Spread spectrum signal long-short time hybrid loop tracking method and system

Abstract

The invention discloses a spread spectrum signal long and short time hybrid loop tracking method and system. The system comprises a multi-stage integrator which is used for carrying out multi-stage integration on a spread spectrum signal to obtain a multi-stage integration result; the carrier ring is used for acquiring an integration result of each integrator connected with the carrier ring and carrying out tracking loop processing; the incoherent integrator is used for obtaining an integration result of the last-stage integrator in the multi-stage integrators and performing incoherent accumulation to obtain an incoherent integration result; the code loop is used for obtaining an incoherent integration result and carrying out code loop processing; wherein the carrier ring connected with the last stage of integrator in the multiple stages of integrators is also used for obtaining an incoherent integration result and carrying out long-time incoherent carrier tracking processing. According to the scheme provided by the invention, a multi-stage integral hybrid loop tracking mode is adopted, a multi-stage integrator is matched, multi-loop joint work is realized, the method is suitable for spread spectrum signal tracking of various symbol rates, complex scenes such as a high dynamic scene and a low dynamic scene are considered at the same time, and the practicability is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of spread spectrum communication, and in particular to a method and system for tracking a long- and short-time hybrid loop of a spread spectrum signal. Background Art

[0002] The Beidou Navigation GNSS system, RDSS short message system, satellite communication system, etc. all widely use the spread spectrum signal system. Spread spectrum signals reduce the requirements of the symbol Eb / No in the channel transmission process by increasing the signal bandwidth, so that the signal can be buried under the noise to improve the concealment and anti-interference performance of the communication. When extracting the information symbols in the spread spectrum signal at the receiving end, it is necessary to first perform despreading by coherent integration. Coherent integration can greatly reduce the noise bandwidth, thereby recovering the signal from the noise. It should be said that to a certain extent, the longer the coherent integration time, the higher the signal-to-noise ratio of the recovered signal. However, the coherent integration time is at least affected by the symbol rate and the signal Doppler frequency deviation. If the symbol is not stripped, it cannot be integrated across symbols. The longer the coherent integration, the worse the Doppler dynamic stress. In common GNSS receiver technology, a fixed period of coherent integration time is generally used, such as half a symbol or a symbol period as the coherent integration time, and based on the coherent integration results of this half symbol or a symbol, frequency or phase discrimination is performed to achieve carrier tracking. This method has poor applicability in spread spectrum signals with multiple symbol rates, and for systems with multiple symbol rates at the same time, coherent integration can only be performed based on the highest symbol rate, such as RDSS systems with 16kbps and 32kbps. More importantly, the loop based on fixed coherent integration is difficult to be compatible with complex scenarios such as high dynamics and low dynamics due to the fixed integration bandwidth. Complex integration time switching and parameter dynamic loading mechanisms are often required to achieve a balance between dynamics and tracking sensitivity. Summary of the invention

[0003] In order to solve the technical problem that common GNSS receivers use a single-cycle coherent integration time and loop that is difficult to be compatible with complex scenarios such as high dynamics and low dynamics, an embodiment of the present invention provides a spread spectrum signal long-time and short-time hybrid loop tracking method and system.

[0004] The technical solution of the embodiment of the present invention is achieved as follows: The embodiment of the present invention provides a long-short-time hybrid loop tracking system for spread spectrum signals, comprising: a multi-stage integrator and a carrier loop connected to each of the integrators, an incoherent integrator connected to the last integrator in the multi-stage integrators, and a code loop connected to the incoherent integrator; the multi-stage integrator is used to perform multi-stage integration on the spread spectrum signal to obtain multi-stage integration results; the carrier loop is used to obtain the integration results of each connected integrator for tracking loop processing; the incoherent integrator is used to obtain the integration results of the last integrator in the multi-stage integrators, perform incoherent accumulation, and obtain incoherent integration results; the code loop is used to obtain the incoherent integration results for code loop processing; wherein the carrier loop connected to the last integrator in the multi-stage integrator is also used to obtain the incoherent integration results for long-time incoherent carrier tracking processing.

[0005] In one embodiment, the multi-stage integrator includes a first-stage short-time integrator and a second-stage long-time integrator; the carrier loop includes a short-time carrier loop connected to the first-stage short-time integrator and a long-time carrier loop connected to the second-stage long-time integrator; the first-stage short-time integrator is used to perform short-time integration on the spread spectrum signal to obtain a short-time integration result; the second-stage long-time integrator is used to perform long-time integration on the spread spectrum signal to obtain a long-time integration result; the short-time carrier loop is used to obtain the short-time integration result for short-time tracking loop processing; the long-time carrier loop is used to obtain the long-time integration result for long-time tracking loop processing.

[0006] In one embodiment, the short-time carrier loop is specifically used to obtain the short-time integration result, track the high symbol rate signal in the spread spectrum signal, or track the signal phase; the long-time carrier loop is specifically used to obtain the long-time integration result, track the low symbol rate signal in the spread spectrum signal, or track the signal frequency.

[0007] In one embodiment, the first-stage short-time integrator is specifically used to perform short-time integration processing on the spread spectrum signal with an integration time of 1 ms to obtain a short-time integration result of 1 ms; the second-stage long-time integrator is specifically used to accumulate the short-time integration result of 1 ms 10 times to obtain a long-time integration result of 10 ms.

[0008] In one embodiment, the short-time carrier loop is a third-order phase-locked loop structure, and the long-time carrier loop is a third-order phase-locked loop structure assisted by a frequency-locked loop.

[0009] The embodiment of the present invention also provides a method for long-short-time hybrid loop tracking of a spread spectrum signal, which is applied to a long-short-time hybrid loop tracking system of a spread spectrum signal, wherein the system comprises a multi-stage integrator and a carrier loop connected to each of the integrators, an incoherent integrator connected to the last integrator of the multi-stage integrator, and a code loop connected to the incoherent integrator; the method comprises: using each integrator of the multi-stage integrator to integrate the spread spectrum signal respectively to obtain a multi-stage integration result; using the incoherent integrator to obtain the integration result of the last integrator of the multi-stage integrator, and performing incoherent accumulation to obtain an incoherent integration result; using the carrier loop connected to each of the integrators to perform tracking loop processing on the integration result of each integrator; using the carrier loop connected to the last integrator of the multi-stage integrator to obtain an incoherent integration result for long-time incoherent carrier tracking processing when the carrier-to-noise ratio is poor and the dynamics are low; and weighted integration is performed on the tracking result of each carrier loop according to a preset weight to obtain a hybrid loop tracking result of the spread spectrum signal.

[0010] In one embodiment, the multi-stage integrator includes a first-stage short-time integrator and a second-stage long-time integrator, and the carrier loop includes a short-time carrier loop connected to the first-stage short-time integrator and a long-time carrier loop connected to the second-stage long-time integrator; each integrator in the multi-stage integrator is used to integrate the spread spectrum signal to obtain a multi-stage integration result. This includes: using the first-stage short-time integrator to perform short-time integration on the spread spectrum signal to obtain a short-time integration result; using the second-stage long-time integrator to perform long-time integration on the spread spectrum signal to obtain a long-time integration result; using the short-time carrier loop to obtain the short-time integration result for short-time tracking loop processing; using the long-time carrier loop to obtain the long-time integration result for long-time tracking loop processing, and when the carrier-to-noise ratio is poor and the dynamic is low, obtaining an incoherent integration result for long-time incoherent carrier tracking processing.

[0011] In one embodiment, the weight setting method includes: obtaining the carrier-to-noise ratio, and assigning a corresponding weight to each of the carrier loops according to the value of the carrier-to-noise ratio; or, obtaining the symbol rate of the spread spectrum signal, and assigning a corresponding weight to each of the carrier loops according to the symbol rate of the spread spectrum signal.

[0012] In one embodiment, a carrier loop connected to the last integrator in the multi-stage integrator is used to perform tracking loop processing on the integration result of the last integrator in the multi-stage integrator using a third-order phase-locked tracking loop; and a frequency-locked loop is used to perform long-term incoherent carrier tracking processing on the incoherent integration result.

[0013] In one embodiment, the method further comprises: utilizing the code loop to obtain the incoherent integration result to perform delay locked loop tracking processing.

[0014] The embodiment of the present invention provides a method and system for long-short-time mixed loop tracking of a spread spectrum signal, comprising: a multi-stage integrator and a carrier loop connected to each of the integrators, an incoherent integrator connected to the last integrator in the multi-stage integrator, and a code loop connected to the incoherent integrator; the multi-stage integrator is used to perform multi-stage integration on the spread spectrum signal to obtain multi-stage integration results; the carrier loop is used to obtain the integration results of each connected integrator for tracking loop processing; the incoherent integrator is used to obtain the integration results of the last integrator in the multi-stage integrator, perform incoherent accumulation, and obtain incoherent integration results; the code loop is used to obtain the incoherent integration results for code loop processing; wherein the carrier loop connected to the last integrator in the multi-stage integrator is also used to obtain the incoherent integration results for long-time incoherent carrier tracking processing. The solution provided by the present invention adopts a multi-stage integral hybrid loop tracking method, cooperates with a multi-stage integrator to realize multi-loop joint operation, is suitable for tracking spread spectrum signals with various symbol rates, and takes into account complex scenarios such as high dynamics and low dynamics, and has stronger practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of a long-short-time hybrid loop tracking system for spread spectrum signals according to an embodiment of the present invention; Figure 2 The figure is a flow chart of a method for long- and short-time hybrid loop tracking of a spread spectrum signal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0017] The embodiment of the present invention provides a spread spectrum signal long-short time hybrid loop tracking system, such as Figure 1 As shown, it includes: a multi-stage integrator C and carrier rings c2 and c4 connected to each of the integrators c1 and c3, a non-coherent integrator c5 connected to the last stage integrator c3 in the multi-stage integrator C, and a code ring c6 connected to the non-coherent integrator c5; The multi-stage integrator C is used to perform multi-stage integration on the spread spectrum signal to obtain a multi-stage integration result; The carrier loops c2 and c4 are used to obtain the integration results of each connected integrator c1 and c3 for tracking loop processing; The non-coherent integrator c5 is used to obtain the integration result of the last-stage integrator c3 in the multi-stage integrator C, perform non-coherent accumulation, and obtain a non-coherent integration result; The code ring c6 is used to obtain the incoherent integration result and perform code ring processing; The carrier loop c4 connected to the last stage integrator c3 in the multi-stage integrator is also used to obtain the incoherent integration result to perform long-term incoherent carrier tracking processing.

[0018] In addition to being a two-stage integrator, the multi-stage integrator in this embodiment can also be expanded to a three-stage integrator, a four-stage integrator, or other multi-stage integrators. The number of stages of the integrator and the supporting loops is not limited, and more flexible hybrid loop tracking can be achieved.

[0019] Specifically, the carrier loop c4 in this embodiment can switch to obtain the incoherent integration result to perform long-term incoherent carrier tracking processing when the carrier-to-noise ratio is low and the first-stage PLL output shows little dynamics.

[0020] In one embodiment, the multi-stage integrator C includes a first-stage short-time integrator c1 and a second-stage long-time integrator c3; the carrier loop includes a short-time carrier loop c2 connected to the first-stage short-time integrator c1 and a long-time carrier loop c4 connected to the second-stage long-time integrator c3; The first-stage short-time integrator c1 is used to perform short-time integration on the spread spectrum signal to obtain a short-time integration result; The second-stage long-time integrator c3 is used to perform long-time integration on the spread spectrum signal to obtain a long-time integration result; The short-time carrier loop c2 is used to obtain the short-time integration result and perform short-time tracking loop processing; The long-time carrier loop c4 is used to obtain the long-time integration result and perform long-time tracking loop processing.

[0021] Specifically, in one embodiment, the short-time carrier loop c2 is also specifically used to obtain the short-time integration result, track the high symbol rate signal in the spread spectrum signal, or track the signal phase; the long-time carrier loop c4 is also specifically used to obtain the long-time integration result, track the low symbol rate signal in the spread spectrum signal, or track the signal frequency.

[0022] By flexibly configuring the short-time carrier loop c2 and the long-time carrier loop c4, this embodiment can take into account complex scenarios such as high dynamics and low dynamics, and is more practical.

[0023] In actual application, the first-stage short-time integrator c1 is specifically used to perform short-time integration processing on the spread spectrum signal with an integration time of 1 ms to obtain a short-time integration result of 1 ms; the second-stage long-time integrator c3 is specifically used to accumulate the short-time integration result of 1 ms 10 times to obtain a long-time integration result of 10 ms.

[0024] Correspondingly, the incoherent integrator c5 is specifically used to obtain the long-time integration result from the second-stage long-time integrator c3, perform 20 times of incoherent accumulation, and obtain the incoherent integration result once every 200 ms.

[0025] In practical applications, in addition to setting the short-time integration time to 1 ms, the short-time integration time can also be set to 5 ms, etc., or even smaller, such as 0.125 ms, etc., to support the receiver to track a larger Doppler change rate. At the same time, the accumulation times of the second-stage long-time integrator C3 and the non-coherent integrator C5 can be set to other values, not limited to 10 times and 20 times.

[0026] In one embodiment, the short-time carrier loop c2 is a third-order phase-locked loop structure, and the long-time carrier loop c4 is a third-order phase-locked loop structure assisted by a frequency-locked loop.

[0027] The short-term carrier loop c2 in this embodiment can also be configured as other order loops or FLL auxiliary, etc. Meanwhile, the long-term carrier loop c4 can also be configured as other order loops or FLL auxiliary, etc.

[0028] The short-time carrier loop c2 in this embodiment can perform carrier loop tracking on the short-time integration result of 1 ms through the third-order phase-locked loop structure. The long-time carrier loop c4 can process the long-time integration result of 10 ms through the third-order PLL phase-locked tracking loop, and implement the carrier frequency-locked loop on the incoherent integration result of 200 ms through the auxiliary frequency-locked loop.

[0029] This embodiment proposes a spread spectrum signal long-short hybrid loop tracking method based on a multi-stage integrator, which adopts a short-time integration loop and a long-time integration hybrid loop tracking method, and cooperates with a multi-stage integrator. The short-time integration loop can be used to track high symbol rates or stronger signals, and supports intermittent loop operations and refreshes. The long-time tracking loop can track low symbol rates, small dynamic signals or weak signals, or the short-time integration loop is used to track the signal phase, and the long-time tracking loop is used to track the signal frequency, etc., and the usage is flexible.

[0030] The embodiment of the present invention also provides a spread spectrum signal long-short time mixed loop tracking method, which is applied to a spread spectrum signal long-short time mixed loop tracking system, wherein the system includes a multi-stage integrator and a carrier loop connected to each of the integrators, an incoherent integrator connected to the last stage integrator of the multi-stage integrator, and a code loop connected to the incoherent integrator; see Figure 2 , the method comprising: Step 101: using each integrator in the multi-stage integrator to integrate the spread spectrum signal respectively to obtain a multi-stage integration result; Step 102: using the non-coherent integrator, obtaining the integration result of the last stage integrator in the multi-stage integrator, performing non-coherent accumulation, and obtaining a non-coherent integration result; Step 103: using a carrier loop connected to each of the integrators to perform tracking loop processing on the integration result of each of the integrators; Step 104: using a carrier loop connected to the last stage integrator in the multi-stage integrator, when the carrier-to-noise ratio is poor and the dynamics are low, obtaining an incoherent integration result to perform long-term incoherent carrier tracking processing; Step 105: weighted integration is performed on the tracking results of each carrier loop according to preset weights to obtain a hybrid loop tracking result of the spread spectrum signal.

[0031] Specifically, in one embodiment, when the multi-stage integrator includes a first-stage short-time integrator and a second-stage long-time integrator, and the carrier loop includes a short-time carrier loop connected to the first-stage short-time integrator and a long-time carrier loop connected to the second-stage long-time integrator; the first-stage short-time integrator is used to perform short-time integration on the spread spectrum signal to obtain a short-time integration result; the second-stage long-time integrator is used to perform long-time integration on the spread spectrum signal to obtain a long-time integration result; the short-time carrier loop is used to obtain the short-time integration result for short-time tracking loop processing; the long-time carrier loop is used to obtain the long-time integration result for long-time tracking loop processing, and when the carrier-to-noise ratio is poor and the dynamics are low, an incoherent integration result is obtained for long-time incoherent carrier tracking processing.

[0032] Here, the weights may be set in the following manner: obtaining a carrier-to-noise ratio, and assigning a corresponding weight to each of the carrier loops according to the value of the carrier-to-noise ratio; or obtaining a symbol rate of a spread spectrum signal, and assigning a corresponding weight to each of the carrier loops according to the symbol rate of the spread spectrum signal.

[0033] In this embodiment, the weight alpha of the short-time carrier loop and the weight beta of the long-time carrier loop can be set according to the limiting conditions of the signal Doppler, acceleration, level, etc. of the target overall application environment, or can be set in combination with the CNR and the real-time change of the carrier output by the short-time PLL. For example, it can be set that when the CNR is large, the result weight of the short-time carrier loop is large, and when the CNR is weak, the weight of the long-time loop is increased, etc.; or the short-time carrier loop is enabled when the current frame is a high symbol rate, the weight is 1, and the long-time carrier loop is 0 to adapt to the variable symbol rate. The long-time carrier loop is enabled when the current frame is a low symbol rate, the weight is 1, and the short-time carrier loop is 0 at this time. Or when the CNR is large, the short-time carrier loop weight is 0.9, the long-time carrier loop weight is 0.1, and so on.

[0034] In one embodiment, a carrier loop connected to the last integrator in the multi-stage integrator is used to perform tracking loop processing on the integration result of the last integrator in the multi-stage integrator using a third-order phase-locked tracking loop; and a frequency-locked loop is used to perform long-term incoherent carrier tracking processing on the incoherent integration result.

[0035] In addition, the method of this embodiment further includes: using the code loop to obtain the incoherent integration result to perform delay locked loop tracking processing.

[0036] This embodiment provides a long-short-time mixed loop tracking method for spread spectrum signals based on a multi-stage integrator. In view of the problem that common GNSS receivers use a single-cycle coherent integration time and loop that is difficult to be compatible with complex scenarios such as high dynamics and low dynamics, a short-time integration loop and a long-time integration mixed loop tracking method are adopted in conjunction with a multi-stage integrator to achieve long-time and short-time loop joint operation. The method is suitable for tracking spread spectrum signals of various symbol rates, while taking into account complex scenarios such as high dynamics and low dynamics, and has stronger practicality.

[0037] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0038] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A spread spectrum signal long-short time hybrid loop tracking system, characterized in that: include: A multi-stage integrator and a carrier loop connected to each of the integrators, a non-coherent integrator connected to the last stage integrator of the multi-stage integrator and a code loop connected to the non-coherent integrator; The multi-stage integrator is used to perform multi-stage integration on the spread spectrum signal to obtain a multi-stage integration result; The carrier loop is used to obtain the integration result of each connected integrator for tracking loop processing; The non-coherent integrator is used to obtain the integration result of the last stage integrator in the multi-stage integrator, perform non-coherent accumulation, and obtain a non-coherent integration result; The code ring is used to obtain the incoherent integration result and perform code ring processing; Wherein, the carrier loop connected to the last stage integrator in the multi-stage integrator is also used to obtain the incoherent integration result to perform long-term incoherent carrier tracking processing.

2. The spread spectrum signal long-short time hybrid loop tracking system according to claim 1, characterized in that: The multi-stage integrator includes a first-stage short-time integrator and a second-stage long-time integrator; the carrier loop includes a short-time carrier loop connected to the first-stage short-time integrator and a long-time carrier loop connected to the second-stage long-time integrator; The first-stage short-time integrator is used to perform short-time integration on the spread spectrum signal to obtain a short-time integration result; The second-stage long-time integrator is used to perform long-time integration on the spread spectrum signal to obtain a long-time integration result; The short-time carrier loop is used to obtain the short-time integration result and perform short-time tracking loop processing; The long-time carrier loop is used to obtain the long-time integration result and perform long-time tracking loop processing.

3. The spread spectrum signal long-short time hybrid loop tracking system according to claim 2, characterized in that: The short-time carrier loop is specifically used to obtain the short-time integration result, track the high symbol rate signal in the spread spectrum signal or track the signal phase; the long-time carrier loop is specifically used to obtain the long-time integration result, track the low symbol rate signal in the spread spectrum signal or track the signal frequency.

4. The spread spectrum signal long-short time hybrid loop tracking system according to claim 2, characterized in that: The first-stage short-time integrator is specifically used to perform short-time integration processing on the spread spectrum signal with an integration time of 1ms to obtain a short-time integration result of 1ms; the second-stage long-time integrator is specifically used to accumulate the short-time integration result of 1ms 10 times to obtain a long-time integration result of 10ms.

5. The spread spectrum signal long-short time hybrid loop tracking system according to claim 2, characterized in that: The short-time carrier loop is a third-order phase-locked loop structure, and the long-time carrier loop is a third-order phase-locked loop structure assisted by a frequency-locked loop.

6. A method for tracking a spread spectrum signal long-short time hybrid loop, characterized in that: The invention is applied to a long-short-time hybrid loop tracking system for spread spectrum signals, the system comprising a multi-stage integrator and a carrier loop connected to each of the integrators, an incoherent integrator connected to the last stage integrator in the multi-stage integrator, and a code loop connected to the incoherent integrator; the method comprises: Using each integrator in the multi-stage integrator, respectively integrate the spread spectrum signal to obtain a multi-stage integration result; Using the non-coherent integrator, obtaining the integration result of the last stage integrator in the multi-stage integrator, performing non-coherent accumulation, and obtaining a non-coherent integration result; Using a carrier loop connected to each of the integrators, tracking loop processing is performed on the integration result of each of the integrators; By using a carrier loop connected to the last stage integrator in the multi-stage integrator, when the carrier-to-noise ratio is poor and the dynamics are low, an incoherent integration result is obtained to perform long-term incoherent carrier tracking processing; According to the preset weights, the tracking results of each carrier loop are weighted and integrated to obtain the hybrid loop tracking result of the spread spectrum signal.

7. The method for tracking a spread spectrum signal long-short time hybrid loop according to claim 6, characterized in that: The multi-stage integrator includes a first-stage short-time integrator and a second-stage long-time integrator, and the carrier loop includes a short-time carrier loop connected to the first-stage short-time integrator and a long-time carrier loop connected to the second-stage long-time integrator; using each integrator in the multi-stage integrator to integrate the spread spectrum signal respectively to obtain a multi-stage integration result, including: Using the first-stage short-time integrator, short-time integrate the spread spectrum signal to obtain a short-time integration result; Using the second-stage long-time integrator, long-time integration is performed on the spread spectrum signal to obtain a long-time integration result; Utilizing the short-time carrier loop, obtaining the short-time integration result to perform short-time tracking loop processing; The long-time carrier loop is used to obtain the long-time integration result for long-time tracking loop processing, and when the carrier-to-noise ratio is poor and the dynamics are low, the incoherent integration result is obtained for long-time incoherent carrier tracking processing.

8. The method for tracking a spread spectrum signal long-short time hybrid loop according to claim 6, characterized in that: The weight setting method includes: Acquire a carrier-to-noise ratio, and assign a corresponding weight to each of the carrier rings according to the value of the carrier-to-noise ratio; or, A symbol rate of a spread spectrum signal is acquired, and a corresponding weight is allocated to each of the carrier loops according to the symbol rate of the spread spectrum signal.

9. The method for tracking a spread spectrum signal long-short time hybrid loop according to claim 6, characterized in that: Using a carrier loop connected to the last integrator in the multi-stage integrator, a third-order phase-locked tracking loop is used to perform tracking loop processing on the integration result of the last integrator in the multi-stage integrator; A frequency locked loop is used to perform long-term incoherent carrier tracking processing on the incoherent integration result.

10. The method for tracking a spread spectrum signal long-short time hybrid loop according to claim 6, characterized in that: The method further comprises: The code loop is used to obtain the incoherent integration result for delay locked loop tracking processing.

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