CN115685271A - A two-stage fast signal acquisition method for time-division navigation signals under Doppler - Google Patents

Abstract

The application relates to a two-stage rapid signal capturing method of time division navigation signals under large Doppler. The method comprises the following steps: acquiring a digital baseband signal received by a navigation receiver, and sampling the digital baseband signal to obtain a first sampling signal; traversing a first code phase searching range, and performing code phase capturing on a time division pulse sequence corresponding to the first sampling signal to obtain a first pseudo code phase capturing result; after waiting for a preset time interval, sampling the digital baseband signal to obtain a second sampling signal, and obtaining a second code phase search range according to the pre-estimated maximum Doppler of the digital baseband signal; traversing a second code phase searching range, and performing code phase capturing on a time division pulse sequence corresponding to a second sampling signal to obtain a second pseudo code phase capturing result; and obtaining carrier Doppler according to the first pseudo code phase acquisition result and the second pseudo code phase acquisition result. By adopting the method, the time division spread spectrum signal with large Doppler frequency offset can be rapidly captured.

Description

A two-stage fast signal acquisition method for time-division navigation signals under Doppler

technical field

The present application relates to the technical field of satellite navigation, in particular to a two-stage fast signal acquisition method for time-division navigation signals under Doppler.

Background technique

The Beidou navigation system has the characteristics of global coverage and all-weather operation. Beidou navigation has been widely used in various industries, including vehicle and aircraft navigation, personal navigation, bridge monitoring, modern agriculture, precision surveying and mapping and other fields. In a GPS receiver, signal acquisition is a prerequisite for signal tracking and demodulation of navigation data bits. During acquisition, it is necessary to simultaneously complete carrier Doppler frequency shift search and C/A code initial phase search for each satellite in the GPS constellation. The Beidou system improves the measurement performance of the system by adding the measurement link of the Ka frequency point. The Ka frequency point signal has a high carrier frequency and a large Doppler dynamic range, and adopts a time-division system signal, that is, on the basis of the traditional continuous navigation signal, a time-division pulse control sequence is modulated, and the continuous signal becomes a discontinuous signal. On the other hand, the use of low-orbit satellites to broadcast enhanced navigation signals can further improve the performance of the Beidou system, but low-orbit satellites are dynamic, resulting in a large range of Doppler changes in enhanced signals. The signal may also adopt a time-division system, so the low-orbit navigation enhancement signal received on the ground is also a Doppler time-division signal.

In the traditional method, to complete the acquisition of the signal, it is necessary to search in the uncertain region of the pseudo-code and Doppler frequency. For the Doppler time-division navigation signal, the traditional continuous signal acquisition method will face a large performance loss , and it is necessary to overcome the problem of a sharp increase in the search space caused by Doppler. Although the method of using auxiliary information can compress the search range during signal acquisition, it needs to know the satellite ephemeris and the approximate position of itself in advance.

Contents of the invention

Based on this, it is necessary to provide a two-stage fast signal acquisition method for time-division navigation signals under Doppler to address the above technical problems.

A two-stage fast signal acquisition method for time-division navigation signals under Doppler, the method comprising:

Obtaining the digital baseband signal received by the navigation receiver, sampling the digital baseband signal to obtain a first sampling signal; the digital baseband signal includes a time-division spread spectrum signal with a large Doppler frequency deviation;

Traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, obtaining a pseudo code phase capture result within the first code phase search range, according to the pseudo code phase capture The maximum value of the result obtains the first pseudocode phase capture result;

At the initial sampling point of the first sampling signal, after waiting for a preset time interval, the digital baseband signal is sampled to obtain a second sampling signal, according to the pre-estimated maximum Doppler corresponding to the digital baseband signal Le calculation obtains the second code phase search range;

Traversing the second code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the second sampling signal, to obtain a corresponding second pseudo code phase capture result;

Carrier Doppler is obtained according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result.

In one of the embodiments, it also includes: the mathematical model of the digital baseband signal is:

为导航接收设备接收到的数字基带信号，

为载波的振幅，

为卫星导航电文，

为采样点，

为信号传输延迟，

为信号的载波多普勒，w (k)为基带噪声，

为导航信号中的扩频码，

为时分脉冲信号，

为虚数单位符号，

为射频载波初始相位。 in,

It is the digital baseband signal received by the navigation receiving equipment,

is the amplitude of the carrier wave,

is the satellite navigation message,

is the sampling point,

is the signal propagation delay,

is the carrier Doppler of the signal, w ( k ) is the baseband noise,

is the spreading code in the navigation signal,

is a time-division pulse signal,

is the imaginary unit symbol,

is the initial phase of the RF carrier.

In one of the embodiments, it also includes: performing non-coherent accumulation on multiple coherent integration results after coherently integrating each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase to obtain the current code phase The non-coherent accumulation result corresponding to the phase; the current code phase is within the preset first code phase search range; the first code phase search range is traversed to obtain the non-coherent value corresponding to each code phase in the first code phase search range For coherent accumulation results, according to the size relationship between each non-coherent accumulation result and the decision threshold, a pseudo code phase capture result within the first code phase search range is obtained.

In one of the embodiments, it also includes: when the non-coherent accumulation result is greater than the decision threshold, the code phase acquisition is successful, and the acquisition result is obtained according to the code phase corresponding to the current local spreading code; when the non-coherent accumulation result is less than Or when it is equal to the decision threshold, the code phase acquisition fails, slide the preset pseudo-code phase search interval backward in the first code phase search range, calculate the non-coherent accumulation result corresponding to the code phase after sliding, and iterate the above process until When each code phase search in the first code phase search range is completed, the iteration is stopped, and the capture result in the first code phase search range is output.

In one of the embodiments, it also includes: performing non-coherent accumulation on multiple coherent integration results after coherently integrating each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase to obtain the current code phase The non-coherent accumulation result corresponding to the phase is:

为码相位为

对应的非相干累加结果，

为基带数字信号的 相位，

为基带复信号，

为第

个脉冲信号的起始采样点位置，

为本地复制的相位为

的扩频码，

为短时相关长度，

为第一采 样信号对应的脉冲个数。 in,

is the code phase of

The corresponding non-coherent accumulation result,

is the phase of the baseband digital signal,

is the baseband complex signal,

for the first

The starting sampling point position of a pulse signal,

The phase for local replication is

The spreading code,

is the short-term correlation length,

is the number of pulses corresponding to the first sampling signal.

In one of the embodiments, it also includes: calculating the second code phase search range according to the pre-estimated maximum Doppler corresponding to the digital baseband signal:

为第二码相位搜索范围，

为数字基带信号对应的最大多普勒，

，

为信号射频频率，

为伪码速率，

表示向上取整运算，

为时间 间隔，

为伪码相位搜索间隔。 in,

is the second code phase search range,

is the maximum Doppler corresponding to the digital baseband signal,

,

is the RF frequency of the signal,

is the pseudocode rate,

Indicates an upward rounding operation,

is the time interval,

Search interval for pseudo code phase.

In one of the embodiments, it also includes: according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result, obtaining the carrier Doppler as:

为载波多普勒，

为信号射频频率与伪码速率的比值，

为第二伪码 相位捕获结果，

为第一伪码相位捕获结果，

为时间间隔。 in,

is the carrier Doppler,

is the ratio of the signal RF frequency to the pseudocode rate,

is the second pseudo-code phase capture result,

is the first pseudocode phase capture result,

for the time interval.

In one of the embodiments, it also includes: the second pseudo-code phase capture result is:

为第二伪码相位捕获结果，

为当

取最大时对应

的值，

为码相位为

对应的非相干累加结果，

为第一伪码相位捕获结果，

为第二码相位搜索范围，

为伪码相位搜索间隔。 in,

is the second pseudo-code phase capture result,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the first pseudocode phase capture result,

is the second code phase search range,

Search interval for pseudo code phase.

In one of the embodiments, it also includes: the first pseudo-code phase capture result is:

为第一伪码相位捕获结果，

为码相位，

为当

取最大时对应

的值，

为码相位为

对应的非相干累加 结果，

为伪码相位搜索间隔，

为伪码相位搜索单元数。 in,

is the first pseudocode phase capture result,

is the code phase,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the pseudocode phase search interval,

Number of cells to search for pseudo code phase.

In one of the embodiments, it also includes: according to the time interval and the pseudo-code phase search interval, the estimation accuracy of carrier Doppler is:

为载波多普勒的估计精度，

为伪码相位搜索间隔，

为信号射频 频率与伪码速率的比值；调整所述时间间隔和所述伪码相位搜索间隔以调整载波多普勒的 捕获精度。 in,

is the estimation accuracy of carrier Doppler,

is the pseudocode phase search interval,

is the ratio of the radio frequency of the signal to the pseudo-code rate; adjusting the time interval and the pseudo-code phase search interval to adjust the acquisition accuracy of carrier Doppler.

A two-stage fast signal acquisition device for time-division navigation signals under Doppler, said device comprising:

A signal acquisition module, configured to acquire a digital baseband signal received by a navigation receiver, and sample the digital baseband signal to obtain a first sampling signal; the digital baseband signal includes a time-division spread spectrum signal of a Doppler frequency deviation;

The first-level search module is used to traverse the preset first code phase search range, and perform code phase capture on the time-division pulse sequence corresponding to the first sampling signal to obtain a pseudo code phase capture result within the first code phase search range. , obtaining a first pseudo-code phase capture result according to the maximum value of the pseudo-code phase capture result;

The search range determination module is used to sample the digital baseband signal after waiting for a preset time interval at the initial sampling point of the first sampling signal to obtain a second sampling signal, according to the pre-estimated digital The maximum Doppler corresponding to the baseband signal is calculated to obtain the second code phase search range;

The second-level search module is configured to traverse the second code phase search range, perform code phase capture on the time-division pulse sequence corresponding to the second sampling signal, and obtain a corresponding second pseudo-code phase capture result;

A carrier Doppler estimation module, configured to obtain carrier Doppler according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result.

A computer device, comprising a memory and a processor, the memory stores a computer program, and the processor implements the following steps when executing the computer program:

Obtaining the digital baseband signal received by the navigation receiver, sampling the digital baseband signal to obtain a first sampling signal; the digital baseband signal includes a time-division spread spectrum signal with a large Doppler frequency deviation;

Traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, obtaining a pseudo code phase capture result within the first code phase search range, according to the pseudo code phase capture The maximum value of the result obtains the first pseudocode phase capture result;

At the initial sampling point of the first sampling signal, after waiting for a preset time interval, the digital baseband signal is sampled to obtain a second sampling signal, according to the pre-estimated maximum Doppler corresponding to the digital baseband signal Le calculation obtains the second code phase search range;

Traversing the second code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the second sampling signal, to obtain a corresponding second pseudo code phase capture result;

Carrier Doppler is obtained according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result.

A computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

Obtaining the digital baseband signal received by the navigation receiver, sampling the digital baseband signal to obtain a first sampling signal; the digital baseband signal includes a time-division spread spectrum signal with a large Doppler frequency deviation;

Traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, obtaining a pseudo code phase capture result within the first code phase search range, according to the pseudo code phase capture The maximum value of the result obtains the first pseudocode phase capture result;

At the initial sampling point of the first sampling signal, after waiting for a preset time interval, the digital baseband signal is sampled to obtain a second sampling signal, according to the pre-estimated maximum Doppler corresponding to the digital baseband signal Le calculation obtains the second code phase search range;

Traversing the second code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the second sampling signal, to obtain a corresponding second pseudo code phase capture result;

Carrier Doppler is obtained according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result.

The above-mentioned two-stage fast signal acquisition method for the time-division navigation signal under Doppler realizes the acquisition of the signal Doppler by performing two serial time dimension searches on the received digital baseband signal. Specifically, the two-dimensional time- The frequency search is converted into one-dimensional time search and one-dimensional frequency estimation. During the one-dimensional time search, the phase of the pseudo code is captured twice. , quickly search the code phase of the signal in a large time range, and complete the initial acquisition of the signal code phase. The second-level capture can greatly compress the time search range of the signal on the basis of the first-level capture, and obtain more accurate Phase search results, after two pseudo-code phase captures, calculate the carrier Doppler according to the two pseudo-code phase capture results, greatly compress the signal Doppler search space, and improve the capture efficiency of Doppler time-division spread spectrum signals , the embodiment of the present invention can quickly capture the time-division spread-spectrum signal in the presence of a Doppler frequency offset.

Description of drawings

Fig. 1 is the schematic flow chart of the two-stage fast signal acquisition method of time-division navigation signal under Doppler in an embodiment;

Fig. 2 is a schematic structural diagram of a time division spread spectrum signal in an embodiment;

Fig. 3 is a schematic diagram of correlation peak results of first-level search and second-level search in one embodiment;

Fig. 4 is the structural block diagram of the two-stage fast signal acquisition device of time-division navigation signal under Doppler in an embodiment;

Figure 5 is an internal block diagram of a computer device in one embodiment.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

In one embodiment, as shown in Figure 1, a two-stage fast signal acquisition method for time-division navigation signals under Doppler is provided, comprising the following steps:

Step 102, acquiring a digital baseband signal received by the navigation receiver, and sampling the digital baseband signal to obtain a first sampling signal.

为脉冲周期，时分脉冲序列在脉冲宽度

内有信号脉冲，在

时间内无信号，因此，在对时分脉冲序列进行码相位捕获时，将时分 脉冲序列与PN码（伪随机码）相乘，则可以对有信号脉冲时的信号进行处理。 The GPS signal is a spread spectrum signal after direct sequence spread spectrum modulation and carrier modulation. For a spread spectrum system, acquisition means that the phase difference between the local reference code and the receiving code is less than one symbol width, and the clock frequency of the receiving and receiving codes is basically the same, and at the same time, the carrier is aligned with each other to realize the synchronization of the input signal and the local signal. In the GPS system, the coarse synchronization process of the pseudo-code phase and the carrier frequency is the pseudo-code acquisition. An effective pseudo-code acquisition method is the core of the research of the high dynamic GPS receiver, and shortening the acquisition time means the improvement of the system performance. When capturing the transmitting signal, only when the pseudocode phase and carrier Doppler frequency reproduced locally by the receiver match the received signal, can the capture be confirmed successfully and the bit synchronization of the transmitting and receiving signals be realized. In the present invention, the digital baseband signal comprises a time-division spread-spectrum signal of Doppler frequency deviation, and the first sampling signal comprises a multi-section time-division pulse signal, as shown in Fig. In terms of signal capture, the time-division spread spectrum signal adds a time-division pulse sequence, which is a discontinuous signal.

is the pulse period, the time-division pulse sequence is in the pulse width

There is a signal pulse within the

There is no signal within the time period, so when the code phase is captured for the time-division pulse sequence, the time-division pulse sequence is multiplied by the PN code (pseudo-random code), and the signal when there is a signal pulse can be processed.

Step 104, traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, obtaining a pseudo code phase capture result within the first code phase search range, and according to the pseudo code phase capture result The maximum value of , the first pseudo-code phase capture result is obtained.

The first code phase search range is the pre-set signal capture time range. Since the duration of the part of the time-division spread spectrum signal with signal is relatively short, the Doppler tolerance range is relatively large, so only the pseudo-code phase can be captured in the capture link. , the code phase acquisition of the time-division pulse sequence corresponding to the first sampling signal is used as the first-level search, and the first pseudo-code phase acquisition result is obtained through the first-level search, and the pseudo-code phase acquisition result is obtained twice through the pseudo-code phase acquisition results. Doppler, and then carrier Doppler, can keep the fast acquisition of the signal when the search space is greatly reduced.

Step 106: At the initial sampling point of the first sampling signal, after waiting for a preset time interval, the digital baseband signal is sampled to obtain a second sampling signal, which is calculated according to the maximum Doppler corresponding to the pre-estimated digital baseband signal The second code phase search range.

的接收信号捕获两次，根据前后两次的码 相位捕获差，计算伪码多普勒，再由伪码多普勒换算至载波多普勒，利用两次码相位捕获的 差分结果实现了载波多普勒的估计，由估计的数字基带信号对应的最大多普勒，计算第二 码相位搜索范围，相比第一级搜索，第二级搜索的搜索范围大大减小。 The principle of Doppler acquisition is the time interval

The received signal is captured twice, and the pseudo code Doppler is calculated according to the difference between the two code phase captures before and after, and then converted from the pseudo code Doppler to the carrier Doppler, and the difference between the two code phase captures is used to realize the carrier For Doppler estimation, the second code phase search range is calculated from the maximum Doppler corresponding to the estimated digital baseband signal. Compared with the first-stage search, the search range of the second-stage search is greatly reduced.

Step 108, traversing the second code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the second sampling signal, and obtaining a corresponding second pseudo code phase capture result.

The code phase capture of the time-division pulse sequence corresponding to the second sampling signal is used as a second-level search, and a second pseudo-code phase capture result is obtained through the second-level search. The second-level search method is the same as the first-level search method, but the search range of the second-level search is reduced and the search accuracy is improved.

Step 110, obtain carrier Doppler according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result.

In the general acquisition method, because there are many units for signal search, the corresponding signal acquisition time is also very long, which is not allowed in some receivers with relatively high real-time requirements. The two-stage capture algorithm proposed by the invention can capture the phase of the pseudocode twice, convert the two-dimensional time-frequency search into one-dimensional time search and one-dimensional frequency estimation, and greatly improve the efficiency of the algorithm.

In the above-mentioned two-stage fast signal acquisition method for time-division navigation signals under Doppler, the signal Doppler acquisition is realized by performing two serial time dimension searches on the received digital baseband signal, specifically, the two-dimensional time dimension -Frequency search is converted into one-dimensional time search and one-dimensional frequency estimation. During one-dimensional time search, the phase of the pseudo-code is captured twice. The first-level capture can be used when the signal has a large Doppler frequency offset. Next, the code phase of the signal is quickly searched in a large time range to complete the initial acquisition of the signal code phase. On the basis of the first-level capture, the second-level capture can greatly compress the time search range of the signal and obtain more accurate The phase search results of the pseudo-code, after two pseudo-code phase captures, calculate the carrier Doppler according to the two pseudo-code phase capture results, greatly compress the search space of the signal Doppler, and improve the capture of the Doppler time-division spread spectrum signal Efficiency, the embodiment of the present invention can quickly capture the time-division spread-spectrum signal under the presence of a Doppler frequency offset.

In one embodiment, the mathematical model of the digital baseband signal is:

为在导航接收设备接收到的数字基带信号，

为载波的振幅，

为卫星导航电文，

为采样点，

为信号传输延迟，

为信号的载波多普 勒，w(k)为基带噪声，

为导航信号中的扩频码，

为时分脉冲信 号，

为虚数单位符号，

为射频载波初始相位。在本实施例中，信号捕获的过程可以描 述为利用已知的导航信号扩频码序列和时分脉冲序列，对接收到的

序列过程中的

和

两个参数进行估计。相比传统的对扩频信号的捕获而言，时分扩频信号增加了时 分脉冲序列，因此在捕获的过程中也需要利用时分脉冲序列实现信号的捕获。 in,

is the digital baseband signal received by the navigation receiving device,

is the amplitude of the carrier wave,

is the satellite navigation message,

is the sampling point,

is the signal propagation delay,

is the carrier Doppler of the signal, w ( k ) is the baseband noise,

is the spreading code in the navigation signal,

is a time-division pulse signal,

is the imaginary unit symbol,

is the initial phase of the RF carrier. In this embodiment, the process of signal acquisition can be described as using the known navigation signal spreading code sequence and time-division pulse sequence to analyze the received

in sequence

and

Two parameters are estimated. Compared with the traditional acquisition of spread-spectrum signals, the time-division spread-spectrum signal adds a time-division pulse sequence, so it is also necessary to use the time-division pulse sequence to achieve signal acquisition during the capture process.

In one embodiment, traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, and obtaining a pseudo code phase capture result within the first code phase search range includes: Each time-division pulse of a sampling signal is coherently integrated with the local spreading code corresponding to the current code phase, and the multiple coherent integration results are non-coherently accumulated to obtain the non-coherent accumulation result corresponding to the current code phase; the current code phase is set in advance Within the first code phase search range; traverse the first code phase search range to obtain the non-coherent accumulation result corresponding to each code phase in the first code phase search range, according to the size relationship between each non-coherent accumulation result and the decision threshold, Obtaining the pseudo-code phase capture result within the first code phase search range; performing non-coherent accumulation on a plurality of coherent integration results after coherently integrating each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase, Obtaining the non-coherent accumulation result corresponding to the current code phase includes: performing non-coherent accumulation on multiple coherent integration results after coherently integrating each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase to obtain the current code phase The non-coherent accumulation result corresponding to the phase is:

为码相位为

对应的非相干累加结果，

为基带数字信号的 相位，

为基带复信号，

为第

个脉冲信号的起始采样点位置，

为本地复制的相位为

的扩频码，

为短时相关长度，

为第一 采样信号对应的脉冲个数。 in,

is the code phase of

The corresponding non-coherent accumulation result,

is the phase of the baseband digital signal,

is the baseband complex signal,

for the first

The starting sampling point position of a pulse signal,

The phase for local replication is

The spreading code,

is the short-term correlation length,

is the number of pulses corresponding to the first sampling signal.

段时分信号进行捕获，

段时分信号的 持续时间为

，

和

由跳时脉冲图案

确定，将

段时分信号与

进行短时相关和后积累运算，得到

对应的非相干累积结果

，短时相关与 脉冲宽度

保持一致，即

，

为信号采样率。当

（

为 预先设置的判决门限）时，码相位捕获成功，此时对应的本地扩频码相位即为捕获结果，否 则继续搜索直至结束或相关结果超过门限Th。 In this embodiment, in the first level search, select

Time-division signals are captured,

The duration of the time-division signal is

,

and

time hopping pattern

sure, will

time-division signal with

Perform short-term correlation and post-accumulation operations to get

The corresponding noncoherent accumulation result

, the short-term correlation with the pulse width

be consistent, i.e.

,

is the signal sampling rate. when

(

is the preset decision threshold), the code phase capture is successful, and the corresponding local spread spectrum code phase is the capture result, otherwise continue to search until the end or the correlation result exceeds the threshold Th .

In one embodiment, according to the size relationship between each non-coherent accumulation result and the decision threshold, the step of obtaining the pseudo-code phase acquisition result in the first code phase search range includes: when the non-coherent accumulation result is greater than the decision threshold, the code If the phase acquisition is successful, the acquisition result is obtained according to the code phase corresponding to the current local spreading code; when the non-coherent accumulation result is less than or equal to the judgment threshold, the code phase acquisition fails, and the preset false value is slid backward within the first code phase search range. Code phase search interval, calculate the non-coherent accumulation result corresponding to the code phase after sliding, iterate the above process until each code phase search in the first code phase search range is completed, stop the iteration, and output the first code phase search range Capture result; the first pseudocode phase capture result is:

为第一伪码相位捕获结果，

为码相位，

为当

取最大时对应

的值，

为码相位为

对应的非相干累加 结果，

为伪码相位搜索间隔，

为伪码相位搜索单元数。在本实施例中，遍历所有伪码 初相的可能，并取所有搜索结果的最大值对应的相位，即可得到信号的伪码相位捕获结果。 in,

is the first pseudocode phase capture result,

is the code phase,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the pseudocode phase search interval,

Number of cells to search for pseudo code phase. In this embodiment, the possibility of traversing all the initial phases of the pseudo-code, and taking the phase corresponding to the maximum value of all search results can obtain the phase capture result of the pseudo-code of the signal.

In one embodiment, the second pseudocode phase capture result is:

为第二伪码相位捕获结果，

为当

取最大时对应

的值，

为码相位为

对应的非相干累加结果，

为第一伪码相位捕获结果，

为第二码相位搜索范围，

为伪码相位搜索间隔；根据 预先估计的数字基带信号对应的最大多普勒计算得到第二码相位搜索范围包括：根据预先 估计的数字基带信号对应的最大多普勒计算得到第二码相位搜索范围为： in,

is the second pseudo-code phase capture result,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the first pseudocode phase capture result,

is the second code phase search range,

is the pseudo-code phase search interval; calculating the second code phase search range according to the maximum Doppler corresponding to the pre-estimated digital baseband signal includes: calculating the second code phase search according to the maximum Doppler corresponding to the pre-estimated digital baseband signal The range is:

为第二码相位搜索范围，

为数字基带信号对应的最大多普勒，

，

为信号射频频率，

为伪码速率，

表示向上取整运算，

为时间 间隔，

为伪码相位搜索间隔。在本实施例中，第二码相位搜索范围包括

个码 相位。 in,

is the second code phase search range,

is the maximum Doppler corresponding to the digital baseband signal,

,

is the RF frequency of the signal,

is the pseudocode rate,

Indicates an upward rounding operation,

is the time interval,

Search interval for pseudo code phase. In this embodiment, the second code phase search range includes

code phase.

In one embodiment, obtaining the carrier Doppler according to the first pseudo code phase acquisition result and the second pseudo code phase acquisition result includes: obtaining the carrier Doppler according to the first pseudo code phase acquisition result and the second pseudo code phase acquisition result Puller is:

为载波多普勒，

为信号射频频率与伪码速率的比值，

为第二伪码 相位捕获结果，

为第一伪码相位捕获结果，

为时间间隔。 in,

is the carrier Doppler,

is the ratio of the signal RF frequency to the pseudocode rate,

is the second pseudo-code phase capture result,

is the first pseudocode phase capture result,

for the time interval.

In one embodiment, the method also includes: according to the time interval and the pseudo-code phase search interval, the estimation accuracy of the carrier Doppler is:

为载波多普勒的估计精度，

为伪码相位搜索间隔，

为信号射频 频率与伪码速率的比值；调整时间间隔和伪码相位搜索间隔以调整载波多普勒的捕获精 度。在本实施例中，利用两次码相位捕获的差分结果实现了载波多普勒的估计，延长

或 者减小

均可以提高信号载波频率的捕获精度，当

、

码片、

时，载波频率的估计精度为620Hz。 in,

is the estimation accuracy of carrier Doppler,

is the pseudocode phase search interval,

is the ratio of signal RF frequency to pseudo-code rate; adjust the time interval and pseudo-code phase search interval to adjust the acquisition accuracy of carrier Doppler. In this embodiment, the carrier Doppler estimation is realized by using the differential results of two code phase acquisitions, extending

or reduce

Both can improve the capture accuracy of the signal carrier frequency, when

,

chips,

, the estimation accuracy of the carrier frequency is 620Hz.

个伪码 相位，判断时间搜索是否完成，若已完成，且已获取载波多普勒，则捕获成功，否则捕获失 败；若第一级搜索的时间搜索未完成，则向后滑动本地信号的伪码相位搜索间隔，将第一采 样信号与本地扩频码和跳时脉冲图案进行短时相关积累运算得到每一伪码相位对应的相 关值，将相关值与门限进行比较，若相关值比门限大，则记录此时的相位，否则，重新判断时 间搜索是否完成，根据捕获的最大相位输出第一伪码相位捕获结果，然后，等待

时间后 对数字基带信号进行采样，得到第二采样信号，在第一码相位搜索范围内根据预先估计的 最大多普勒计算第二码相位搜索范围，在第二码相位搜索范围内对第二采样信号进行第二 级搜索，得到第二伪码相位捕获结果，最后，根据第一伪码相位捕获结果和第二伪码相位捕 获结果计算得到载波多普勒，完成信号捕获。 In a specific embodiment, the present invention provides a two-stage acquisition algorithm for Doppler time-division signals, the specific steps are shown in the table below, at first, obtain the digital baseband signal to be captured, and sample the digital baseband signal, then, The first-level search is performed on the first sampled signal, and the total number of code phases searched in the first code phase search range is

Pseudo-code phase, judge whether the time search is completed, if it has been completed, and the carrier Doppler has been obtained, then the acquisition is successful, otherwise the acquisition fails; if the time search of the first-level search is not completed, then slide the pseudo code of the local signal backward Code phase search interval, the short-term correlation accumulation operation is performed on the first sampling signal with the local spread spectrum code and the time-hopping pulse pattern to obtain the correlation value corresponding to each pseudo-code phase, and the correlation value is compared with the threshold, if the correlation value is greater than the threshold is large, then record the phase at this time, otherwise, re-judge whether the time search is completed, output the first pseudocode phase capture result according to the maximum captured phase, and then wait

Sampling the digital baseband signal after a period of time to obtain the second sampled signal, calculating the second code phase search range according to the pre-estimated maximum Doppler within the first code phase search range, and performing the second code phase search range within the second code phase search range The sampled signal is searched at the second stage to obtain the second pseudo-code phase acquisition result, and finally, the carrier Doppler is calculated according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result, and the signal acquisition is completed.

Table 1 Two-stage acquisition algorithm for Doppler time-division signals

In a specific embodiment, as shown in FIG. 3 , a schematic diagram of the correlation peak results of the first-level search and the second-level search is provided. It can be seen from FIG. 3 that the scope of the second-level search is compared with that of the first-level search. The range is greatly reduced, and the Doppler frequency offset of the signal can be directly calculated by capturing the two-stage code phase, and it is no longer necessary to search the Doppler of the signal, which shows that the method of the present invention can greatly simplify the Doppler frequency offset Acquisition complexity of time-division navigation signals.

It should be understood that although the various steps in the flow chart of FIG. 1 are displayed sequentially as indicated by the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in Fig. 1 may include multiple sub-steps or multiple stages, these sub-steps or stages are not necessarily executed at the same time, but may be executed at different times, the execution of these sub-steps or stages The order is not necessarily performed sequentially, but may be performed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

In one embodiment, as shown in FIG. 4 , a two-stage fast signal acquisition device for Doppler time-division navigation signals is provided, including: a signal acquisition module 402, a first-stage search module 404, and a search range determination module 406 , second stage search module 408 and carrier Doppler estimation module 410, wherein:

The signal acquisition module 402 is used to obtain the digital baseband signal received by the navigation receiver, and sample the digital baseband signal to obtain the first sampling signal; the digital baseband signal includes a time-division spread spectrum signal with a Doppler frequency deviation;

The first-stage search module 404 is configured to traverse the preset first code phase search range, perform code phase capture on the time-division pulse sequence corresponding to the first sampling signal, and obtain a pseudo code phase capture result within the first code phase search range, According to the maximum value of the pseudo-code phase capture result, the first pseudo-code phase capture result is obtained;

The search range determination module 406 is used to sample the digital baseband signal after waiting for a preset time interval at the initial sampling point of the first sampling signal to obtain the second sampling signal. Doppler calculation obtains the second code phase search range;

The second-level search module 408 is used to traverse the second code phase search range, and perform code phase capture on the time-division pulse sequence corresponding to the second sampling signal to obtain a corresponding second pseudo-code phase capture result;

The carrier Doppler estimation module 410 is configured to obtain the carrier Doppler according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result.

In one of the embodiments, the signal acquisition module 402 also uses the mathematical model of the digital baseband signal as:

为导航接收设备接收到的数字基带信号，

为载波的振幅，

为卫星导航电文，

为采样点，

为信号传输延迟，

为信号的载波多普 勒，w(k)为基带噪声，

为导航信号中的扩频码，

为时分脉冲信 号，

为虚数单位符号，

为射频载波初始相位。 in,

It is the digital baseband signal received by the navigation receiving equipment,

is the amplitude of the carrier wave,

is the satellite navigation message,

is the sampling point,

is the signal propagation delay,

is the carrier Doppler of the signal, w ( k ) is the baseband noise,

is the spreading code in the navigation signal,

is a time-division pulse signal,

is the imaginary unit symbol,

is the initial phase of the RF carrier.

In one of the embodiments, the first-stage search module 404 is also used to non-coherently accumulate multiple coherent integration results after coherent integration of each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase , to obtain the non-coherent accumulation result corresponding to the current code phase; the current code phase is within the preset first code phase search range; traverse the first code phase search range, and obtain the non-coherent accumulation results corresponding to each code phase in the first code phase search range For the coherent accumulation results, according to the size relationship between each non-coherent accumulation result and the decision threshold, a pseudo-code phase capture result within the first code phase search range is obtained.

In one of the embodiments, the first-stage search module 404 is also used to obtain the capture result according to the code phase corresponding to the current local spreading code when the non-coherent accumulation result is greater than the decision threshold, and the code phase acquisition is successful; when the non-coherent accumulation When the result is less than or equal to the decision threshold, the code phase acquisition fails, slide the preset pseudo-code phase search interval backward in the first code phase search range, calculate the non-coherent accumulation result corresponding to the code phase after sliding, and iterate the above process until When the search of each code phase within the first code phase search range is completed, the iteration is stopped, and the capture result within the first code phase search range is output.

In one of the embodiments, the first-stage search module 404 is also used to non-coherently accumulate multiple coherent integration results after coherent integration of each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase , the non-coherent accumulation result corresponding to the current code phase is:

为码相位为

对应的非相干累加结果，

为基带数字信号 的相位，

为基带复信号，

为第

个脉冲信号的起始采样点位置，

为本地复制的相位为

的扩频码，

为短时相关长度，

为第一采 样信号对应的脉冲个数。 in,

is the code phase of

The corresponding non-coherent accumulation result,

is the phase of the baseband digital signal,

is the baseband complex signal,

for the first

The starting sampling point position of a pulse signal,

The phase for local replication is

The spreading code,

is the short-term correlation length,

is the number of pulses corresponding to the first sampling signal.

In one of the embodiments, the search range determination module 406 is further configured to calculate and obtain the second code phase search range according to the maximum Doppler corresponding to the pre-estimated digital baseband signal:

为第二码相位搜索范围，

为预先估计的数字基带信号对应的最 大多普勒，

，

为信号射频频率，

为伪码速率，

表示向上取整运算，

为时间间隔，

为伪码相位搜索间隔。 in,

is the second code phase search range,

is the maximum Doppler corresponding to the pre-estimated digital baseband signal,

,

is the RF frequency of the signal,

is the pseudocode rate,

Indicates an upward rounding operation,

is the time interval,

Search interval for pseudo code phase.

In one of the embodiments, the carrier Doppler estimation module 410 is further configured to obtain the carrier Doppler according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result as:

为载波多普勒，

为信号射频频率与伪码速率的比值，

为第二伪码 相位捕获结果，

为第一伪码相位捕获结果，

为时间间隔。 in,

is the carrier Doppler,

is the ratio of the signal RF frequency to the pseudocode rate,

is the second pseudo-code phase capture result,

is the first pseudocode phase capture result,

for the time interval.

In one of the embodiments, the second-level search module 408 is also used for the second pseudo-code phase acquisition result as follows:

为第二伪码相位捕获结果，

为当

取最大时对应

的值，

为码相位为

对应的非相干累加结果，

为第一伪码相位捕获结果，

为第二码相位搜索范围，

为伪码相位搜索间隔。 in,

is the second pseudo-code phase capture result,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the first pseudocode phase capture result,

is the second code phase search range,

Search interval for pseudo code phase.

In one of the embodiments, the first-level search module 404 is also used for the first pseudo-code phase acquisition result as follows:

为第一伪码相位捕获结果，

为码相位，

为当

取最大时对应

的值，

为码相位为

对应的非相干累加 结果，

为伪码相位搜索间隔，

为伪码相位搜索单元数。 in,

is the first pseudocode phase capture result,

is the code phase,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the pseudocode phase search interval,

Number of cells to search for pseudo code phase.

In one of the embodiments, it is also used to obtain the carrier Doppler estimation accuracy according to the time interval and the pseudo-code phase search interval as:

为载波多普勒的估计精度，

为伪码相位搜索间隔，

为信号射频 频率与伪码速率的比值；调整时间间隔和伪码相位搜索间隔以调整载波多普勒的捕获精 度。 in,

is the estimation accuracy of carrier Doppler,

is the pseudocode phase search interval,

is the ratio of signal RF frequency to pseudo-code rate; adjust the time interval and pseudo-code phase search interval to adjust the acquisition accuracy of carrier Doppler.

For the specific limitations of the two-stage fast signal acquisition device for Doppler-based time-division navigation signals, please refer to the above-mentioned definition of the two-stage fast signal acquisition method for Doppler-based time-division navigation signals, which will not be repeated here. Each module in the above-mentioned two-stage fast signal acquisition device for time-division navigation signals under Doppler can be fully or partially realized by software, hardware and combinations thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, and can also be stored in the memory of the computer device in the form of software, so that the processor can invoke and execute the corresponding operations of the above-mentioned modules.

In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure may be as shown in FIG. 5 . The computer device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. Wherein, the processor of the computer device is used to provide calculation and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a two-stage fast signal acquisition method for time-division navigation signals under Doppler is realized. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a button, a trackball or a touch pad provided on the casing of the computer device , and can also be an external keyboard, touchpad, or mouse.

Those skilled in the art can understand that the structure shown in Figure 5 is only a block diagram of a part of the structure related to the solution of this application, and does not constitute a limitation to the computer equipment on which the solution of this application is applied. The specific computer equipment can be More or fewer components than shown in the figures may be included, or some components may be combined, or have a different arrangement of components.

In one embodiment, a computer device is provided, including a memory and a processor, the memory stores a computer program, and the processor implements the steps of the methods in the above embodiments when executing the computer program.

In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the methods in the above-mentioned embodiments are implemented.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the computer programs can be stored in a non-volatile computer-readable memory In the medium, when the computer program is executed, it may include the processes of the embodiments of the above-mentioned methods. Wherein, any references to memory, storage, database or other media used in the various embodiments provided in the present application may include non-volatile and/or volatile memory. Nonvolatile memory can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Chain Synchlink DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

The technical features of the above embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

The above-mentioned embodiments only represent several implementation modes of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the scope of the patent for the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims (10)

1. a kind of two-stage fast signal acquisition method of time-division navigation signal under Doppler, it is characterized in that, described method comprises: Obtaining the digital baseband signal received by the navigation receiver, sampling the digital baseband signal to obtain a first sampling signal; the digital baseband signal includes a time-division spread spectrum signal with a large Doppler frequency deviation; Traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, obtaining a pseudo code phase capture result within the first code phase search range, according to the pseudo code phase capture The maximum value of the result obtains the first pseudocode phase capture result; At the initial sampling point of the first sampling signal, after waiting for a preset time interval, the digital baseband signal is sampled to obtain a second sampling signal, according to the pre-estimated maximum Doppler corresponding to the digital baseband signal Le calculation obtains the second code phase search range; Traversing the second code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the second sampling signal, to obtain a corresponding second pseudo code phase capture result; Carrier Doppler is obtained according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result. 2. method according to claim 1, is characterized in that, the mathematical model of described digital baseband signal is:

in,

It is the digital baseband signal received by the navigation receiving equipment,

is the amplitude of the carrier wave,

is the satellite navigation message,

is the sampling point,

is the signal propagation delay,

is the carrier Doppler of the signal, w ( k ) is the baseband noise,

is the spreading code in the navigation signal,

is a time-division pulse signal,

is the imaginary unit symbol,

is the initial phase of the RF carrier. 3. The method according to claim 1, characterized in that traversing the preset first code phase search range, performing code phase capture on the time-division pulse sequence corresponding to the first sampling signal, to obtain the first code phase Pseudo-code phase capture results within the search range include: performing non-coherent accumulation on a plurality of coherent integration results after coherent integration of each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase to obtain a non-coherent accumulation result corresponding to the current code phase; The current code phase is within the preset first code phase search range; Traverse the first code phase search range to obtain the non-coherent accumulation result corresponding to each code phase in the first code phase search range, and obtain the first code phase according to the size relationship between each of the non-coherent accumulation results and the decision threshold Pseudo-code phase capture results within the search range. 4. method according to claim 3, it is characterized in that, according to the size relation of each described incoherent accumulation result and decision threshold, obtain the step of the pseudo-code phase capture result in the first code phase search range, comprising: When the non-coherent accumulation result is greater than the decision threshold, the code phase acquisition is successful, and the acquisition result is obtained according to the code phase corresponding to the current local spreading code; When the non-coherent accumulation result is less than or equal to the decision threshold, the code phase acquisition fails, slide the preset pseudo-code phase search interval backward in the first code phase search range, and calculate the non-coherent code phase corresponding to the code phase after sliding Accumulate results, and iterate the above process until each code phase in the first code phase search range is searched, stop the iteration, and output the capture result in the first code phase search range. 5. The method according to claim 3, characterized in that, performing a plurality of coherent integration results after performing coherent integration on each time-division pulse of the first sampling signal and the local spread spectrum code corresponding to the current code phase Non-coherent accumulation, the non-coherent accumulation results corresponding to the current code phase include: After coherently integrating each time-division pulse of the first sampling signal and the local spreading code corresponding to the current code phase, a plurality of coherent integration results are non-coherently accumulated, and the non-coherent accumulation result corresponding to the current code phase is obtained as follows:

in,

is the code phase of

The corresponding non-coherent accumulation result,

is the phase of the baseband digital signal,

is the baseband complex signal,

for the first

The starting sampling point position of a pulse signal,

The phase for local replication is

The spreading code,

is the short-term correlation length,

is the number of pulses corresponding to the first sampling signal. 6. The method according to claim 1, wherein the second code phase search range obtained according to the maximum Doppler calculation corresponding to the pre-estimated digital baseband signal comprises: According to the maximum Doppler calculation corresponding to the pre-estimated digital baseband signal, the second code phase search range is:

in,

is the second code phase search range,

is the maximum Doppler corresponding to the pre-estimated digital baseband signal,

,

is the RF frequency of the signal,

is the pseudocode rate,

Indicates an upward rounding operation,

is the time interval,

Search interval for pseudo code phase. 7. The method according to claim 1, wherein, according to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result, obtaining carrier Doppler comprises: According to the first pseudo-code phase acquisition result and the second pseudo-code phase acquisition result, the carrier Doppler is obtained as:

in,

is the carrier Doppler,

is the ratio of the signal RF frequency to the pseudocode rate,

is the second pseudo-code phase capture result,

is the first pseudocode phase capture result,

for the time interval. 8. according to the method described in any one of claim 1 or 7, it is characterized in that, described second pseudo-code phase acquisition result is:

in,

is the second pseudo-code phase capture result,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the first pseudocode phase capture result,

is the second code phase search range,

Search interval for pseudo code phase. 9. according to the method described in any one of claim 1 or 7, it is characterized in that, described first pseudo-code phase acquisition result is:

in,

is the first pseudocode phase capture result,

is the code phase,

for when

corresponding to the maximum

the value of

is the code phase of

The corresponding non-coherent accumulation result,

is the pseudocode phase search interval,

Number of cells to search for pseudo code phase. 10. The method according to claim 7, further comprising: According to the time interval and the pseudo-code phase search interval, the estimation accuracy of the carrier Doppler is:

in,

is the estimation accuracy of carrier Doppler,

is the pseudocode phase search interval,

is the ratio of signal RF frequency to pseudocode rate; The time interval and the pseudo-code phase search interval are adjusted to adjust the acquisition accuracy of carrier Doppler.

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