Satellite signal acquisition methods and devices

Abstract

This document discloses a method and apparatus for acquiring satellite signals, comprising: searching a search unit using a pre-set acquisition mode, and making a detection decision on the quantity to be detected in the search unit according to a pre-set acquisition threshold and an exclusion threshold; when it is determined that a satellite signal may be acquired in the search unit, continuing to search the search unit using another pre-set acquisition mode, and making a detection decision on the quantity to be detected in the search unit according to a pre-set acquisition threshold and an exclusion threshold; repeating the search and detection decision process for the search unit until it is determined that a satellite has been acquired or no satellite signal has been detected; wherein the integration time and / or number of integrations are different between the acquisition modes. This application can at least improve the accuracy of the acquisition detection decision.

Description

Technical Field

[0001] This invention relates to the field of navigation technology, and more particularly to a method and apparatus for acquiring satellite signals. Background Technology

[0002] Navigation technology has played a vital role in the development of human history, and with continuous social progress, this technology, especially satellite navigation and positioning technology, is becoming increasingly intertwined with people's lives. Currently, the world's major satellite navigation systems include the Global Positioning System (GPS), BD2 (BeiDou-2), GLONASS, and Galileo. Both GPS and BD2 utilize CDMA (Code Division Multiple Access) technology, and their physical layer frame structures share many similarities. Therefore, their receiver designs are similar, both including radio frequency front-end processing, baseband digital signal processing, and positioning and navigation calculations. The baseband digital signal processing typically includes acquisition, tracking, bit synchronization, and frame synchronization.

[0003] The process of satellite navigation receivers acquiring satellite signals includes mixing, correlation, coherent / incoherent integration, and decision-making. The principle of navigation signal acquisition is as follows: Figure 1 As shown, during the acquisition of a satellite signal by the receiver, the digital intermediate frequency (IF) signal is first mixed with a sinusoidal carrier on a receiving in-phase branch and a cosine carrier on a quadrature branch, respectively. The mixing result is then correlated with a copied C / A code. Next, the coherent results from the in-phase and quadrature branches are coherently integrated over a period of time to generate two coherent integration results. Finally, these two coherent integration results are incoherently integrated to obtain the quantity to be detected, which is then sent to the detection decision unit. The detection decision unit performs a detection decision on the calculation result according to its pre-set decision rules. The receiver determines its next action based on the success or failure of this decision. Therefore, the success or failure of signal detection and subsequent processing depend on the decision result of the detection decision unit; thus, the rationality of the design of the detection decision unit directly affects the acquisition performance of the receiver.

[0004] All related detection and decision-making technologies suffer from low accuracy in capture, detection, and decision-making, especially for satellite signals with changing signal strength. Summary of the Invention

[0005] This invention provides a method and apparatus for acquiring satellite signals, which can at least improve the accuracy of acquisition detection and decision-making.

[0006] This application provides the following technical solution.

[0007] A method for acquiring satellite signals, comprising:

[0008] The search unit is searched using a pre-set capture mode, and the detection decision of the quantity to be detected in the search unit is made according to the pre-set capture threshold and expulsion threshold.

[0009] When it is determined that a satellite signal may be captured in the search unit, another pre-set capture mode is used to continue searching the search unit, and the detection quantity of the search unit is detected and determined according to the pre-set capture threshold and expulsion threshold.

[0010] The search and detection decision are repeatedly performed on the search unit until the decision is made that a satellite has been captured or no satellite signal is detected on the search unit; wherein the integration time and / or number of integrations are different between the capture modes.

[0011] The capture modes include: fast scan mode and high sensitivity mode; wherein the integration time and / or number of integrations in the fast scan mode are less than those in the high sensitivity mode.

[0012] The step of detecting and deciding the quantity to be detected by the search unit according to the preset capture threshold and expulsion threshold includes: firstly, detecting and deciding the quantity to be detected by the search unit according to the capture threshold, and then detecting and deciding the quantity to be detected by the search unit according to the result of the decision and the expulsion threshold.

[0013] The step of detecting and deciding the quantity to be detected by the search unit based on a pre-set capture threshold and an expulsion threshold includes:

[0014] The quantity to be detected by the incoherent integration of the search unit is compared with the capture threshold and the expulsion threshold, respectively.

[0015] If the quantity to be detected is not less than the acquisition threshold, it is determined that a satellite signal has been acquired in the current search unit;

[0016] If the quantity to be detected is less than the expulsion threshold, it is determined that no satellite signal was detected in the current search unit;

[0017] If the quantity to be detected is less than the capture threshold but not less than the expulsion threshold, it is determined that a satellite signal may have been captured in the search unit.

[0018] The step of detecting and deciding the quantity to be detected by the search unit according to the preset capture threshold and expulsion threshold includes: first comparing the quantity to be detected by the incoherent integration of the search unit with the capture threshold; and when the quantity to be detected is less than the capture threshold, comparing the quantity to be detected with the expulsion threshold.

[0019] A satellite signal acquisition device includes: a search processing unit and a detection decision unit; wherein the search processing unit is configured to search for a search unit using a preset acquisition mode; and to continue searching for the search unit using another preset acquisition mode after receiving a notification from the detection decision unit; the detection decision unit is configured to perform a detection decision on the quantity to be detected in the search unit according to preset acquisition thresholds and exclusion thresholds; to notify the search processing unit when it is determined that a satellite signal may be acquired in the search unit; and to notify the search processing unit to terminate the search of the search unit when it is determined that a satellite has been acquired or no satellite signal has been detected in the search unit; wherein the integration time and / or number of integrations are different between the acquisition modes.

[0020] The capture modes include: fast scan mode and high sensitivity mode; wherein the integration time and / or number of integrations in the fast scan mode are less than those in the high sensitivity mode.

[0021] The detection and decision unit includes:

[0022] The first decision-maker is used to make a detection decision on the quantity to be detected by the search unit according to the capture threshold;

[0023] The second decision-maker is used to make a detection decision on the quantity to be detected by the search unit based on the decision result of the first decision-maker and the expulsion threshold.

[0024] Specifically, the first decision unit is used to compare the quantity to be detected by the incoherent integration of the search unit with the acquisition threshold; when the quantity to be detected is not less than the acquisition threshold, it is determined that a satellite signal has been acquired in the current search unit; when the quantity to be detected is less than the acquisition threshold, the quantity to be detected is sent to the second decision unit; the second decision unit is used to compare the quantity to be detected by the incoherent integration of the search unit with the expulsion threshold; when the quantity to be detected is less than the expulsion threshold, it is determined that no satellite signal has been detected in the current search unit; when the quantity to be detected is not less than the expulsion threshold, it is determined that a satellite signal may have been acquired in the search unit, and the search processing unit is notified.

[0025] A navigation receiver includes a means for acquiring the aforementioned satellite signals.

[0026] The advantages of this application include at least the following:

[0027] In this embodiment of the invention, satellite signal acquisition is achieved by combining two thresholds (i.e., acquisition threshold and expulsion threshold) with two acquisition modes. This not only improves the accuracy of acquisition detection decision and thus enhances the accuracy of acquisition verification, but also adapts to satellite signals with varying signal strength, avoiding missed detections or false alarms.

[0028] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0029] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0030] Figure 1 This is a schematic diagram illustrating the principle of navigation signal acquisition.

[0031] Figure 2 This is a schematic diagram of the satellite signal acquisition method in Example 1;

[0032] Figure 3 This is an exemplary flowchart of satellite signal acquisition in Embodiment 1;

[0033] Figure 4 This is a flowchart illustrating the satellite signal acquisition process in a specific example of Embodiment 1;

[0034] Figure 5 This is a schematic diagram of the satellite signal acquisition device in Example 2. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0036] The steps illustrated in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases the steps shown or described may be performed in a different order than that presented here.

[0037] Among related technologies, detection and decision-making technologies mainly fall into the following three categories:

[0038] 1. Compare the maximum noncoherent integral amplitude with the threshold value. Specifically, if the maximum value of the noncoherent integral amplitude is less than the acquisition threshold, the detection decision unit determines that the signal has not yet been found. Therefore, the receiver adjusts the carrier digitally controlled oscillator and the C / A code digitally controlled oscillator according to the predetermined search step size and continues to search for and detect the signal in the next search unit; otherwise, as long as the maximum value of the noncoherent integral amplitude is not less than the acquisition threshold, the detection decision unit determines that the signal has been found.

[0039] The performance of this detection and decision method is highly dependent on the threshold setting. If the threshold is too low or too high, there will be a large probability of false alarms or missed detections, resulting in low accuracy of the detection and decision. In addition, this method cannot detect satellites whose signal strength changes from weak to strong, and is not suitable for detecting and deciding satellite signals whose signal strength is changing.

[0040] 2. The ratio of the maximum incoherent integral amplitude to the second largest incoherent integral amplitude is compared with a threshold value. Specifically, the maximum value of the incoherent integral amplitude is first identified, along with the second largest incoherent integral amplitude after removing the code phase containing the maximum value and the half code phases to its left and right. The detection decision unit compares the ratio of the maximum to the second largest incoherent integral amplitude to a preset threshold. If the ratio is less than the threshold, the detection decision unit determines that the signal has not yet been found, and the receiver adjusts the carrier digitally controlled oscillator and the C / A code digitally controlled oscillator according to a predetermined search step size to continue signal search and detection in the next search unit. Otherwise, if the ratio is not less than the threshold, the detection decision unit determines that the signal has been found, and the receiver typically proceeds to further confirm the successful signal acquisition.

[0041] The threshold value of the ratio in this detection and decision method is relatively difficult to determine, which may result in a high false alarm rate or false alarm probability, thus leading to low accuracy of the detection and decision.

[0042] 3. Dual-threshold method.

[0043] Specifically, first, two threshold values ​​are set, one high and one low, let's say threshold 1 and threshold 2. Three peak values ​​of the incoherent integral amplitude are identified, and the code phase, Doppler shift, and amplitude-to-noise ratio for each peak are given and sent to the detection decision unit. If the amplitude of the largest peak is not less than threshold 1, the search ends early, and the corresponding satellite is directly switched to the tracking phase. If the amplitude of the largest peak is less than threshold 2, the search ends, and it is determined that no satellite signal was detected in this acquisition. If the amplitude of the largest peak is less than threshold 1 but not less than threshold 2, a consistency check is initiated. The consistency check examines the code phase and Doppler shift of the three peaks; both must be consistent for a satellite to be considered correctly acquired, and then tracking begins; otherwise, the search is considered a failure. Code phase consistency is defined as: the code phase difference between the peaks obtained in the acquisition and verification phases is sufficiently small, approximately within two chip ranges; Doppler shift consistency refers to the Doppler shift difference between the peaks obtained in the acquisition and verification phases being sufficiently small.

[0044] This detection and decision method cannot guarantee the reasonableness of the three peak values. Theoretically, the three peak values ​​should be on the same frequency point, and the code phase interval should not exceed one chip. Therefore, there is a high probability of false alarms.

[0045] As can be seen from the above, the accuracy of acquisition detection and decision-making in related technologies is not high, especially for satellite signals with changing signal strength. To address this technical problem, this application proposes the following technical solution, which can improve the accuracy of acquisition detection and decision-making, thereby improving the accuracy of acquisition verification, and can also adapt to satellite signals with changing signal strength.

[0046] The implementation method of the technical solution of this application will be described in detail below.

[0047] Example 1

[0048] like Figure 2 As shown, this embodiment provides a method for acquiring satellite signals, which may include:

[0049] Step 201: Search for the search unit using a preset capture mode, and detect and decide the incoherent integral amplitude of the search unit according to the preset capture threshold and dismissal threshold.

[0050] Step 202: When it is determined that a satellite signal may be captured in the search unit, the search unit is continued to be searched using another preset capture mode, and the incoherent integral amplitude of the search unit is detected and determined according to the preset capture threshold and dismissal threshold.

[0051] The search and detection decisions in steps 201 and 202 are repeated on the search unit until a satellite is captured or no satellite signal is detected on the search unit; wherein the integration time and / or number of integrations are different between the capture modes.

[0052] In this embodiment, satellite signal acquisition is achieved by combining two thresholds (i.e., acquisition threshold and expulsion threshold) with two acquisition modes. This not only improves the accuracy of acquisition detection decision and thus enhances the accuracy of acquisition verification, but also adapts to satellite signals with varying signal strength, avoiding missed detections or false alarms.

[0053] In this embodiment, the capture threshold V H This refers to the lower limit of the amplitude at which a successful capture can be determined; that is, at least this threshold must be reached to determine that the capture in this round is successful. The threshold V is the exclusion threshold. L This refers to the upper limit of the amplitude at which the current capture can be determined to have failed. In other words, as long as the amplitude is less than this threshold, the capture in this round on the current search unit can be determined to have failed.

[0054] In this embodiment, the quantity to be detected can be the amplitude or energy value of the signal obtained when integration ends after searching the current search unit. The energy value can be expressed as the square of the signal amplitude. In one implementation, the detected value can be the peak value of the maximum amplitude of the incoherent integral obtained when integration ends after searching the current search unit.

[0055] In one implementation of this embodiment, the scanning mode may include a fast scanning mode and a high-sensitivity mode; wherein the integration time and / or number of integrations in the fast scanning mode are less than those in the high-sensitivity mode. Specifically, the fast scanning mode can be used first for searching. If it is determined that a satellite signal may be captured in the search unit, the high-sensitivity mode is then used to search the current search unit. If it is determined that a satellite signal may be captured in the search unit, the fast scanning mode is used again to search the current search unit. This process is repeated until it is determined that a satellite signal has been captured in the current search unit, or no satellite signal has been detected in the current search unit, or the number of searches reaches a preset value (for example, the number of searches is controlled by a counter, and the search of the current search unit stops when the number of searches reaches the maximum value of the counter; this method avoids infinite loops). Thus, by combining the fast scanning and high-sensitivity scanning modes, not only can the search efficiency be improved, but the accuracy of the capture and detection decision can also be improved, which is particularly suitable for capturing satellite signals with changing signal strength.

[0056] In one implementation of this embodiment, the detection decision of the target quantity of the search unit can be performed first based on the acquisition threshold, and then the detection decision of the target quantity of the search unit can be performed based on the decision result and the expulsion threshold. In this way, by first determining the satellite signals that the current search unit can capture through the acquisition threshold, and then making further detection decisions for the satellite signals that may be captured, the processing efficiency of the acquisition detection decision can be improved.

[0057] In one implementation of this embodiment, the quantity to be detected by the incoherent integration of the search unit can be compared with the acquisition threshold and the exclusion threshold respectively. If the quantity to be detected is not less than the acquisition threshold, it is determined that a satellite signal has been acquired in the current search unit; if the quantity to be detected is less than the exclusion threshold, it is determined that no satellite signal has been detected in the current search unit; if the quantity to be detected is less than the acquisition threshold but not less than the exclusion threshold, it is determined that a satellite signal may have been acquired in the search unit. Specifically, the quantity to be detected by the incoherent integration of the search unit can be compared with the acquisition threshold first; if the quantity to be detected is less than the acquisition threshold, it can then be compared with the exclusion threshold to improve the processing efficiency of the detection decision. Of course, this application can also be implemented in other ways. For example, the quantity to be detected by the incoherent integration of the search unit can be compared with the acquisition threshold and the exclusion threshold simultaneously, or it can be compared with the exclusion threshold first, and then compared with the acquisition threshold based on the result of this comparison. The specific implementation method of the processing procedure is not limited in this document.

[0058] In one exemplary processing method of this embodiment, two acquisition modes are divided. The first mode is Fast-Scan (FS) mode, which uses a shorter integration time or fewer integration iterations during acquisition to quickly scan the satellite signal. The second mode is High-Sensitivity (HS) mode, which uses a longer integration time or more integration iterations during acquisition to complete a high-precision scan of the satellite signal, improving acquisition sensitivity. Additionally, two threshold values ​​are set, one high and one low, assuming they are the acquisition threshold and the rejection threshold, respectively. Two decision units are set: Decision Unit 1 and Decision Unit 2, each corresponding to an acquisition threshold V. H (High threshold) and an expulsion threshold V L .

[0059] like Figure 3 The diagram illustrates the specific process of the above exemplary processing method, which may include:

[0060] Step 301: When the satellite navigation receiver acquires the signal of a certain satellite, it first uses the FS mode to perform a fast search. When making a detection decision for the quantity to be detected in a certain search unit, it first enters the decision unit 1.

[0061] Step 302, the decision maker 1 compares the quantity to be detected in the search unit with the capture threshold V. H Make a judgment. If the judgment result of the decision-maker 1 is success, continue to step 303; if the judgment result of the decision-maker 1 is failure, proceed to decision-maker 2 and jump to step 304.

[0062] Step 303: When the decision result of the decision device 1 is successful, the decision is made that a satellite signal has been captured on the current search unit, the search ends, and the corresponding satellite is directly switched to the tracking stage.

[0063] Step 304: After entering decision unit 2, decision unit 2 compares the quantity to be detected in the search unit with the expulsion threshold V. L Make a judgment. If the judgment result of the decision device 2 is failure, continue to step 305; if the judgment result of the decision device 2 is success, it means that there is a high probability that a satellite signal can be captured in the current search unit, then enter HS mode and jump to step 306.

[0064] Step 305: If the decision result of the decision device 2 is failure, it is determined that no satellite signal was detected in the current search unit during this capture.

[0065] Step 306: Continue searching the current search unit in HS mode, that is, perform a fine-grained search on the current search unit to further confirm whether the current satellite signal exists.

[0066] Once the HS mode is entered, a high-sensitivity search is performed on the current search unit. Specifically, this involves adding a longer coherent integration time and more incoherent integration iterations to the current search unit. After integration is complete, when making a detection decision for the quantity to be detected in a certain search unit, the system still first enters the decision unit 1.

[0067] Step 307, Decision Maker 1 compares the quantity to be detected in the search unit with the capture threshold V. H The process proceeds to a decision. If decision 1 determines success, the process returns to step 303, indicating that a satellite has been acquired on the current search unit, the search ends prematurely, and the corresponding satellite is directly switched to the tracking phase. If decision 1 determines failure, the process proceeds to decision 2 and jumps to step 308.

[0068] Step 308: After entering decision unit 2, decision unit 2 compares the quantity to be detected in the search unit with the expulsion threshold V. LThe process proceeds to a decision. If the decision by decision 2 is a failure, the process returns to step 305, indicating that no satellite signal was detected in the current search unit. If the decision by decision 2 is a success, it means that a satellite signal was very likely to be captured in the current search unit. In this case, the process re-enters FS mode, i.e., returns to step 301, and continues to perform a fast search on the current search unit.

[0069] As satellite signal strength changes over time, the above process involves repeatedly searching the current search unit by switching acquisition modes until a satellite is detected or no satellite signal is detected, at which point the search for the current search unit ends. Furthermore, the search for the current search unit can be stopped when the number of searches reaches a preset value, thus avoiding infinite loops. For example, a counter can be used to control the number of searches for a search unit; when the number of searches for a search unit reaches the maximum value of the counter, the search for that search unit stops.

[0070] The specific implementation process of this embodiment will be explained in detail below with examples.

[0071] Example

[0072] like Figure 4 As shown, the exemplary procedure for satellite signal acquisition in this example may include:

[0073] Step 401: When the satellite navigation receiver acquires the signal of a certain satellite, it first uses FS mode for fast search.

[0074] Step 402: When detecting and deciding the incoherent integral amplitude of a certain search unit, first compare the amplitude V of the maximum peak value with the threshold V. H The relationship. If the amplitude V of the maximum peak is not less than the threshold V. H Then continue to step 403. If the amplitude V of the maximum peak value is less than the threshold V H Then proceed to step 404;

[0075] Step 403: If a satellite is detected in the current search unit, the search ends prematurely, and the corresponding satellite is directly switched to the tracking phase.

[0076] Step 404: Further compare the amplitude V of the maximum peak value with the threshold V. L The relationship is that if the amplitude V of the maximum peak is less than the threshold V L Then proceed to step 405. If the amplitude V of the maximum peak value is not less than the threshold V... L If so, it means that a satellite signal is very likely to be captured in the current search unit, and proceed to step 406;

[0077] Step 405: Determine that no satellite signal was detected in the current search unit during this capture, and the search ends.

[0078] Step 407: Enter HS mode, which is to perform a fine-grained search on the current search unit to further confirm the existence of the current satellite signal.

[0079] In this step, after entering HS mode, a high-sensitivity search is performed on the current search unit. Specifically, a longer coherent integration time and more incoherent integration times are added to the current search unit. After integration is completed, step 408 is entered.

[0080] Step 408: Detect and decide the incoherent integral amplitude of a certain search unit by first comparing the amplitude V of the maximum peak value with the threshold V. H The relationship. If the amplitude V of the maximum peak is not less than the threshold V. H Then return to step 403; if the amplitude V of the maximum peak value is less than the threshold V H Then proceed to step 409;

[0081] Step 409: Further compare the amplitude V of the maximum peak value with the threshold V. L The relationship. If the amplitude V of the maximum peak is less than V... L If no satellite signal is detected in the current search unit, then it is determined that no satellite signal was detected during this acquisition. If the amplitude V of the maximum peak value is not less than the threshold V... L If the signal is positive, it means that a satellite signal is very likely to be captured in the current search unit. Then, the system will re-enter FS mode, that is, return to step 401 and continue to perform a fast search on the current search unit.

[0082] Because the strength of satellite signals changes over time, the process in this example repeatedly searches the current search unit until it is determined that a satellite has been captured or that no satellite signal was detected during the capture, at which point the search for the current search unit ends.

[0083] In practical applications, the method described in this embodiment can be applied to satellite navigation receivers, specifically through a baseband digital signal processing module.

[0084] Example 2

[0085] like Figure 5 As shown, this application also provides a satellite signal acquisition device, including: a search processing unit 51 and a detection and decision unit 52; wherein,

[0086] The search processing unit 51 can be used to search for the search unit using a preset capture mode; and, after receiving a notification from the detection decision unit, to continue searching for the search unit using another preset capture mode.

[0087] The detection and decision unit 52 can be used to make a detection decision on the quantity to be detected by the search unit according to the preset capture threshold and expulsion threshold; when it is determined that the search unit may capture a satellite signal, it notifies the search processing unit 51; when it is determined that a satellite has been captured or no satellite signal has been detected on the search unit, it notifies the search processing unit to end the search of the search unit.

[0088] The integration time and / or number of integrations differ among the capture modes.

[0089] In one implementation of this embodiment, the scanning mode may include a fast scanning mode and a high-sensitivity mode; wherein the integration time and / or number of integrations in the fast scanning mode are less than those in the high-sensitivity mode. In a specific implementation, the search processing unit 51 may first use the fast scanning mode to search, and then use the high-sensitivity mode to search the current search unit when the detection decision unit 52 determines that a satellite signal may be captured in the search unit. When the detection decision unit 52 determines that a satellite signal may be captured in the search unit, the fast scanning mode is used again to search the current search unit, and this process is repeated until the detection decision unit 52 determines that a satellite signal has been captured in the current search unit or that no satellite signal has been detected in the current search unit. Thus, by combining the fast scanning and high-precision scanning modes, not only can the search efficiency be improved, but the accuracy of the capture detection decision can also be improved, which is particularly suitable for capturing satellite signals with changing signal strength.

[0090] In one implementation of this embodiment, the detection decision unit 52 may include: a first decision unit 521, used to make a detection decision on the quantity to be detected in the search unit according to the capture threshold; and a second decision unit 522, used to make a detection decision on the quantity to be detected in the search unit according to the decision result of the first decision unit and the expulsion threshold. That is, these two decision units correspond to a capture threshold (high threshold) and an expulsion threshold (low threshold), respectively. Here, the quantity to be detected may be the amplitude or energy value of the signal obtained after the integration ends following the search of the current search unit, and the energy value may be expressed as the square of the signal amplitude. In one implementation, the detection value may be the peak value of the maximum amplitude of the non-coherent integral obtained after the integration ends following the search of the current search unit. Correspondingly, the decision unit here may be an amplitude comparator, an energy value comparator, etc.

[0091] Specifically, the first decision unit 521 can be used to compare the quantity to be detected by the incoherent integration of the search unit with the acquisition threshold; if the quantity to be detected is not less than the acquisition threshold, it is determined that a satellite signal has been acquired in the current search unit; if the quantity to be detected is less than the acquisition threshold, the quantity to be detected is sent to the second decision unit; the second decision unit 522 can be used to compare the quantity to be detected by the incoherent integration of the search unit with the expulsion threshold, and if the quantity to be detected is less than the expulsion threshold, it is determined that no satellite signal has been detected in the current search unit, and if the quantity to be detected is not less than the expulsion threshold, it is determined that a satellite signal may have been acquired in the search unit, and the search processing unit is notified.

[0092] In practical applications, the satellite signal acquisition device in this embodiment can be implemented through a navigation receiver or integrated within the navigation receiver. In one implementation, the acquisition device can be implemented through the baseband digital signal processing module of the navigation receiver. The search processing unit 51 and the detection decision unit 52 can be software, hardware, or a combination of both. In another implementation, the search processing unit 51 may include… Figure 1 The mixer 1, mixer 2, correlator 1, correlator 2, C / A code generator, and carrier digitally controlled oscillator are included. The detection and decision unit 52 may include... Figure 1 The detection and decision-making device in the middle.

[0093] Other technical details of this embodiment can be found in Embodiment 1.

[0094] Example 3

[0095] This application also provides a navigation receiver, which includes the aforementioned satellite signal acquisition device. Specific technical details can be found in Embodiments 1 and 2.

[0096] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes to the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for acquiring satellite signals, comprising: The search unit is searched using a fast scan mode, and the quantity to be detected in the search unit is determined according to the preset capture threshold and expulsion threshold. Whenever it is determined that a satellite signal may be captured in the search unit, the search unit is searched again using another preset capture mode, and the detection quantity of the search unit is detected again according to the preset capture threshold and expulsion threshold. The search and detection decision are repeatedly performed on the search unit until the decision is made that a satellite has been captured or no satellite signal is detected on the search unit; the capture mode includes: fast scan mode and high sensitivity mode; wherein the integration time and / or number of integrations in the fast scan mode is less than that in the high sensitivity mode.

2. The capture method according to claim 1, characterized in that, The step of detecting and deciding the quantity to be detected by the search unit based on a pre-set capture threshold and a rejection threshold includes: First, the detection decision of the quantity to be detected by the search unit is made according to the capture threshold, and then the detection decision of the quantity to be detected by the search unit is made according to the result of the decision and the expulsion threshold.

3. The capture method according to claim 1 or 2, characterized in that, The step of making a detection decision on the quantity to be detected by the search unit based on a preset capture threshold and a rejection threshold includes: The quantity to be detected by the incoherent integration of the search unit is compared with the capture threshold and the expulsion threshold, respectively. If the quantity to be detected is not less than the acquisition threshold, it is determined that a satellite signal has been acquired in the current search unit; If the quantity to be detected is less than the expulsion threshold, it is determined that no satellite signal was detected in the current search unit; If the quantity to be detected is less than the capture threshold but not less than the expulsion threshold, it is determined that a satellite signal may have been captured in the search unit.

4. The capture method according to claim 3, characterized in that, The step of making a detection decision on the quantity to be detected by the search unit based on a preset capture threshold and a rejection threshold includes: First, the quantity to be detected by the incoherent integration of the search unit is compared with the capture threshold; if the quantity to be detected is less than the capture threshold, then the quantity to be detected is compared with the expulsion threshold.

5. A satellite signal acquisition device, characterized in that, include: The search processing unit and the detection decision unit; among them. The search processing unit is configured to search the search unit using a fast scan mode; and to switch to another pre-set capture mode to continue searching the search unit after receiving a notification from the detection decision unit. The detection and decision unit is used to re-detect and decide on the quantity to be detected by the search unit according to the preset capture threshold and expulsion threshold; whenever it is determined that the search unit may capture a satellite signal, it notifies the search processing unit; when it is determined that a satellite has been captured or no satellite signal is detected on the search unit, it notifies the search processing unit to end the search of the search unit. The capture modes include: fast scan mode and high sensitivity mode; wherein the integration time and / or number of integrations in the fast scan mode are less than those in the high sensitivity mode.

6. The capturing device according to claim 5, characterized in that, The detection decision unit includes: The first decision-maker is used to make a detection decision on the quantity to be detected by the search unit according to the capture threshold; The second decision-maker is used to make a detection decision on the quantity to be detected by the search unit based on the decision result of the first decision-maker and the expulsion threshold.

7. The capturing device according to claim 6, characterized in that, The first decision unit is specifically used to compare the quantity to be detected by the incoherent integration of the search unit with the acquisition threshold; when the quantity to be detected is not less than the acquisition threshold, it is determined that a satellite signal has been acquired in the current search unit; when the quantity to be detected is less than the acquisition threshold, the quantity to be detected is sent to the second decision unit. The second decision unit is specifically used to compare the quantity to be detected by the incoherent integration of the search unit with the expulsion threshold. When the quantity to be detected is less than the expulsion threshold, it is determined that no satellite signal has been detected in the current search unit. When the quantity to be detected is not less than the expulsion threshold, it is determined that a satellite signal may have been captured in the search unit, and the search processing unit is notified.

8. A navigation receiver, characterized in that, The navigation receiver includes a satellite signal acquisition device as described in any one of claims 5 to 7.

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