KR101043689B1 - Method and apparatus for acquiring initial synchronous signal for gps - Google Patents

Abstract

The present invention relates to an initial synchronization signal acquisition method and apparatus for GPS, and to provide an initial synchronization signal acquisition method and apparatus capable of realizing a small logic size while acquiring an initial synchronization signal for GPS at high speed. In this regard, the method of obtaining an initial synchronization signal according to the present invention includes a Doppler frequency correction step of recursively accumulating Doppler frequency correction signals generated by performing Doppler frequency correction on a GPS miracle band signal for each PRN phase during a synchronous and asynchronous accumulation period. Obtaining a PRN correlation value for the accumulated Doppler frequency correction signal during a synchronous accumulation period, calculating a synchronous accumulation value by recursively accumulating for each PRN phase, and performing an asynchronous calculation on the synchronous accumulation value during an asynchronous accumulation period And calculating asynchronous cumulative values by regression accumulation for each PRN phase, and obtaining a Doppler frequency and a PRN phase value using the asynchronous cumulative values.

GPS Sync Acquisition, Sync Accumulation, Asynchronous Accumulation, Doppler Frequency, Phase Sync

Description

Acquisition method and apparatus for initial synchronization signal for GPS {METHOD AND APPARATUS FOR ACQUIRING INITIAL SYNCHRONOUS SIGNAL FOR GPS}

The present invention relates to a method and apparatus for acquiring an initial synchronization signal for a global positioning system (GPS), and more particularly, to an initial synchronization for a GPS capable of realizing a small logic size while acquiring an initial synchronization signal for a GPS at high speed. A method and apparatus for signal acquisition.

Acquiring GPS initial synchronization is the task of searching for Doppler frequencies caused by the movement of satellites and GPS terminals and delayed PRN (Pseudo Random Noise) phases that occur during signal transmission from satellite to terminal. Early synchronization acquisition of GPS has traditionally used a serial correlator with a small logic size or a matched filter correlator or fast fourier transform (FFT) correlator to reduce search time.

In general, the serial correlator and the matched filter correlator have a structure that obtains an accurate PRN phase value by obtaining a correlation value from a PRN phase correlator on a received signal having Doppler correction.

1 is a flowchart illustrating a method of obtaining GPS initial synchronization using a conventional serial correlator or a matched filter correlator. First, the Doppler frequency included in the input GPS baseband signal is corrected and removed (101). Next, a PRN pattern is generated 102 for despreading, and a demodulation symbol of 1023 PRN intervals is generated by despreading the PRN phase included in the GPS baseband signal (103). Next, the generated demodulation symbol is accumulated and superimposed (synchronous accumulation) 104, and the square value of the synchronized accumulation value is accumulated and superimposed (asynchronous accumulation) 105. Next, the maximum Doppler frequency value and the PRN phase value of the asynchronous cumulative value are calculated (106).

However, since the serial correlator method sequentially performs frequency correction and PRN phase search for each PRN phase, there is a problem in that the structure is simple and the logic size is small but the search time is long.

Also, the matched filter correlator method searches for several PRN phases simultaneously by using the frequency-compensated signal, which reduces the search time, but uses a plurality of matched filter correlators to shorten the search time. There is a problem that the size is large.

Meanwhile, the FFT correlator stores the input sampling signal without correction and uses the method of simultaneously searching for Doppler frequency and PRN phase by performing signal processing such as FFT and IFFT (Inverse FFT) on the stored signal and PRN correlation value. . Since the FFT correlator is directly implemented in hardware, the logic complexity is increased. Therefore, in general, the FFT correlator is implemented by a software program in a system on chip (SoC) hardware structure having a digital signal processor rather than dedicated hardware.

However, such a FFT correlator requires a memory for storing a large number of received input signals in order to shorten the search time, and as the size of the memory increases, the size (complexity) according to the SoC structure increases and power is consumed. There is this.

The present invention aims to solve these problems of the prior art.

Specifically, an object of the present invention is to provide a method and apparatus for acquiring an initial synchronization signal for GPS, which can realize a small logic size while acquiring an initial synchronization signal for GPS at high speed.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, the present invention provides a method for acquiring an initial synchronization signal for GPS, wherein the Doppler frequency correction signal generated by performing Doppler frequency correction on the GPS miracle band signal during the synchronous and asynchronous accumulation periods for each PRN phase. A Doppler frequency correction step of regression accumulation, a synchronous calculation step of obtaining a PRN correlation value for the Doppler frequency correction signal accumulated during the synchronization accumulation period, recursively accumulating by PRN phases, and calculating a synchronization accumulation value; Performing an asynchronous calculation on the cumulative value and recursively accumulating the PRN phases to calculate an asynchronous cumulative value, and obtaining a Doppler frequency and a PRN phase value using the asynchronous cumulative value.

In addition, the present invention is a device for obtaining an initial synchronization signal for GPS, the Doppler frequency correction signal to generate a Doppler frequency correction signal by performing the Doppler frequency correction on the GPS baseband signal during the synchronous and asynchronous cumulative period, and the Doppler regression accumulating for each PRN phase A frequency correction unit, a synchronization calculation unit for obtaining a PRN correlation value for the Doppler frequency correction signal accumulated during the synchronization accumulation period, and recursively accumulating the PRN phases to calculate a synchronization accumulation value; And an asynchronous calculation unit configured to perform an asynchronous calculation on the PRN phase, recursively accumulate the PRN phases, and calculate an asynchronous accumulation value, and obtain a Doppler frequency and a PRN phase value using the asynchronous accumulation value.

The present invention compensates the predicted Doppler frequency instead of storing a GPS baseband input signal, without having a plurality of matched filters, in order to reduce the logic size for initial synchronization signal acquisition for GPS and to obtain the synchronization signal at high speed. Store a signal, but change its storage method and store it in memory. Here, the present invention recursively accumulates the Doppler frequency correction signal for each PRN phase without performing the Doppler frequency correction and storing the GPS baseband input signal as it is in the memory. This storage method can significantly reduce the storage space.

) 간격으로 동일 메모리에 중첩 저장하여 저장 메모리를 줄이고 다시 데이터 저장 중 저장 값의 크기를 적절히 조절하여 저장 시 필요한 메모리 크기를 최소화한다. That is, the initial synchronization signal acquisition device for the GPS of the present invention divides the Doppler frequency generated by the movement of the GPS satellites and the movement of the GPS terminal by dividing the frequency into a resolution based on the GPS resolution within a tolerance range (± 10KHz). The data signal is pre-corrected to the expected Doppler frequency in the band signal. Here, the method of storing data is 1023 PRN (

Save the memory by overlapping it in the same memory at intervals and minimize the size of memory required by saving the data by adjusting the size of the data again.

As such, minimizing the Doppler frequency correction superimposed signal memory width bits can reduce the time delay line and the adder tree bits of the matched filter.

At this time, the stored Doppler frequency correction data has a structure of obtaining PRN phase synchronization by obtaining a correlation value through a specific PRN correlator and increasing the signal acquisition probability by applying coherent accumulation and non-coherent accumulation.

Synchronous and Asynchronous Accumulation can be replaced with Hybrid Synchronous and Hybrid Asynchronous Accumulation, which performs both synchronous and asynchronous accumulation and Differential Accumulation, and in this case, performance improvement is achieved compared to synchronous and asynchronous accumulation. Can be. In addition, since once stored Doppler frequency correction superposition data can be repeatedly used for multiple PRNs, initial synchronization search time can be drastically reduced for the entire GPS PRN.

As described above, the present invention has an effect of realizing a small logic size by regressively accumulating Doppler frequency correction signals for each PRN phase. In addition, since the present invention can apply the frequency correction cumulative value to other PRNs, the synchronization acquisition time for the entire PRN can be drastically reduced.

The above objects, features, and advantages will become more apparent from the following detailed description with reference to the accompanying drawings, and as such, those skilled in the art to which the present invention pertains may share the spirit of the present invention. It will be easy to implement. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

2 is a block diagram of an embodiment of an initial synchronization signal acquisition device for GPS according to the present invention. As shown, the initial synchronization signal acquisition device for GPS according to the present invention, the Doppler frequency correction unit 21, the synchronous and asynchronous calculation unit 22, and the frequency and PRN phase synchronization acquisition unit 23 do. The Doppler frequency corrector 21 includes a Doppler frequency corrector 211, a frequency corrected overlap accumulator 212, and an accumulator multiplexer 213, and the synchronous and asynchronous calculator 22 includes a PRN correlator 221. ), A PRN generator 222, a synchronous accumulator 223, an asynchronous calculator 224, and an asynchronous accumulator 225.

The Doppler frequency corrector 211 of the Doppler frequency corrector 21 includes a Doppler frequency generator 2111 that generates the Doppler frequency, and corrects and removes the Doppler frequency included in the GPS baseband input signal. At this time, the Doppler frequency corrector 211 sets an appropriate correction frequency interval proportional to each synchronization accumulation period, and performs frequency correction on the input signal using the expected Doppler frequency value.

The frequency corrected overlap accumulator 212 includes a frequency corrected overlap accumulator (hereinafter, referred to as a 'first cumulative size converter') 2121 and a frequency corrected cumulative accumulator (hereinafter, referred to as a 'first cumulative memory') ( 2122, and recursively accumulates a signal whose frequency is corrected by the Doppler frequency corrector 211 (that is, the Doppler frequency correction signal) for each PRN phase during the synchronous and asynchronous accumulation periods.

The first cumulative size converter 2121 adjusts the size of data accumulated in the first cumulative memory 2122 during the cumulative period in order to reduce the size of the first cumulative memory 2122. The first cumulative size converter 2121 calculates a required significant number according to the overlapped cumulative value and adjusts the size of the input signal (Doppler frequency correction signal), so that the memory bit width of the first cumulative memory 2122 is measured. Reduce

A relationship between a data accumulation position in the first cumulative memory 2122 is illustrated in FIG. 3. As shown in FIG. 3, data is accumulated by overlapping input signals for each 1023 PRN phase. In this case, the PRN phase synchronization may be different for each required PRN phase synchronization resolution. For example, when the resolution value is N, the depth of the first cumulative memory 2122 may have a value of 1023XN. Although the present invention is not limited thereto, it will be described as 1023 PRN for convenience.

The frequency corrected overlap accumulator 212 having such a component needs to accumulate as many times as asynchronous calculations.

The accumulator multiplexer 213 sequentially transfers the frequency corrected overlap accumulator value accumulated in the frequency corrected overlap accumulator 212 to the input of the PRN correlator 221 of the synchronous and asynchronous calculator 22. The function of the accumulator multiplexer 213 is performed when the number of asynchronous times of the frequency corrected overlap accumulator 212 is two or more.

One embodiment of the present invention may be provided with a plurality of such Doppler frequency correction unit 21, in this case, it is possible to determine the multiple Doppler frequency correction signal at the same time to reduce the initial synchronization acquisition time for GPS have.

The PRN correlator 221 of the synchronous and asynchronous calculator 22 uses a frequency corrected overlap accumulator memory value and a PRN pattern for despreading generated by the PRN generator 222 to generate one frequency corrected overlap accumulator 212. The PRN correlation value is obtained during the output of (). That is, the PRN correlator 221 despreads the PRN phase included in the GPS baseband signal to generate demodulated symbols with a 1023 PRN interval. In this case, the PRN correlator 221 may be a serial or matched filter correlator.

Since the PRN correlator 221 uses the frequency corrected cumulative memory value, the correlation value for all 1023 PRN phases during one synchronization accumulation period (PRN correlation value) in order to ensure continuity of the input signal for obtaining the PRN correlation value. Until is found, recursively use the corresponding frequency corrected cumulative cumulative memory value.

The synchronous accumulator 223 includes a synchronous cumulative size converter (hereinafter referred to as a 'second cumulative size converter') 2231 and a synchronous cumulative memory (hereinafter referred to as a 'second cumulative memory') 2232. By using this, the PRN correlation value obtained by the PRN correlator 221 is accumulated and accumulated for each PRN phase. In other words, the synchronization accumulator 223 accumulates the demodulation symbols in an overlapped manner (synchronous accumulation).

The second cumulative size converter 2231 adjusts the size of data accumulated in the second cumulative memory 2232 during the synchronous cumulative period to reduce the size of the second cumulative memory 2232. The second cumulative size converter 2231 reduces the memory bit width of the second cumulative memory 2232 by calculating the significant digit to adjust the magnitude of the input signal (PRN correlation value).

The asynchronous calculator 224 calculates an asynchronous calculation value for the I and Q correlation values using all the synchronous correlation values for the 1023 PRN phase accumulated by the synchronous accumulator 223.

The asynchronous accumulator 225 includes an asynchronous cumulative size converter (hereinafter referred to as 'third cumulative size converter') 2251 and asynchronous cumulative memory (hereinafter referred to as 'third cumulative memory') 2252, By using this, the asynchronous calculation value calculated by the asynchronous calculator 224 is accumulated and accumulated for each PRN phase (asynchronous accumulation).

The third cumulative size converter 2251 adjusts the size of data accumulated in the third cumulative memory 2252 during the asynchronous cumulative calculation period to reduce the size of the third cumulative memory 2252. The third cumulative size converter 2251 reduces the memory bit width of the third cumulative memory 2252 by calculating the significant digit to adjust the magnitude of the input signal (asynchronous calculation value).

In this case, the synchronous accumulator 223, the asynchronous calculator 224, the asynchronous accumulator 225, the synchronous accumulator size converter 2231, the synchronous accumulator memory 2232, the asynchronous accumulator size converter 2251, and the asynchronous accumulator memory ( 2252 may be replaced with a hybrid synchronous accumulator, a hybrid asynchronous calculator, a hybrid synchronous accumulator, a hybrid synchronous cumulative size converter, a hybrid asynchronous cumulative size converter, and a hybrid asynchronous cumulative memory, respectively. Here, the hybrid synchronous accumulator calculates and accumulates two or more synchronous accumulations for differential calculations, the hybrid asynchronous calculator performs asynchronous calculations and differential calculations (hybrid asynchronous calculations), and the hybrid asynchronous accumulator calculates hybrid asynchronous calculation values. Accumulate. In this case, the hybrid synchronous accumulator, the hybrid asynchronous calculator, the hybrid synchronous accumulator, the hybrid synchronous cumulative size converter, the hybrid asynchronous cumulative size converter, and the hybrid asynchronous accumulator memory have a performance of about 1 to 2 dB compared to the general synchronous and asynchronous accumulation methods. Improvements can be made. This will be described in more detail with reference to FIGS. 4A and 4B.

In the present invention, the synchronous and asynchronous calculator 22 may be provided in plural. In this case, a plurality of PRN phase synchronizations may be simultaneously determined, thereby reducing initial synchronization acquisition time for GPS.

The frequency and PRN phase synchronization acquirer 23 obtains a corresponding Doppler frequency and PRN phase value using an asynchronous cumulative memory value. Here, the Doppler frequency is an expected Doppler frequency used to obtain a PRN correlation value, and the PRN phase may be selected from local maxima among asynchronous cumulative memory values. The frequency and PRN phase synchronization acquirer 23 delivers the Doppler frequency value and the PRN phase value from which the selected local maximum value is calculated.

Here, the other PRN may be repeatedly obtained by the synchronous and asynchronous calculation unit 22 and the frequency and PRN phase synchronization acquirer 23 without having to recalculate the frequency corrected overlap accumulator value.

4A is an explanatory diagram of one embodiment of a conventional general synchronous and asynchronous accumulation method, and FIG. 4B is an explanatory diagram of an embodiment of the hybrid synchronous and hybrid asynchronous accumulation method according to the present invention. Here, in order to clarify the difference between the synchronous and asynchronous accumulation method and the hybrid synchronous and hybrid asynchronous accumulation method, mutual multiplication (except for a common item, a square item (self product item, described as const in FIGS. 4A and 4B)) Only based on cross product).

순으로 정합 필터 상관기에 입력될 시, 이를 일반적인 동기 누적과 비동기 누적을 수행하는 방식을 나타낸다. 즉, 종래의 일반적인 동기 및 비동기 누적 방법은 수학식 1과 같다.4a shows that the input

When input to the matched filter correlator in order, it represents the general synchronous and asynchronous accumulation. That is, the conventional general synchronous and asynchronous accumulation method is shown in Equation (1).

은 PRN 역확산된 심볼의 시간적인 순서를 의미한다.At this time,

Denotes a temporal order of PRN despread symbols.

Meanwhile, FIG. 4B illustrates a hybrid synchronous and hybrid asynchronous scheme in which general synchronous and asynchronous items and differential items are added. That is, the hybrid synchronous and hybrid asynchronous methods according to the present invention are shown in Equation 2.

)라고 된 값들을 혼성 계산 결과 값을 계산할 시에 넣을 수도 있고, 뺄 수도 있다는 것을 의미한다. 또한, 비동기 계산 값과 차 등 계산 값에 동등 또는 차등 가중치를 둔다는 것은, 예를 들어 도 4b의 덧셈기의 입력에서 비동기 계산 값 경로(즉, '2로 나눔'이 있는 경로)와 차등 계산 값 경로에 각각 크기 변환기(401, 402)를 두어 스케일(scale)을 동등하게 하거나 다르게 할 수 있다는 것을 의미한다. 이때, 크기 변환기(401, 402)는 혼성 비동기 계산 값의 품질을 조절할 수 있다.In this case, the hybrid asynchronous calculation method may include a basic structure for removing a squared item and an application structure without removing the squared item. The final hybrid asynchronous calculation value is obtained by giving equal or differential weights to the asynchronous calculation value and the differential calculation value. Here, it is possible to have a basic structure for removing a squared item and an application structure for not removing it. For example, in the above formula, const (for example,

The value of) means you can add or subtract the result of the hybrid calculation. In addition, giving equal or differential weights to asynchronous calculated values and calculated values, such as differential, means that the asynchronous calculated value path (i.e., 'divided by two') and the differential calculated value at the input of the adder of FIG. 4B, for example. This means that the size converters 401 and 402 may be placed in the paths to equalize or different scales. In this case, the size converters 401 and 402 may adjust the quality of the hybrid asynchronous calculation value.

의 상호 곱셈 항목이 더 많음을 알 수 있으며, 혼성 비동기 횟수가 많아질수록 전체적으로 일반적인 동기 및 비동기 방식에 비하여 혼성 동기 및 혼성 비동기 방식이 약 1 ~ 2dB의 성능 향상을 이룰 수 있다. As described above, comparing the multiplication items of FIGS. 4A and 4B, hybrid synchronous and hybrid asynchronous schemes for the same input

It can be seen that there are more cross-multiplication items of, and as the number of hybrid asynchronouss increases, the hybrid synchronous and hybrid asynchronous methods can achieve a performance improvement of about 1 to 2 dB compared to the general synchronous and asynchronous methods as a whole.

5 is a flowchart illustrating an exemplary method of obtaining an initial synchronization signal for GPS according to the present invention.

First, the Doppler frequency corrector 211 corrects and removes the Doppler frequency included in the GPS baseband signal (501). Next, the frequency corrected superposition accumulator 212 overlaps and accumulates the Doppler frequency corrected signal (ie, the Doppler frequency corrected signal) (502). Here, the frequency corrected overlap accumulator 212 determines whether the synchronous accumulation period and the asynchronous accumulation period are overlapped when accumulating the Doppler frequency correction signals (503), and overlaps the Doppler frequency correction signals in the synchronous and asynchronous accumulation periods. If the accumulation is not performed (that is, when the synchronous and asynchronous accumulation periods are completed), the overlap accumulation is completed.

The PRN correlator 221 despreads the PRN phase included in the GPS baseband signal by using the PRN pattern 504 generated by the PRN generator 222 and the accumulated frequency correction signal to decode the demodulated symbols at intervals of 1023 PRN. Create 505. The synchronous accumulator 223 then accumulates the generated demodulation symbols (synchronous accumulating) 506, and the asynchronous calculator 224 and the asynchronous accumulator 225 accumulates the asynchronous calculation of the synchronous accumulating value (asynchronous). Cumulative) (507).

In this case, the hybrid synchronous accumulator may operate in place of the synchronous accumulator 223, and the hybrid asynchronous calculator and the hybrid asynchronous accumulator operate in place of the asynchronous calculator 224 and the asynchronous accumulator 225 to operate the asynchronous accumulator 225. The asynchronous calculation of can be calculated as a hybrid asynchronous calculation (asynchronous and differential).

Thereafter, the frequency and PRN phase synchronization acquirer 23 transmits the Doppler frequency value and the PRN phase value at which the maximum value of the asynchronous cumulative values is calculated (508).

If it is necessary to search for another PRN signal, the process proceeds to step 504, whereby another PRN can be repeatedly obtained using data accumulated in the frequency corrected overlap accumulator without having to recalculate the frequency corrected accumulator. On the other hand, if there is no need to search for another PRN signal, the PRN signal search is completed.

FIG. 6 is an explanatory diagram of an embodiment comparing design efficiency related to search time and size between a method using a conventional matched filter correlator and an initial synchronization signal acquisition method for GPS according to the present invention when the number of asynchronous accumulations is increased. .

In general, the search time St and the logic size Ls are inversely related. This is because increasing the logic size can reduce the synchronization acquisition time. Therefore, if the logic size is doubled to reduce the search time by 1/2, the overall design efficiency cannot be improved. There may be several architectures for the initial sync acquirer, and ultimately a design with a short search time and a small logic size is required.

Here, to compare the design efficiency between the conventional matched filter correlator method and the initial synchronization signal acquisition method for GPS according to the present invention, the design efficiency index De is defined as being proportional to the multiplication of the search time and the logic size. It was. In other words, the smaller the value of the design efficiency index De, the shorter the search time and the smaller the size.

6 shows a conventional matched filter structure and the present invention, based on 24 GPS PRN signal searches, 20 ms synchronous search, Doppler frequencies in 25 Hz intervals, Doppler frequencies in the range of -10 KHz to +10 KHz, and matched filters in a 2046 correlator structure. A design efficiency index for the frequency-corrected superposition matched filter structure is obtained, and a conventional matched filter displays a value normalized to a design efficiency index when searching for 20 ms synchronous and one asynchronous signal.

Here, as the number of asynchronous times increases, the search time increases, and the design efficiency index value increases. As shown in FIG. 6, the structure of the frequency-corrected superposition matched filter according to the present invention approaches the conventional matched filter structure as the number of asynchronous times increases, but the structure of the frequency-corrected superposition matched filter according to the present invention increases as the number of asynchronous times decreases. It can be seen that the design efficiency is excellent. That is, compared with the conventional matched filter structure, the structure of the frequency-corrected overlapped matched filter according to the present invention means that the size is small if the same search time is satisfied, and the search time is short if the size is the same.

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is a flowchart illustrating a method of obtaining GPS initial synchronization using a conventional serial correlator or a matched filter correlator.

2 is a block diagram of an embodiment of an initial synchronization signal acquisition device for GPS according to the present invention.

3 is a structural diagram of an embodiment of writing and reading a frequency corrected overlapping memory according to the present invention.

4A is an explanatory diagram of one embodiment of a conventional general synchronous and asynchronous accumulation method.

4B is an explanatory diagram of an embodiment of a hybrid synchronous and hybrid asynchronous accumulation method according to the present invention.

5 is a flowchart illustrating an exemplary method of obtaining an initial synchronization signal for GPS according to the present invention.

FIG. 6 is an explanatory diagram of an exemplary embodiment comparing design efficiency related to search time and size between a method using a conventional matched filter correlator and an initial synchronization signal acquisition method for GPS according to the present invention.

[Description of Symbols for Main Parts of Drawing]

21: Doppler frequency correction unit 22: synchronous and asynchronous calculation unit

23: frequency and PRN phase synchronization acquisition unit 211: Doppler frequency corrector

212: Frequency Correction Overlap Accumulator 213: Accumulator Multiplexer

221: PRN correlator 222: PRN generator

223: Synchronous Accumulator 224: Asynchronous Calculator

225: Asynchronous Accumulator 2111: Doppler Frequency Generator

2121: Frequency Correction Overlapping Cumulative Size Converter

2122: Cumulative Frequency Overlapping Memory 2231: Synchronous Cumulative Size Converter

2232: Synchronous Cumulative Memory 2251: Asynchronous Cumulative Size Converter

2252: asynchronous cumulative memory

Claims (20)

In the method for obtaining an initial synchronization signal for GPS, A Doppler frequency correction step of recursively accumulating Doppler frequency correction signals generated by performing Doppler frequency correction on the GPS miracle band signal for each Pseudo Random Noise (PRN) phase during the synchronous accumulation period and the asynchronous accumulation period; During the synchronization accumulation period, a PRN correlation value is calculated using a frequency correction accumulation value of the regression accumulated Doppler frequency correction signal and a PRN pattern for despreading, and the PRN correlation value is accumulated and superimposed by the PRN phases. A synchronization calculation step of calculating a synchronization accumulation value; During the asynchronous accumulation period, the I correlation value and the Q correlation value of the synchronous accumulation value are squared for each of the PRN phases, and then summed to calculate an asynchronous calculation value, and the accumulated asynchronous calculation value is overlapped and accumulated for each PRN phase. An asynchronous calculation step of calculating an asynchronous cumulative value; And Acquiring a Doppler frequency and a PRN phase value using the asynchronous cumulative value. The method of claim 1, In the Doppler frequency correction step, a correction frequency interval is set for each synchronization accumulation period, and Doppler frequency correction is performed on the GPS miracle band signal using the obtained PRN phase value as an expected Doppler frequency value. Acquisition method of initial synchronization signal. The method of claim 1, The Doppler frequency correction step may include adjusting a magnitude of the Doppler frequency correction signal according to the accumulated frequency correction value of the Doppler frequency correction signal, and recursively accumulating the Doppler frequency correction signal by the number of calculations of the asynchronous calculation value. And obtaining a memory bit width. The method of claim 1, The synchronizing calculation step, the method of acquiring the initial synchronization signal, characterized in that for reducing the memory bit width of the memory to accumulate the synchronization cumulative value by adjusting the size of the calculated PRN correlation value. The method of claim 1, The asynchronous calculation step, the method of acquiring the initial synchronization signal, characterized in that for reducing the memory bit width of the memory to accumulate the asynchronous cumulative value by adjusting the size of the calculated asynchronous calculated value. The method of claim 1, In the synchronous calculation step, a plurality of synchronous accumulation values are calculated, and a differential calculation value is calculated by cross product of the plurality of calculated synchronous accumulation values, and then the differential calculation value is calculated. The method of obtaining an initial synchronization signal, characterized in that the cumulative accumulation for each PRN phase. The method of claim 1, The acquiring may include calculating the Doppler frequency using an expected Doppler frequency used to calculate the PRN correlation value and selecting a maximum value as the PRN phase value from the asynchronous cumulative value. Way. The method of claim 6, In the asynchronous calculation step, the square item of symbols according to the PRN pattern is removed from the synchronous accumulation value, and the asynchronous calculation value and the differential calculation value are calculated according to whether the square item is removed. And obtaining a final asynchronous calculated value by giving equal or differential weights to the differential calculated values. The method of claim 1, The Doppler frequency correction signal generated in the Doppler frequency correction step is applied to the Doppler frequency correction accumulation value recursively accumulated in all PRNs to obtain synchronization, thereby reducing the synchronization acquisition time for the entire PRN. Acquisition method. An apparatus for acquiring an initial synchronization signal for a global positioning system (GPS), During the synchronous and asynchronous accumulation periods, a Doppler frequency correction signal is generated by performing Doppler frequency correction on the GPS baseband signal, and a Doppler frequency beam recursively accumulating the generated Doppler frequency correction signal by PRN (Pseudo Random Noise) phase. government; During the synchronization accumulation period, a PRN correlation value is calculated using a frequency correction accumulation value of the regression accumulated Doppler frequency correction signal and a PRN pattern for despreading, and the PRN correlation value is accumulated and superimposed by the PRN phases. A synchronization calculation unit for calculating a synchronization accumulation value; During the asynchronous accumulation period, the I correlation value and the Q correlation value of the synchronous accumulation value are squared for each of the PRN phases, and then summed to calculate an asynchronous calculation value, and the accumulated asynchronous calculation value is overlapped and accumulated for each PRN phase. An asynchronous calculation unit for calculating an asynchronous cumulative value; And And a PRN phase synchronization acquiring unit for acquiring a Doppler frequency and a PRN phase value using the asynchronous cumulative value. The method of claim 10, The Doppler frequency corrector further includes an accumulator multiplexer that sequentially outputs a frequency correction accumulated value of the regression accumulated Doppler frequency correction signal when the number of calculations of the asynchronous calculation value is 2 or more. Acquisition device. The method according to claim 10 or 11, wherein The Doppler frequency correction unit sets a correction frequency interval for each synchronization accumulation period, and acquires an initial synchronization signal for performing Doppler frequency correction on the GPS miracle band signal using the obtained PRN phase value as an expected Doppler frequency value. Device. The method according to claim 10 or 11, wherein The Doppler frequency correction unit, A first cumulative memory for recursively accumulating the Doppler frequency correction signal by the number of calculations of the asynchronous calculation value; And The size of the Doppler frequency correction signal is adjusted according to the accumulated frequency correction value of the Doppler frequency correction signal to decrease the memory bit width of the first cumulative memory, and the adjusted Doppler frequency correction signal is accumulated in the first accumulation. And a first cumulative magnitude converter for providing the memory. The method of claim 13, And a length of the first cumulative memory has a value of 1023XN when the PRN phase synchronization resolution is N. 10. The method according to claim 10 or 11, wherein The synchronization calculation unit, A PRN correlator for calculating the PRN correlation value using the frequency corrected cumulative value and the PRN pattern; A second cumulative memory that accumulates the calculated PRN correlation values; And And a second cumulative size converter for reducing the memory bit width of the second cumulative memory by adjusting the calculated PRN correlation value and providing the adjusted PRN correlation value to the second cumulative memory. Apparatus for acquiring the initial synchronization signal, characterized in that. The method according to claim 10 or 11, wherein The asynchronous calculation unit, An asynchronous calculator for calculating the asynchronous calculation value using the PRN correlation value accumulated in the synchronization calculation unit as the synchronous accumulation value; A third cumulative memory that accumulates the calculated asynchronous calculation values; And And a third cumulative size converter for adjusting the size of the calculated asynchronous cumulative value to reduce the memory bit width of the third cumulative memory and providing the adjusted asynchronous cumulative value to the third cumulative memory. Apparatus for acquiring the initial synchronization signal, characterized in that. The method according to claim 10 or 11, wherein The sync calculation unit calculates a plurality of sync accumulation values, cross-products the calculated plurality of sync accumulation values, calculates a differential calculation value, and then calculates the differential calculation value. An apparatus for acquiring an initial synchronization signal, wherein the PRN phase accumulates for each phase. The method according to claim 10 or 11, wherein The frequency and PRN phase synchronization obtaining unit calculates the Doppler frequency using an expected Doppler frequency used to calculate the PRN correlation value, and selects a maximum value as the PRN phase value from the asynchronous cumulative value. Signal acquisition device. The method of claim 17, The asynchronous calculation unit removes a square item of symbols according to the PRN pattern from the synchronous accumulation value, calculates the asynchronous calculation value and the differential calculation value according to whether the squared yield is removed, and the asynchronous calculation value and the And obtaining a final asynchronous calculation value by giving equal or differential weights to the differential calculation values. The method according to claim 10 or 11, wherein The Doppler frequency correction signal generated by the Doppler frequency correction unit recursively accumulates the Doppler frequency correction cumulative value to all the PRN to obtain the synchronization to reduce the acquisition time of the initial synchronization signal, characterized in that Acquisition device.

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