on the radio frequency signals output by the VGA and converts high frequency signals into intermediate frequency signals. The reference oscillator is typically a high precision quartz clock that is used to provide a reference clock for the RF front end circuitry. The ADC inputs a radio frequency signal that meets a standard level requirement, converts the radio frequency signal from an analog signal to a digital signal, and outputs an in-phase quadrature (IQ) signal, where the output of the ADC is usually a set of IQ signals. The digital filter separates a Beidou BPIQ signal (Baseband and Processor IQ, IQ signal in Baseband Processor), a GPS (Global Positioning System) BPIQ signal and a GLONASS (Global Navigation Satellite System) BPIQ signal from the IQ signal, and the signals enter respective Baseband processors. In a baseband processor, effective BPIQ signals are firstly captured to obtain rough estimation values of parameters such as Doppler frequency shift, code phase and the like, then the rough estimation values are sent to a tracking loop to accurately and continuously track the signals, simultaneously, demodulated satellite CN0 values (carrier-noise power spectral density ratio) and necessary navigation data are output, and finally, positioning information such as the position, the speed and the like of a user is obtained through ephemeris extraction, satellite position calculation, pseudo-range estimation and position calculation.

From the processing flow of the Beidou receiver to the satellite signals, the effective signal quality of the Beidou BPIQ signals directly influences the capture and demodulation of the baseband processor to the satellite signals, so that the Beidou positioning performance is influenced. When no interference signal enters the Beidou receiver, the baseband processor can normally process effective Beidou BPIQ signals. However, after the interference signal enters the big dipper receiver, the VGA in the RF front end amplifies the effective big dipper BPIQ signal together with the interference signal, and because the interference signal is strong (usually much stronger than the big dipper BPIQ signal), in order to ensure that the output power of the VGA meets the input requirement of the ADC, then through the feedback function of the AGC, the VGA can adjust the self gain to a very low level, so that although the whole signal level meets the input requirement of the ADC, the amplification of the effective big dipper BPIQ signal is seriously insufficient, so that the amplitude of the big dipper BPIQ signal entering the baseband processor is very low, further resulting in the baseband processor being unable to effectively demodulate the big dipper BPIQ signal, thereby resulting in the problems of positioning time deviation, poor positioning sensitivity, even being unable to successfully position, and the like.

Aiming at the problems, the traditional solution is to judge whether the Beidou receiver causes interference or not by testing other modules and the Beidou receiver to work together in the product development stage, weaken or eliminate the interference as much as possible by EMI optimization measures such as shielding and grounding if the interference is tested, and prevent the interference from entering the Beidou receiver. However, in the conventional solution, performance changes of the Beidou receiver and all other modules during working together need to be tested, a large amount of manpower investment is needed for testing, and even then, the real use scene of a user cannot be completely simulated, so that whether interference exists cannot be comprehensively discovered. Even if the existence of the interference is found, various EMI measures are required to eliminate the interference, the EMI sources of different modules are different, more research and development efforts are required to be invested in the process of eliminating the EMI interference, and higher cost is required for final solutions such as increasing shielding, increasing grounding and the like.

Therefore, how to enable the Beidou receiver to be capable of adaptively detecting interference and eliminating the influence of the interference on the Beidou positioning performance on the premise of reducing the cost of manpower and material resources becomes a technical problem to be solved urgently by technical personnel in the field.

Disclosure of Invention

The embodiment of the application provides a satellite signal receiving device and a method for processing received satellite signals, which can automatically detect interference signals in the satellite signals on the premise of reducing the cost of manpower and material resources, and eliminate the influence of the interference signals on the positioning performance of the satellite signal receiving device, so that the anti-interference performance and the working stability of the satellite signal receiving device are improved.

In order to achieve the above technical object, the present application provides a method for processing a received satellite signal by a satellite signal receiving apparatus; the satellite signal receiving device comprises a radio frequency front end and a baseband circuit, and also comprises a programmable gain amplifier which is connected between the radio frequency front end and a digital filter in the baseband circuit in series,

when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the IQ amplitude of a target satellite signal filtered by the digital filter is smaller than a preset amplitude, adjusting the gain value of the programmable gain amplifier to enable the IQ amplitude to reach the preset amplitude; otherwise, setting the gain value of the programmable gain amplifier to 0.

Preferably, the satellite signal includes a signal in a GNSS frequency band, and the target satellite signal is a beidou B1 frequency band signal, a GPS signal, or a GLONASS signal.

Correspondingly, the application also provides a satellite signal receiving device, which comprises a radio frequency front end and a baseband circuit, and further comprises a gain adjusting module and a programmable gain amplifier connected in series between the radio frequency front end and a digital filter in the baseband circuit,

the gain adjusting module is used for adjusting the gain value of the programmable gain amplifier when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the IQ amplitude of a target satellite signal filtered by the digital filter is smaller than a preset amplitude so that the IQ amplitude reaches the preset amplitude; otherwise, setting the gain value of the programmable gain amplifier to 0.

Correspondingly, the application also provides another satellite signal receiving device which comprises a radio frequency front end and a baseband circuit, and further comprises a programmable gain amplifier connected in series between the radio frequency front end and a digital filter in the baseband circuit, wherein the digital filter is used for feeding back the filtered IQ signal corresponding to the target satellite signal to the programmable gain amplifier;

the programmable gain amplifier is used for adjusting a gain value when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the amplitude of the IQ signal is smaller than a preset amplitude so as to enable the amplitude of the IQ signal to reach the preset amplitude; otherwise, the gain value is set to 0.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the beneficial technical effects that:

the embodiment of the application discloses a satellite signal receiving device and a method for processing received satellite signals, when a gain value of a VGA (video graphics array) in a radio frequency front end is smaller than a preset gain and an IQ amplitude of a target satellite signal filtered by a digital filter is smaller than the preset amplitude, an interference signal is judged to be mixed in the satellite signal, then the gain value of a programmable gain amplifier is adjusted, the IQ signal output by the radio frequency front end is amplified, and the interference signal is also amplified.

Drawings

In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a prior art Beidou receiver;

fig. 2 is a schematic flow chart of a method for processing received satellite signals by a satellite signal receiving device according to a preferred embodiment of the present application;

fig. 3 is a schematic structural diagram of a satellite signal receiving device according to a preferred embodiment of the present application;

fig. 4 is a schematic structural diagram of another satellite signal receiving device proposed in the preferred embodiment of the present application;

fig. 5 is a distribution diagram of civil frequency bands of a satellite signal receiving apparatus according to a preferred embodiment of the present application;

fig. 6 is a graph of S21 frequency of a prior art GNSS filter.

Detailed Description

In view of the problems mentioned in the background of the application, the interference caused by other modules when working together with the Beidou receiver needs to be detected by investing a large amount of manpower and material resources, and various solutions need to be taken to eliminate the interference.

The application provides a satellite signal receiving device and a method for processing received satellite signals, interference is detected through a gain value of a VGA in a radio frequency front end and an IQ amplitude value of a target satellite signal filtered by a digital filter, and the influence of the interference on positioning performance is eliminated by adjusting the gain value of a programmable gain amplifier, so that the anti-interference performance and the working stability of the satellite signal receiving device are improved, extra manpower and material resources are not required to be invested to test the interference, and different processing aiming at different interferences is not required.

The embodiment of the invention provides a method for processing a received satellite signal by a satellite signal receiving device, wherein the satellite signal receiving device comprises a radio frequency front end and a baseband circuit, and the satellite signal receiving device further comprises a Programmable Gain Amplifier (PGA) which is connected between the radio frequency front end and a digital filter in the baseband circuit in series. The method comprises the following steps: when the gain value of a VGA in the radio frequency front end is smaller than a preset gain and the IQ amplitude of a target satellite signal filtered by the digital filter is smaller than a preset amplitude, adjusting the gain value of the PGA to enable the IQ amplitude to reach the preset amplitude; otherwise, setting the gain value of the PGA to 0.

The main body of the method may be PGA, a baseband processor, or another chip. This is not limited by the present application.

Optionally, the Satellite signal includes a signal in a GNSS (Global Navigation Satellite System) frequency band, and the target Satellite signal is a beidou B1 frequency band signal, a GPS signal, or a GLONASS signal.

When the target satellite signal is a GPS signal, detecting a gain value of a VGA in a radio frequency front end and an IQ amplitude value of the GPS signal filtered by a digital filter, if the detected gain value of the VGA is smaller than a preset gain and the IQ amplitude value of the GPS signal filtered by the digital filter is smaller than a preset amplitude value of an IQ signal corresponding to the GPS signal, judging that the GPS signal is mixed with an interference signal, adjusting the gain value of the PGA according to a difference value between the gain value of the VGA and the preset gain and a difference value between the IQ amplitude value of the GPS signal and the preset amplitude value, and amplifying the IQ signal output by the radio frequency front end according to the adjusted gain value of the PGA to enable the IQ amplitude value of the GPS signal filtered by the digital filter to reach the preset amplitude value so as to meet the requirement required by subsequent demodulation processing; if the detected gain value of the VGA is larger than or equal to the preset gain, or the IQ amplitude of the GPS signal filtered by the digital filter is larger than or equal to the preset amplitude of the IQ signal corresponding to the GPS signal, judging that the GPS signal does not have an interference signal, setting the gain value of the PGA to be 0, and not processing the IQ signal output by the radio frequency front end.

When the target satellite signal is a Beidou B1 frequency band signal, detecting a gain value of a VGA in the radio frequency front end and an IQ amplitude value of the Beidou B1 frequency band signal filtered by a digital filter, if the gain value of the VGA is detected to be smaller than a preset gain, and the IQ amplitude value of the Beidou B1 frequency band signal filtered by the digital filter is smaller than a preset amplitude value of an IQ signal corresponding to the Beidou B1 frequency band signal, judging that the Beidou B1 frequency band signal is mixed with an interference signal, adjusting the gain value of the PGA according to a difference value between the gain value of the VGA and the preset gain and a difference value between the IQ amplitude value of the Beidou B1 frequency band signal and the preset amplitude value, and amplifying the IQ signal output by the radio frequency front end according to the adjusted gain value of the PGA to enable the IQ amplitude value of the Beidou B1 frequency band signal to reach the preset amplitude value so as to meet the requirement required by subsequent demodulation processing; if the detected gain value of the VGA is larger than or equal to the preset gain, or the IQ amplitude of the Beidou B1 frequency band signal filtered by the digital filter is larger than or equal to the preset amplitude of the IQ signal corresponding to the Beidou B1 frequency band signal, judging that the Beidou B1 frequency band signal does not have an interference signal, setting the gain value of the PGA to be 0, and not processing the IQ signal output by the radio frequency front end.

When the target satellite signal is a GLONASS signal, detecting a gain value of a VGA (video graphics array) in a radio frequency front end and an IQ amplitude of the GLONASS signal filtered by a digital filter, if the gain value of the VGA is detected to be smaller than a preset gain, and the IQ amplitude of the GLONASS signal filtered by the digital filter is smaller than a preset amplitude of an IQ signal corresponding to the GLONASS signal, judging that the GLONASS signal is mixed with an interference signal, adjusting the gain value of a PGA (programmable Gate array) according to a difference value between the gain value of the VGA and the preset gain and a difference value between the IQ amplitude of the GLONASS signal and the preset amplitude, and amplifying the IQ signal output by the radio frequency front end according to the adjusted gain value of the PGA to enable the IQ amplitude of the GLONASS signal to reach the preset amplitude so as to meet the requirement of subsequent demodulation processing; if the detected gain value of the VGA is larger than or equal to the preset gain, or the IQ amplitude of the GLONASS signal filtered by the digital filter is larger than or equal to the preset amplitude of the IQ signal corresponding to the GLONASS signal, judging that the GLONASS signal does not have an interference signal, setting the gain value of the PGA to be 0, and not processing the IQ signal output by the radio frequency front end.

Referring to fig. 2, a schematic flowchart of a method for processing a received satellite signal by a satellite signal receiving apparatus according to an embodiment of the present invention is shown, where the method includes:

s1, converting satellite signals received by an antenna and processed by an LNA and Saw into IQ signals through an RF front end;

s2, transmitting the IQ signal to a digital filter through the PGA;

s3, filtering an IQ signal corresponding to the target satellite signal from the IQ signal through a digital filter;

s4, extracting a gain value of a VGA in an RF front end and an IQ amplitude of a target satellite signal filtered by the digital filter;

s5, judging whether the gain value of the VGA is smaller than a preset gain value or not, and judging whether the IQ amplitude of the target satellite signal is smaller than a preset amplitude value or not; if yes, executing step S6, otherwise, executing step S7;

s6, adjusting the gain value of the PGA to enable the IQ amplitude to reach the preset amplitude;

and S7, setting the gain value of the PGA to 0.

According to the scheme provided by the embodiment of the application, when the gain value of the VGA in the radio frequency front end is smaller than the preset gain and the IQ amplitude of the target satellite signal filtered by the digital filter is smaller than the preset amplitude, the fact that an interference signal is mixed in the satellite signal is judged, the gain value of the PGA is further adjusted, the IQ signal output by the radio frequency front end is amplified, and meanwhile the interference signal is also amplified.

It should be noted that the described embodiments are part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.

In order to more clearly illustrate the solutions provided by the foregoing embodiments of the present application, the embodiments of the present application further provide a satellite signal receiving apparatus based on the same inventive concept as the method for processing the received satellite signal by the above-mentioned satellite signal receiving apparatus. In an optional embodiment, the satellite signal receiving device is a beidou receiver.

Referring to fig. 3, a schematic structural diagram of a satellite signal receiving apparatus according to an embodiment of the invention includes an RF front end, a PGA, a baseband circuit, an antenna, an LNA, and a Saw. The baseband circuit comprises a digital filter and a baseband processor, the RF front end comprises a VGA, an AGC, a mixer and an ADC, and the satellite signal receiving device further comprises a reference oscillator. The PGA is connected in series between the RF front-end and the digital filter in the baseband circuit.

The RF front end is configured to convert the satellite signal received by the antenna and processed by the LNA and the Saw into an IQ signal output to the PGA. The digital filter is used for filtering an IQ signal (such as a Beidou BPIQ signal) corresponding to a target satellite signal from the IQ signal. And the PGA is used for adjusting the gain value of the PGA when the gain value of the VGA is detected to be smaller than the preset gain and the IQ amplitude of the target satellite signal is lower than the preset amplitude, so that the IQ amplitude of the target satellite signal filtered by the digital filter reaches the preset amplitude.

In this embodiment, the gain value of the VGA and the IQ amplitude of the target satellite signal filtered by the digital filter are detected by the PGA, and if it is detected that the gain value of the VGA is greater than or equal to the preset gain, or the IQ amplitude of the target satellite signal is greater than or equal to the preset amplitude, it is determined that the target satellite signal does not have an interference signal, the gain value of the PGA is set to 0 by default, and the IQ signal output from the RF front end is not processed; if the gain value of the VGA is detected to be smaller than the preset gain and the IQ amplitude of the target satellite signal filtered in the digital filter is detected to be smaller than the preset amplitude, determining that the target satellite signal has an interference signal, adjusting the gain value of the PGA according to the difference between the gain value of the VGA and the preset gain and the difference between the IQ amplitude of the target satellite signal and the preset amplitude, amplifying the IQ signal output by the RF front end according to the adjusted gain value of the PGA, so that the digital filter filters the interference signal, and the IQ amplitude of the filtered target satellite signal reaches the preset amplitude, thereby realizing effective detection of the interference signal, realizing re-amplification of the IQ signal output by the RF front end by adjusting the gain value of the PGA after the interference is detected, and eliminating the influence of the interference signal on a satellite signal receiving device. The satellite signals comprise signals in a GNSS frequency band, and the target satellite signals are Beidou B1 frequency band signals, GPS signals or GLONASS signals. As shown in fig. 2, the digital filter filters out the big dipper BPIQ signal, the GPS BPIQ signal, and the GLO BPIQ signal that meet the requirements of the baseband processor, and the baseband processor obtains the positioning information by demodulating these signals, thereby ensuring the normal operation of the satellite signal receiving apparatus.

According to the scheme provided by the embodiment of the application, the gain value of the VGA and the IQ amplitude of the target satellite signal filtered from the digital filter are detected through the PGA to judge whether the satellite signal is mixed with an interference signal, after the satellite signal is judged to be mixed with the interference signal, the IQ signal output by the RF front end is amplified again by adjusting the gain value of the PGA, the influence of the interference signal on the satellite signal receiving device is eliminated, the anti-interference performance and the working stability of the satellite signal receiving device are improved, the interference is tested without extra investment in manpower and material cost, and different processing is not required for different interferences.

It should be noted that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The technical solutions in the present application will be described clearly and completely with reference to the accompanying drawings in the present application, and it is obvious that the described embodiments are some, not all embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

As shown in fig. 4, which is a schematic structural diagram of another satellite signal receiving apparatus proposed in the preferred embodiment of the present application, the satellite signal receiving apparatus implements detection of an interference signal in a band near a target satellite signal through a gain adjustment module and a PGA connected in series between a radio frequency front end and a digital filter in a baseband circuit, and adjusts a gain value of the PGA after the interference signal is detected, so as to eliminate the interference signal in the band near the target satellite signal.

In an alternative embodiment, the function of the gain adjustment module is implemented by the baseband processor.

It should be noted that, in order to realize the commercial application of the beidou navigation system, the government actively encourages the development work of the beidou chip, and many chip manufacturers in China have continuously developed the beidou second-generation passive positioning navigation chip at present. And because the big dipper satellite navigation system still can only cover the Asia-Pacific region at present, in order to realize the more extensive application of navigation chip, almost all big dipper positioning chips still compatible design the signal reception to two big satellite navigation systems that have realized global coverage of GPS and GLONASS. This requires the satellite signal receiving device to have a wider bandwidth, and the wider the bandwidth of the satellite signal receiving device, the more interference signals will enter while receiving effective satellite signals.

In the signals received by the satellite signal receiving device, the effective frequency band of the Beidou B1 wave band is as follows: 1559-1563MHz, and effective frequency ranges of a GPS are as follows: 1574.4-1576.4 MHz, the effective frequency range of GLONASS is: 1597 to 1606MHz, as shown in FIG. 5. Wherein, big dipper B1 has a frequency band of 11MHz away from GPS, and 38MHz away from GLONASS. In the conventional Satellite signal receiving device compatible with and supporting a BDS (Compass Navigation Satellite System), a GPS (global positioning System) and a GLONASS, the BDS, the GPS and the GLONASS share the same radio frequency channel and the same band-pass filter, so that signals in the range from 1559MHz of the Beidou to 1576.4MHz of the GPS (or to 1606MHz of the GLONASS) can enter the Satellite signal receiving device without damage, and effective target Satellite signals, namely Beidou B1 frequency band signals, GPS signals and GLONASS signals, also comprise interference signals close to a target Satellite signal band. Referring to fig. 6, which is a graph of the S21 frequency of a typical GNSS filter, it can be seen that interference signals falling exactly between the BDS and GPS frequencies or between the GPS and GLONASS frequencies enter the satellite receiving apparatus without loss while the BDS signal, the GPS signal and the GLONASS signal enter the chip. Such interference is referred to as out-of-band interference in the adjacent B1 band, since it is in the GNSS band but not in the effective band of the BDS, GPS or GLONASS. Because the out-of-band interference close to the Beidou B1 wave band is very close to the effective frequency band of the Beidou B1, the out-of-band interference close to the Beidou B1 wave band is difficult to eliminate in a radio frequency circuit filtering mode, so that the out-of-band interference close to other target signal wave bands can enter the satellite signal receiving device in a lossless manner.

In order to ensure that the ADC in the satellite signal receiving device works normally and adapts to a variable satellite environment, the ADC is provided with a wide gain range, for example, the VGA gain range inside the high-pass GNSS chip is-11 to +17dB. In addition, in order to ensure that the baseband processor in the satellite signal receiving apparatus can demodulate a valid target satellite signal normally, the IQ amplitude of the target satellite signal input to the baseband circuit should satisfy a certain range, which if exceeded will result in a deterioration of positioning performance. And out-of-band interference close to the target satellite signal can cause the IQ amplitude of the VGA gain value and the target satellite signal to be reduced, and a plurality of interferences which are too strong can cause the IQ amplitude of the VGA gain value and the target satellite signal to be lower than a reasonable value range, thereby influencing the detection and demodulation of the baseband processor on the target satellite signal and causing the positioning performance of the satellite signal receiving device to be deteriorated. Therefore, it is necessary to effectively detect whether out-of-band interference in a band close to a target satellite signal enters a satellite signal receiving apparatus, and to eliminate the influence of such interference on the positioning performance of the satellite signal receiving apparatus once it is determined that out-of-band interference in a band close to a target satellite signal enters.

In this embodiment, when the gain adjustment module detects that the gain value of the VGA in the RF front end is smaller than the preset gain and the IQ amplitude of the target satellite signal filtered by the digital filter is smaller than the preset amplitude, the gain adjustment module adjusts the gain value of the PGA so that the IQ amplitude reaches the preset amplitude; otherwise, the gain value of the PGA is set to 0.

Specifically, the satellite signal receiving apparatus without interference is tested to obtain a preset gain and a preset amplitude of an IQ signal corresponding to a target satellite signal under the condition of no interference. For example, when the target satellite signal is a beidou B1 frequency band signal, a preset gain of a VGA and a preset amplitude of an IQ signal corresponding to the beidou B1 frequency band signal are obtained, and it can be known through calculation that the strength of a signal transmitted by a beidou satellite on an orbital plane in the earth after atmospheric attenuation reaches about-130 dBm on the earth surface, and the range of the satellite signal received by the satellite signal receiving device can be calculated to be-160 dBm to-120 dBm in consideration of the antenna gain (which may be a positive gain in a certain direction) of the satellite signal receiving device and the signal processing capability of a baseband chip. In an environment where there is no interference, the default gain value of the PGA is set to 0. In the test, satellite signals of-160 dBm to-120 dBm are input to the satellite signal receiving device, and the gain value of the VGA and the IQ amplitude value of the Beidou B1 frequency band signal under each power level are recorded for statistical analysis, so that the preset gain of the VGA and the preset amplitude value of the IQ signal corresponding to the Beidou B1 frequency band signal are obtained. The test data of the satellite signal receiving apparatus is shown in table 1.

TABLE 1

Wherein CN0 is a carrier-to-noise power spectral density ratio, which is commonly used to measure signal strength or define GNSS receiver sensitivity. As can be known from data in the table, in the process of inputting satellite signals of-160 dBm to-120 dBm by the satellite signal receiving device, the VGA gain value is basically kept unchanged, the IQ amplitude of the Beidou B1 frequency band signal is slightly reduced along with the reduction of the satellite signals, but when the satellite signals are reduced to a certain level, the IQ amplitude of the Beidou B1 frequency band signal tends to be stable. According to the test result, the preset gain of the VGA and the preset amplitude of the IQ signal corresponding to the Beidou B1 frequency band signal can be obtained by combining the detection capability of the baseband processor on the Beidou B1 frequency band signal, and the preset gain and the preset amplitude are stored in the gain adjusting module.

In an actual working scene of the satellite signal receiving device, the gain adjusting module extracts a gain value of a VGA in an RF front end and an IQ amplitude of a target satellite signal filtered by a digital filter in real time, compares the gain value of the VGA with a preset gain, and compares the IQ amplitude of the target satellite signal with the preset amplitude to judge whether out-of-band interference close to the target satellite signal enters the satellite signal receiving device. If the gain value of the VGA is larger than or equal to a preset gain or the IQ amplitude of the target satellite signal is larger than or equal to a preset amplitude, judging that no out-of-band interference close to the target satellite signal enters the satellite signal receiving device; and if the VGA gain value is smaller than the preset gain and the IQ amplitude of the target satellite signal is smaller than the preset amplitude, judging that out-of-band interference close to the target satellite signal enters the satellite signal receiving device.

When the interference signal close to the target satellite signal is not detected, the default PGA gain value is 0, that is, no amplification process is performed on the IQ signal output from the ADC. When out-of-band interference close to a target satellite signal is detected, the gain adjusting module automatically adjusts the gain value of the PGA according to the difference between the current VGA gain value and the preset gain and the difference between the IQ amplitude of the target satellite signal and the preset amplitude, so that the PGA further amplifies the IQ signal output by the ADC according to the adjusted PGA gain value, and meanwhile, the interference signal is amplified. Therefore, after the amplified IQ signals pass through the digital filter, the out-of-band interference signals are completely filtered, and only the IQ signals corresponding to the target satellite signals amplified to the preset amplitude enter the baseband processor, so that the baseband processor can correctly demodulate the satellite signals.

In specific application scene, for example, the smart phone can start big dipper locate function (the positional information of record photo) when opening the camera and shoot, and at this moment, the target satellite signal is big dipper B1 wave band signal. And because the MCLK of the camera is 23.88MHz, the 66 frequency multiplication is 1576.08MHz, the distance from the Beidou B1 wave band (1559-1563 MHz) is 13MHz, and the MCLK is just in the GPS frequency band, interference signals of the camera can enter the inside of the satellite receiving device without attenuation. As shown in table 2, it is assumed that the preset gain of the VGA of a certain satellite receiving device is 0, and the preset amplitude of the IQ signal corresponding to the beidou B1 band signal is 200.

TABLE 2

When the camera does not work, the VGA gain value detected by the gain adjusting module is 2dB and higher than the preset gain, the IQ amplitude of the Beidou B1 frequency band signal is 300 and higher than the preset amplitude, the interference-free signal is judged to enter the satellite receiving device, and the gain value of the PGA cannot be adjusted, namely the PGA uses the default gain (the default gain value is set to be 0 dB). When the camera is started to shoot, due to the fact that strong interference exists at 1576.08MHz, the gain value of the VGA is reduced from 2dB to-8 dB and is lower than a preset gain, the gain value of the VGA is reduced to cause that effective amplification of Beidou B1 frequency band signals is insufficient, the IQ amplitude of the Beidou B1 frequency band signals is reduced from 300 to 100 and is lower than the preset amplitude, at the moment, the gain adjusting module judges that interference signals enter the satellite receiving device, the gain value of the PGA is improved from 0dB to 10dB, the PGA with the improved gain is used for amplifying IQ signals output by the ADC again, the IQ amplitude of the Beidou B1 frequency band signals passing through the digital filter is guaranteed to reach the preset amplitude, namely the IQ amplitude of the Beidou B1 frequency band signals is improved from 100 before adjustment to 300, and therefore the normal positioning performance of the satellite signal receiving device cannot be affected even if the camera is used for shooting.

According to the scheme provided by the embodiment of the application, when the gain value of the VGA in the radio frequency front end is smaller than the preset gain and the IQ amplitude of the target satellite signal filtered by the digital filter is smaller than the preset amplitude, the interference signal mixed in the satellite signal is judged, the gain value of the PGA is further adjusted, and the IQ amplitude of the target satellite signal is amplified, so that the IQ amplitude of the target satellite signal meets the requirement required by subsequent demodulation processing, the influence of the interference on the positioning performance is eliminated, the anti-interference performance and the working stability of the satellite signal receiving device are improved, the interference is tested without extra investment in manpower and material resources cost, and different processing aiming at different interferences is not required.

Through the above description of the embodiments, those skilled in the art will clearly understand that the present invention may be implemented by hardware, or by software plus a necessary general hardware platform. Based on such understanding, the technical solution of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a usb disk, a removable hard disk, etc.), and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the method according to the implementation scenarios of the present invention.

Those skilled in the art will appreciate that the drawings are merely schematic representations of preferred embodiments and that the blocks or flowchart illustrations are not necessary to practice the present invention.

Those skilled in the art can understand that the modules in the device in the implementation scenario may be distributed in the device in the implementation scenario according to the implementation scenario description, and may also be located in one or more devices different from the present implementation scenario with corresponding changes. The modules of the implementation scenario may be combined into one module, or may be further split into a plurality of sub-modules.

The above-mentioned serial numbers of the present invention are merely for description, and do not represent the merits of the implementation scenario.

The above disclosure is only for a few concrete implementation scenarios of the present invention, however, the present invention is not limited to these, and any variations that can be considered by those skilled in the art are intended to fall within the scope of the present invention.

Claims

1. A method for processing a received satellite signal by a satellite signal receiving device, the satellite signal receiving device comprises a radio frequency front end and a baseband circuit, characterized in that the satellite signal receiving device further comprises a programmable gain amplifier connected in series between the radio frequency front end and a digital filter in the baseband circuit,

when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the IQ amplitude of a target satellite signal filtered by the digital filter is smaller than a preset amplitude, adjusting the gain value of the programmable gain amplifier to enable the IQ amplitude to reach the preset amplitude; otherwise, the gain value of the programmable gain amplifier is set to 0.

2. The method of claim 1, wherein the satellite signals comprise signals in the GNSS frequency band and the target satellite signal is a beidou B1 frequency band signal, a GPS signal, or a GLONASS signal.

3. A satellite signal receiving device comprises a radio frequency front end and a baseband circuit, and is characterized by also comprising a gain adjusting module and a programmable gain amplifier connected between a digital filter in the radio frequency front end and the baseband circuit in series,

the gain adjusting module is used for adjusting the gain value of the programmable gain amplifier when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the IQ amplitude of a target satellite signal filtered by the digital filter is smaller than a preset amplitude so as to enable the IQ amplitude to reach the preset amplitude; otherwise, setting the gain value of the programmable gain amplifier to 0.

4. The satellite signal receiving device of claim 3, wherein the satellite signal comprises a signal in a GNSS frequency band, and the target satellite signal is a Beidou B1 frequency band signal, a GPS signal or a GLONASS signal.

5. A satellite signal receiving device comprises a radio frequency front end and a baseband circuit, and is characterized by further comprising a programmable gain amplifier connected in series between the radio frequency front end and a digital filter in the baseband circuit, wherein the digital filter is used for feeding back an IQ signal corresponding to a target satellite signal filtered out to the programmable gain amplifier;

the programmable gain amplifier is used for adjusting the gain value when the gain value of the VGA in the radio frequency front end is smaller than a preset gain and the amplitude of the IQ signal is smaller than a preset amplitude so as to enable the amplitude of the IQ signal to reach the preset amplitude; otherwise, the gain value is set to 0.

6. The satellite signal receiving device of claim 5, wherein the satellite signal comprises a signal in a GNSS frequency band, and the target satellite signal is a Beidou B1 frequency band signal, a GPS signal or a GLONASS signal.