Method for implementing a receiver tracking loop adapted to intermittent network transmissions

Abstract

The application provides a receiver tracking loop implementation method suitable for network intermittent transmission, which comprises a carrier tracking loop composed of a carrier generator, an integral accumulator, a carrier phase error buffer, a first least square linear fitter, a carrier phase discriminator and a carrier loop filter, and a pseudo code tracking loop composed of a pseudo code generator, an integral accumulator, a second least square linear fitter, a code phase discriminator and a code loop filter. The method effectively solves the phenomena of loop jitter loss of lock and system divergence instability of the receiver tracking loop when data interface data packets are intermittently transmitted. The method introduces a linear fitting prediction method, and when the data intermittent transmission phenomenon occurs, the phase error is predicted and output by using the least square linear fitting method, so that the receiver loop can still realize stable tracking operation, and the system reliability is enhanced.

Description

Technical Field

[0001] This invention relates to the field of aerospace telemetry and control technology, and more specifically, to a receiver tracking loop implementation method adapted to intermittent network transmission. Background Technology

[0002] The architecture of aerospace telemetry, tracking, and command (TT&C) ground systems is evolving towards a cloud-based TT&C architecture grounded in network and virtualization technologies. In this cloud architecture, the TT&C baseband processing software is deployed on a cloud platform built from general-purpose servers, known as the cloud baseband. The radio frequency (RF) front-end and the cloud baseband transmit and receive digital signals via a network interface. Compared to traditional TT&C architectures characterized by dedicated baseband processing and RF cable connections, the IP-based, high-efficiency network transmission technology of the cloud TT&C architecture offers advantages such as simplified signal transmission link complexity, improved signal transmission efficiency, and enhanced overall system flexibility. However, it also introduces new challenges.

[0003] The IP-based telemetry and control system architecture changes the traditional signal flow-based, point-to-point, dedicated link transmission mode, replacing it with a data packet-based transmission architecture. Due to network impairments, a certain degree of delay, jitter, and even packet loss is inevitably introduced, causing intermittent data transmission. Distance and velocity measurement are crucial functions of telemetry and control systems. Compared to information demodulation, distance and velocity measurement applications have higher requirements for signal phase stability and data packet loss rate. Ensuring the stability of distance and velocity measurement accuracy under this architecture is one of the key technologies that needs to be addressed.

[0004] Therefore, it is necessary to propose a new receiver loop tracking method to solve the problem of loop jitter and loss of lock caused by intermittent data transmission at the network interface, while ensuring receiver loop tracking performance in the event of data loss. Summary of the Invention

[0005] The present invention aims to at least solve the technical problem in the prior art where the receiver tracking loop experiences loop jitter and loss of lock, and system divergence and instability when data is transmitted intermittently at the network interface.

[0006] Therefore, the present invention provides a receiver tracking loop implementation method adapted to intermittent network transmission.

[0007] The present invention provides a receiver tracking loop implementation method adapted to intermittent network transmission. The receiver tracking loop includes: a carrier tracking loop consisting of at least a carrier generator, an integrator accumulator, a carrier phase error buffer, and a first least squares linear fitter, and a pseudocode tracking loop consisting of at least a pseudocode generator, an integrator accumulator, and a second least squares linear fitter.

[0008] The method includes the following steps:

[0009] S1. Input the digital baseband signal into the receiver tracking loop. The digital baseband signal is divided into two branches: the I-path baseband signal and the Q-path baseband signal.

[0010] S2. During initial operation, in the carrier tracking loop, the two branches of the digital baseband signal are integrated and accumulated by an integrator and accumulator respectively. The phase error between the local carrier signal and the digital baseband signal during the integration period is detected, and the phase error between the local carrier signal and the digital baseband signal is used as loop feedback input to the carrier generator. In the pseudocode tracking loop, each branch of the digital baseband signal is divided into a leading sub-branch, a real-time sub-branch, and a lagging sub-branch. The signal on each sub-branch is integrated and accumulated by an integrator and accumulator respectively. The code phase error between the local real-time code and the digital baseband signal during the integration period is detected, and the code phase error between the local real-time code and the digital baseband signal is used as loop feedback input to the pseudocode generator.

[0011] S3. The carrier phase error buffer stores the accumulated phase error values ​​of the local carrier signal and the digital baseband signal in real time, and transmits the data to the first least squares linear fitter. The first least squares linear fitter uses the accumulated carrier phase error value corresponding to the index value of the sampled data to obtain the first fitting function in real time through linear fitting. At the same time, the carrier generator normally outputs the output phase and frequency status of the local reproduced carrier. The code phase error buffer stores the accumulated code phase error values ​​of the local instant code and the digital baseband signal in real time, and transmits the data to the second least squares linear fitter. The second least squares linear fitter uses the accumulated code phase error value corresponding to the index value of the sampled data to obtain the second fitting function in real time through linear fitting. At the same time, the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code.

[0012] S4. In the carrier tracking loop, the I-channel baseband signal and the Q-channel baseband signal are mixed and multiplied with the local carrier signal generated by the carrier generator to obtain two first mixed signals. The two first mixed signals are multiplied with the real-time sub-branch components reproduced by the pseudo-code generator of their respective branches and then integrated and accumulated. The phase error between the local carrier signal and the digital baseband signal during the integration period is detected, and the phase error between the local carrier signal and the digital baseband signal is used as loop feedback input to the carrier generator. In the pseudo-code tracking loop, the sub-branch signal of the digital baseband signal is mixed and multiplied with the leading component, real-time component, and lagging component generated by the pseudo-code generator and then integrated and accumulated. The code phase error between the local instant code and the digital baseband signal during the integration period is detected, and the code phase error between the local instant code and the digital baseband signal is used as loop feedback input to the pseudo-code generator.

[0013] S5. When a received digital baseband signal is lost, resulting in packet loss: In the carrier tracking loop, the index value of the subsequently lost sampled data is immediately sent to the first least squares linear fitter. The first least squares linear fitter substitutes the index value into the first fitting function to obtain the accumulated value of the carrier phase error when the signal is missing and sends it to the carrier generator. This allows the local reproduction of the carrier's output phase and frequency state, maintaining the carrier loop locked state. In the pseudocode tracking loop, the index value of the subsequently lost sampled data is immediately sent to the second least squares linear fitter. The second least squares linear fitter substitutes the index value into the second fitting function to obtain the accumulated value of the code phase error when the signal is missing and sends it to the pseudocode generator. This allows the local reproduction of the code's phase and frequency state to be output, maintaining the code loop locked state.

[0014] S6. When the digital baseband signal is input into the receiver tracking loop again, the carrier generator normally outputs the output phase and frequency status of the local reproduced carrier, and at the same time, the first least squares linear fitter performs data fitting synchronously; the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code, and at the same time, the second least squares linear fitter performs data fitting synchronously; the receiver loop enters the corresponding tracking lock state according to the newly received digital baseband signal.

[0015] The receiver tracking loop implementation method for intermittent network transmission according to the above-described technical solution of the present invention may further have the following additional technical features:

[0016] In the above technical solution, the carrier tracking loop further includes a carrier phase detector and a carrier loop filter;

[0017] The carrier phase detector is used to detect the phase error between the local carrier signal and the digital baseband signal during integration. The phase error between the local carrier signal and the digital baseband signal is passed through the carrier loop filter and then used as loop feedback input to the carrier generator.

[0018] In the above technical solution, the pseudo-code tracking loop further includes a code phase detector and a code loop filter;

[0019] The code phase detector is used to detect the code phase error between the local instant code and the digital baseband signal during integration. The code phase error between the local instant code and the digital baseband signal is passed through a code loop filter and then used as loop feedback input to the pseudo code generator.

[0020] In the above technical solution, the first fitting function is:

[0021]

[0022] The coefficients a0 and a1 are solved using the least squares linear fitting determinant, and the calculation method is as follows:

[0023]

[0024]

[0025] Where x represents the sampled data, y i For sampled data x i The index value i corresponds to the accumulated carrier phase error.

[0026] In the above technical solution, the second fitting function is:

[0027] ω(x)=b0+b1x

[0028] The coefficients b0 and b1 are solved using the least squares linear fitting determinant, and the calculation method is as follows:

[0029]

[0030]

[0031] Where x is the sampled data, y′ i For sampled data x i The accumulated code phase error value corresponding to the index value i.

[0032] In the above technical solution, the receiver tracking loop further includes an error accumulation calculation unit;

[0033] In S5, the error accumulation calculation unit uses the first least squares linear fitter to substitute the index value into the first fitting function to obtain the carrier phase error accumulation value when the signal is missing and sends it to the carrier generator; and / or

[0034] In S5, the error accumulation calculation unit uses the second least squares linear fitter to substitute the index value into the second fitting function to obtain the accumulated value of the missing signal's time code phase error and sends it to the pseudo code generator.

[0035] In the above technical solution, S2 employs a two-quadrant arctangent function method to detect the phase error between the local carrier signal and the digital baseband signal during the integration period. The two-quadrant arctangent function method includes:

[0036]

[0037] Among them, I p Q is the real-time component on the I-channel baseband signal. p For the real-time components on the Q-band baseband signal, This represents the phase difference at that time.

[0038] In the above technical solution, S2 employs a unitized incoherent lead-lag assignment method to detect the code phase error of the local instantaneous code and digital baseband signal during integration. This unitized incoherent lead-lag assignment method includes:

[0039]

[0040] Where E represents a lead-copy C / A code, L represents a lag-copy C / A code, the correlation interval is 1 / 2 symbol, and δ cp This represents the code phase difference at that time.

[0041] In the above technical solution, the receiver tracking loop further includes an interrupt detector, which is used to detect whether packet loss occurs in the digital baseband signal. The interrupt detector is connected to the first least squares linear fitter and the second least squares linear fitter respectively.

[0042] In summary, due to the adoption of the above-mentioned technical features, the beneficial effects of the present invention are:

[0043] This effectively solves the problems of loop jitter and loss of lock, as well as system divergence and instability, that occur in the receiver tracking loop when data packets are transmitted intermittently at the data interface. By introducing a linear fitting prediction method, when intermittent data transmission occurs, the phase error is predicted using a least-squares linear fitting method, ensuring stable tracking operation of the receiver loop and enhancing system reliability.

[0044] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0045] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0046] Figure 1 This is a schematic diagram of the receiver tracking loop in a receiver tracking loop implementation method adapted to intermittent network transmission according to an embodiment of the present invention.

[0047] Figure 2 This is a graph showing the unpredictable cumulative output error during network intermittent transmission in a receiver tracking loop implementation method adapted to network intermittent transmission according to an embodiment of the present invention.

[0048] Figure 3 This is a graph showing the cumulative output error after prediction during intermittent network transmission in a receiver tracking loop implementation method adapted to intermittent network transmission according to an embodiment of the present invention.

[0049] Figure 4This is a convergence curve of the carrier tracking loop that was not predicted during network intermittent transmission in a receiver tracking loop implementation method adapted to network intermittent transmission according to an embodiment of the present invention.

[0050] Figure 5 This is a convergence curve of the predicted carrier tracking loop in a receiver tracking loop implementation method adapted to intermittent network transmission according to an embodiment of the present invention. Detailed Implementation

[0051] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0052] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0053] The following reference Figures 1 to 5 This describes a receiver tracking loop implementation method adapted to intermittent network transmission provided by some embodiments of the present invention.

[0054] Some embodiments of this application provide a receiver tracking loop implementation method adapted to intermittent network transmission.

[0055] The first embodiment of the present invention proposes a receiver tracking loop implementation method adapted to intermittent network transmission. The receiver tracking loop includes: a carrier tracking loop consisting of at least a carrier generator, an integrator accumulator, a carrier phase error buffer, and a first least squares linear fitter, and a pseudocode tracking loop consisting of at least a pseudocode generator, an integrator accumulator, and a second least squares linear fitter.

[0056] The method includes the following steps:

[0057] S1. Input the digital baseband signal into the receiver tracking loop. The digital baseband signal is divided into two branches: the I-path baseband signal and the Q-path baseband signal.

[0058] S2. During initial operation, in the carrier tracking loop, the two branches of the digital baseband signal are integrated and accumulated by an integrator and accumulator respectively. The phase error between the local carrier signal and the digital baseband signal during the integration period is detected, and the phase error between the local carrier signal and the digital baseband signal is used as loop feedback input to the carrier generator. In the pseudocode tracking loop, each branch of the digital baseband signal is divided into a leading sub-branch, a real-time sub-branch, and a lagging sub-branch. The signal on each sub-branch is integrated and accumulated by an integrator and accumulator respectively. The code phase error between the local real-time code and the digital baseband signal during the integration period is detected, and the code phase error between the local real-time code and the digital baseband signal is used as loop feedback input to the pseudocode generator.

[0059] S3. The carrier phase error buffer stores the accumulated phase error values ​​of the local carrier signal and the digital baseband signal in real time, and transmits the data to the first least squares linear fitter. The first least squares linear fitter uses the accumulated carrier phase error value corresponding to the index value of the sampled data to obtain the first fitting function in real time through linear fitting. At the same time, the carrier generator normally outputs the output phase and frequency status of the local reproduced carrier. The code phase error buffer stores the accumulated code phase error values ​​of the local instant code and the digital baseband signal in real time, and transmits the data to the second least squares linear fitter. The second least squares linear fitter uses the accumulated code phase error value corresponding to the index value of the sampled data to obtain the second fitting function in real time through linear fitting. At the same time, the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code.

[0060] S4. In the carrier tracking loop, the I-channel baseband signal and the Q-channel baseband signal are mixed and multiplied with the local carrier signal generated by the carrier generator to obtain two first mixed signals. The two first mixed signals are multiplied with the real-time sub-branch components reproduced by the pseudo-code generator of their respective branches and then integrated and accumulated. The phase error between the local carrier signal and the digital baseband signal during the integration period is detected, and the phase error between the local carrier signal and the digital baseband signal is used as loop feedback input to the carrier generator. In the pseudo-code tracking loop, the sub-branch signal of the digital baseband signal is mixed and multiplied with the leading component, real-time component, and lagging component generated by the pseudo-code generator and then integrated and accumulated. The code phase error between the local instant code and the digital baseband signal during the integration period is detected, and the code phase error between the local instant code and the digital baseband signal is used as loop feedback input to the pseudo-code generator.

[0061] S5. When a received digital baseband signal is lost, resulting in packet loss: In the carrier tracking loop, the index value of the subsequently lost sampled data is immediately sent to the first least squares linear fitter. The first least squares linear fitter substitutes the index value into the first fitting function to obtain the accumulated value of the carrier phase error when the signal is missing and sends it to the carrier generator. This allows the local reproduction of the carrier's output phase and frequency state, maintaining the carrier loop locked state. In the pseudocode tracking loop, the index value of the subsequently lost sampled data is immediately sent to the second least squares linear fitter. The second least squares linear fitter substitutes the index value into the second fitting function to obtain the accumulated value of the code phase error when the signal is missing and sends it to the pseudocode generator. This allows the local reproduction of the code's phase and frequency state to be output, maintaining the code loop locked state.

[0062] S6. When the digital baseband signal is input into the receiver tracking loop again, the carrier generator normally outputs the output phase and frequency status of the local reproduced carrier, and at the same time, the first least squares linear fitter performs data fitting synchronously; the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code, and at the same time, the second least squares linear fitter performs data fitting synchronously; the receiver loop enters the corresponding tracking lock state according to the newly received digital baseband signal.

[0063] The second embodiment of this invention proposes a receiver tracking loop implementation method adapted to intermittent network transmission. Based on the first embodiment, the receiver tracking loop includes: a carrier tracking loop composed of a carrier generator, an integrator-accumulator, a carrier phase error buffer, a first least-squares linear fitter, a carrier phase detector, and a carrier loop filter; and a pseudo-code tracking loop composed of a pseudo-code generator, an integrator-accumulator, a second least-squares linear fitter, a code phase detector, and a code loop filter. The connection method of each component is as follows: Figure 1 As shown, the carrier generator is an NCO carrier generator. The receiver tracking loop also includes an interrupt detector and two error accumulation calculation units. One error accumulation calculation unit is connected to both the NCO carrier generator and the first least squares linear fitter, while the other error accumulation calculation unit is connected to both the pseudocode generator and the second least squares linear fitter. It can be understood that the two error accumulation calculation units can also be combined into one calculation unit, as long as it can simultaneously perform operations on the first and second fitting functions. The interrupt detector receives the digital baseband signal and is connected to both the first and second least squares linear fitters. It is used to detect whether packet loss occurs in the digital baseband signal and transmits the detection result to both the first and second least squares linear fitters.

[0064] The specific steps of implementing a receiver tracking loop to adapt to intermittent network transmission are as follows:

[0065] S1. Input the digital baseband signal into the receiver tracking loop. The digital baseband signal is divided into two branches: I-path baseband signal and Q-path baseband signal. In this embodiment, the frequency offset and code offset of the digital baseband signal are both 50Hz.

[0066] S2. During initial operation, in the carrier tracking loop, the two branch signals I and Q of the digital baseband signal are integrated and accumulated by an integrator and accumulator, respectively. The integration result is input to the carrier phase detector to detect the phase error between the local carrier signal and the digital baseband signal during the integration period. The phase error between the local carrier signal and the digital baseband signal is then filtered by the carrier loop and used as loop feedback input to the NCO carrier generator. In the pseudocode tracking loop, each branch of the digital baseband signal is divided into a leading sub-branch E, a real-time sub-branch P, and a lagging sub-branch L. The signal on each sub-branch is integrated and accumulated by an integrator and accumulator, respectively. The integration result is input to the code phase detector to detect the code phase error between the local instantaneous code and the digital baseband signal during the integration period. The code phase error between the local instantaneous code and the digital baseband signal is then filtered by the code loop and used as loop feedback input to the pseudocode generator.

[0067] In some embodiments, the carrier phase detector in S2 uses a two-quadrant arctangent function method to detect the phase error between the local carrier signal and the digital baseband signal during integration. The use of the two-quadrant arctangent function method includes:

[0068]

[0069] Among them, I p Q is the real-time component on the I-channel baseband signal. p For the real-time components on the Q-band baseband signal, This represents the phase difference at that time.

[0070] In some embodiments, the code phase detector in S2 uses a normalized incoherent lead-hysteresis assignment method to detect the code phase error of the local instantaneous code and the digital baseband signal during integration. The normalized incoherent lead-hysteresis assignment method includes:

[0071]

[0072] Where E represents a lead-copy C / A code, L represents a lag-copy C / A code, the correlation interval is 1 / 2 symbol, and δ cp This represents the code phase difference at that time.

[0073] S3, the carrier phase error buffer stores the accumulated phase error values ​​of the local carrier signal and the digital baseband signal in real time, and transmits the data to the first least squares linear fitter. The first least squares linear fitter uses the sampled data x i The index value i corresponds to the accumulated carrier phase error yi The first fitting function is obtained in real time through linear fitting, while the carrier generator outputs the output phase and frequency state of the locally reproduced carrier normally. The code phase error buffer stores the accumulated code phase error values ​​of the local instantaneous code and digital baseband signal in real time, and transmits the data to the second least squares linear fitter. The second least squares linear fitter uses the sampled data x i The accumulated code phase error value y′ corresponding to the index value i i The second fitting function is obtained in real time through linear fitting, while the pseudocode generator outputs the output phase and frequency status of the local reproducible code normally.

[0074] Specifically, the first fitting function is:

[0075]

[0076] The coefficients a0 and a1 are solved using the least squares linear fitting determinant, and are expressed in matrix form as follows:

[0077]

[0078] Based on the properties of determinants, the calculation methods for a0 and a1 are as follows:

[0079]

[0080]

[0081] Where x represents the sampled data, y i For sampled data x i The index value i corresponds to the accumulated carrier phase error.

[0082] Specifically, the second fitting function is:

[0083] ω(x)=b0+b1x

[0084] Among them, the coefficients b0 and b1 are solved using the least squares linear fitting determinant, along with a0 and a1. The calculation method is as follows:

[0085]

[0086]

[0087] Where x is the sampled data, y′ i For sampled data x i The accumulated code phase error value corresponding to the index value i.

[0088] S4. In the carrier tracking loop, the I-channel baseband signal and the Q-channel baseband signal are mixed and multiplied with the local carrier signal generated by the NCO carrier generator to obtain two first mixed signals, wherein the I-channel signal is multiplied with the sine carrier signal and the Q-channel signal is multiplied with the cosine carrier signal. The two first-channel mixing signals are multiplied by the real-time sub-branch P component reproduced by the pseudo-code generator corresponding to their respective branches, and then integrated and accumulated. The integration result is input to the carrier phase detector to detect the phase error between the local carrier signal and the digital baseband signal during the integration period. The phase error between the local carrier signal and the digital baseband signal is then passed through the carrier loop filter and used as loop feedback input to the NCO carrier generator. In the pseudo-code tracking loop, the sub-branch signals E, P, and L of the digital baseband signal are mixed and multiplied by the leading component, real-time component, and lagging component generated by the pseudo-code generator, respectively, and then integrated and accumulated. The integration result is input to the code phase detector to detect the code phase error between the local instantaneous code and the digital baseband signal during the integration period. The code phase error between the local instantaneous code and the digital baseband signal is then passed through the code loop filter and used as loop feedback input to the pseudo-code generator.

[0089] S5. During the receiver loop's stable tracking phase, when a lost digital baseband signal occurs, resulting in packet loss, the interrupt detector is triggered. In the carrier tracking loop, after the interrupt detector is triggered, the subsequently lost sampling data is immediately processed. index value The data is sent to the first least squares linear fitter, and the error accumulation calculation unit uses the first least squares linear fitter to calculate the index value. Substitute into the first fitting function The accumulated value of carrier phase error when the missing signal is obtained The data is then sent to the NCO carrier generator, which locally reproduces the carrier's output phase and frequency, maintaining the carrier loop locked state. In the pseudocode tracking loop, after the interrupt detector is triggered, the subsequently lost sampling data is immediately processed. index value The data is sent to the second least squares linear fitter, and the error accumulation calculation unit uses the second least squares linear fitter to calculate the index value. Substituting the second fitting function ω(x), we obtain the accumulated value of the time-code phase error of the missing signal. It is then sent to the pseudocode generator, which in turn outputs the phase and frequency of the local reproducible code, maintaining the code ring locked state.

[0090] In one specific embodiment, step 5 takes a carrier tracking loop as an example. Figure 2 (2~2.5)*10 were lost. 6The cumulative carrier phase error curve during the sampling data shows an irregular abrupt change in the curve during the data loss interval. The fitting function ε(x) of the first least-squares linear fitter in the carrier tracking loop during this period is -2.8161 + 1.581x * 10. -6 The cumulative output error curve is obtained by linearly fitting the predicted data. Figure 3 . Figure 4 The loop divergence curve during the period of data loss. Figure 5 To obtain the convergence curve of the carrier tracking loop after linearly fitting the predicted data, the tracking is locked at a frequency offset of 50Hz. The pseudocode loop can be obtained similarly.

[0091] S6. When the digital baseband signal is input into the receiver tracking loop again, the NCO carrier generator normally outputs the output phase and frequency status of the local reproduced carrier, and at the same time, the first least squares linear fitter performs data fitting synchronously; the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code, and at the same time, the second least squares linear fitter performs data fitting synchronously; the receiver loop enters the corresponding tracking lock state according to the newly received digital baseband signal.

[0092] In this specification, the illustrative expressions of the terms used do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0093] Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention shall be included within the scope of protection of this invention.

Claims

1. A receiver tracking loop implementation method adapted to intermittent network transmission, characterized in that, The receiver tracking loop includes: a carrier tracking loop consisting of at least a carrier generator, an integrator accumulator, a carrier phase error buffer, and a first least squares linear fitter, and a pseudocode tracking loop consisting of at least a pseudocode generator, an integrator accumulator, and a second least squares linear fitter; The method includes the following steps: S1. Input the digital baseband signal into the receiver tracking loop. The digital baseband signal is divided into two branches: the I-path baseband signal and the Q-path baseband signal. S2. During initial operation, in the carrier tracking loop, the two branches of the digital baseband signal are integrated and accumulated by an integrator and accumulator respectively. The phase error between the local carrier signal and the digital baseband signal during the integration period is detected, and the phase error between the local carrier signal and the digital baseband signal is used as loop feedback input to the carrier generator. In the pseudocode tracking loop, each branch of the digital baseband signal is divided into a leading sub-branch, a real-time sub-branch, and a lagging sub-branch. The signal on each sub-branch is integrated and accumulated by an integrator and accumulator respectively. The code phase error between the local real-time code and the digital baseband signal during the integration period is detected, and the code phase error between the local real-time code and the digital baseband signal is used as loop feedback input to the pseudocode generator. S3. The carrier phase error buffer stores the accumulated phase error values ​​of the local carrier signal and the digital baseband signal in real time, and transmits the data to the first least squares linear fitter. The first least squares linear fitter uses the accumulated carrier phase error value corresponding to the index value of the sampled data to obtain the first fitting function in real time through linear fitting. At the same time, the carrier generator normally outputs the output phase and frequency status of the local reproduced carrier. The code phase error buffer stores the accumulated code phase error values ​​of the local instant code and the digital baseband signal in real time, and transmits the data to the second least squares linear fitter. The second least squares linear fitter uses the accumulated code phase error value corresponding to the index value of the sampled data to obtain the second fitting function in real time through linear fitting. At the same time, the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code. S4. In the carrier tracking loop, the I-channel baseband signal and the Q-channel baseband signal are mixed and multiplied with the local carrier signal generated by the carrier generator to obtain two first mixed signals. The two first mixed signals are multiplied with the real-time sub-branch components reproduced by the pseudo-code generator of their respective branches and then integrated and accumulated. The phase error between the local carrier signal and the digital baseband signal during the integration period is detected, and the phase error between the local carrier signal and the digital baseband signal is used as loop feedback input to the carrier generator. In the pseudo-code tracking loop, the sub-branch signal of the digital baseband signal is mixed and multiplied with the leading component, real-time component, and lagging component generated by the pseudo-code generator and then integrated and accumulated. The code phase error between the local instant code and the digital baseband signal during the integration period is detected, and the code phase error between the local instant code and the digital baseband signal is used as loop feedback input to the pseudo-code generator. S5. When a received digital baseband signal is lost, resulting in packet loss: In the carrier tracking loop, the index value of the subsequently lost sampled data is immediately sent to the first least squares linear fitter. The first least squares linear fitter substitutes the index value into the first fitting function to obtain the accumulated value of the carrier phase error when the signal is missing and sends it to the carrier generator. This allows the local reproduction of the carrier's output phase and frequency state, maintaining the carrier loop locked state. In the pseudocode tracking loop, the index value of the subsequently lost sampled data is immediately sent to the second least squares linear fitter. The second least squares linear fitter substitutes the index value into the second fitting function to obtain the accumulated value of the code phase error when the signal is missing and sends it to the pseudocode generator. This allows the local reproduction of the code's phase and frequency state to be output, maintaining the code loop locked state. S6. When the digital baseband signal is input into the receiver tracking loop again, the carrier generator normally outputs the output phase and frequency status of the local reproduced carrier, and at the same time, the first least squares linear fitter performs data fitting synchronously; the pseudocode generator normally outputs the output phase and frequency status of the local reproduced code, and at the same time, the second least squares linear fitter performs data fitting synchronously; the receiver loop enters the corresponding tracking lock state according to the newly received digital baseband signal.

2. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, The carrier tracking loop also includes a carrier phase detector and a carrier loop filter; The carrier phase detector is used to detect the phase error between the local carrier signal and the digital baseband signal during integration. The phase error between the local carrier signal and the digital baseband signal is passed through the carrier loop filter and then used as loop feedback input to the carrier generator.

3. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, The pseudocode tracking loop also includes a code phase detector and a code loop filter; The code phase detector is used to detect the code phase error between the local instant code and the digital baseband signal during integration. The code phase error between the local instant code and the digital baseband signal is passed through a code loop filter and then used as loop feedback input to the pseudo code generator.

4. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, The first fitting function is: The coefficients a0 and a1 are solved using the least squares linear fitting determinant, and the calculation method is as follows: Where x represents the sampled data, y i For sampled data x i The index value i corresponds to the accumulated carrier phase error.

5. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, The second fitting function is: ω(x)=b0+b1x The coefficients b0 and b1 are solved using the least squares linear fitting determinant, and the calculation method is as follows: Where x is the sampled data, y′ i For sampled data x i The accumulated code phase error value corresponding to the index value i.

6. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, The receiver tracking loop also includes an error accumulation and calculation unit; In S5, the error accumulation calculation unit uses the first least squares linear fitter to substitute the index value into the first fitting function to obtain the carrier phase error accumulation value when the signal is missing and sends it to the carrier generator; and / or In S5, the error accumulation calculation unit uses the second least squares linear fitter to substitute the index value into the second fitting function to obtain the accumulated value of the missing signal's time code phase error and sends it to the pseudo code generator.

7. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, S2 employs a two-quadrant arctangent function method to detect the phase error between the local carrier signal and the digital baseband signal during integration. The two-quadrant arctangent function method includes: Among them, I p Q is the real-time component on the I-channel baseband signal. p For the real-time components on the Q-band baseband signal, This represents the phase difference at that time.

8. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, In S2, a normalized incoherent lead-lag assignment method is used to detect the code phase error of the local instantaneous code and the digital baseband signal during the integration period. The normalized incoherent lead-lag assignment method includes: Where E represents a lead-copy C / A code, L represents a lag-copy C / A code, the correlation interval is 1 / 2 symbol, and δ cp This represents the code phase difference at that time.

9. The receiver tracking loop implementation method for intermittent network transmission according to claim 1, characterized in that, The receiver tracking loop also includes an interrupt detector, which is used to detect whether packet loss occurs in the digital baseband signal. The interrupt detector is connected to the first least squares linear fitter and the second least squares linear fitter respectively.

Images