阅读说明：本技术 一种高动态导航卫星信号接收方法及接收机 (High dynamic navigation satellite signal receiving method and receiver ) 是由 陈丽 李胜 陈春阳 李金立 于 2020-07-31 设计创作，主要内容包括：本发明涉及一种高动态导航卫星信号接收方法及接收机,属于卫星导航技术领域；方法包括导航卫星信号的捕获和跟踪步骤,在捕获步骤的匹配滤波算法中,通过对降采样后的卫星基带信号与本地生成的PN码进行短时相关累加、FFT扫频、非相干累加以及峰值判断后捕获卫星信号,并获得卫星信号的多普勒频率；在跟踪步骤的跟踪通道建立中,建立双跟踪通道,分别对捕获的多普勒频率和对所述多普勒频率进行去折叠后的频率进行跟踪,对两通道的跟踪结果进行信噪比估计,选择信噪比高的通道信号作为跟踪的输出信号。本发明可以实现在传统接收机占用资源相同的情况下,信号多普勒捕获能力扩大一倍,有效提升高动态信号接收处理能力。(The invention relates to a high dynamic navigation satellite signal receiving method and a receiver, belonging to the technical field of satellite navigation; the method comprises the steps of acquisition and tracking of navigation satellite signals, wherein in a matched filtering algorithm in the acquisition step, the satellite signals are acquired after short-time correlation accumulation, FFT frequency sweep, noncoherent accumulation and peak value judgment are carried out on satellite baseband signals subjected to down-sampling and PN codes generated locally, and the Doppler frequency of the satellite signals is obtained; in the tracking channel establishment of the tracking step, establishing double tracking channels, respectively tracking the captured Doppler frequency and the frequency obtained after the Doppler frequency is unfolded, performing signal-to-noise ratio estimation on the tracking results of the two channels, and selecting a channel signal with a high signal-to-noise ratio as a tracking output signal. The invention can realize that the signal Doppler capturing capability is doubled under the condition that the traditional receiver occupies the same resources, and effectively improves the dynamic signal receiving and processing capability.)

1. A high dynamic navigation satellite signal receiving method comprises the steps of acquisition and tracking of navigation satellite signals; it is characterized in that the preparation method is characterized in that,

in the matched filtering algorithm of the capturing step, satellite signals are captured after short-time correlation accumulation, FFT frequency sweeping, incoherent accumulation and peak value judgment are carried out on the satellite baseband signals subjected to down sampling and PN codes generated locally, and the Doppler frequency of the satellite signals is obtained;

in the tracking channel establishment of the tracking step, establishing double tracking channels, respectively tracking the captured Doppler frequency and the frequency obtained after the Doppler frequency is unfolded, performing signal-to-noise ratio estimation on the tracking results of the two channels, and selecting a channel signal with a high signal-to-noise ratio as a tracking output signal.

2. The method for receiving high dynamic navigation satellite signal according to claim 1, wherein the specific process of the matched filtering algorithm comprises:

1) carrying out down-conversion on intermediate frequency data of the satellite signal to obtain a baseband signal of the satellite signal;

2) down-sampling the baseband signal to N MHz, and storing in RAM for subsequent capture processing;

3) reading down-sampling data from the RAM, and performing M-point short-time correlation with a locally generated PN code to obtain a signal with a signal frequency fs being N/M;

4) setting the FFT frequency sweep range to be +/-fs/2, and carrying out FFT frequency sweep on the short-time correlated signals;

5) performing incoherent accumulation on the FFT frequency sweeping result for a set number of times;

6) and carrying out peak value detection on the result of the incoherent accumulation to obtain a capturing result of the satellite signal and obtain the Doppler frequency of the satellite signal.

3. The method for receiving high dynamic navigation satellite signal according to claim 2, characterized in that the number of points of the FFT frequency sweep satisfies the requirement of frequency search resolution.

4. The method of claim 3, wherein the frequency search resolution is based on a frequency mismatch loss of coherent integration Determining; wherein, ω is_IFIs the frequency of the carrier of the signal,

5. The method for receiving high dynamic navigation satellite signal according to claim 4, characterized in that when the number of samples accumulated by M points in short time correlation is less than the number of FFT sweep frequency points, the zero padding method is used to perform zero padding on the samples, so that the number of samples satisfies the number of FFT sweep frequency points.

6. The method for receiving high dynamic navigation satellite signal according to claim 1, wherein the process of establishing a tracking channel to track the acquisition signal comprises:

1) receiving the Doppler frequency fa of the satellite signal output in the acquisition step;

2) unfolding the Doppler frequency fa in the satellite signal; expanding the Doppler frequency fa to obtain Doppler frequencies with frequency points fa-fs, fa, fa + fs, and cutting off the Doppler frequency outside the frequency range +/-fs;

3) respectively sending the remaining two Doppler frequency candidate values into two tracking channels for tracking;

4) respectively carrying out signal-to-noise ratio estimation on the tracking results of the two tracking channels;

5) the channel signal with high signal-to-noise ratio is selected as the output signal for tracking.

7. A navigation satellite signal receiver to which the high dynamic navigation satellite signal receiving method of any one of claims 1-6 is applied, comprising an acquisition module and a tracking module; it is characterized in that the preparation method is characterized in that,

in the acquisition module, satellite signals are acquired after short-time correlation accumulation, FFT frequency sweep, noncoherent accumulation and peak value judgment are carried out on the satellite baseband signals subjected to down sampling and PN codes generated locally, and the Doppler frequency of the satellite signals is obtained;

in a tracking module, establishing double tracking channels, respectively tracking the captured Doppler frequency and the frequency obtained after the Doppler frequency is unfolded, carrying out signal-to-noise ratio estimation on tracking results of the two channels, and selecting a channel signal with a high signal-to-noise ratio as a tracked output signal.

8. The navigation satellite signal receiver of claim 7, wherein the acquisition module comprises a down-conversion module, a down-sampling storage module, a short-time correlation accumulation module, an FFT frequency sweep module, a non-coherent accumulation storage module, and a peak threshold detection module;

the down-conversion module is used for down-converting the intermediate frequency data of the satellite signal to obtain a baseband signal of the satellite signal;

the down-sampling storage module is used for down-sampling the baseband signal to N MHz and storing the down-sampled data in the RAM;

the short-time correlation accumulation module is used for reading down-sampling data from the RAM, performing M-point short-time correlation with a locally generated PN code, and obtaining a short-time correlation accumulation signal with the signal frequency fs being N/M;

the FFT frequency sweeping module is used for carrying out FFT frequency sweeping on the signal after short-time correlation within a set frequency sweeping range +/-fs/2;

the incoherent accumulation storage module is used for performing incoherent accumulation on the FFT frequency sweeping result for a set number of times and storing an incoherent accumulation result;

and the peak threshold detection module is used for carrying out peak detection on the incoherent accumulation result to obtain a satellite signal acquisition result.

9. The navigation satellite signal receiver of claim 8, wherein the number of sweep points of the FFT sweep module is required to meet a frequency search resolution requirement.

10. The navigation satellite signal receiver of claim 7, wherein the tracking module includes a frequency spreading module, a first tracking channel, a second tracking channel, and a comparison and combining module;

the frequency expansion module is used for unfolding the Doppler frequency fs of the captured satellite signals; expanding the Doppler frequency fa to obtain Doppler frequencies with frequency points fa-fs, fa, fa + fs, and cutting off the Doppler frequency outside the frequency range +/-fs;

the first tracking channel is used for tracking a capture signal with the Doppler frequency fs and estimating the signal-to-noise ratio of the tracking signal;

the second tracking channel is used for tracking the capture signal of the reserved Doppler frequency within the frequency range +/-fs and estimating the signal-to-noise ratio of the tracking signal;

and the comparison and combination module is used for comparing the signal-to-noise ratio estimation results of the two tracking channels, omitting the channels with low signal-to-noise ratio, and taking the tracking result of the high signal-to-noise ratio channel as a final tracking result.

Technical Field

The invention relates to the technical field of satellite navigation, in particular to a high-dynamic navigation satellite signal receiving method and a receiver.

Background

For the reception and processing of navigation satellite signals in high dynamic situations, the doppler range of the satellite signals is larger. In the prior art, the Doppler frequency is captured by expanding the range of FFT frequency sweeping, but expanding the range of FFT frequency sweeping can greatly increase the data volume of subsequent incoherent accumulation, require more computing resources and increase the power consumption, volume and cost of a receiver. Therefore, under the condition that the power consumption volume cost of the receiver has strict requirements, the existing navigation satellite receiving and processing method cannot meet the requirements of receiving and processing high-dynamic navigation satellite signals.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a high dynamic navigation satellite signal receiving method and receiver; the method is used for solving the receiving and processing problems caused by large Doppler frequency of high dynamic navigation satellite signals.

The invention discloses a high dynamic navigation satellite signal receiving method, which comprises the steps of capturing and tracking navigation satellite signals;

in the matched filtering algorithm of the capturing step, satellite signals are captured after short-time correlation accumulation, FFT frequency sweeping, incoherent accumulation and peak value judgment are carried out on the satellite baseband signals subjected to down sampling and PN codes generated locally, and the Doppler frequency of the satellite signals is obtained;

in the tracking channel establishment of the tracking step, establishing double tracking channels, respectively tracking the captured Doppler frequency and the frequency obtained after the Doppler frequency is unfolded, performing signal-to-noise ratio estimation on the tracking results of the two channels, and selecting a channel signal with a high signal-to-noise ratio as a tracking output signal.

Further, the specific process of the matched filtering algorithm includes:

1) carrying out down-conversion on intermediate frequency data of the satellite signal to obtain a baseband signal of the satellite signal;

2) down-sampling the baseband signal to N MHz, and storing in RAM for subsequent capture processing;

3) reading down-sampling data from the RAM, and performing M-point short-time correlation with a locally generated PN code to obtain a signal with a signal frequency fs being N/M;

4) setting the FFT frequency sweep range to be +/-fs/2, and carrying out FFT frequency sweep on the short-time correlated signals;

5) performing incoherent accumulation on the FFT frequency sweeping result for a set number of times;

6) and carrying out peak value detection on the result of the incoherent accumulation to obtain a capturing result of the satellite signal and obtain the Doppler frequency of the satellite signal.

Further, the number of points of the FFT frequency sweep needs to meet the requirement of the frequency search resolution.

Further, the frequency search resolution is based on frequency mismatch loss of coherent integration

Determining; wherein, ω is_IFIs the frequency of the carrier of the signal,

t is the coherent integration time for the local carrier frequency.

Further, when the number of samples accumulated by the M points in a short-time correlation is less than the number of FFT frequency sweep points, zero filling is performed on the samples through a zero filling method, so that the number of the samples meets the number of the FFT frequency sweep points.

Further, the process of establishing a tracking channel to track the captured signal includes:

1) receiving the Doppler frequency fa of the satellite signal output in the acquisition step;

2) unfolding the Doppler frequency fa in the satellite signal; expanding the Doppler frequency fa to obtain Doppler frequencies with frequency points fa-fs, fa, fa + fs, and cutting off the Doppler frequency outside the frequency range +/-fs;

3) respectively sending the remaining two Doppler frequency candidate values into two tracking channels for tracking;

4) respectively carrying out signal-to-noise ratio estimation on the tracking results of the two tracking channels;

5) the channel signal with high signal-to-noise ratio is selected as the output signal for tracking.

The invention also discloses a navigation satellite signal receiver applying the high dynamic navigation satellite signal receiving method, which comprises a capturing module and a tracking module; it is characterized in that the preparation method is characterized in that,

in the acquisition module, satellite signals are acquired after short-time correlation accumulation, FFT frequency sweep, noncoherent accumulation and peak value judgment are carried out on the satellite baseband signals subjected to down sampling and PN codes generated locally, and the Doppler frequency of the satellite signals is obtained;

in a tracking module, establishing double tracking channels, respectively tracking the captured Doppler frequency and the frequency obtained after the Doppler frequency is unfolded, carrying out signal-to-noise ratio estimation on tracking results of the two channels, and selecting a channel signal with a high signal-to-noise ratio as a tracked output signal.

Furthermore, the capturing module comprises a down-conversion module, a down-sampling storage module, a short-time correlation accumulation module, an FFT frequency sweep module, an incoherent accumulation storage module and a peak threshold detection module;

the down-conversion module is used for down-converting the intermediate frequency data of the satellite signal to obtain a baseband signal of the satellite signal;

the down-sampling storage module is used for down-sampling the baseband signal to N MHz and storing the down-sampled data in the RAM;

the short-time correlation accumulation module is used for reading down-sampling data from the RAM, performing M-point short-time correlation with a locally generated PN code, and obtaining a short-time correlation accumulation signal with the signal frequency fs being N/M;

the FFT frequency sweeping module is used for carrying out FFT frequency sweeping on the signal after short-time correlation within a set frequency sweeping range +/-fs/2;

the incoherent accumulation storage module is used for performing incoherent accumulation on the FFT frequency sweeping result for a set number of times and storing an incoherent accumulation result;

and the peak threshold detection module is used for carrying out peak detection on the incoherent accumulation result to obtain a satellite signal acquisition result.

Further, the frequency sweeping point number of the FFT frequency sweeping module needs to meet the requirement of frequency searching resolution.

Further, the tracking module comprises a frequency expanding module, a first tracking channel, a second tracking channel and a comparison and combination module;

the frequency expansion module is used for unfolding the Doppler frequency fs of the captured satellite signals; expanding the Doppler frequency fa to obtain Doppler frequencies with frequency points fa-fs, fa, fa + fs, and cutting off the Doppler frequency outside the frequency range +/-fs;

the first tracking channel is used for tracking a capture signal with the Doppler frequency fs and estimating the signal-to-noise ratio of the tracking signal;

the second tracking channel is used for tracking the capture signal of the reserved Doppler frequency within the frequency range +/-fs and estimating the signal-to-noise ratio of the tracking signal;

and the comparison and combination module is used for comparing the signal-to-noise ratio estimation results of the two tracking channels, omitting the channels with low signal-to-noise ratio, and taking the tracking result of the high signal-to-noise ratio channel as a final tracking result.

The invention has the following beneficial effects:

the invention can realize that the signal Doppler capturing capability is doubled under the condition that the traditional receiver occupies the same resources, and effectively improves the dynamic signal receiving and processing capability.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

Fig. 1 is a schematic diagram illustrating a principle of a method for receiving a high dynamic navigation satellite signal in a first embodiment;

FIG. 2 is a schematic view of a sampling law folding in the first embodiment;

FIG. 3 is an original diagram of a capture module according to a second embodiment;

FIG. 4 is an original diagram of a conventional trace module in the second embodiment;

fig. 5 is an original schematic diagram of the tracking module in the second embodiment.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.