Method and device for capturing satellite signal, storage medium and electronic equipment

文档序号：1086085 发布日期：2020-10-20 浏览：12次中文

阅读说明：本技术 卫星信号的捕获方法、装置、存储介质和电子设备 (Method and device for capturing satellite signal, storage medium and electronic equipment ) 是由周彬朱凌许百成于 2020-06-24 设计创作，主要内容包括：本公开涉及一种卫星信号的捕获方法、装置、存储介质和电子设备,该方法包括：利用中频本振信号对接收到的卫星信号进行混频,得到中频信号,按照预设的粗捕获载波频率和目标卫星的伪码,对中频信号进行粗捕获,以获取粗捕获载波频率对应的至少一个粗捕获码相位,根据预设的精捕获载波频率序列和至少一个粗捕获码相位,对中频信号进行精捕获,以获取精捕获载波频率下,至少一个粗捕获码相位对应的非相干累加值,若目标精捕获载波频率下,目标粗捕获码相位对应的非相干累加值大于或等于预设的捕获门限,将目标粗捕获码相位、目标精捕获载波频率,作为目标卫星的捕获结果。本公开能够有效减少卫星捕获过程中的运算量和存储器消耗,提高卫星捕获效率。(The present disclosure relates to a method, an apparatus, a storage medium, and an electronic device for capturing a satellite signal, the method comprising: the method comprises the steps of carrying out frequency mixing on received satellite signals by utilizing an intermediate-frequency local oscillator signal to obtain intermediate-frequency signals, carrying out coarse acquisition on the intermediate-frequency signals according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, carrying out fine acquisition on the intermediate-frequency signals according to a preset fine acquisition carrier frequency sequence and at least one coarse acquisition code phase to obtain an incoherent accumulated value corresponding to at least one coarse acquisition code phase under the fine acquisition carrier frequency, and taking the target coarse acquisition code phase and the target fine acquisition carrier frequency as an acquisition result of the target satellite if the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to a preset acquisition threshold under the target fine acquisition carrier frequency. The method and the device can effectively reduce the operation amount and the memory consumption in the satellite capturing process, and improve the satellite capturing efficiency.)

1. A method for acquiring satellite signals, the method comprising:

mixing the received satellite signals by using an intermediate-frequency local oscillator signal to obtain an intermediate-frequency signal;

according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite, performing coarse acquisition on the intermediate frequency signal to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, wherein the coarse acquisition carrier frequency is a frequency determined according to the frequency of the intermediate frequency local oscillator signal and a preset coarse frequency offset hypothesis, and the target satellite is any one of satellites to be acquired;

performing fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and the at least one coarse acquisition code phase to acquire an incoherent accumulated value corresponding to the at least one coarse acquisition code phase under each fine acquisition carrier frequency; the fine acquisition carrier frequency sequence comprises a plurality of fine acquisition carrier frequencies, each fine acquisition carrier frequency is determined according to the coarse acquisition carrier frequency and a preset fine frequency offset hypothesis, and the fine frequency offset hypothesis is smaller than the coarse frequency offset hypothesis;

if the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to a preset acquisition threshold at the target fine acquisition carrier frequency, taking the target coarse acquisition code phase and the target fine acquisition carrier frequency as the acquisition result of the target satellite, wherein the target fine acquisition carrier frequency is any one of the fine acquisition carrier frequencies, and the target coarse acquisition code phase is the coarse acquisition code phase with the largest incoherent accumulated value at the target fine acquisition carrier frequency.

2. The method of claim 1, wherein the performing coarse acquisition on the if signal according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency comprises:

demodulating the intermediate frequency signal by using a coarse capture carrier to obtain a first baseband signal, wherein the frequency of the coarse capture carrier is the coarse capture carrier frequency;

performing sliding correlation on the first baseband signal and a local pseudo code to obtain correlation values of a plurality of sampling points included in each first data segment in the first baseband signal, wherein the sampling points included in each first data segment correspond to the sampling points included in the local pseudo code one to one, and the local pseudo code is determined according to the pseudo code of the target satellite;

coherent accumulation and non-coherent accumulation are carried out on correlation values of a plurality of sampling points included in each first data segment in the first baseband signal, so that a non-coherent accumulation value of each sampling point in the local pseudo code is obtained;

if the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point in the local pseudo code is greater than or equal to a preset coarse acquisition threshold value, determining the coarse acquisition code phase according to the sampling point corresponding to the maximum incoherent accumulated value;

and if the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point in the local pseudo code is smaller than the coarse acquisition threshold value, determining the specified number of phases of the coarse acquisition code according to the sampling points corresponding to the maximum specified number of incoherent accumulated values.

3. The method of claim 2, wherein the performing fine acquisition on the if signal according to a preset fine acquisition carrier frequency sequence and the at least one coarse acquisition code phase to obtain an incoherent accumulation value corresponding to the at least one coarse acquisition code phase at each fine acquisition carrier frequency comprises:

for each fine capture carrier, multiplying the first baseband signal by the fine frequency offset hypothesis corresponding to the fine capture carrier to obtain a second baseband signal corresponding to the fine capture carrier, where the frequency of the fine capture carrier corresponds to one fine capture carrier frequency in the sequence of fine capture carrier frequencies;

performing sliding correlation on the second baseband signal and a local pseudo code to obtain a correlation value of a sampling point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal, where the sampling point included in each second data segment corresponds to the sampling point included in the local pseudo code one to one;

and performing coherent accumulation and non-coherent accumulation on the correlation value of the sampling point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal according to a maximum likelihood estimation method to obtain the non-coherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the local pseudo code.

4. The method of claim 3, wherein the coherently accumulating and non-coherently accumulating the correlation values of the samples corresponding to the at least one coarse acquisition code phase in each of the second data segments of the second baseband signal according to a maximum likelihood estimation method to obtain the non-coherent accumulation value of the samples corresponding to the at least one coarse acquisition code phase in the local pseudo code, comprises:

performing maximum likelihood coherent accumulation on a correlation value of a sampling point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal to obtain a coherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the second baseband signal;

and performing incoherent accumulation on the coherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the second baseband signal to obtain the incoherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the local pseudo code.

5. The method of claim 1, further comprising:

if the incoherent accumulated value corresponding to the target coarse acquisition code phase is smaller than the acquisition threshold under the target fine acquisition carrier frequency, updating the coarse acquisition carrier frequency according to the coarse frequency offset hypothesis;

and repeatedly executing the coarse acquisition according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite, performing coarse acquisition on the intermediate frequency signal to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, and performing fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and the at least one coarse acquisition code phase to obtain an incoherent accumulated value corresponding to the at least one coarse acquisition code phase under each fine acquisition carrier frequency until the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to the acquisition threshold.

6. An apparatus for acquiring a satellite signal, the apparatus comprising:

the frequency mixing module is used for mixing the received satellite signals by using the intermediate-frequency local oscillation signals to obtain intermediate-frequency signals;

the coarse acquisition module is used for performing coarse acquisition on the intermediate frequency signal according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite so as to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, wherein the coarse acquisition carrier frequency is a frequency determined according to the frequency of the intermediate frequency local oscillator signal and a preset coarse frequency offset hypothesis, and the target satellite is any one of the satellites to be acquired;

the fine acquisition module is used for performing fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and the at least one coarse acquisition code phase so as to acquire an incoherent accumulated value corresponding to the at least one coarse acquisition code phase under each fine acquisition carrier frequency; the fine acquisition carrier frequency sequence comprises a plurality of fine acquisition carrier frequencies, each fine acquisition carrier frequency is determined according to the coarse acquisition carrier frequency and a preset fine frequency offset hypothesis, and the fine frequency offset hypothesis is smaller than the coarse frequency offset hypothesis;

and the determining module is configured to, if an incoherent accumulated value corresponding to a target coarse acquisition code phase is greater than or equal to a preset acquisition threshold at a target fine acquisition carrier frequency, use the target coarse acquisition code phase and the target fine acquisition carrier frequency as an acquisition result of the target satellite, where the target fine acquisition carrier frequency is any one of the fine acquisition carrier frequencies, and the target coarse acquisition code phase is a coarse acquisition code phase with the largest incoherent accumulated value at the target fine acquisition carrier frequency.

7. The apparatus of claim 6, wherein the coarse acquisition module comprises:

the demodulation submodule is used for demodulating the intermediate frequency signal by using a coarse capture carrier to obtain a first baseband signal, and the frequency of the coarse capture carrier is the coarse capture carrier frequency;

a first sliding correlation submodule, configured to perform sliding correlation on the first baseband signal and a local pseudo code to obtain correlation values of multiple sampling points included in each first data segment in the first baseband signal, where the sampling points included in each first data segment correspond to the sampling points included in the local pseudo code one to one, and the local pseudo code is determined according to the pseudo code of the target satellite;

a first obtaining sub-module, configured to perform coherent accumulation and non-coherent accumulation on correlation values of multiple sampling points included in each first data segment in the first baseband signal, so as to obtain a non-coherent accumulation value of each sampling point in the local pseudo code;

the first determining sub-module is used for determining the coarse acquisition code phase according to the sampling point corresponding to the maximum incoherent accumulated value if the maximum incoherent accumulated value is greater than or equal to a preset coarse acquisition threshold value in the incoherent accumulated values of each sampling point in the local pseudo code;

and the second determining submodule is used for determining the specified number of the coarse acquisition code phases according to the sampling points corresponding to the maximum specified number of the incoherent accumulated values if the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point in the local pseudo code is smaller than the coarse acquisition threshold value.

8. The apparatus of claim 7, wherein the fine capture module comprises:

a second obtaining sub-module, configured to, for each fine capture carrier, multiply the first baseband signal by using the fine frequency offset hypothesis corresponding to the fine capture carrier to obtain a second baseband signal corresponding to the fine capture carrier, where a frequency of the fine capture carrier corresponds to one fine capture carrier frequency in the fine capture carrier frequency sequence;

a second sliding correlation sub-module, configured to perform sliding correlation on the second baseband signal and the local pseudo code to obtain a correlation value of a sample point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal, where the sample points included in each second data segment correspond to the sample points included in the local pseudo code one to one;

a third obtaining sub-module, configured to perform coherent accumulation and non-coherent accumulation on a correlation value of a sample point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal according to a maximum likelihood estimation method, so as to obtain a non-coherent accumulation value of a sample point corresponding to the at least one coarse acquisition code phase in the local pseudo code.

9. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 5.

10. An electronic device, comprising:

a memory having a computer program stored thereon;

a processor for executing the computer program in the memory to carry out the steps of the method of any one of claims 1 to 5.

Technical Field

The present disclosure relates to the field of electronic control technologies, and in particular, to a method and an apparatus for capturing a satellite signal, a storage medium, and an electronic device.

Background

When a satellite navigation receiver acquires a satellite, the satellite navigation receiver needs to perform coarse acquisition and fine acquisition on a satellite signal to determine a satellite number, a carrier frequency and a code phase. The receiver performs coarse acquisition on the intermediate frequency signal subjected to the down-mixing according to the coarse frequency offset hypothesis to acquire a coarse acquisition code phase corresponding to each coarse frequency offset hypothesis, and then performs fine acquisition on the intermediate frequency signal according to each acquired coarse acquisition code phase and the fine frequency offset hypothesis to acquire a carrier frequency and a code phase, thereby acquiring a satellite. In the acquisition process, it is necessary to calculate a coarse acquisition code phase corresponding to each coarse frequency offset hypothesis, and store the coarse frequency offset hypothesis and the corresponding coarse acquisition code phase for subsequent fine acquisition to perform mixing and correlation calculation, and not only is the amount of calculation large in the acquisition process, but also a large amount of Memory consumption is caused, and the satellite acquisition efficiency is reduced.

Disclosure of Invention

The present disclosure is directed to a method, an apparatus, a storage medium, and an electronic device for acquiring a satellite signal, which are used to solve the problem of low satellite acquisition efficiency in the prior art.

According to a first aspect of embodiments of the present disclosure, there is provided a method for acquiring a satellite signal, the method including:

mixing the received satellite signals by using an intermediate-frequency local oscillator signal to obtain an intermediate-frequency signal;

Optionally, the performing coarse acquisition on the intermediate frequency signal according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency includes:

Optionally, the performing fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and the at least one coarse acquisition code phase to obtain an incoherent accumulated value corresponding to the at least one coarse acquisition code phase at each fine acquisition carrier frequency includes:

Optionally, the performing coherent accumulation and non-coherent accumulation on the correlation value of the sampling point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal according to a maximum likelihood estimation method to obtain a non-coherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the local pseudo code includes:

Optionally, the method further comprises:

According to a second aspect of the embodiments of the present disclosure, there is provided an apparatus for acquiring a satellite signal, the apparatus comprising:

the frequency mixing module is used for mixing the received satellite signals by using the intermediate-frequency local oscillation signals to obtain intermediate-frequency signals;

and the determining module is configured to, if an incoherent accumulated value corresponding to a target coarse acquisition code phase is greater than or equal to a preset acquisition threshold at a target fine acquisition carrier frequency, use the target coarse acquisition code phase and the target fine acquisition carrier frequency as an acquisition result of the target satellite, where the target fine acquisition carrier frequency is any one of the fine acquisition carrier frequencies, and the target coarse acquisition code phase is a fine acquisition code phase with the largest incoherent accumulated value at the target fine acquisition carrier frequency.

Optionally, the coarse capture module comprises:

Optionally, the fine capture module comprises:

Optionally, the third obtaining sub-module is configured to:

Optionally, the apparatus further comprises:

an updating module, configured to update the coarse acquisition carrier frequency according to the coarse frequency offset assumption if an incoherent accumulated value corresponding to the target coarse acquisition code phase is smaller than the acquisition threshold under the target fine acquisition carrier frequency;

and the execution module is used for repeatedly executing the pseudo code according to the preset coarse acquisition carrier frequency and the target satellite, performing coarse acquisition on the intermediate frequency signal to acquire at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, and performing fine acquisition on the intermediate frequency signal to acquire an incoherent accumulated value corresponding to the at least one coarse acquisition code phase under each fine acquisition carrier frequency until the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to the acquisition threshold.

According to a third aspect of embodiments of the present disclosure, there is provided a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the method described in the first aspect of embodiments of the present disclosure.

According to a fourth aspect of the embodiments of the present disclosure, there is provided an electronic apparatus including:

a memory having a computer program stored thereon;

a processor for executing the computer program in the memory to implement the steps of the method in the first aspect of an embodiment of the disclosure.

According to the technical scheme, in the method, firstly, an intermediate frequency local oscillator signal is utilized to carry out frequency mixing on a received satellite signal to obtain an intermediate frequency signal, then, the intermediate frequency signal is roughly captured according to a preset rough capture carrier frequency and a pseudo code of a target satellite to obtain at least one rough capture code phase corresponding to the rough capture carrier frequency, wherein the rough capture carrier frequency is a frequency determined according to the frequency of the intermediate frequency local oscillator signal and a preset rough frequency offset hypothesis, the target satellite is any one of the satellites to be captured, then, the intermediate frequency signal is finely captured according to a preset fine capture carrier frequency sequence comprising a plurality of fine capture carrier frequencies and at least one rough capture code phase to obtain an incoherent accumulated value corresponding to at least one rough capture code phase under each fine capture carrier frequency, and each fine capture carrier frequency is a frequency determined according to the rough capture carrier frequency and a preset fine frequency offset hypothesis smaller than the rough frequency offset hypothesis, and finally, judging an incoherent accumulated value corresponding to the target coarse acquisition code phase, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is larger than or equal to a preset acquisition threshold under the target fine acquisition carrier frequency, taking the target coarse acquisition code phase and the target fine acquisition carrier frequency as the acquisition result of the target satellite, wherein the target fine acquisition carrier frequency is any fine acquisition carrier frequency, and the target coarse acquisition code phase is the coarse acquisition code phase with the largest incoherent accumulated value under the target fine acquisition carrier frequency. The method and the device perform coarse capture on the intermediate frequency signal according to a preset coarse capture carrier frequency, perform fine capture on the intermediate frequency signal according to the obtained coarse capture code phase, complete capture on a target satellite if a target coarse capture code phase with an incoherent accumulated value larger than or equal to a preset capture threshold exists in the target fine capture carrier frequency, and only need to calculate and store the target fine capture carrier frequency in the coarse capture carrier frequency and the incoherent accumulated value of a sampling point corresponding to the coarse capture code phase in the target fine capture carrier frequency, so that the computation amount and the memory consumption in the satellite capture process can be effectively reduced, and the satellite capture efficiency is improved.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is a flow chart illustrating a method of acquisition of satellite signals according to an exemplary embodiment;

FIG. 2 is a flow chart illustrating another method of acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 3 is a flow chart illustrating another method of acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 4 is a flow chart illustrating another method of acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 5 is a block diagram illustrating an apparatus for acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 6 is a block diagram illustrating another apparatus for acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 7 is a block diagram illustrating another apparatus for acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 8 is a block diagram illustrating another apparatus for acquisition of satellite signals in accordance with an exemplary embodiment;

FIG. 9 is a block diagram illustrating an electronic device in accordance with an example embodiment.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of methods and apparatus consistent with certain aspects of the present disclosure, as detailed in the appended claims.

Before introducing the method, the apparatus, the storage medium, and the electronic device for acquiring a satellite signal provided by the present disclosure, an application scenario related to various embodiments of the present disclosure is first introduced. The application scenario may be a satellite navigation receiver, that is, the execution subject of the method for acquiring a satellite signal provided by the present disclosure is the satellite navigation receiver. A satellite navigation receiver may receive satellite signals transmitted by satellites. The Satellite Navigation receiver may be, for example, a BDS (beidou Navigation Satellite System, chinese: beidou Satellite Navigation System) receiver, or a GPS (Global Positioning System, chinese: Global Positioning System) receiver, a GLONASS (Global Navigation Satellite System, chinese: Global Satellite Navigation System) receiver, a Galileo Satellite Navigation System (Galileo Satellite Navigation System) receiver, and the like, which is not limited in the present disclosure.

Fig. 1 is a flowchart illustrating a method of acquiring satellite signals according to an exemplary embodiment, as shown in fig. 1, the method including:

step 101, mixing the received satellite signals by using an intermediate frequency local oscillation signal to obtain an intermediate frequency signal.

Step 102, performing coarse acquisition on the intermediate frequency signal according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, wherein the coarse acquisition carrier frequency is a frequency determined according to the frequency of the intermediate frequency local oscillator signal and a preset coarse frequency offset hypothesis, and the target satellite is any one of the satellites to be acquired.

For example, after receiving a high-frequency satellite signal, the satellite navigation receiver may filter and amplify the satellite signal through a pre-filter and a pre-amplifier, generate an intermediate-frequency local oscillator signal by using a local oscillator, and mix the filtered and amplified satellite signal with the intermediate-frequency local oscillator signal to obtain an intermediate-frequency signal corresponding to the satellite signal. The frequency of the intermediate frequency local oscillator signal may be, for example, 4.076 MHz. It should be noted that, if the frequency of the intermediate-frequency local oscillation signal is 0 (that is, the satellite navigation receiver is a zero intermediate-frequency receiver), because of high-speed operation of the satellite, the satellite signal received by the satellite navigation receiver has a large doppler shift, and therefore, the satellite signal is mixed by using the intermediate-frequency local oscillation signal with the frequency of 0, and the obtained intermediate-frequency signal is not a real baseband signal, but an intermediate-frequency signal.

After the intermediate frequency signal is obtained, the satellite navigation receiver performs coarse acquisition on the intermediate frequency signal according to a preset coarse acquisition carrier frequency and a pseudo code of a target satellite. Wherein, the coarse capture carrier frequency is assumed according to the frequency of the intermediate frequency local oscillator signal and the preset coarse frequency offsetFor example, the determined frequency may be set to 4.076MHz, if the target satellite is a GPS satellite, the coarse frequency offset assumption step may be set to 250Hz, and if the target satellite is a BDS satellite, the coarse frequency offset assumption step may be set to 500 Hz. The corresponding coarse frequency offset hypothesis may be one or more coarse frequency offset hypothesis steps, i.e., coarse frequency offset hypothesis (n × coarse frequency offset hypothesis step). Taking the target satellite as the BDS satellite as an example, the method can be based on f_c＝f₀N × 500 to determine the coarse acquisition carrier frequency. Wherein f is_cRepresenting the coarse acquisition carrier frequency, f₀The frequency of the intermediate-frequency local oscillator signal is represented, n is an integer, the value range of n can be, for example, -24 to +24, and the value range of the coarse capture carrier frequency can be f₀-12kHz to f₀+12 kHz. The value of n may be determined according to a preset rule, for example, the initial value of n may be set to be the minimum value in the value range, and n is increased by 1 every time step 102 is executed. With f₀For example, 4.076MHz with n being 6, the coarse acquisition carrier frequency is 4.079 MHz. The target satellite is any one of the satellites to be captured, and the pseudo code of the target satellite is determined by the target satellite according to a pseudo code generation rule agreed in an ICD (Interface Control Document, Chinese).

Specifically, a coarse capture carrier may be generated according to the coarse capture carrier frequency, and then the intermediate frequency signal may be demodulated (i.e., down-mixed) by using the coarse capture carrier to obtain the baseband signal. And then generating a corresponding local pseudo code according to the pseudo code of the target satellite. For example, the satellite navigation receiver may generate the local pseudo code according to the number of the target satellite and the pseudo code generation rule agreed in the ICD. And the satellite navigation receiver despreads the baseband signal according to the pseudo code of the target satellite. The despreading process may be understood as performing sliding correlation on a plurality of samples included in each data segment in the baseband signal and the local pseudo code, and after performing the sliding correlation, obtaining correlation values of the plurality of samples included in each data segment. The length of each data segment is the same as the length of the local pseudo code, for example, the length of the local pseudo code is 1ms, then the length of each data segment may also be set to 1ms, and the number of samples in each data segment is determined by a preset sampling rate, that is, the samples included in each data segment correspond to the samples included in the local pseudo code one to one. After the correlation values of the multiple sampling points are obtained, coherent accumulation and incoherent accumulation can be performed on the correlation values of the multiple sampling points according to a preset formula, so as to obtain an incoherent accumulation value of each sampling point. If the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point is greater than or equal to the preset coarse acquisition threshold value, the coarse acquisition code phase can be determined according to the sampling point corresponding to the maximum incoherent accumulated value. If the maximum incoherent accumulated value of the incoherent accumulated values of each sampling point is smaller than the preset coarse acquisition threshold, a preset number of coarse acquisition code phases may be determined according to a preset number (e.g., 4) of sampling points corresponding to the incoherent accumulated value closest to the coarse acquisition threshold. The coarse acquisition code phase may be one or more. The preset coarse capture threshold may be determined by, for example, a noise average power and a threshold coefficient. After one or more coarse acquisition code phases are determined based on the non-coherent accumulation value and the coarse acquisition threshold for each sample, the determined coarse acquisition code phases may be stored to enable the receiver to perform subsequent fine acquisition based on each coarse acquisition code phase. Compared with the prior art, the coarse acquisition process needs to store the coarse acquisition code phase corresponding to each coarse acquisition carrier frequency in all possible coarse acquisition carrier frequencies, only one coarse acquisition carrier frequency needs to be coarsely acquired in the step 102, the calculation amount is greatly reduced, correspondingly, the number of the stored coarse acquisition code phases is greatly reduced, and the consumption of a memory is reduced.

Step 103, performing fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and at least one coarse acquisition code phase to obtain an incoherent accumulated value corresponding to at least one coarse acquisition code phase at each fine acquisition carrier frequency. The fine acquisition carrier frequency sequence comprises a plurality of fine acquisition carrier frequencies, each fine acquisition carrier frequency is determined according to the coarse acquisition carrier frequency and a preset fine frequency offset hypothesis, and the fine frequency offset hypothesis is smaller than the coarse frequency offset hypothesis.

And 104, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to a preset acquisition threshold under the target fine acquisition carrier frequency, taking the target coarse acquisition code phase and the target fine acquisition carrier frequency as the acquisition result of the target satellite, wherein the target fine acquisition carrier frequency is any one of the fine acquisition carrier frequencies, and the target coarse acquisition code phase is the coarse acquisition code phase with the largest incoherent accumulated value under the target fine acquisition carrier frequency.

For example, after acquiring one or more coarse acquisition code phases, the receiver may perform fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and each coarse acquisition code phase. The fine acquisition carrier frequency sequence comprises a plurality of fine acquisition carrier frequencies, and each fine acquisition carrier frequency is determined according to the coarse acquisition carrier frequency and a preset fine frequency offset hypothesis which is smaller than the coarse frequency offset hypothesis. In the fine acquisition carrier frequency sequence, the number of fine acquisition carrier frequencies can be determined according to a preset fine frequency offset assumption step length and a preset coarse frequency offset assumption step length, if a target satellite is a satellite of a GPS, the fine frequency offset assumption step length can be set to 31.25Hz, the corresponding coarse frequency offset assumption step length is set to 250Hz, if the target satellite is a satellite of a BDS, the fine frequency offset assumption step length can be set to 62.5Hz, and the corresponding coarse frequency offset assumption step length is set to 500Hz, that is, the coarse frequency offset assumption step length can be equally divided into 8 parts according to the fine frequency offset assumption step length, that is, 9 fine frequency offset assumptions are obtained, and 9 fine acquisition carrier frequencies are correspondingly obtained.

After the intermediate frequency signal is subjected to fine acquisition, an incoherent accumulated value corresponding to each coarse acquisition code phase under each fine acquisition carrier frequency can be acquired. Specifically, the target fine capture carrier frequency may be determined according to any fine capture carrier frequency in the fine capture carrier frequency sequence, where the target fine capture carrier frequency is any fine capture carrier frequency. And then generating a corresponding fine capture carrier according to the target fine capture carrier frequency, and then multiplying the fine frequency offset hypothesis corresponding to the fine capture carrier by the baseband signal corresponding to the coarse capture carrier to obtain the baseband signal corresponding to the fine capture carrier. For the fine acquisition carrier, in each data segment of the baseband signal corresponding to the fine acquisition carrier, a sampling point corresponding to the coarse acquisition code phase is subjected to sliding correlation with the local pseudo code, and after the sliding correlation is performed, a correlation value of the sampling point corresponding to each coarse acquisition code phase in each data segment can be obtained. The length of each data segment is the same as the length of the local pseudo code, for example, the length of the local pseudo code lasts for 1ms, then the length of each data segment may also be set to 1ms, and the number of samples in each data segment is determined by a preset sampling rate, that is, samples included in each data segment in the baseband signal corresponding to the fine capture carrier correspond to samples included in the local pseudo code one to one. After the correlation value of the sampling point corresponding to each coarse acquisition code phase is obtained at the target fine acquisition carrier frequency, coherent accumulation and incoherent accumulation may be performed on the correlation value of the sampling point corresponding to each coarse acquisition code phase according to a preset method (for example, a maximum likelihood estimation method) to obtain an incoherent accumulation value of the sampling point corresponding to each coarse acquisition code phase in the local pseudo code. After the incoherent accumulated value of the sampling point corresponding to the coarse acquisition code phase is obtained, the incoherent accumulated value of the sampling point corresponding to the coarse acquisition code phase can be stored, and the coarse acquisition code phase corresponding to the sampling point with the largest incoherent accumulated value is used as the target coarse acquisition code phase. After the target coarse acquisition code phase is determined, other coarse acquisition code phases may be deleted. Compared with the prior art, the fine acquisition process can be executed only after each coarse acquisition carrier frequency in all possible coarse acquisition carrier frequencies is subjected to coarse acquisition, and the fine acquisition process in the embodiment of the disclosure only needs to store a target fine acquisition carrier frequency in one coarse acquisition carrier frequency and an incoherent accumulated value of sampling points corresponding to coarse acquisition code phases in the target fine acquisition carrier frequency. That is, in the present disclosure, each sampling point is not calculated and stored, but only the incoherent accumulated value of the sampling point corresponding to the coarse acquisition code phase determined in the coarse acquisition process is calculated and stored, so that the calculation amount is reduced, and the consumption of the memory is correspondingly reduced. Furthermore, in the embodiment of the present disclosure, after the target coarse acquisition code phase is determined, other coarse acquisition code phases may be deleted, so that the consumption of the memory is further reduced.

If the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to the preset acquisition threshold under the target fine acquisition carrier frequency, which indicates that the optimal acquisition result is obtained through the current fine acquisition, the target coarse acquisition code phase and the target fine acquisition carrier frequency can be used as the acquisition result of the target satellite. If the incoherent accumulated value corresponding to the target coarse acquisition code phase is smaller than the preset acquisition threshold, which indicates that the optimal acquisition result cannot be obtained through the current fine acquisition, the target coarse acquisition code phase and the target fine acquisition carrier frequency can be stored as the fine acquisition result of the coarse acquisition carrier frequency. And then, updating the coarse acquisition carrier frequency according to the assumed step length of the coarse frequency offset (namely updating the value of n), re-executing the step 102 to the step 104 according to the updated coarse acquisition carrier frequency, and so on until the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to the acquisition threshold under the target fine acquisition carrier frequency, so as to complete the fine acquisition of the satellite signal, and thus obtain the acquisition result of the target satellite. If the incoherent accumulated values corresponding to the plurality of stored target coarse acquisition code phases are still smaller than the preset acquisition threshold after all the coarse acquisition carrier frequencies are traversed, the target coarse acquisition code phase with the largest incoherent accumulated value and the corresponding target fine acquisition carrier frequency in all the target coarse acquisition code phases can be used as the acquisition result of the target satellite. Wherein the capture threshold may be determined by the noise power and the threshold coefficient. Compared with the prior art, the fine acquisition process can be executed only after each coarse acquisition carrier frequency in all possible coarse acquisition carrier frequencies is subjected to coarse acquisition, and in the embodiment of the disclosure, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to the preset acquisition threshold under the target fine acquisition carrier frequency, the acquisition of the target satellite can be directly completed, and the efficiency of satellite acquisition can be effectively improved.

Further, after the acquisition result of the target satellite is determined, the target coarse acquisition code phase, the target fine acquisition carrier frequency corresponding to the target coarse acquisition code phase, and the number of the target satellite can be sent to a tracking module of the satellite navigation receiver, so that the satellite navigation receiver tracks the satellite signal, and thus the navigation message in the satellite signal is obtained, and positioning and fixed speed are realized.

To sum up, in the disclosure, first, an intermediate frequency local oscillator signal is utilized to perform frequency mixing on a received satellite signal to obtain an intermediate frequency signal, then, the intermediate frequency signal is coarsely captured according to a preset coarse capture carrier frequency and a pseudo code of a target satellite to obtain at least one coarse capture code phase corresponding to the coarse capture carrier frequency, where the coarse capture carrier frequency is a frequency determined according to a frequency of the intermediate frequency local oscillator signal and a preset coarse frequency offset hypothesis, the target satellite is any one of satellites to be captured, then, the intermediate frequency signal is finely captured according to a preset fine capture carrier frequency sequence including a plurality of fine capture carrier frequencies and at least one coarse capture code phase to obtain an incoherent accumulated value corresponding to at least one coarse capture code phase at each fine capture carrier frequency, and each fine capture carrier frequency is a frequency determined according to the coarse capture carrier frequency and a preset fine frequency offset hypothesis smaller than the coarse capture carrier frequency offset, and finally, judging an incoherent accumulated value corresponding to the target coarse acquisition code phase, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is larger than or equal to a preset acquisition threshold under the target fine acquisition carrier frequency, taking the target coarse acquisition code phase and the target fine acquisition carrier frequency as the acquisition result of the target satellite, wherein the target fine acquisition carrier frequency is any fine acquisition carrier frequency, and the target coarse acquisition code phase is the coarse acquisition code phase with the largest incoherent accumulated value under the target fine acquisition carrier frequency. The method and the device perform coarse capture on the intermediate frequency signal according to a preset coarse capture carrier frequency, perform fine capture on the intermediate frequency signal according to the obtained coarse capture code phase, complete capture on a target satellite if a target coarse capture code phase with an incoherent accumulated value larger than or equal to a preset capture threshold exists in the target fine capture carrier frequency, and only need to calculate and store the target fine capture carrier frequency in the coarse capture carrier frequency and the incoherent accumulated value of a sampling point corresponding to the coarse capture code phase in the target fine capture carrier frequency, so that the computation amount and the memory consumption in the satellite capture process can be effectively reduced, and the satellite capture efficiency is improved.

Fig. 2 is a flow chart illustrating another method for acquiring satellite signals according to an exemplary embodiment, where step 102 includes, as shown in fig. 2:

step 1021, demodulating the intermediate frequency signal by using the coarse capture carrier to obtain a first baseband signal, where the frequency of the coarse capture carrier is a coarse capture carrier frequency.

Step 1022, performing sliding correlation on the first baseband signal and the local pseudo code to obtain correlation values of a plurality of sampling points included in each first data segment in the first baseband signal, where the sampling points included in each first data segment correspond to the sampling points included in the local pseudo code one to one, and the local pseudo code is determined according to the pseudo code of the target satellite.

Step 1023, coherent accumulation and non-coherent accumulation are performed on the correlation values of the multiple samples included in each first data segment in the first baseband signal, so as to obtain a non-coherent accumulation value of each sample in the local pseudo code.

And step 1024, if the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point in the local pseudo code is greater than or equal to a preset coarse acquisition threshold value, determining the coarse acquisition code phase according to the sampling point corresponding to the maximum incoherent accumulated value.

And 1025, if the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point in the local pseudo code is smaller than the coarse acquisition threshold value, determining the specified number of coarse acquisition code phases according to the sampling points corresponding to the maximum specified number of incoherent accumulated values.

For example, after obtaining the intermediate frequency signal, the satellite navigation receiver first generates a coarse acquisition carrier according to a preset coarse acquisition carrier frequency, and then demodulates the intermediate frequency signal by using the coarse acquisition carrier to obtain the first baseband signal. And then the satellite navigation receiver can generate a local pseudo code according to the number of the target satellite and the pseudo code generation rule agreed in the ICD. After determining the first baseband signal and the local pseudo code, the receiver may perform sliding correlation between the first baseband signal and the local pseudo code according to a predetermined calculation method, such as according to a formulaA calculation of the sliding correlation is performed. Wherein the content of the first and second substances,

is the correlation value of the ith sample point, c_iFor the ith sample point, p, in each first data segment in the first baseband signal_iFor the ith chip, N in the local pseudo code_segIs the number of samples, N_seg＝0.001*F_s，F_sIs the sampling rate of the samples. Further, the data may be divided according to preset data segments, and then the above formula may be expressed asWherein N is_ncohRefers to the incoherent sum length, N_cohRefers to the coherent accumulation length.

After performing sliding correlation on the plurality of samples included in each first data segment in the first baseband signal and the local pseudo code, correlation values of the plurality of samples included in each first data segment in the first baseband signal may be obtained. The number of sampling points in each first data segment is determined by a preset sampling rate, and if the length of each first data segment is set to be 1ms, the number of sampling points N is determined_seg＝0.001*F_sWherein F is_sFor the sampling rate of the sampling points, the sampling points included in each first data segment correspond to the sampling points included in the local pseudo code one to one. After the correlation values of the multiple sampling points included in each first data segment in the first baseband signal are obtained, coherent accumulation and non-coherent accumulation may be performed on the correlation values of the multiple sampling points according to a coherent accumulation formula and a non-coherent accumulation formula, respectively, so as to obtain a non-coherent accumulation value of each sampling point in the local pseudo code. Since coherent accumulation and non-coherent accumulation are performed by folding and accumulating correlation values of a plurality of samples included in a plurality of first data segments, the accumulated results of coherent accumulation and non-coherent accumulation may be normalized (e.g., averaged) to limit the data range. The formula for coherent accumulation may be, for example:

wherein the content of the first and second substances,is the coherent accumulation result of the ith sample point in the mth first data segment,

is a correlation value, N, on a sample point_cohFor the coherent accumulation length, m is the sequence number of the first data segment of the non-coherent accumulation, n is the sequence number of the first data segment of the coherent accumulation, and i is the sequence number of the sampling point.

The formula for non-coherent accumulation may be, for example:

wherein the content of the first and second substances,for non-coherent accumulation results, N_ncohI is the number of samples for the incoherent integration length,

is the modulus of coherent accumulation of the ith sample point in the mth first data segment, and m is the sequence number of the noncoherent accumulated first data segment. The coherent accumulation time (i.e., coherent accumulation length) may be set to 2ms if the target satellite is a satellite of the GPS, and may be set to 1ms if the target satellite is a satellite of the BDS. It should be noted that, the correlation values of the multiple samples included in each first data segment are complex numbers with phase information, and the non-coherent accumulation is to accumulate real numbers, so when performing the non-coherent accumulation, a modulus of the correlation values of the multiple samples included in each first data segment may be obtained first, and then the non-coherent accumulation is performed according to the obtained modulus, or a sum of squares of a real part and an imaginary part of the correlation values of the multiple samples included in each first data segment may be obtained first, and then the non-coherent accumulation is performed according to the obtained sum of squares, which is not limited in this disclosure.

After the incoherent accumulated value of each sampling point in the local pseudo code is obtained, the incoherent accumulated value of each sampling point may be determined according to a preset coarse capture threshold, which may be determined by, for example, noise average power and a threshold coefficient. Specifically, if the maximum incoherent accumulated value in the incoherent accumulated values of each sampling point is greater than or equal to the coarse acquisition threshold, the coarse acquisition code phase may be determined according to the sampling point corresponding to the maximum incoherent accumulated value, that is, the position of the sampling point corresponding to the maximum incoherent accumulated value is used as the coarse acquisition code phase. If the maximum incoherent accumulated value of the incoherent accumulated values of each sampling point is smaller than the coarse acquisition threshold, a specified number of coarse acquisition code phases may be determined according to a specified number (e.g., 4) of sampling points corresponding to the incoherent accumulated values closest to the coarse acquisition threshold, that is, according to the sampling points corresponding to the maximum specified number of incoherent accumulated values, which may be understood as taking the position of each sampling point in the sampling points corresponding to the maximum specified number of incoherent accumulated values as the coarse acquisition code phase. Therefore, one or more coarse acquisition code phases may be acquired after the coarse acquisition of the intermediate frequency signal. After determining one or more coarse acquisition code phases, the determined coarse acquisition code phases can be stored to enable a receiver to complete fine acquisition of the intermediate frequency signal according to each determined coarse acquisition code phase.

Fig. 3 is a flow chart illustrating another method for acquiring satellite signals according to an exemplary embodiment, where step 103 includes, as shown in fig. 3:

step 1031, for each fine capture carrier, multiplying the first baseband signal by using the fine frequency offset hypothesis corresponding to the fine capture carrier to obtain a second baseband signal corresponding to the fine capture carrier, where the frequency of the fine capture carrier corresponds to one fine capture carrier frequency in the fine capture carrier frequency sequence.

Step 1032, performing sliding correlation on the second baseband signal and the local pseudo code to obtain a correlation value of a sample point corresponding to at least one coarse acquisition code phase in each second data segment in the second baseband signal, where the sample point included in each second data segment corresponds to the sample point included in the local pseudo code one to one.

Step 1033, performing coherent accumulation and non-coherent accumulation on the correlation value of the sampling point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal according to a maximum likelihood estimation method to obtain a non-coherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the local pseudo code.

Illustratively, after coarse acquisition of the intermediate frequency signal, one or more coarse acquisition code phases may be acquired. If only one coarse acquisition code phase is obtained, the intermediate frequency signal can be subjected to fine acquisition according to the coarse acquisition code phase and a preset fine acquisition carrier frequency sequence. If the number of the acquired coarse acquisition code phases is multiple, the intermediate frequency signal can be precisely acquired sequentially according to each of the multiple coarse acquisition code phases and a preset precise acquisition carrier frequency sequence. The fine acquisition carrier frequency sequence comprises a plurality of fine acquisition carrier frequencies, and each fine acquisition carrier frequency is determined according to a coarse acquisition carrier frequency corresponding to the coarse acquisition code phase and a preset fine frequency offset hypothesis. For example according to a formulaDetermining each fine capture carrier frequency, wherein delta f is a fine frequency offset hypothesis step size, G is a fine frequency offset hypothesis serial number, G is a number of fine frequency offset hypotheses, the fine frequency offset hypothesis step size delta f is equal to a G equal division of a coarse frequency offset hypothesis step size, f is equal to the coarse frequency offset hypothesis step size_gIs a fine frequency offset hypothesis (the sum of the coarse acquisition carrier frequency and the fine frequency offset hypothesis is the fine acquisition carrier frequency). After each fine capture carrier frequency in the fine capture carrier frequency sequence is determined, a corresponding fine capture carrier wave can be generated according to each fine capture carrier frequency, and then, for each fine capture carrier wave, a second baseband signal corresponding to the fine capture carrier wave is obtained by multiplying the first baseband signal by using a fine frequency offset hypothesis corresponding to the fine capture carrier wave. After the second baseband signal is acquired, the second baseband signal may be divided into a plurality of second data segments, and the number of sampling points in each second data segment is determined by a preset sampling rate. The samples included in each second data segment correspond one-to-one to the samples included in the local pseudo code, such that the samples are to be transmitted in the local pseudo codeWhen the second baseband signal is subjected to sliding correlation with the local pseudo code, the sampling point that needs to be subjected to sliding correlation in each second data segment may be determined according to the coarse acquisition code phase, and then the sampling point that needs to be subjected to sliding correlation is subjected to sliding correlation with the local pseudo code, so as to obtain the correlation value of the sampling point corresponding to the coarse acquisition code phase in each second data segment in the second baseband signal. Therefore, only the sampling points corresponding to the coarse acquisition code phase need to be subjected to sliding correlation, and the calculated amount in the fine acquisition process is further reduced.

After the correlation value of the sampling point corresponding to the coarse acquisition code phase in each second data segment in the second baseband signal is obtained, the obtained correlation value may be stored first, and then coherent accumulation and non-coherent accumulation are performed on the correlation value of the sampling point corresponding to the coarse acquisition code phase in each second data segment, where the calculation of coherent accumulation and non-coherent accumulation is the same as the calculation in the coarse acquisition process, which is not described herein again, and in order to further improve the signal-to-noise ratio, the coherent accumulation length in the fine acquisition process may be greater than the coherent accumulation length in the coarse acquisition process, for example, the coherent accumulation length in the fine acquisition process (i.e., coherent accumulation time) may be set to 8 ms.

In the process of coherent accumulation and non-coherent accumulation, the correlation value in the accumulation sequence may be influenced by the period of the navigation message of the satellite signal to generate bit jump (the jump position may be any position), so in order to reduce the influence of the bit jump on the coherent accumulation and the non-coherent accumulation, the coherent accumulation and the non-coherent accumulation can be performed according to a maximum likelihood estimation method. And performing coherent accumulation calculation by a maximum likelihood estimation method to obtain all combinations of positive and negative correlation values possibly appearing at each position in each second data segment, and taking the accumulated result with the maximum modulus value or square sum in all combinations of accumulated sequences as a coherent accumulated value corresponding to the second data segment. The coherent accumulated values obtained by the maximum likelihood estimation method can effectively reduce the mutual offset among the coherent accumulated values caused by bit jump, so that the power of useful signals is lost, and satellite signals can be captured in the environment with low signal-to-noise ratio. After a coherent accumulated value of a correlation value of a sampling point corresponding to the coarse acquisition code phase in each second data segment is obtained, non-coherent accumulation is carried out according to the coherent accumulated value of the sampling point corresponding to the coarse acquisition code phase in each second data segment, then a modulus value of the non-coherent accumulated value or a square sum of a real part and an imaginary part of the non-coherent accumulated value is obtained, and the obtained modulus value or the square sum is used as the non-coherent accumulated value of the sampling point corresponding to each coarse acquisition code phase in the local pseudo code.

Optionally, step 1033 is for:

firstly, maximum likelihood coherent accumulation is carried out on the correlation value of the sampling point corresponding to at least one coarse acquisition code phase in each second data segment in the second baseband signal, so as to obtain the coherent accumulation value of the sampling point corresponding to at least one coarse acquisition code phase in the second baseband signal.

And then, carrying out non-coherent accumulation on the coherent accumulation value of the sampling point corresponding to at least one coarse acquisition code phase in the second baseband signal to obtain the non-coherent accumulation value of the sampling point corresponding to at least one coarse acquisition code phase in the local pseudo code.

For example, when coherent accumulation and non-coherent accumulation are performed on the correlation values of the samples corresponding to the coarse acquisition code phase in each second data segment of the second baseband signal, if the coherent accumulation length is smaller than the period of the navigation message of the satellite signal, a bit jump may occur in the sequence of coherent accumulation. Taking the period of the navigation message of the satellite signal as 10ms as an example, when the coherent accumulation length is less than 10ms and the preset phase step is 1, the phase of the second baseband signal may be the following cases:

{1，1，1，1，1，1，1，1，1，1}；

{1，1，1，1，1，1，1，1，1，-1}；

{1，1，1，1，1，1，1，1，-1，-1}；

{1，1，1，1，1，1，1，-1，-1，-1}；

{1，1，1，1，1，1，-1，-1，-1，-1}；

{1，1，1，1，1，-1，-1，-1，-1，-1}；

{1，1，1，1，-1，-1，-1，-1，-1，-1}；

{1，1，1，-1，-1，-1，-1，-1，-1，-1}；

{1，1，-1，-1，-1，-1，-1，-1，-1，-1}；

{1，-1，-1，-1，-1，-1，-1，-1，-1，-1}。

therefore, when the second baseband signal is subjected to sliding correlation with the local pseudo code, the sampling point which needs to be subjected to sliding correlation in the second data segment can be determined according to the coarse acquisition code phase, and then the sampling point which needs to be subjected to sliding correlation is subjected to sliding correlation with the local pseudo code, so as to obtain the correlation value of the sampling point corresponding to the coarse acquisition code phase in each second data segment in the second baseband signal. After the correlation value of the sampling point corresponding to the coarse acquisition code phase in each second data segment in the second baseband signal is obtained, maximum likelihood coherent accumulation may be performed on the correlation value of the sampling point corresponding to the coarse acquisition code phase in each second data segment in the second baseband signal, so as to obtain a coherent accumulation value of the sampling point corresponding to the coarse acquisition code phase in the second baseband signal. Specifically, the maximum likelihood coherent accumulation may be understood as that, in the case of calculating each possible phase, a modulus of a correlation value of a sample point corresponding to the coarse acquisition code phase in each second data segment in the second baseband signal is calculated, and then a coherent accumulation value of a sample point corresponding to the coarse acquisition code phase in the second baseband signal is determined according to a phase corresponding to the correlation value with the largest modulus. Finally, the coherent accumulated values of the sampling points corresponding to the coarse acquisition code phases in the second baseband signal may be subjected to incoherent accumulation to obtain the incoherent accumulated value of the sampling point corresponding to each coarse acquisition code phase in the local pseudo code.

The formula for maximum likelihood coherent accumulation may be, for example:

wherein the content of the first and second substances,

representing the result of the coherent accumulation of the fine acquisition of the ith sample in the mth second data segment, M, in the second baseband signal_cohRepresenting the coherent accumulation length, s, of the fine acquisition_k∈(-1,1)，s_kRepresents an optimal set of sign combinations for maximum likelihood coherent accumulation,

denotes M by M_coh(ii) correlation value of ith sample point on + k second data segments, T_segThe time interval representing two adjacent correlation values, the time interval of the GPS and BDS may be set to 0.001 (i.e., 1ms), M_ncohRepresenting the incoherent integration length of the fine acquisition.

Fig. 4 is a flow chart illustrating another method of acquiring satellite signals according to an example embodiment, as shown in fig. 4, the method further includes:

and 105, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is smaller than the acquisition threshold under the target fine acquisition carrier frequency, updating the coarse acquisition carrier frequency according to the coarse frequency offset hypothesis.

And then, repeatedly executing the steps of carrying out coarse acquisition on the intermediate frequency signal according to a preset coarse acquisition carrier frequency and a pseudo code of the target satellite so as to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, and carrying out fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and at least one coarse acquisition code phase so as to obtain an incoherent accumulated value corresponding to at least one coarse acquisition code phase under each fine acquisition carrier frequency until the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to an acquisition threshold.

In an example, after the intermediate frequency signal is subjected to fine acquisition, and an incoherent accumulated value corresponding to each coarse acquisition code phase is obtained at each fine acquisition carrier frequency, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is smaller than a preset acquisition threshold at the target fine acquisition carrier frequency, it indicates that an optimal acquisition result cannot be obtained through the current fine acquisition, and then the target coarse acquisition code phase and the corresponding target fine acquisition carrier frequency can be stored as a fine acquisition result of the coarse acquisition carrier frequency. A new coarse frequency offset hypothesis is then determined based on the coarse frequency offset hypothesis step size to update the coarse acquisition carrier frequency (i.e., update the value of n). After the coarse acquisition carrier frequency is updated, coarse acquisition can be performed on the intermediate frequency signal according to the updated coarse acquisition carrier frequency and the pseudo code of the target satellite to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, then fine acquisition can be performed on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and at least one coarse acquisition code phase to obtain an incoherent accumulated value corresponding to at least one coarse acquisition code phase at each fine acquisition carrier frequency, and when the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to an acquisition threshold, acquisition of the target satellite is completed. If the incoherent accumulated values corresponding to the plurality of stored target coarse acquisition code phases are still smaller than the preset acquisition threshold after traversing all the coarse acquisition carrier frequencies, the target coarse acquisition code phase with the largest incoherent accumulated value and the corresponding target fine acquisition carrier frequency in all the target coarse acquisition code phases can be used as the acquisition result of the target satellite, and the acquisition of the target satellite is completed. After completing the acquisition of the target satellite, the receiver may continue to acquire the satellite signal of the next satellite to be acquired, and then repeat the above steps (i.e., steps 102 to 105) to complete the acquisition of the next satellite to be acquired.

Fig. 5 is a block diagram illustrating an apparatus for acquiring a satellite signal according to an exemplary embodiment, and as shown in fig. 5, the apparatus 200 includes:

the frequency mixing module 201 is configured to perform frequency mixing on the received satellite signal by using an intermediate frequency local oscillator signal to obtain an intermediate frequency signal.

The coarse acquisition module 202 is configured to perform coarse acquisition on the intermediate frequency signal according to a preset coarse acquisition carrier frequency and a pseudo code of the target satellite, so as to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, where the coarse acquisition carrier frequency is a frequency determined according to a frequency of the intermediate frequency local oscillator signal and a preset coarse frequency offset hypothesis, and the target satellite is any one of the satellites to be acquired.

The fine acquisition module 203 is configured to perform fine acquisition on the intermediate frequency signal according to a preset fine acquisition carrier frequency sequence and at least one coarse acquisition code phase, so as to obtain an incoherent accumulated value corresponding to the at least one coarse acquisition code phase at each fine acquisition carrier frequency. The fine acquisition carrier frequency sequence comprises a plurality of fine acquisition carrier frequencies, each fine acquisition carrier frequency is determined according to the coarse acquisition carrier frequency and a preset fine frequency offset hypothesis, and the fine frequency offset hypothesis is smaller than the coarse frequency offset hypothesis.

The determining module 204 is configured to, if the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to a preset acquisition threshold at the target fine acquisition carrier frequency, use the target coarse acquisition code phase and the target fine acquisition carrier frequency as an acquisition result of the target satellite, where the target fine acquisition carrier frequency is any one of the fine acquisition carrier frequencies, and the target coarse acquisition code phase is the coarse acquisition code phase with the largest incoherent accumulated value at the target fine acquisition carrier frequency.

Fig. 6 is a block diagram illustrating another apparatus for acquiring satellite signals according to an exemplary embodiment, and as shown in fig. 6, the coarse acquisition module 202 includes:

the demodulation sub-module 2021 is configured to demodulate the intermediate frequency signal by using a coarse acquisition carrier to obtain a first baseband signal, where the frequency of the coarse acquisition carrier is a coarse acquisition carrier frequency.

The first sliding correlation sub-module 2022 is configured to perform sliding correlation on the first baseband signal and the local pseudo code to obtain correlation values of a plurality of samples included in each first data segment in the first baseband signal, where the samples included in each first data segment correspond to the samples included in the local pseudo code one to one, and the local pseudo code is determined according to the pseudo code of the target satellite.

The first obtaining sub-module 2023 is configured to perform coherent accumulation and non-coherent accumulation on correlation values of a plurality of samples included in each first data segment of the first baseband signal to obtain a non-coherent accumulation value of each sample in the local pseudo code.

The first determining sub-module 2024 is configured to determine, if the largest incoherent accumulated value of the incoherent accumulated values of each sampling point in the local pseudo code is greater than or equal to a preset coarse acquisition threshold, a coarse acquisition code phase according to the sampling point corresponding to the largest incoherent accumulated value.

The second determining sub-module 2025 is configured to determine, if the largest incoherent accumulated value of the incoherent accumulated values of each sampling point in the local pseudo code is smaller than the coarse acquisition threshold, a specified number of coarse acquisition code phases according to the sampling points corresponding to the largest specified number of incoherent accumulated values.

Fig. 7 is a block diagram illustrating another acquisition apparatus for satellite signals according to an exemplary embodiment, and as shown in fig. 7, the fine acquisition module 203 includes:

the second obtaining sub-module 2031 is configured to, for each fine acquisition carrier, multiply the first baseband signal by using a fine frequency offset hypothesis corresponding to the fine acquisition carrier to obtain a second baseband signal corresponding to the fine acquisition carrier, where a frequency of the fine acquisition carrier corresponds to one fine acquisition carrier frequency in the fine acquisition carrier frequency sequence.

The second sliding correlation sub-module 2032 is configured to perform sliding correlation on the second baseband signal and the local pseudo code to obtain a correlation value of a sample corresponding to at least one coarse acquisition code phase in each second data segment of the second baseband signal, where the sample included in each second data segment corresponds to the sample included in the local pseudo code one to one.

The third obtaining sub-module 2033 is configured to perform coherent accumulation and non-coherent accumulation on the correlation value of the sampling point corresponding to the at least one coarse acquisition code phase in each second data segment in the second baseband signal according to a maximum likelihood estimation method, so as to obtain a non-coherent accumulation value of the sampling point corresponding to the at least one coarse acquisition code phase in the local pseudo code.

Optionally, the third obtaining sub-module 2033 is configured to:

Fig. 8 is a block diagram illustrating another apparatus for acquiring satellite signals according to an exemplary embodiment, and as shown in fig. 8, the apparatus 200 further includes:

the updating module 205 is configured to update the coarse acquisition carrier frequency according to the coarse frequency offset assumption if the incoherent accumulated value corresponding to the target coarse acquisition code phase is smaller than the acquisition threshold under the target fine acquisition carrier frequency.

An executing module 206, configured to repeatedly execute the pseudo code according to the preset coarse acquisition carrier frequency and the target satellite, perform coarse acquisition on the intermediate frequency signal to obtain at least one coarse acquisition code phase corresponding to the coarse acquisition carrier frequency, and perform fine acquisition on the intermediate frequency signal to obtain an incoherent accumulated value corresponding to at least one coarse acquisition code phase at each fine acquisition carrier frequency until the incoherent accumulated value corresponding to the target coarse acquisition code phase is greater than or equal to an acquisition threshold.

With regard to the apparatus in the above-described embodiment, the specific manner in which each part performs the operation has been described in detail in the embodiment related to the method, and will not be described in detail here.

Fig. 9 is a block diagram illustrating an electronic device 700 in accordance with an example embodiment. As shown in fig. 9, the electronic device 700 may include: a processor 701 and a memory 702. The electronic device 700 may also include one or more of a multimedia component 703, an input/output (I/O) interface 704, and a communication component 705.

The processor 701 is configured to control the overall operation of the electronic device 700, so as to complete all or part of the steps in the above-mentioned method for acquiring a satellite signal. The memory 702 is used to store various types of data to support operation at the electronic device 700, such as instructions for any application or method operating on the electronic device 700 and application-related data, such as contact data, transmitted and received messages, pictures, audio, video, and the like. The Memory 702 may be implemented by any type of volatile or non-volatile Memory device or combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic Memory, flash Memory, magnetic disk, or optical disk. The multimedia components 703 may include screen and audio components. Wherein the screen may be, for example, a touch screen and the audio component is used for outputting and/or inputting audio signals. For example, the audio component may include a microphone for receiving external audio signals. The received audio signal may further be stored in the memory 702 or transmitted through the communication component 705. The audio assembly also includes at least one speaker for outputting audio signals. The I/O interface 704 provides an interface between the processor 701 and other interface modules, such as a keyboard, mouse, buttons, etc. These buttons may be virtual buttons or physical buttons. The communication component 705 is used for wired or wireless communication between the electronic device 700 and other devices. Wireless communication, such as Wi-Fi, bluetooth, Near Field Communication (NFC), 2G, 3G, 4G, NB-IOT, eMTC, or other 5G, etc., or a combination of one or more of them, which is not limited herein. The corresponding communication component 705 may thus include: Wi-Fi module, Bluetooth module, NFC module, etc.

In an exemplary embodiment, the electronic Device 700 may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components for performing the above-mentioned satellite Signal capturing method.

In another exemplary embodiment, there is also provided a computer readable storage medium including program instructions, which when executed by a processor, implement the steps of the above-described satellite signal acquisition method. For example, the computer readable storage medium may be the memory 702 described above comprising program instructions executable by the processor 701 of the electronic device 700 to perform the satellite signal acquisition method described above.

Although the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the present disclosure is not limited to the specific details of the embodiments, and other embodiments of the present disclosure can be easily conceived by those skilled in the art within the technical spirit of the present disclosure after considering the description and practicing the present disclosure, and all fall within the protection scope of the present disclosure.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable way without contradiction, and in order to avoid unnecessary repetition, the disclosure does not need to be separately described in various possible combinations, and should be considered as the disclosure of the disclosure as long as the concepts of the disclosure are not violated.

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Method and device for capturing satellite signal, storage medium and electronic equipment

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