CN104407361A - Satellite searching method and receiver - Google Patents

Abstract

The application discloses a satellite searching method and a receiver. In the satellite searching method, satellites are searched according to the weighted average visibility of the satellites relative to a time and space grid set, wherein the weight of the weighted average visibility is confirmed according to time and space position information. With application of the satellite searching method and the receiver disclosed by the application, searching sequence of the satellites can be confirmed according to the weighted visibility of the satellites so that capture hit rate is enhanced and thus satellite searching efficiency is further enhanced.

Description

Satellite search method and receiver

technical field

The application relates to the field of satellite navigation and positioning, in particular to a satellite search method and a receiver. the

Background technique

With the development of satellite positioning and navigation technology, the requirements for the search speed and search efficiency of the receiver are getting higher and higher. In particular, the current rapid development of various global navigation satellite systems (for example, the GPS global positioning system of the United States, the Beidou system of China, the Galileo system of Europe, the global navigation satellite system of Russia, etc.), requires the receiver to be able to utilize the expanded joint Constellation to improve positioning accuracy and availability. However, the expanded joint constellation also means that the complexity of the receiver's search for satellite signals increases, which limits the positioning speed of the receiver. the

In order to improve the positioning speed, Kun-Tso Chen proposed a dynamic satellite search algorithm. According to the results of each satellite search by the receiver, the algorithm uses the space-time subset to calculate the average visibility of the satellites, and dynamically adjusts the order of the next search satellites. Only using the average visibility of satellites to adjust the search sequence of satellites cannot meet the requirements of receiver search efficiency. For example, Chen's algorithm wastes prior information. In addition, Chen's algorithm does not have the ability to resist occlusion. When the receiver fails to capture satellites due to ground obstacles, it will lead to "chain errors" and cause the performance of the algorithm to deteriorate. the

Contents of the invention

The purpose of this application is to provide a satellite search method and receiver, which can determine the order of satellite search and improve the efficiency of satellite search. the

According to one aspect of the present application, a satellite search method is disclosed. In the method, the satellite is searched according to the weighted average visibility of the satellite relative to the set of space-time grids, wherein the weight of the weighted average visibility is determined according to the space-time position information. the

According to another aspect of the present application, a receiver is disclosed. The receiver includes: a processor that determines a weighted value for calculating the weighted average visibility of a satellite relative to a set of space-time grids according to the space-time position information, and according to the The weighted value determines the weighted average visibility; and a satellite searcher searches for satellites according to the determined weighted average visibility. the

Through the satellite search method and receiver disclosed in the present application, the satellite search order can be determined according to the weighted visibility of the satellites, which improves the hit rate of capture, thereby further improving the efficiency of satellite search. the

Description of drawings

Fig. 1 shows a flowchart of a satellite search method according to an embodiment of the present application. the

Fig. 2 shows a schematic diagram of a receiver according to an embodiment of the present application. the

Fig. 3 shows a schematic diagram of a receiver according to another embodiment of the present application. the

Fig. 4 shows a flowchart of a satellite search method in a specific application scenario according to the present application. the

Detailed ways

The satellite search method disclosed in the present application will be described in detail below with reference to the accompanying drawings. For the sake of brevity, in the descriptions of the embodiments of the present application, the same or similar devices use the same or similar reference numerals. the

Fig. 1 shows a flowchart of a satellite search method according to an embodiment of the present application. As shown in the figure, in step 110, according to the space-time position information, determine the weight for calculating the weighted average visibility of the satellite relative to the space-time grid set; in step 120, determine the weighted average visibility according to the determined weight; In step 130, satellites are searched based on the determined weighted average visibility. In this way, the search sequence or search priority for searching satellites can be determined according to the weighted average visibility. the

In one embodiment, the spatio-temporal location information may be the possibility that the receiver is located in a certain spatio-temporal cell in the set of spatio-temporal cells, that is, the confidence level that the receiver is located in the spatio-temporal cell. the

In this way, the space-time position information, such as the confidence of the receiver in the space-time grid, is used as a weight to determine the weighted average visibility of satellites, and accordingly determine the search order of satellites, which can improve the hit rate of capture, thereby improving the efficiency of satellite search . the

During a satellite navigation fix, the receiver searches for satellites in the satellite constellation. Usually, before the first positioning, the time and space where the receiver is located are unknown, but their values have a certain range. For example, the spatial extent may be the entire Earth's surface. The time range may be a range near the clock of the receiver, for example, within one hour before and after the clock of the receiver. These time and spaces can be divided into time grids and space grids, and mapped to space-time subsets {G}. Each spatio-temporal cell in the spatio-temporal cell set {G} corresponds to a certain time division and space division. the

Since the operation mode and orbit of each satellite in the satellite group are known, for each satellite among the satellites to be searched by the receiver, it can be determined whether the satellite is visible to a certain space-time grid. For example, the elevation angle of the orbital position to the spatial grid can be calculated according to the orbital position of the satellite and the determined space-time grid, and whether the satellite is visible can be determined according to the elevation value. For example, the visibility of the satellite can be 1 to indicate that the satellite is The space-time grid is visible, and a visibility of 0 means that the satellite is invisible to the space-time grid. By traversing the list of satellites to be searched {S} and the set of space-time grids {G}, the satellite visibility corresponding to the space-time grid can be obtained. For example, it can be recorded as the visibility matrix V, which does not change with the number of searches. the

For a space-time subset, the probability that the receiver is located in any space-time cell in the space-time subset is not the same, which is called the confidence that the receiver is located in each space-time cell in the space-time subset. The possibility that the receiver is in a space-time subset can be represented by a confidence matrix C. When the possibility of the receiver being located in a certain space-time cell is higher, the value of the element in the confidence matrix C corresponding to the space-time cell is larger. The search priority of the satellite to be searched is determined by the confidence of the receiver being located in each space-time grid in the space-time grid and the visibility of the satellite. In this way, the average satellite visibility of satellites visible to grids with high confidence is "raised", and the average visibility of satellites invisible to grids with high confidence is "depressed". Therefore, a reasonable satellite search sequence can be obtained, and the satellite search efficiency can be improved. the

According to an embodiment of the present application, the confidence can be adjusted according to whether the matching relationship between the satellite and the visibility of the satellite is found, and the probability of satellite occlusion, and the satellite relative to the space-time grid can be updated according to the adjusted confidence. The weighted average visibility of , and further search for satellites based on the updated weighted average visibility. the

After the i-th satellite search, the weighted average visibility of satellite s in the set of spatiotemporal grids {G} ^<i> is updated by

${{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Avg</span>}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; where</span>}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&times;</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}$

Among them, {G} ^<i> represents the set of space-time grids after the i-th search, and G _{t, p} is the element in the set of space-time grids, which means that the t-th grid point in the time dimension and the p-th grid point in the space dimension The space-time grid formed by the mapping; {S} ^<i> indicates the set of remaining satellites to be searched after the i-th search; V _{t, p, s} are the elements in the visibility matrix V, and the value is 0 (invisible) or 1 (visible), indicating the visibility of the satellite numbered s to the space-time grid G _t,p ; C ^<i> _t,p is the element of the confidence matrix C ^<i> , indicating that the receiver is located in the space-time grid after the i-th search G _{t, the possibility of p} ; ∑ () represents the summation function, and Avg () represents the averaging function.

After obtaining the weighted average visibility of each satellite in the set of satellites to be searched, the satellite with the highest weighted average visibility can be used as the next satellite to be searched:

${{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}}\mathrm{<span\; class="notranslate">\; max</span>}{{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}$

Where s ^<i+1> _search is the number of the satellite to be searched in the i+1th search, Indicates that s is used as a parameter, so that The s-value with the largest value.

In addition to being affected by satellite visibility, satellite search results may also be affected by the occlusion of the receiver's location. According to the embodiment of the present application, the occlusion probability e of the satellite can be set, and the confidence of the receiver being located in each space-time grid on the space-time subset can be updated according to the search result of the satellite and the occlusion probability e of the satellite. the

The occlusion probability e of the satellite can be set as a fixed value. For example, the possible average occlusion probability can be counted, and the confidence of the space-time grid can be calculated by the average occlusion probability. Alternatively, a fixed occlusion probability can be set according to user experience. The occlusion probability e of the satellite can also be set according to the space-time grid factor. It can be considered that the elevation angle of each satellite relative to each space-time grid is determined. The larger the elevation angle, the smaller the probability of the satellite being blocked for the receiver in the space-time grid; otherwise, the higher the probability of being blocked. Therefore, the occlusion probability can be set for each satellite for each space-time grid in the space-time grid set. The occlusion probability e of the satellite can also be set according to the environmental factors where the receiver is located. For example, the terrain and landform where the receiver is located will affect the probability of satellite occlusion. The occlusion probability in open areas is relatively small; the occlusion probability in urban canyons (such as places with dense high-rise buildings) is relatively high. the

In one embodiment, the method for updating the confidence of the receiver in each space-time grid on the space-time subset according to the search result of the satellite and the occlusion probability e of the satellite includes:

When the i+1th time, the satellite search result s ^<i+1> _search is successful,

$\left\{\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ {{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.$

Among them, e is the probability of satellite occlusion; Indicates the visibility of the satellite numbered s ^<i+1> _search for the space-time grid G _t,p .

In this way, if a satellite is searched, and the visibility of the corresponding space-time grid to the satellite is 1, the confidence corresponding to the space-time grid is multiplied by the probability that the satellite is not blocked; If the visibility of the satellite is 0, then the confidence corresponding to the space-time grid is set to 0. the

When the search result s ^<i+1> _search of the i+1th satellite is a search failure,

$\left\{\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ {{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.$

In this way, if no satellite is found and the visibility of the corresponding space-time grid is 1, the confidence corresponding to the space-time grid is multiplied by the satellite occlusion probability of the satellite; If the visibility of the satellite is 0, the confidence corresponding to the space-time grid remains unchanged. the

According to this embodiment, all space-time cells that do not match the capture result will not be eliminated due to the result of failure to capture a certain satellite signal, but the confidence of these space-time cells will be reduced. Confidence is raised for spatiotemporal bins that match captures. If it is indeed because of occlusion that the capture fails, and the confidence of some space-time grids is reduced, as long as the confidence is not 0, in the next round of search, the grid has a chance to regain a higher confidence. Although occlusion is unpredictable, the consequences of occlusion are correctable. This avoids the "chain error" caused when the receiver fails to acquire satellites due to ground obstacles. the

According to one embodiment, the set of spatio-temporal grids can be updated according to the adjusted confidence, for example, the spatio-temporal grid whose confidence is 0 is deleted from the set of spatio-temporal grids:

{G} ^<i+1> = {G _t,p |G _t,p ∈ {G} ^<i> ,C ^<i> _t,p ≠0},

In this way, the set of space-time grids can be reduced, thereby reducing the amount of computation. the

According to an embodiment of the present application, the searched satellites may be deleted from the set of satellites to be searched. That is, satellites that have already been searched will no longer be searched. In addition, when the number of searched satellites meets the requirements, the satellite search is stopped. the

According to an embodiment of the present application, the initial value of the confidence level is determined according to the priori time and space information of the receiver. For example, the receiver has a certain prior knowledge of its own position and time, for example, the current position of the receiver is likely to be near the last positioning position, thereby improving the prior spatial information. The receiver's clock can also provide a priori time information. the

Fig. 2 shows a schematic diagram of a receiver 200 according to an embodiment of the present application. The receiver 200 receives and processes satellite signals to enable positioning and navigation of the receiver. Generally, the receiver 200 receives radio frequency signals of all visible satellites through the antenna 201 . The radio frequency signal enters the down converter 204 after being amplified by the pre-filter 202 and the pre-amplifier 203 . The down-converter 204 uses the signal mixing frequency synthesized by the frequency synthesizer 205 to down-convert the amplified radio frequency signal to obtain an intermediate frequency signal or a baseband signal. Wherein, the reference clock signal required by the frequency synthesizer 205 to synthesize the signal mixing frequency is provided by the oscillator 206 . The down-converted intermediate frequency signal or baseband signal is converted from an analog signal to a digital signal through the A/D converter 207 . The above process can be regarded as the main function of the radio frequency module 210 of the receiver. The digital signal obtained after the radio frequency signal processing by the radio frequency module 210 generally includes signals of multiple satellites, but it is unknown which satellite signals are included. The receiver according to the present application is able to determine the search order and efficiently search for satellites. the

According to an embodiment of the present application, the receiver 200 includes a processor 220 and a satellite searcher 230 . The processor 220 may determine a weighted value according to the spatio-temporal location information, and determine a weighted average visibility according to the weighted value, so as to determine a search priority. The satellite searcher 230 may search for satellites according to the determined weighted average visibility. the

In one embodiment, the spatio-temporal location information may be the possibility that the receiver is located in a certain spatio-temporal cell in the set of spatio-temporal cells, that is, the confidence level that the receiver is located in the spatio-temporal cell. the

According to an embodiment of the present application, the processor 220 can adjust the confidence level according to whether the matching relationship between the satellite and the visibility of the satellite is found, and the probability of satellite occlusion, and update the relative position of the satellite according to the adjusted confidence level. The weighted average visibility of the space-time grid set, and further search satellites according to the updated weighted average visibility, so as to realize the dynamic search of satellites. the

According to an implementation manner, as shown in FIG. 3 , the processor 220 may include a visibility calculation module 221 . After the i-th satellite search, the visibility calculation module 221 updates the weighted average visibility of the satellite s in the space-time grid set {G} ^<i> in the following way

${{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Avg</span>}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; where</span>}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&times;</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}$

Among them, {G} ^<i> represents the set of space-time grids after the i-th search, and G _{t, p} is the element in the set of space-time grids, which means that the t-th grid point in the time dimension and the p-th grid point in the space dimension The space-time grid formed by the mapping; {S} ^<i> indicates the set of remaining satellites to be searched after the i-th search; V _{t, p, s} are the elements in the visibility matrix V, and the value is 0 (invisible) or 1 (visible), indicating the visibility of the satellite numbered s to the space-time grid G _t,p ; C ^<i> _t,p is the element of the confidence matrix C ^<i> , indicating that the receiver is located in the space-time grid after the i-th search G _{t, the possibility of p} ; ∑ () represents the summation function, and Avg () represents the averaging function.

After obtaining the weighted average visibility of each satellite in the set of satellites to be searched, the satellite searcher 230 can use the satellite with the highest weighted average visibility as the satellite to be searched next time:

${{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}}\mathrm{<span\; class="notranslate">\; max</span>}{{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}$

Where s ^<i+1> _search is the number of the satellite to be searched in the i+1th search, Indicates that s is used as a parameter, so that The s-value with the largest value.

In addition to being affected by satellite visibility, satellite search results may also be affected by the occlusion of the receiver's location. According to an embodiment of the present application, the processor 220 may set the satellite occlusion probability e, and update the confidence that the receiver is located in each space-time grid on the space-time subset according to the satellite search result and the satellite occlusion probability e. the

According to an implementation manner, the processor 220 may use a fixed occlusion probability to calculate the confidence of the space-time grid. The processor 220 may also set the occlusion probability e of the satellite according to the space-time grid factor. According to another implementation manner, the processor 220 may also set the satellite occlusion probability e according to the environmental factors where the receiver is located. the

According to an embodiment, the environmental parameters of the receiver can be obtained through the information collector 240 . The information collector may be an information input unit, and the user directly inputs environmental parameters. The information collector can also be a sensor unit arranged in the receiver, such as a camera, etc., which obtains environmental parameters by sensing the surrounding environment information. The information collector can also be a parameter storage unit, storing default environment parameters. The information collector can also be a communication module that receives environmental parameters published or transmitted by information sources other than the receiver. the

According to an implementation manner of the present application, the processor 220 further includes a confidence adjustment module 222 . The confidence level adjustment module of the processor 220 updates the confidence level according to the search result (acquisition success or acquisition failure), the corresponding visibility (1 or 0) of the satellite in the visibility matrix V, and the occlusion probability e of the satellite. the

When the i+1 satellite search result s ^<i+1> _search is successful,

$\left\{\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ {{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.$

Among them, e is the probability of satellite occlusion; Indicates the visibility of the satellite numbered s ^<i+1> _search for the space-time grid G _t,p .

In this way, if a satellite is searched, and the visibility of the corresponding space-time grid to the satellite is 1, the confidence corresponding to the space-time grid is multiplied by the probability that the satellite is not blocked; If the visibility of the satellite is 0, then the confidence corresponding to the space-time grid is set to 0. the

When the search result s ^<i+1> _search of the i+1th satellite is a search failure,

$\left\{\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ {{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.$

In this way, if no satellite is found and the visibility of the corresponding space-time grid is 1, the confidence corresponding to the space-time grid is multiplied by the satellite occlusion probability of the satellite; If the visibility of the satellite is 0, the confidence corresponding to the space-time grid remains unchanged. the

According to an implementation manner, the processor 220 may delete a space-time cell whose confidence level is 0 from the space-time cell set. In this way, the set of space-time grids can be reduced, thereby reducing the amount of computation. the

According to an embodiment of the present application, the processor 220 will delete the searched satellite from the list of satellites to be searched. That is, the receiver, specifically the satellite searcher 230 will no longer search for already searched satellites. the

According to an embodiment of the present application, when the result of searching for satellites is that the acquisition is successful, the processor 220 will judge whether the number of captured satellites meets the requirements, and if the requirements are met, the satellite search is stopped. the

According to an embodiment of the present application, the initial value of the confidence level may be determined according to the priori time and space information of the receiver. The receiver's a priori temporal and spatial information may be provided by the information collector 240 of the receiver 200 . the

The search method of the present application will be further described in detail below with reference to a specific application of satellite search by a receiver as an example. It can be understood that, according to requirements or various scenarios, the search method disclosed in this application may have various specific applications. the

In this application, as shown in FIG. 4 , preprocessing parameters can be set in step 310 to determine the space-time grid set {G}, the initial value of the confidence matrix C, and the visibility matrix V. It can be understood that the above parameters can be set by the user, and can also be pre-stored in the receiver. Alternatively, the above parameters can also be set by the receiver itself, for example, by integrating a communication link, inertial navigation, camera, thermometer and/or barometer, etc. on the receiver to perform parameter setting. the

The set parameters include space-time range, space-time grid division parameters and prior information. Spatio-temporal extent refers to the temporal and spatial extent in which the user believes that the receiver may be located. The spatio-temporal grid division parameter may include the step size of the spatio-temporal grid. When the space-time grid is divided evenly, the step length of the space-time grid is a fixed value; when the space-time grid is divided unevenly, the step size of the space-time grid can be set to different step values according to needs. It is used to configure the size of the divided space-time grid; prior information refers to the user's prior space-time position information before searching. the

The space-time range is divided according to the space-time grid division parameters to form a set {G} of space-time grids. For example, if the specified spatial range is the global surface, and the division step length latitude and longitude are both 10°, the spatial range will be divided into 180/10*360/10=648 spatial grids; if the specified time range is 1 hour before and after the time with the clock, and the division step is 30 minutes, then the time range will be divided into 2*60/30=4 time grids. The time grid and the space grid can be cross-extended to obtain 648*4=2592 space-time grids, which form the set {G} of space-time grids. Each grid in {G} is assigned a corresponding time point and space point, for example, the midpoint of the time grid and the midpoint of the space grid can be taken. the

The prior information gives the possible time and space of the receiver, so the initial value of the confidence matrix can be set according to the prior information. The assignment method of the confidence matrix C can be satisfied that when the probability that the receiver is in a certain space-time grid is higher, the value of the element corresponding to the corresponding grid in the confidence matrix C is larger. The confidence matrix C can be assigned a value according to the above assignment method according to the prior information. When there is no prior information, each element in the confidence matrix C can also be assigned the same non-zero value. the

The GNSS satellites that the receiver can handle constitute the list {S} of satellites to be searched. For each satellite in the searched satellite list {S}, calculate its visibility to each space-time grid in the space-time grid set {G}. To this end, first read the almanac of the designated satellite to obtain its orbital elements, and then calculate the orbital position of the satellite at the time point corresponding to the space-time grid according to a certain model, and combine this orbital position with the determined space-time grid. space point, the elevation angle value of the orbital position for this space point can be calculated, and the relationship between the elevation angle value and the preset elevation angle threshold value can be compared—if it is greater than the preset elevation angle threshold value, it is determined that the satellite is visible (marked is the value 1), if it is less than the preset elevation angle threshold, it is determined that the satellite is invisible (marked as a value of 0). The visibility matrix V is obtained by traversing the satellite list {S} to be searched and the set of space-time grids {G}. the

After determining the set of space-time grids {G}, the initial value of the confidence matrix C, and the visibility matrix V, the dynamic search of satellites can be performed. In this application, the probability that the satellite signal is blocked can be set as e. It can be understood that the occlusion probability e may have different values in different environments and different space-time grids. the

Step 320, calculating satellite weighted average visibility. For each satellite s in the searched satellite list {S}, calculate its satellite weighted average visibility:

${{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Avg</span>}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; where</span>}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&times;</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&Element;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; \}</span>}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}$

For the specified satellite, retrieve the visibility matrix V to get its visibility for each space-time grid, and each space-time grid can find its corresponding weight in the confidence matrix C, according to the weight provided by the confidence matrix C The distribution weights the visibility of the specified satellites to these space-time grids to obtain the weighted average visibility of each satellite in the set of satellites to be searched. the

Step 330, determine the satellite signal to be searched in this round. You can choose to take the satellite with the largest satellite-weighted average visibility: ${{\mathrm{the\; s}}^{<i+1>}}_{\mathrm{search}}=\underset{\mathrm{the\; s}\&Element;{\left\{S\right\}}^{<i>}}{\arg }\max {{\tilde{V}}_{\mathrm{the\; s}}}^{<i+1>}.$

Step 340, the receiver tries to acquire the signal of the satellite, and returns the acquisition result. If the acquisition is successful, it is judged in step 350 whether the number of acquired satellite signals is enough, if enough, the satellite search process is ended; otherwise, step 360 is performed. If the capture fails, go to step 360 . the

Step 360, updating the confidence matrix C. When satellite s ^<i+1> _search succeeds,

$\left\{\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ {{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.$

When satellite s ^<i+1> _search fails,

$\left\{\begin{array}{c}{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ {{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ></span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; if</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>}\mathrm{<span\; class="notranslate">\; search</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; .</span>$

Step 370, shrink the set of space-time grids {G}. Retrieve each element in the confidence matrix C, and remove the space-time cells corresponding to the 0-value elements in C from the space-time cell set {G}. the

Step 380, updating the list {S} of satellites to be searched. Remove the satellites that are trying to be captured in this round of capture from the satellites to be captured: {G} ^<i+1> ＝{G _t,p |G _t,p ∈{G} ^<i> ,C ^<i> _{t, p} ≠ 0}.

The above steps 320 to 380 are repeated until a sufficient number of satellites are found and the satellite search process is stopped. the

The exemplary embodiments of the present application are described above with reference to the accompanying drawings. It should be understood by those skilled in the art that the above-mentioned embodiments are only examples for the purpose of illustration, and are not used for limitation. Any modifications, equivalent replacements, etc. All should be included in the protection scope of this application. the

Claims (16)

1. a method for search of satellite, according to the weighted mean visibility search of satellite of satellite relative to the set of space-time grid, wherein, the weights of described weighted mean visibility are determined according to time space position information.

2. the method for search of satellite as claimed in claim 1, wherein, described time space position information comprises the degree of confidence that receiver is in contained space-time grid in the set of described space-time grid.

3. the method for search of satellite as claimed in claim 2, wherein, probability is blocked according to the matching relationship whether searched between satellite and the visibility of this satellite and satellite, degree of confidence is adjusted, the weighted mean visibility of satellite relative to the set of space-time grid is upgraded according to the degree of confidence after adjustment, and further according to the weighted mean visibility search of satellite after renewal.

4. the method for search of satellite as claimed in claim 3, wherein, after carrying out i-th satellite acquisition, to upgrade in satellite set to be searched each satellite in the following manner at space-time grid set { G} ^<i>in weighted mean visibility

${\tilde{V}}_s^{<i+1>}=\mathrm{Avg}\left(\underset{t,p,\mathrm{where}{G}_{t,p}\&Element;{\left\{G\right\}}^{<i>}}{\mathrm{\&Sigma;}}(V_{t,p,s}\&times;{C^{<i>}}_{t,p})\right),s\&Element;{\left\{S\right\}}^{<i>}$

Wherein, { G} ^<i>represent the space-time grid set after having carried out i-th search, G _t,pfor the element in the set of space-time grid, to represent on time dimension t, on Spatial Dimension p lattice point map the space-time grid of formation; { S} ^<i>the set of satellite to be searched remaining after representing i-th search; V _{t, p, s}for the element in visibility matrix V, value is 0 or 1, represents that the satellite being numbered s is for space-time grid G _t,pvisibility; C ^<i> _t,pfor degree of confidence Matrix C ^<i>element, represent i-th time search after receiver be positioned at space-time grid G _t,ppossibility; ∑ () represents summing function, and Avg () expression is averaging function.

5. the method for search of satellite as claimed in claim 4, wherein, in the following manner according to weighted mean visibility search of satellite:

${s^{<i+1>}}_{\mathrm{search}}=\underset{s\&Element;{\left\{S\right\}}^{<i>}}{\arg }\max {\tilde{V}}_s^{<i+1>}$

Wherein s ^<i+1> _searchthe numbering of the satellite will searched for when being the i-th+1 time search, represent with s to be parameter, make be worth maximum s value.

6. the method for search of satellite as claimed in claim 5, wherein, block probability according to the matching relationship whether searched between satellite and the visibility of this satellite and satellite, in the following manner degree of confidence is adjusted:

In satellite s ^<i+1> _searchwhen searching for successfully,

$\left\{\begin{array}{c}{C^{<i+1>}}_{t,p}={C^{<i>}}_{t,p}*(1-e),\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=1\\ {C^{<i+1>}}_{t,p}=0,\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=0\end{array}\right.$

In satellite s ^<i+1> _searchwhen searching for unsuccessfully,

$\left\{\begin{array}{c}{C^{<i+1>}}_{t,p}={C^{<i>}}_{t,p}*e,\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=1\\ {C^{<i+1>}}_{t,p}={C^{<i>}}_{t,p},\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=0\end{array}\right.$

Wherein, e is that satellite blocks probability; represent and be numbered s ^<i+1> _searchsatellite for space-time grid G _t,pvisibility.

7. the method for search of satellite as claimed in claim 6, wherein, upgrading the set of space-time grid according to the degree of confidence after adjustment in the following manner, is that the space-time grid of 0 is deleted from the set of space-time grid by degree of confidence:

{G} ^<i+1>＝{G _t,p|G _t,p∈{G} ^<i>,C ^<i> _t,p≠0}。

8. the method for search of satellite as claimed in claim 2, wherein, the initial value of described degree of confidence is determined according to the priori Time and place information of receiver.

9. a receiver, described receiver comprises:

Processor, determines calculating the weights of satellite relative to the weighted mean visibility of space-time grid set according to time space position information, and determines described weighted mean visibility according to described weights; And

Satellite acquisition device, according to the weighted mean visibility search of satellite determined.

10. receiver as claimed in claim 9, wherein, described time space position information comprises the degree of confidence that receiver is in contained space-time grid in the set of described space-time grid.

11. receivers as claimed in claim 10, wherein, described processor blocks probability according to the matching relationship whether searched between satellite and the visibility of this satellite and satellite, degree of confidence is adjusted, upgrades the weighted mean visibility of satellite relative to the set of space-time grid according to the degree of confidence after adjustment; Described satellite acquisition device is further according to the weighted mean visibility search of satellite after renewal.

12. receivers as claimed in claim 11, wherein, described processor comprises visibility computing module, and after carrying out i-th satellite acquisition, described visibility computing module to upgrade in satellite set to be searched each satellite in the following manner at space-time grid set { G} ^<i>in weighted mean visibility ${\tilde{V}}_s^{<i+1>}:$

${\tilde{V}}_s^{<i+1>}=\mathrm{Avg}\left(\underset{t,p,\mathrm{where}{G}_{t,p}\&Element;{\left\{G\right\}}^{<i>}}{\mathrm{\&Sigma;}}(V_{t,p,s}\&times;{C^{<i>}}_{t,p})\right),s\&Element;{\left\{S\right\}}^{<i>}$

Wherein, { G} ^<i>represent the space-time grid set after having carried out i-th search, G _t,pfor the element in the set of space-time grid, to represent on time dimension t, on Spatial Dimension p lattice point map the space-time grid of formation; { S} ^<i>the set of satellite to be searched remaining after representing i-th search; V _{t, p, s}for the element in visibility matrix V, value is 0 or 1, represents that the satellite being numbered s is for space-time grid G _t,pvisibility; C ^<i> _t,pfor degree of confidence Matrix C ^<i>element, represent i-th time search after receiver be positioned at space-time grid G _t,ppossibility; ∑ () represents summing function, and Avg () expression is averaging function.

13. receivers as claimed in claim 12, wherein, described satellite acquisition device is in the following manner according to weighted mean visibility search of satellite:

${s^{<i+1>}}_{\mathrm{search}}=\underset{s\&Element;{\left\{S\right\}}^{<i>}}{\arg }\max {\tilde{V}}_s^{<i+1>}$

Wherein s ^<i+1> _searchthe numbering of the satellite will searched for when being the i-th+1 time search, represent with s to be parameter, make be worth maximum s value.

14. receivers as claimed in claim 13, wherein, described processor comprises degree of confidence adjusting module further, described degree of confidence adjusting module blocks probability according to the matching relationship whether searched between satellite and the visibility of this satellite and satellite, adjusts in the following manner to degree of confidence:

In satellite s ^<i+1> _searchwhen searching for successfully,

$\left\{\begin{array}{c}{C^{<i+1>}}_{t,p}={C^{<i>}}_{t,p}*(1-e),\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=1\\ {C^{<i+1>}}_{t,p}=0,\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=0\end{array}\right.$

In satellite s ^<i+1> _searchwhen searching for unsuccessfully,

$\left\{\begin{array}{c}{C^{<i+1>}}_{t,p}={C^{<i>}}_{t,p}*e,\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=1\\ {C^{<i+1>}}_{t,p}={C^{<i>}}_{t,p},\mathrm{if}{V}_{{t,p,s}^{{<i+1>}_{\mathrm{search}}}}=0\end{array}\right.$

Wherein, e is that satellite blocks probability; represent and be numbered s ^<i+1> _searchsatellite for space-time grid G _t,pvisibility.

15. receivers as claimed in claim 14, wherein, described processor upgrades the set of space-time grid according to the degree of confidence after adjustment in the following manner, is that the space-time grid of 0 is deleted from the set of space-time grid by degree of confidence:

{G} ^<i+1>＝{G _t,p|G _t,p∈{G} ^<i>,C ^<i> _t,p≠0}。

16. receivers as claimed in claim 10, wherein, described receiver also comprises information collector, obtain the priori Time and place information of receiver, wherein, the priori Time and place information of the receiver that described receiver obtains according to described information collector, determines that described satellite blocks the initial value of probability and described degree of confidence.