Pseudo code tracking method and device

Abstract

The invention relates to a pseudo code tracking method and device, and relates to the technical field of communication, in the method, a target detection interval and a target receiving rate used for tracking a pseudo code in a target signal can be determined according to correlation peak characteristics captured by a pseudo code phase in the target signal, and the target detection interval and the target receiving rate are determined for the target signal; tracking a correlation peak of the target signal according to the target receiving rate and the target detection interval, and determining a phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval under the condition that the correlation peak of the tracked target signal accords with a preset threshold value, a sampling clock rate in the target receive rate is regulated based on the phase deviation vector. Therefore, the phase discrimination range of the pseudo code tracking loop can be effectively expanded by setting the target detection interval, so that the carrier high-dynamic adaptive capacity of the receiving end is improved, a correlator for pseudo code tracking does not need to be specially set in the pseudo code tracking process, the investment of equipment cost is reduced, and the waste of system resources can be reduced.

Description

Background Art

[0002] In a direct sequence spread spectrum communication system, the synchronization system is a prerequisite for data demodulation, and the pseudo-code tracking technology is one of the key synchronization technologies. The receiving end usually uses a matched filter to achieve the initial synchronization of the spread spectrum signal and uses a pseudo-code tracking loop to accurately track the local pseudo-code phase.

[0003] After the acquisition circuit completes the coarse synchronization of the pseudo-code, the received pseudo-code and the local pseudo-code are not completely aligned, and due to the existence of the frequency difference between the two, the pseudo-code synchronization will soon be lost; in order to maintain synchronization, a pseudo-code tracking loop needs to be adopted. At present, there are two methods to implement the pseudo-code tracking loop: the delay locked loop and the alternating correlation locked loop.

[0004] The delay locked loop is a special loop for capturing and tracking a single pseudo-code, mainly used in digital circuits for phase delay compensation and clock adjustment. In order to synchronize the receiver spread spectrum sequence, at least two correlators are required, namely the early correlator and the late correlator. The local pseudo-code phase used by the early correlator is ahead of the accurately estimated local pseudo-code phase, and the local pseudo-code phase used by the late correlator is behind the accurately estimated phase. The energy difference between the outputs of the early and late correlators is used to determine the subtle difference between the timings of the early and late input spread spectrum sequences.

[0005] The delay locked loop takes the difference between the energy accumulation value of the late branch minus the energy accumulation value of the early branch as the phase error signal. After this error signal is fed into the loop filter, it controls the generation of the local pseudo-code. Restricted by the sharp correlation peak, the phase discrimination range of the loop is very small, and the absolute value of its phase discrimination range does not exceed the period of one pseudo-code chip. In a high-dynamic environment, when the loop is locked, if the pseudo-code phase at the receiving end changes by more than one chip, the input of the phase discriminator will exceed its phase discrimination range, resulting in loop unlocking, thus making the dynamic performance of the delay locked loop poor.

[0006] The biggest advantage of the alternating correlation locked loop compared to the delay locked loop is that it only requires one correlator, while the delay locked loop requires two correlators. Its disadvantage is that due to the time-division sharing of the front and rear pseudo-code channels, the signal-to-noise ratio performance of the alternating correlation locked loop deteriorates by about 3 dB, and other performances are similar to those of the delay locked loop.

[0007] In summary, the existing pseudo-code tracking loops have problems such as a small loop phase discrimination range and poor dynamic performance of the carrier. At the same time, in the process of hardware implementation, the tracking loop requires a dedicated correlator, which will lead to additional hardware overhead. It should be noted that the information invented in the above background art section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0008] To overcome the problems existing in the related art, the present disclosure provides a pseudo-code tracking method and apparatus, so as to at least solve the problems that the existing pseudo-code tracking loop in the related art has a small loop phase discrimination range and poor dynamic performance of the carrier, and at the same time, a dedicated correlator is required for the tracking loop during the hardware implementation process, which will cause additional hardware overhead.

[0009] According to one aspect of the present disclosure, a pseudo-code tracking method is provided. The method includes: determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal; for the target signal, tracking the correlation peak of the target signal according to the target reception rate and the target detection interval; when the correlation peak of the target signal being tracked meets a preset threshold, determining a phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval; and regulating the sampling clock rate in the target reception rate based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal.

[0010] Optionally, determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal includes: capturing the pseudo-code phase in the target signal when the spread spectrum signal of the matched filter achieves initial synchronization with the target signal; setting a target detection interval for tracking the pseudo-code in the target signal according to the position of the pseudo-code phase in the target signal; and determining a target reception rate for tracking the pseudo-code in the target signal according to the occurrence frequency of the pseudo-code in the target signal.

[0011] Optionally, after tracking the correlation peak of the target signal according to the target reception rate and the target detection interval for the target signal, the method further includes: counting the correlation peaks of the target signal tracked in the target detection interval within a preset time period, and determining a target ratio of the peak value of the correlation peak of the target signal exceeding the maximum correlation peak threshold; determining whether the tracked target ratio meets the ratio threshold corresponding to the maximum correlation peak threshold; if it meets, performing the operation of determining the phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval; if it does not meet, re-determining the target detection interval, and performing the operation of determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal.

[0012] Optionally, the phase deviation vector includes a phase deviation value and a phase deviation polarity. Determining the phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval includes: determining the phase deviation polarity of the correlation peak of the target signal in the target detection interval according to the relationship between the maximum value position of the correlation peak of the target signal and the center position of the target detection interval; determining the phase deviation value of the correlation peak of the target signal in the target detection interval according to the deviation value between the maximum value of the correlation peak of the target signal and the intermediate value of the target detection interval.

[0013] Optionally, regulating the sampling clock rate in the target reception rate based on the phase deviation vector includes: adjusting the delay of sampling by the local pseudo-code generator according to the phase deviation polarity; controlling the clock rate of the local pseudo-code generator according to the phase deviation value.

[0014] According to an aspect of the present disclosure, there is provided a pseudo-code tracking device, the device includes: a first determination module, configured to determine a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal; a tracking module, configured to, for the target signal, track the correlation peak of the target signal according to the target reception rate and the target detection interval; a second determination module, configured to determine a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval when the correlation peak of the target signal being tracked meets a preset threshold value; a regulation module, configured to regulate the sampling clock rate in the target reception rate based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal.

[0015] Optionally, the first determination module is further configured to: capture the corresponding position of the maximum value of the correlation peak of the target signal when achieving initial synchronization with the target signal by using the spread spectrum signal of the matched filter; set a target detection interval for tracking the pseudo-code in the target signal according to the corresponding position of the maximum value of the correlation peak of the target signal; determine the target reception rate for tracking the pseudo-code in the target signal according to the occurrence frequency of the pseudo-code in the target signal.

[0016] Optionally, the device further includes: a statistics module, configured to count the correlation peaks of the target signal tracked in the target detection interval within a preset time period, and determine a target ratio of the correlation peaks of the target signal whose peak values exceed the correlation peak maximum threshold; a judgment module, configured to judge whether the tracked target ratio meets the ratio threshold corresponding to the correlation peak maximum threshold; if it meets, perform an operation of determining a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval; if it does not meet, re-determine the target detection interval, and perform an operation of determining a target detection interval for tracking the pseudo-code in the target signal and a target reception rate according to the correlation peak characteristics of the pseudo-code phase capture in the target signal.

[0017] Optionally, the phase deviation vector includes a phase deviation value and a phase deviation polarity. The second determination module is further configured to: determine the phase deviation polarity of the correlation peak of the target signal in the target detection interval according to the relationship between the correlation peak maximum position of the target signal and the center position of the target detection interval; determine the phase deviation value of the correlation peak of the target signal in the target detection interval according to the deviation value between the correlation peak maximum of the target signal and the intermediate value of the target detection interval.

[0018] Optionally, the regulation module is further configured to: adjust the time delay of the sampling of the local pseudo-code generator according to the phase deviation polarity; control the clock rate of the local pseudo-code generator according to the phase deviation value.

[0019] In summary, the pseudo-code tracking method provided by the embodiment of the present invention can first determine a target detection interval for tracking the pseudo-code in the target signal and a target reception rate according to the correlation peak characteristics of the pseudo-code phase capture in the target signal. For the target signal, track the correlation peak of the target signal according to the target reception rate and the target detection interval. When the correlation peak of the target signal meets the preset threshold value, determine a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval, and regulate the sampling clock rate in the target reception rate based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal. In this way, on the one hand, by setting the target detection interval, the phase discrimination range of the pseudo-code tracking loop can be effectively expanded, thereby improving the high-dynamic adaptability of the carrier at the receiving end. On the other hand, during the pseudo-code tracking process, there is no need to specifically set a correlator for pseudo-code tracking. The pseudo-code tracking and pseudo-code capture share the same matched filter through time-division multiplexing, which can reduce the consumption of hardware resources, thereby reducing the investment in equipment costs, and then reducing the waste of system resources.

[0020] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Description of the Drawings

[0021] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments in line with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 is a flowchart of steps of a pseudo-code tracking method provided by an embodiment of the present disclosure;

[0023] Figure 2 is a structural diagram of a pseudo-code tracking loop provided by an embodiment of the present disclosure;

[0024] Figure 3 is a structural diagram of the implementation of a matched filter provided by an embodiment of the present disclosure;

[0025] Figure 4 is a flowchart of signal processing of a pseudo-code tracking loop provided by an embodiment of the present disclosure;

[0026] Figure 5 is a block diagram of a pseudo-code tracking device provided by an embodiment of the present disclosure. Detailed implementation manners

[0027] Now, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, well-known technical solutions are not shown or described in detail to avoid obscuring the various aspects of the present disclosure.

[0028] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0029] In a direct sequence spread spectrum communication system, the synchronization system is a prerequisite for data demodulation, and the pseudo-code tracking technology is one of the key technologies for synchronization. At the receiving end, a matched filter is usually used to achieve the initial synchronization of the spread spectrum signal, and a pseudo-code tracking loop is used to accurately track the local pseudo-code phase.

[0030] After the acquisition circuit completes the coarse synchronization of the pseudo-code, the received pseudo-code and the local pseudo-code are not completely aligned, and due to the existence of the frequency difference between the two, the pseudo-code synchronization will soon be lost; in order to maintain synchronization, a pseudo-code tracking loop needs to be adopted. Currently, there are two methods to implement the pseudo-code tracking loop: the delay locked loop and the alternating correlation locked loop.

[0031] The delay locked loop is a special loop for acquiring and tracking a single pseudo-code, mainly used in digital circuits for phase delay compensation and clock adjustment. To synchronize the receiver spread spectrum sequence, at least two correlators are required, namely the early correlator and the late correlator. The local pseudo-code phase used by the early correlator is ahead of the accurately estimated local pseudo-code phase, and the local pseudo-code phase used by the late correlator is behind the accurately estimated phase. The energy difference between the outputs of the early and late correlators is used to determine the subtle difference between the timings of the early and late input spread spectrum sequences.

[0032] The delay locked loop uses the difference between the accumulated energy value of the late branch and the accumulated energy value of the early branch as the phase error signal. After this error signal is sent to the loop filter, it controls the generation of the local pseudo-code. Restricted by the sharp correlation peak, the phase discrimination range of the loop is very small, and the absolute value of its phase discrimination range does not exceed the period of one pseudo-code chip. In a high-dynamic environment, when the loop locks in, if the pseudo-code phase at the receiving end changes by more than one chip, the input of the phase discriminator will exceed its phase discrimination range, resulting in loop unlocking, thus making the dynamic performance of the delay locked loop poor.

[0033] The biggest advantage of the alternating correlation locked loop compared to the delay locked loop is that it only requires one correlator, while the delay locked loop requires two correlators. Its disadvantage is that due to the time-division sharing of the front and rear pseudo-code channels, the signal-to-noise ratio performance of the alternating correlation locked loop deteriorates by about 3 dB, and other performances are similar to those of the delay locked loop.

[0034] In summary, the existing pseudo-code tracking loops have problems such as a small phase discrimination range of the loop and poor dynamic performance of the carrier. At the same time, in the process of hardware implementation, the tracking loop also requires a dedicated correlator, which will lead to additional hardware overhead and increase costs.

[0035] To solve the above technical problems, embodiments of the present disclosure provide a pseudo-code tracking method. First, according to the correlation peak characteristics of the pseudo-code phase capture in the target signal, a target detection interval and a target reception rate for tracking the pseudo-code in the target signal are determined. For the target signal, the correlation peak of the target signal is tracked according to the target reception rate and the target detection interval. When the correlation peak of the target signal meets a preset threshold, a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval is determined. Based on the phase deviation vector, the sampling clock rate in the target reception rate is adjusted so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal. In this way, on the one hand, by setting the target detection interval, the phase discrimination range of the pseudo-code tracking loop can be effectively extended, thereby improving the high-dynamic adaptability of the receiver. On the other hand, during the pseudo-code tracking process, there is no need to specifically set a correlator for pseudo-code tracking, which can reduce the investment in equipment costs and thus reduce the waste of system resources.

[0036] Figure 1 is a flowchart of the steps of a pseudo-code tracking method provided by an embodiment of the present disclosure, as Figure 1 shown, the method may include:

[0037] Step S101: Determine a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal.

[0038] Step S102: For the target signal, track the correlation peak of the target signal according to the target reception rate and the target detection interval.

[0039] Step S103: When the correlation peak of the target signal meets a preset threshold, determine a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval.

[0040] Step S104: Based on the phase deviation vector, adjust the sampling clock rate in the target reception rate so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal.

[0041] Based on Figure 1In the illustrated embodiment, first, according to the correlation peak characteristics of the pseudo-code phase capture in the target signal, the target detection interval and the target reception rate for tracking the pseudo-code in the target signal can be determined. For the target signal, the correlation peak of the target signal is tracked according to the target reception rate and the target detection interval. When the correlation peak of the target signal meets the preset threshold, the phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval is determined, and the sampling clock rate in the target reception rate is adjusted based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal. In this way, on the one hand, by setting the target detection interval, the phase discrimination range of the pseudo-code tracking loop can be effectively expanded, thereby improving the high-dynamic adaptability of the receiver. On the other hand, there is no need to specifically set the correlator for pseudo-code tracking during the pseudo-code tracking process, which can reduce the investment in equipment costs and thus reduce the waste of system resources.

[0042] In an alternative embodiment of the present disclosure, when performing the step of determining the target detection interval and the target reception rate for tracking the pseudo-code in the target signal in S101 of the embodiment of the present disclosure according to the correlation peak characteristics of the pseudo-code phase capture in the target signal, the corresponding position of the maximum value of the correlation peak of the target signal can be captured under the condition of realizing the initial synchronization with the target signal by using the spread-spectrum signal of the matched filter; according to the corresponding position of the maximum value of the correlation peak of the target signal, the target detection interval for tracking the pseudo-code in the target signal is set; according to the occurrence frequency of the pseudo-code in the target signal, the target reception rate for tracking the pseudo-code in the target signal is determined.

[0043] Among them, the target detection interval can also be referred to as the range gate. The maximum value of the correlation peak of the target signal is not the maximum correlation value within the entire chip range.

[0044] Exemplarily, the receiver can preferentially use the matched filter to realize the initial synchronization of the spread-spectrum signal, so that under the condition of initial synchronization, the corresponding position of the maximum value of the correlation peak of the target signal is captured, and then the range gate (i.e., the target detection interval) is set according to the position where the captured maximum correlation peak appears, so that the center of the range gate is aligned with the maximum correlation peak.

[0045] In an alternative embodiment, in the step of capturing the corresponding position of the maximum value of the correlation peak of the target signal, at the rising edge of the range gate (in a digital circuit, the rising edge refers to the moment when the digital level changes from a low level (digital "0") to a high level (digital "1")), the initial value of the register is set to zero. In the subsequent time, as long as the current correlation peak is greater than the register value, the register value is set to the current correlation peak value, and at the falling edge of the range gate (in a digital circuit, the falling edge refers to the moment when the digital level changes from a high level (digital "1") to a low level (digital "0")), the register value is used as the value of the maximum correlation peak. At this time, the corresponding position of the maximum value of the correlation peak of the target signal can be captured.

[0046] Exemplarily, in the pseudo-code tracking stage, it is necessary to always align the target detection interval of the pseudo-code in the target signal with the corresponding position of the maximum value of the correlation peak. Thereafter, if the rates of the transmitted and received pseudo-codes are the same, the pseudo-code synchronization states will always be the same and maintained, so that the center position of the target detection interval will always be aligned with the corresponding position of the maximum value of the correlation peak.

[0047] In practical applications, since there is always a frequency difference between the transmitted and received pseudo-codes, after a period of time after entering the pseudo-code tracking state, if no pseudo-code tracking processing is performed, the transmitted and received pseudo-code signals will quickly lose synchronization, and the center of the target detection interval will no longer be aligned with the maximum value of the correlation peak. Therefore, in order to ensure that the receiver can resume normal operation in the case of loop lock loss caused by some abnormal conditions, the receiver needs to continuously search for the maximum correlation peak within the target detection interval.

[0048] In an alternative embodiment of the present disclosure, the receiver can count the correlation peaks of the target signal tracked in the target detection interval within a preset time period, determine the target ratio of the peak value of the correlation peak of the target signal exceeding the correlation peak maximum threshold; determine whether the tracked target ratio meets the ratio threshold corresponding to the correlation peak maximum threshold; if it meets, perform the operation of determining the phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval; if it does not meet, re-determine the target detection interval, and perform the operation of determining the target detection interval for tracking the pseudo-code in the target signal and the target reception rate according to the correlation peak characteristics of the pseudo-code phase capture of the target signal.

[0049] Exemplarily, the target ratio of the maximum value of the correlation peak exceeding the correlation peak maximum threshold within the target detection interval / range gate can be counted, and this target ratio can be compared with the preset ratio threshold corresponding to the correlation peak maximum threshold. If this target ratio exceeds the preset ratio threshold, it indicates that the loop tracking is normal, and the operation of determining the phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval can be continued.

[0050] Conversely, if the target ratio does not exceed the ratio threshold corresponding to the maximum value threshold of the relevant peak, it indicates that the relevant peak is not within the target detection interval / range gate. At this time, the loop is in a locked - out state. The receiver then needs to switch back to the pseudo - code acquisition state to re - perform pseudo - code tracking in order to achieve continuous tracking of the pseudo - code.

[0051] Optionally, in the embodiments of the present disclosure, the phase deviation vector includes a phase deviation value and a phase deviation polarity. The operation of determining the phase deviation vector between the position of the relevant peak of the target signal and the central position of the target detection interval may specifically include: determining the phase deviation polarity of the relevant peak of the target signal in the target detection interval according to the relationship between the maximum value position of the relevant peak of the target signal and the central position of the target detection interval; determining the phase deviation value of the relevant peak of the target signal in the target detection interval according to the deviation value between the maximum value of the relevant peak of the target signal and the intermediate value of the target detection interval.

[0052] Exemplarily, in order to further achieve continuous tracking of the pseudo - code, it is necessary to continuously search for the maximum value of the relevant peak of the target signal within the target detection interval / range gate. And calculate the distance between the position of the maximum value of the relevant peak and the central position of the target detection interval / range gate. The polarity of the distance value (i.e., the phase deviation polarity) between the position of the maximum value of the relevant peak and the central position of the target detection interval / range gate characterizes whether the local pseudo - code is ahead of the pseudo - code in the received signal or the local pseudo - code lags behind the pseudo - code in the received signal.

[0053] Among them, the magnitude of the phase difference between the local pseudo - code and the received pseudo - code, that is, the phase deviation value, can be characterized by the absolute value of the distance value between the position of the maximum value of the relevant peak of the target signal and the central position of the target detection interval.

[0054] Optionally, in the embodiments of the present disclosure, the operation of regulating the sampling clock rate of the target reception rate based on the phase deviation vector may specifically include: adjusting the sampling delay of the local pseudo - code generator according to the phase deviation polarity; controlling the clock rate of the local pseudo - code generator according to the phase deviation value.

[0055] Exemplarily, the sampling delay of the local pseudo - code generator can be adjusted according to the phase deviation polarity, that is, the rate of the output clock of the NCO(1.6) is regulated according to the phase deviation polarity, which is also the sampling clock rate in the matched filter(1.4). In this way, through continuous feedback and iterative processing of the loop, the central position of the target detection interval / range gate will be aligned with the maximum value of the relevant peak. After subtraction, there is no error output, the control voltage of the NCO tends to zero, and finally the sampling clock rate of the matched filter and the rate of the received pseudo - code signal are kept relevant, thereby achieving the tracking of the pseudo - code.

[0056] To reduce the influence of the change in the length of the pseudo-code period caused by the Doppler effect during the movement of the carrier on the correlation peak, the frequency estimation output of the carrier tracking loop is used to assist the pseudo-code tracking. The specific implementation process is as follows:

[0057] Multiply the frequency deviation value between the local carrier of the target signal and the input signal carrier by a scaling factor, and then send it into the pseudo-code carrier tracking circuit to control the clock rate of the pseudo-code NCO, thereby changing the period length of the local pseudo-code. Since the jitter noise of the carrier tracking loop is much smaller than the noise of the pseudo-code tracking loop, the carrier tracking loop can always provide assistance to the pseudo-code tracking loop, further improving the tracking accuracy of the pseudo-code tracking loop.

[0058] In addition, in the traditional pseudo-code tracking loop, a correlator is used to perform the correlation operation on the received signal. Affected by the sharp autocorrelation characteristic of the pseudo-code, the correlator can only obtain the correlation value when the phase difference between the received pseudo-code and the local pseudo-code does not exceed one code element, which determines that the absolute value of the phase discrimination range of the early-late gate loop based on the correlator does not exceed the width of one pseudo-code element.

[0059] In response to this, the embodiment of the present disclosure uses a matched filter, which can perform the correlation operation with the received signal at all pseudo-code phases, and uses a range gate, that is, the target detection interval, to limit the detection interval of the correlation peak of the target signal. Subsequently, the phase discrimination range of the loop is the width of the target detection interval. Compared with the traditional pseudo-code tracking loop, the phase discrimination range of the loop can be effectively expanded.

[0060] Furthermore, the user can adjust the width of the target detection interval / range gate, thereby adjusting the phase discrimination range of the pseudo-code tracking loop and realizing the online real-time adjustment of the phase discrimination range of the loop.

[0061] In this embodiment, the online real-time adjustment of the phase discrimination range of the loop is considered because in the high-dynamic environment of the carrier, the position of the maximum value of the correlation peak will continuously drift relative to the center position of the target detection interval / range gate. By reasonably setting the width of the range gate or adjusting it in real time, it can be ensured that the position of the maximum value of the correlation peak in the next pseudo-code period is still within the range gate, thereby improving the high-dynamic adaptability of the pseudo-code tracking loop to the carrier.

[0062] The following will combine Figure 2 to make an exemplary description of the structure diagram of a pseudo-code tracking loop provided by the embodiment of the present disclosure.

[0063] Figure 2 is the structure diagram of a pseudo-code tracking loop provided by the embodiment of the present disclosure, as shown in Figure 2As shown in the figure, the pseudo-code closed-loop tracking device based on range gate and maximum correlation peak addressing includes an analog-to-digital conversion A / D (1.1), a down-conversion unit (1.2), a low-pass filter (Low-pass filter, abbreviated as LPF) (1.3), a matched filter (MDF) (1.4), a phase discriminator (1.5), a numerically controlled oscillator (Numerically Controlled Oscillator, abbreviated as NCO) (1.6), and a pseudo-code generator (1.7). After the externally connected analog input intermediate frequency signal is converted into a digital signal by the analog-to-digital conversion A / D (1.1), it enters the down-conversion unit (1.2) and becomes a complex baseband signal. Then, the baseband complex signal is filtered by the low-pass filter (1.3) to remove the upper sideband signal and then enters the matched filter (1.4) for correlation processing. The correlation processing result is sent to the phase discriminator (1.5) for phase discrimination, and the clock frequency output by the NCO (1.6) is controlled according to the phase discrimination result. The output of the NCO (1.6) is connected to the matched filter (1.4) for the clock used in correlation processing.

[0064] Exemplarily, when the pseudo-code tracking device is powered on, internal initialization settings are performed for each module (corresponding to Figure 4 steps 300-310 in). After the settings are completed, the receiver enters the pseudo-code acquisition state. At the same time, the A / D (1.1) performs analog-to-digital conversion on the input analog intermediate frequency signal. After subsequent down-conversion (1.2) and low-pass filtering (1.3) processing, I / Q two-channel baseband signals are obtained. The matched filter (1.4) uses the input I / Q baseband signals for matched filtering processing and outputs the correlation value between the received signal and the local pseudo-code.

[0065] Further, in an optional embodiment of the present disclosure, the matched filter used in the above embodiment may be a delay line matched filter. Its working principle is to use the pseudo-random sequence for spreading spectrum at the transmitting end as the tap coefficients of a digital finite impulse response filter, also known as a non-recursive filter (Finite Impulse Response, abbreviated as FIR filter), and perform correlation filtering on the received spread spectrum signal.

[0066] The following will combine Figure 3 to give an exemplary illustration of the structure of the above-mentioned used matched filter.

[0067] Figure 3 is a structure diagram of a matched filter implementation provided by an embodiment of the present disclosure. As Figure 3 shown, the matched filter mainly consists of three parts: a shift register, a multiplier, and a multi-input parallel adder, and is a structure similar to an FIR digital filter.

[0068] By such as Figure 3The matching filter structure performs the operation of the following formula (1) on the input target signal:

[0069]

[0070] In formula (1), r(n) is the signal output after being processed by the matching filter; x(n) is the input target signal; h(-i) is the filter coefficient, which is determined by the PN code at the receiving end. The length of the matching filter is equal to the pseudo-code period N. Since the value of the filter coefficient h(-i) is 1 or -1, multiplication can be simplified to addition and subtraction operations. When h(-i) is 1, it corresponds to an addition operation, and when h(-i) is -1, it corresponds to a subtraction operation, thus greatly reducing the hardware resource consumption of the matching filter.

[0071] Exemplarily, Figure 4 is a flowchart of pseudo-code tracking loop signal processing provided by an embodiment of the present disclosure. As Figure 4 shown, 310. The device is powered on; 311. Initialize the device; 312. Calculate the correlation value using the matching filter; 313. Capture the pseudo-code of the target signal; 314. Determine whether the correlation peak ratio of the captured target signal meets a preset threshold. If it meets, execute 315. If it does not meet, execute 312; 315. Set the target detection interval for tracking the target signal according to the correlation value; 316. Search for the correlation peak where the target signal appears within the target detection interval; 317. Statistically calculate the ratio of the maximum value of the correlation peak within the target detection interval that meets the preset threshold; 318. Determine whether the code loop is unlocked. If it is, execute 312. If it is not, execute 319; 319. Address the position of the maximum correlation peak; 320. Calculate the deviation between the position of the maximum correlation peak and the center of the distance gate; 321. Use the carrier loop-assisted digital control oscillator to regulate the sampling clock rate; 322. The pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal.

[0072] Figure 5 is a block diagram of a pseudo-code tracking device provided by an embodiment of the present disclosure. As Figure 5 shown, the pseudo-code tracking device 50 may include a first determination module 501, a tracking module 502, a second determination module 503, and a regulation module 504.

[0073] Among them, the first determination module 501 is configured to determine a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal; the tracking module 502 is configured to, for the target signal, track the correlation peak of the target signal according to the target reception rate and the target detection interval; the second determination module 503 is configured to determine a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval when the correlation peak of the target signal being tracked meets a preset threshold; the regulation module 504 is configured to regulate the sampling clock rate in the target reception rate based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal.

[0074] Based on the above-provided pseudo-code tracking device, it is possible to first determine a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal. For the target signal, track the correlation peak of the target signal according to the target reception rate and the target detection interval. When the correlation peak of the target signal being tracked meets a preset threshold, determine a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval, and regulate the sampling clock rate in the target reception rate based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal. In this way, on the one hand, by setting the target detection interval, the phase discrimination range of the pseudo-code tracking loop can be effectively expanded, thereby improving the high-dynamic adaptation ability of the receiver. On the other hand, during the pseudo-code tracking process, there is no need to specifically set a correlator for pseudo-code tracking, which can reduce the investment in equipment costs and thus reduce the waste of system resources.

[0075] Optionally, the first determination module 501 is further configured to: when achieving initial synchronization with the target signal by using the spread-spectrum signal of the matched filter, capture the corresponding position of the maximum value of the correlation peak of the target signal; set a target detection interval for tracking the pseudo-code in the target signal according to the corresponding position of the maximum value of the correlation peak of the target signal; determine a target reception rate for tracking the pseudo-code in the target signal according to the occurrence frequency of the pseudo-code in the target signal.

[0076] Optionally, the preset threshold includes a maximum correlation peak threshold and a corresponding ratio threshold. The apparatus 50 further includes: a statistics module and a determination module. The statistics module is configured to count the correlation peaks of the target signal tracked in the target detection interval within a preset time period, and determine a target ratio of the correlation peak value of the target signal exceeding the maximum correlation peak threshold. The determination module is configured to determine whether the tracked target ratio meets the ratio threshold corresponding to the maximum correlation peak threshold. If it meets, perform an operation of determining a phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval. If it does not meet, re-determine the target detection interval, and perform an operation of determining a target detection interval for tracking the pseudo-code in the target signal and a target reception rate according to the correlation peak characteristics of the pseudo-code phase capture in the target signal.

[0077] Optionally, the phase deviation vector includes a phase deviation value and a phase deviation polarity. The second determination module 503 is further configured to: determine the phase deviation polarity of the correlation peak of the target signal in the target detection interval according to the relationship between the maximum correlation peak position of the target signal and the center position of the target detection interval; and determine the phase deviation value of the correlation peak of the target signal in the target detection interval according to the deviation value between the maximum correlation peak of the target signal and the intermediate value of the target detection interval.

[0078] Optionally, the regulation module 504 is further configured to: adjust the time delay of the sampling of the local pseudo-code generator according to the phase deviation polarity; and control the clock rate of the local pseudo-code generator according to the phase deviation value.

[0079] The specific details of each module in the above pseudo-code tracking apparatus have been described in detail in the corresponding pseudo-code tracking method, and thus will not be elaborated here.

[0080] It should be noted that although several modules or units of the devices for action execution are mentioned in the above detailed description, such a division is not mandatory. In fact, according to the embodiments of the present disclosure, the features and functions of the two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0081] In addition, although the steps of the methods in the present disclosure are described in a specific order in the drawings, this does not require or imply that these steps must be executed in that specific order, or that all the steps shown must be executed to achieve the desired result. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step for execution, and / or one step may be decomposed into multiple steps for execution, etc.

[0082] Those skilled in the art can understand that various aspects of the present disclosure can be implemented as a system, a method, or a program product. Therefore, various aspects of the present disclosure can be specifically implemented in the following forms, namely: a complete hardware implementation, a complete software implementation (including firmware, microcode, etc.), or an implementation combining hardware and software aspects, which can be collectively referred to as "circuitry", "module", or "system" here.

[0083] In addition, the above-mentioned drawings are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, rather than for the purpose of limitation. It is easy to understand that the processes shown in the above-mentioned drawings do not indicate or limit the chronological order of these processes. Additionally, it is also easy to understand that these processes can be executed, for example, synchronously or asynchronously in multiple modules.

[0084] After considering the specification and practicing the invention herein, those skilled in the art will readily conceive of other embodiments of the present disclosure. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include well-known knowledge or conventional technical means in the technical field not invented by the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the claims.

Claims

1. A pseudo-code tracking method, characterized in that The method includes: Determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal; For the target signal, tracking the correlation peak of the target signal at the target reception rate and within the target detection interval; When the correlation peak of the target signal being tracked meets a preset threshold value, determining a phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval; Based on the phase deviation vector, regulating the sampling clock rate in the target reception rate so that the sampling clock rate matches the pseudo-code rate of the target signal, and enabling the pseudo-code frequency and phase generated by the local pseudo-code generator to be synchronized with the pseudo-code of the target signal.

2. The method according to claim 1, wherein The determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal includes: When achieving initial synchronization with the target signal by using a spread-spectrum signal of a matched filter, capturing the corresponding position of the maximum value of the correlation peak of the target signal; Setting a target detection interval for tracking the pseudo-code in the target signal according to the corresponding position of the maximum value of the correlation peak of the target signal; Determining a target reception rate for tracking the pseudo-code in the target signal according to the occurrence frequency of the pseudo-code in the target signal.

3. The method according to claim 1, wherein The preset threshold value includes a correlation peak maximum threshold and a corresponding ratio threshold. After tracking the correlation peak of the target signal at the target reception rate and within the target detection interval for the target signal, it further includes: Counting the correlation peaks of the target signal tracked within the target detection interval during a preset time period, and determining a target ratio of the peak value of the correlation peak of the target signal exceeding the correlation peak maximum threshold; Judging whether the tracked target ratio meets the ratio threshold corresponding to the correlation peak maximum threshold; If it meets, performing the operation of determining the phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval; If it does not meet, re-determining the target detection interval and performing the operation of determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal.

4. The method according to claim 3, wherein The phase deviation vector includes a phase deviation value and a phase deviation polarity. The determining a phase deviation vector between the position of the correlation peak of the target signal and the center position of the target detection interval includes: Determining the phase deviation polarity of the correlation peak of the target signal in the target detection interval according to the relationship between the maximum value position of the correlation peak of the target signal and the center position of the target detection interval; Determining the phase deviation value of the correlation peak of the target signal in the target detection interval according to the deviation value between the maximum value of the correlation peak of the target signal and the intermediate value of the target detection interval.

5. The method according to claim 4, characterized in that, The regulating the sampling clock frequency in the target reception rate based on the phase deviation vector includes: Adjust the time delay of sampling by the local pseudo-code generator according to the phase deviation polarity; Control the clock rate of the local pseudo-code generator according to the phase deviation value.

6. A pseudo-code tracking device, characterized in that, The device includes: A first determination module, configured to determine a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal; A tracking module, configured to track the correlation peak of the target signal at the target reception rate and within the target detection interval for the target signal; A second determination module, configured to determine a phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval when the correlation peak of the target signal being tracked meets a preset threshold; A regulation module, configured to regulate the sampling clock rate in the target reception rate based on the phase deviation vector, so that the sampling clock rate matches the pseudo-code rate of the target signal, and the pseudo-code frequency and phase generated by the local pseudo-code generator are synchronized with the pseudo-code of the target signal.

7. The device according to claim 6, characterized in that, The first determination module is further configured to: Capture the corresponding position of the maximum value of the correlation peak of the target signal when achieving initial synchronization with the target signal using the spread-spectrum signal of the matched filter; Set a target detection interval for tracking the pseudo-code in the target signal according to the corresponding position of the maximum value of the correlation peak of the target signal; Determine a target reception rate for tracking the pseudo-code in the target signal according to the occurrence frequency of the pseudo-code in the target signal.

8. The device according to claim 6, wherein The preset threshold includes a correlation peak maximum threshold and a corresponding ratio threshold, and the device further includes: A statistics module, configured to count the peak values of the correlation peaks of the target signal tracked within the target detection interval within a preset time period, and determine a target ratio of the peak values of the correlation peaks of the target signal exceeding the correlation peak maximum threshold; A judgment module, configured to judge whether the tracked target ratio meets the ratio threshold corresponding to the correlation peak maximum threshold; if it meets, perform the operation of determining the phase deviation vector between the correlation peak position of the target signal and the center position of the target detection interval; if it does not meet, re-determine the target detection interval, and perform the operation of determining a target detection interval and a target reception rate for tracking the pseudo-code in the target signal according to the correlation peak characteristics of the pseudo-code phase capture in the target signal.

9. The device according to claim 8, characterized in that, The phase deviation vector includes a phase deviation value and a phase deviation polarity, and the second determination module is further configured to: Determine the phase deviation polarity of the correlation peak of the target signal in the target detection interval according to the relationship between the maximum value position of the correlation peak of the target signal and the center position of the target detection interval; Determine the phase deviation value of the correlation peak of the target signal in the target detection interval according to the deviation value between the maximum value of the correlation peak of the target signal and the intermediate value of the target detection interval.

10. The device according to claim 9, characterized in that, The regulation module is further configured to: Adjust the time delay of sampling by the local pseudo-code generator according to the phase deviation polarity; Control the clock rate of the local pseudo-code generator according to the phase deviation value.

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