A carrier frequency synchronization method

Abstract

The application provides a carrier frequency synchronization method applied to a frequency hopping data transmission system, the frequency hopping data transmission system comprising a transmitting end and a receiving end, and the method comprises the following steps: the transmitting end processes to-be-sent data into a data frame, adds a pilot head based on a ZC sequence to the data frame to form a frequency hopping data transmission frame, and sends a radio frequency signal carrying the frequency hopping data transmission frame to the receiving end; the receiving end acquires the radio frequency signal, processes the radio frequency signal into a digital signal; carrier synchronization processing is performed on the digital signal, carrier frequency scanning is performed on multiple frequency hopping points to screen effective communication frequency points; the starting position of the data frame is determined according to the effective communication frequency points, data demodulation and decoding are performed on the data frame, and original data is recovered. Through the application, the excellent autocorrelation characteristics of the ZC sequence and the intelligent double-peak detection mechanism are utilized to realize carrier frequency synchronization without strict time synchronization, and fast and anti-interference data transmission is completed.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically to a carrier frequency synchronization method. Background Technology

[0002] Existing data transmission systems primarily employ either the direct method or the pilot insertion method for carrier synchronization. The direct method is suitable when the modulated signal itself contains a carrier component, while the pilot insertion method involves inserting a known pilot signal at the transmitting end, which the receiving end then detects to recover the carrier. However, in OFDM frequency-hopping data transmission systems, current technologies generally rely on time-point-based carrier synchronization, meaning the receiver and transmitter agree to switch carrier frequencies at a specific time. This time-point-based synchronization method presents a serious technical problem: it requires strict time synchronization between the transmitting and receiving ends. Any time anomalies or deviations between the two ends can lead to frequency synchronization failure, thereby interrupting communication. Summary of the Invention

[0003] Therefore, the present invention provides a carrier frequency synchronization method, which aims to solve the technical problem that the existing technology requires strict synchronization of the time on both the transmitting and receiving sides when performing carrier synchronization based on time points, and is heavily dependent on timing information.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] According to a first aspect of the present invention, the present invention provides a carrier frequency synchronization method applied to a frequency hopping data transmission system, the frequency hopping data transmission system including a transmitter and a receiver, the method comprising: The transmitting end processes the data to be transmitted into a data frame, adds a pilot header based on the ZC sequence to the data frame to form a frequency hopping data transmission frame, and sends the radio frequency signal carrying the frequency hopping data transmission frame to the receiving end. The receiving end acquires the radio frequency signal and processes the radio frequency signal into a digital signal; Carrier synchronization processing is performed on the digital signal by scanning the carrier frequency of multiple frequency hopping points to select effective communication frequency points; The starting position of the data frame is determined based on the effective communication frequency point, so as to demodulate and decode the data frame and recover the original data.

[0006] Furthermore, before adding a pilot header based on a ZC sequence to the data frame to form a frequency-hopping data transmission frame, the method further includes: Generating the frequency domain pilot head based on the ZC sequence specifically includes: Generate a multi-point pilot header according to the following formula:

[0007] in, Represents a ZC sequence; Indicates the root index; Indicates the offset parameter; Represents the imaginary unit; Pi is a constant. Indicates the length of the ZC sequence; Indicates a sequence index; The frequency domain pilot head is generated by mapping the multi-point pilot head to the corresponding effective subcarrier positions. The frequency domain pilot head is subjected to an inverse fast Fourier transform to generate a time domain pilot head to be transmitted, which serves as the pilot head.

[0008] Further, adding a pilot header based on a ZC sequence to the data frame to form a frequency-hopping data transmission frame includes: According to the preset number of frequency hopping, the specified number of pilot headers, timing synchronization headers and data frames are spliced ​​together in a preset format to form a complete frequency hopping data transmission frame; The number of pilot heads is four times the preset number of frequency hopping plus one.

[0009] Furthermore, the carrier synchronization processing for the digital signal, which involves scanning multiple frequency hopping points to filter for valid communication frequencies, includes: The receiving end performs carrier frequency scanning on multiple frequency hopping points with a preset number of pilot head times as the switching period; During the frequency dwell time at each frequency hopping point, frequency switching and AGC gain adjustment are performed using the first pilot head time, and carrier synchronization and carrier validity are performed using the subsequent pilot head time. A dual-peak detection mechanism based on dynamic threshold is used to determine whether the current frequency hopping point is a valid communication frequency point. If the current frequency hopping point is not a valid communication frequency point, then the next frequency hopping point is switched according to the switching cycle and a valid communication frequency point judgment is performed until the valid communication frequency point is determined.

[0010] Furthermore, the step of using a dynamic threshold-based dual-peak detection mechanism to determine whether the current frequency hopping point is a valid communication frequency point includes: For the current frequency hopping point, perform a point-by-point sliding correlation operation on the digital signal based on a time window according to the local ZC sequence to obtain the correlation operation result; Compare the correlation calculation result with a preset minimum threshold. When the correlation calculation result exceeds the preset minimum threshold for the first time, it is considered that a first correlation peak is detected, and the first correlation peak information including the time point and the correlation power value is recorded. Calculate the decision threshold for the second relevant peak value based on the relevant power value; and determine the time range in which the second relevant peak value occurs based on the time point. If a second correlation peak value higher than the decision threshold is detected within the time range, the current frequency hopping point is considered a valid communication frequency point.

[0011] Furthermore, the method also includes: After detecting the first correlation peak, the correlation calculation results are continuously monitored within the time window. If a new correlation peak with a higher correlation power value than the first correlation peak appears, the first correlation peak information is updated using the new correlation peak. The decision threshold and time range of the second relevant peak value are updated based on the updated first relevant peak value information.

[0012] Furthermore, the calculation formula for the sliding correlation operation is as follows:

[0013] in, Indicates the index of the starting sampling point of the current sliding window; Represents the complex conjugate operation; This indicates the offset of the sampling points within the sliding window, covering the local ZC sequence; S represents a digital signal; S represents a known reference template. Indicates the first The relevant calculation results corresponding to each initial sampling point.

[0014] Furthermore, the formula for calculating the preset minimum threshold is as follows:

[0015] in, Indicates the first The relevant calculation results corresponding to each initial sampling point; Indicates the first The preset minimum threshold corresponding to each initial sampling point; This represents the noise figure.

[0016] Further, determining the start position of the data frame based on the effective communication frequency point includes: Lock the effective communication frequency point and continuously perform sliding correlation detection on the digital signal to match the timing synchronization header in the frequency hopping data transmission frame; The starting position of the data frame is determined based on the position of the timing synchronization header.

[0017] Further, the process of processing the data to be sent into data frames includes: The data to be transmitted is encoded and modulated to form the data frame; And / or, The step of processing the radio frequency signal into a digital signal includes: The radio frequency signal is down-converted, processed by an ADC, and then subjected to digital low-pass filtering to obtain the digital signal.

[0018] The present invention, by adopting the above technical solution, has at least the following beneficial effects: This invention provides a carrier frequency synchronization method applied to a frequency-hopping data transmission system. The system includes a transmitter and a receiver. The method comprises: the transmitter processing the data to be transmitted into data frames; adding a pilot header based on a ZC sequence to the data frames to form frequency-hopping data transmission frames; and transmitting a radio frequency signal carrying the frequency-hopping data transmission frames to the receiver. The receiver acquires the radio frequency signal and processes it into a digital signal. Carrier synchronization processing is performed on the digital signal by scanning multiple frequency-hopping points to select effective communication frequencies. The starting position of the data frame is determined based on the effective communication frequencies, and the data frame is demodulated and decoded to recover the original data. This invention utilizes the excellent autocorrelation characteristics of the ZC sequence and an intelligent double-peak detection mechanism to achieve carrier frequency synchronization without strict time synchronization, enabling fast and interference-resistant data transmission.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the structure of a frequency hopping data transmission system provided in an embodiment of the present invention is shown; Figure 2 A schematic flowchart of a carrier frequency synchronization method provided in an embodiment of the present invention is shown; Figure 3 A schematic diagram illustrating the principle of frequency domain mapping provided in an embodiment of the present invention is shown; Figure 4 A schematic diagram of the structure of a frequency hopping data transmission frame provided in an embodiment of the present invention is shown; Figure 5A schematic diagram of a carrier synchronization process provided in an embodiment of the present invention is shown; Figure 6 A schematic diagram illustrating the principle of frequency hopping communication provided in an embodiment of the present invention is shown; Figure 7 A flowchart illustrating the determination of valid communication frequency points according to an embodiment of the present invention is shown. Detailed Implementation

[0022] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0023] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0024] This invention proposes a carrier frequency synchronization method, applicable to, for example... Figure 1 The frequency-hopping data transmission system shown consists of a transmitting device (hereinafter referred to as the transmitter) and a receiving device (hereinafter referred to as the receiver), which transmit wireless signals through an antenna. Figure 2 As shown, the carrier frequency synchronization method provided in this embodiment of the invention may include at least the following steps S201~S204: In step S201, the transmitting end processes the data to be transmitted into a data frame, adds a pilot header based on the ZC sequence to the data frame to form a frequency hopping data transmission frame, and sends the radio frequency signal carrying the frequency hopping data transmission frame to the receiving end.

[0025] First, the transmitting end encodes and modulates the data to be transmitted to form a data frame. By adding a pilot header to the data frame, a complete frequency-hopping data transmission frame (wireless frame) is formed. The wireless frame can then be up-converted and amplified through the radio frequency link to generate a radio frequency signal and be sent to the air interface, so that the receiving end can receive the radio frequency signal through the air interface.

[0026] This invention employs a pilot head based on the ZC sequence. The ZC sequence has the following characteristics: constant envelope and low peak-to-average power ratio (PAPR): all elements have constant amplitudes, reducing the risk of nonlinear distortion in the RF power amplifier; zero cyclic autocorrelation: the autocorrelation value is zero during non-zero shifts, ensuring precise synchronization; fixed cross-correlation: the cross-correlation values ​​of different root sequences are normalized to... , This indicates the length of the ZC sequence; Fourier transform invariance: the transformed sequence remains a ZC sequence, suitable for frequency domain processing in frequency-hopping data transmission systems. Understandably, based on these superior characteristics, the ZC sequence can effectively resist interference and efficiently support accurate carrier synchronization and frequency estimation.

[0027] Specifically, the formula for generating the ZC sequence is as follows:

[0028] in, Represents a ZC sequence; Indicates the root index; Indicates the offset parameter, according to The parity values; Represents the imaginary unit; Pi is a constant. Indicates the length of the ZC sequence; This represents a sequence index. In practical applications of this invention, it is preferred to... =138, =9, c=0.

[0029] Therefore, a 139-point pilot header can be generated according to the above formula, which can be simplified as follows: , ,..., Then, the 139 pilot points can be mapped in the frequency domain to the corresponding effective subcarrier positions to obtain the frequency domain pilot, and the time domain pilot to be transmitted can be generated through inverse fast Fourier transform. Specifically, as follows... Figure 3 The diagram shows the principle of frequency domain mapping. It can be seen that there are 58 idle subcarriers on each side, serving as guard bands to reduce spectrum leakage and adjacent channel interference; the DC subcarrier is located at the center of the frequency domain and typically does not carry data, but is used for synchronization and calibration; excluding the idle and DC subcarriers, the middle portion consists of effective subcarriers, carrying a total of 138 frequency selection symbols. By performing a 256-point inverse fast Fourier transform (IFFT), a 256-point time-domain pilot header to be transmitted is generated, represented as: , ,..., It is necessary to pre-store this time-domain pilot header at the receiver for use in performing carrier synchronization.

[0030] Furthermore, in this embodiment of the invention, a pilot header based on a ZC sequence is added to the data frame to form a frequency-hopping data transmission frame. In practical applications, a specified number of pilot headers, timing synchronization headers, and data frames carrying core transmission data can be spliced ​​together according to a preset format based on a preset number of frequency hopping steps to form a complete frequency-hopping data transmission frame. For example... Figure 4 As shown, the splicing order from left to right is pilot header, timing synchronization header, and data frame. Assuming the number of frequency hopping is N, then 4 pilot headers need to be sent. N+1 items.

[0031] Step S202: The receiving end acquires the radio frequency signal and processes the radio frequency signal into a digital signal.

[0032] The receiving end acquires the radio frequency (RF) signal and performs down-conversion, ADC (Analog-to-Digital Converter) processing, and digital low-pass filtering on the RF signal to filter out out-of-band interference in the ADC data, retain the useful signal bandwidth, and avoid interference affecting the accuracy of subsequent related calculations. The low-pass filtered digital signal is denoted as... .

[0033] Step S203: Carrier synchronization processing is performed on the digital signal by scanning the carrier frequency of multiple frequency hopping points to select effective communication frequency points.

[0034] Specifically, such as Figure 5 As shown, the specific implementation of step S203 includes at least the following steps S203-1 to S203-3: Step S203-1: The receiving end performs carrier frequency scanning on multiple frequency hopping points with a preset number of pilot head times as the switching period.

[0035] Based on the relationship between the number of frequency hopping steps and the number of transmitting pilot heads, the receiver preferably performs carrier frequency scanning according to the time interval of 4 pilot heads, switching the receiving frequency once every 4 pilot head intervals. Among them, 1 pilot head is used for frequency switching and AGC gain adjustment, and 3 pilot heads are used for carrier synchronization.

[0036] In step S203-2, during the frequency dwell period of each frequency hopping point, frequency switching and AGC gain adjustment are performed using the first pilot head time, and carrier synchronization and carrier validity are performed using the subsequent pilot head time. A dual-peak detection mechanism based on dynamic threshold is used to determine whether the current frequency hopping point is a valid communication frequency point.

[0037] like Figure 6As shown, frequency-hopping communication is illustrated using three frequency hopping points as an example. Assume the frequency-hopping data transmission system communicates between three frequency hopping points f0, f1, and f2. The transmitter sends radio frames on these frequency points, and each radio frame contains a pilot header based on a ZC sequence and a data frame. The receiver's goal is to quickly and accurately lock onto the current effective communication frequency point without knowing the transmitter's frequency hopping order and precise timing.

[0038] In other words, the transmitting end sends radio frames at three frequencies, f0, f1, and f2, using a specific frequency hopping pattern. Each radio frame consists of 13 carrier synchronization frequency selection headers, 1 timing synchronization header, and a data frame. The receiving end switches between the three frequencies, f0, f1, and f2, changing the receiving frequency every four frequency selection headers. During carrier frequency scanning, when a valid carrier signal is detected at a certain frequency (e.g., f0), indicating a valid communication frequency, the receiving end stops frequency switching, locks onto f0, and enters the timing synchronization phase.

[0039] In this embodiment of the invention, a dual-peak detection mechanism based on dynamic thresholds is used to determine whether the current frequency hopping point is a valid communication frequency point. Figure 7 As shown, it may include at least the following steps S203-2-1 to S203-2-4: Step S203-2-1 involves performing a point-by-point sliding correlation operation on the digital signal based on a time window, according to the local ZC sequence, for the current frequency hopping point, to obtain the correlation operation result.

[0040] First, the receiver switches the frequency to the target frequency (e.g., f0) and waits for the received signal power to stabilize to avoid transient fluctuations during frequency switching. Then, it initiates the sliding correlation operation, which processes the digital signal after digital low-pass filtering. The calculation is performed point-by-point with the local 256-point ZC sequence, using the following formula:

[0041] in, Indicates the index of the starting sampling point of the current sliding window; Represents the complex conjugate operation; This represents the sampling point offset within the sliding window, covering the local ZC sequence; S represents a known reference template. Indicates the first The relevant calculation results corresponding to each initial sampling point.

[0042] Step S203-2-2: Compare the correlation calculation result with the preset minimum threshold. When the correlation calculation result is higher than the preset minimum threshold for the first time, it is considered that the first correlation peak is detected, and the first correlation peak information including the time point and the correlation power value is recorded.

[0043] This step involves comparing the current relevant calculation results. and preset minimum threshold To determine whether the first relevant peak has occurred, the formula for calculating the preset minimum threshold is as follows:

[0044] In the formula, Indicates the first The relevant calculation results corresponding to each initial sampling point; Indicates the first The preset minimum threshold corresponding to each initial sampling point; This represents the noise figure, with a preferred value of 32.

[0045] It is understandable that the core function of the preset minimum threshold is to dynamically adapt to the noise environment: when the channel noise is strong, the preset minimum threshold will automatically increase to avoid noise falsely triggering peak detection; when the noise is weak, the preset minimum threshold will decrease to ensure effective detection of weak signals.

[0046] If it appears for the first time > If so, the receiving end determines it as the first relevant peak value and records the corresponding time point (sampling point index). and related power values .

[0047] Step S203-2-3: Calculate the decision threshold of the second related peak value based on the related power value; and determine the time range of the second related peak value based on the time point.

[0048] The receiving end determines the time range of the second correlation peak based on the first correlation peak information calculated in step S203-2-1. And calculate the decision threshold used to verify the second correlation peak. The calculation formula is as follows:

[0049] in, This represents the correlation power value corresponding to the first correlation peak.

[0050] It should be noted that, in this embodiment of the invention, after detecting the first correlation peak, the receiving end does not stop immediately, but rather within a time window (e.g., to (Within +252 range) Continuously monitor the relevant calculation results; if the result is higher than the relevant power value... New related peak ,Right now > Then, the first correlation peak information is updated using the new correlation peak information, and the decision threshold of the second correlation peak is updated based on the updated first correlation peak information. and time range .

[0051] Step S203-2-4: If a second correlation peak value higher than the decision threshold is detected within the time range, the current frequency hopping point is considered to be a valid communication frequency point.

[0052] After completing the dynamic update of the first relevant peak value, the receiver will, within a predetermined time range... Inside, look for the second correlation peak. If in Successfully detected within range ,and The relevant power value is greater than the decision threshold. If this happens, the receiver will determine that the current frequency hopping point f0 is a valid communication frequency. At this point, the receiver will lock onto frequency point f0, stop frequency scanning, and enter the subsequent timing synchronization and data demodulation / decoding stages.

[0053] Step S203-3: If the current frequency hopping point is not a valid communication frequency point, switch to the next frequency hopping point according to the switching cycle and perform a valid communication frequency point judgment until a valid communication frequency point is determined.

[0054] If the receiving end fails to [do something] during the above process A valid bimodal range was detected (i.e., no matching condition was found). If the frequency hopping frequency f0 is not a valid communication frequency, the receiver will switch to the next frequency hopping frequency (e.g., f1) when the frequency switching time arrives, and repeat the above steps S203-2 until a valid communication frequency is found and locked.

[0055] Therefore, through this mechanism based on ZC sequence and dual-peak detection, the receiver can autonomously, efficiently and reliably complete carrier frequency synchronization without knowing the frequency hopping sequence or precise frequency hopping time of the transmitter in advance, thereby realizing frequency hopping communication.

[0056] Step S204: Determine the starting position of the data frame based on the effective communication frequency point, so as to demodulate and decode the data frame and recover the original data.

[0057] This step involves locking onto a valid communication frequency and continuously performing sliding correlation detection on the digital signal to match the timing synchronization header in the radio frame, thus achieving timing synchronization. Once this specific timing synchronization header is detected, the start position of the data frame can be precisely located. For example, if the timing synchronization header appears after a certain fixed offset, the receiver can calculate the accurate sampling point of the first symbol of the data frame, thereby initiating subsequent data demodulation and decoding to ensure correct data processing. After the entire process is completed, the receiver can then enter the next round of carrier frequency scanning, achieving continuous carrier frequency synchronization and data transmission.

[0058] This invention provides a carrier frequency synchronization method applied to a frequency-hopping data transmission system. The frequency-hopping data transmission system includes a transmitter and a receiver. The method includes: the transmitter processing data to be transmitted into data frames, adding a pilot header based on a ZC sequence to the data frames to form frequency-hopping data transmission frames, and transmitting a radio frequency signal carrying the frequency-hopping data transmission frames to the receiver; the receiver acquiring the radio frequency signal, processing the radio frequency signal into a digital signal; performing carrier synchronization processing on the digital signal by scanning multiple frequency-hopping frequencies to select effective communication frequencies; determining the start position of the data frame based on the effective communication frequencies, and demodulating and decoding the data frame to recover the original data. Compared with the prior art, this invention has at least the following beneficial effects: 1) Using ZC sequences as pilot heads provides stronger anti-interference capabilities due to their excellent autocorrelation performance. Furthermore, by grouping pilot heads (e.g., every 4) and assigning them different functions (frequency switching, AGC), the system can quickly adapt to new frequency hopping points, optimizing frequency scanning efficiency and reducing waiting time in non-communication states. Dedicated pilot heads (e.g., 3) to carrier synchronization allow the receiver to obtain richer related information. This may improve the accuracy and anti-interference capability of the "dual-peak detection mechanism" in the core scheme and reduce the probability of misjudgment through the accumulation or comparison of multiple correlation results.

[0059] 2) The use of "correlation operation → dual-peak detection mechanism" for effective communication frequency determination reduces the probability of false alarms and improves the sensitivity of system carrier synchronization. Among them, the introduction of dynamic minimum threshold and its specific calculation formula enable the system to intelligently adjust the detection sensitivity according to the real-time channel noise level, significantly reducing the probability of false alarms in complex noise environments, while ensuring effective detection of weak signals and greatly enhancing the robustness of synchronization. The setting of the second peak decision threshold provides a quantitative standard to verify the effectiveness of the second correlation peak, distinguishing the true ZC sequence signal from the secondary peak generated by random noise or interference, further reducing the probability of false alarms and improving the accuracy of carrier frequency locking.

[0060] 3) Carrier frequency synchronization solves the frequency deviation problem, while timing synchronization solves the uncertainty of the data frame start position. This mechanism ensures that the receiver can not only receive the signal frequency correctly, but also accurately align the data frame in time, thereby achieving complete frame synchronization and laying the foundation for subsequent data demodulation and decoding.

[0061] 4) It achieves rapid frequency switching, and the transceiver module does not need to rely on timing information for data transmission. The receiver is self-synchronizing. Moreover, the receiver does not need to know the frequency hopping order of the transmitter to quickly complete frequency synchronization and data transmission, and has strong anti-interference capability.

[0062] Those skilled in the art will clearly understand that the specific working process of the systems, devices, modules and units described above can be referred to the corresponding process in the foregoing method embodiments. For the sake of brevity, it will not be repeated here.

[0063] Furthermore, the functional units in the various embodiments of the present invention can be physically independent of each other, or two or more functional units can be integrated together, or all functional units can be integrated into one processing unit. The integrated functional units described above can be implemented in hardware, or in software or firmware.

[0064] Those skilled in the art will understand that if the integrated functional unit is implemented in software and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or all or part of it, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computing device (e.g., a personal computer, server, or network device) to execute all or part of the steps of the methods described in the embodiments of the present invention when running the instructions. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0065] Alternatively, all or part of the steps of the foregoing method embodiments can be implemented by hardware (such as a computing device, personal computer, server, or network device) related to program instructions. The program instructions can be stored in a computer-readable storage medium. When the program instructions are executed by the processor of the computing device, the computing device executes all or part of the steps of the methods described in the various embodiments of the present invention.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that within the spirit and principles of the present invention, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the corresponding technical solutions to depart from the protection scope of the present invention.

Claims

1. A carrier frequency synchronization method, characterized in that, Applied to a frequency-hopping data transmission system, the frequency-hopping data transmission system including a transmitter and a receiver, the method includes: The transmitting end processes the data to be transmitted into a data frame, adds a pilot header based on the ZC sequence to the data frame to form a frequency hopping data transmission frame, and sends the radio frequency signal carrying the frequency hopping data transmission frame to the receiving end. The receiving end acquires the radio frequency signal and processes the radio frequency signal into a digital signal; Carrier synchronization processing is performed on the digital signal by scanning the carrier frequency of multiple frequency hopping points to select effective communication frequency points; The starting position of the data frame is determined based on the effective communication frequency point, so as to demodulate and decode the data frame and recover the original data.

2. The method according to claim 1, characterized in that, Before adding a pilot header based on a ZC sequence to the data frame to form a frequency-hopping data transmission frame, the method further includes: Generating a frequency domain pilot head based on the ZC sequence specifically includes: Generate a multi-point pilot header according to the following formula: in, Represents a ZC sequence; Indicates the root index; Indicates the offset parameter; Represents the imaginary unit; Pi is a constant. Indicates the length of the ZC sequence; Indicates a sequence index; The frequency domain pilot head is generated by mapping the multi-point pilot head to the corresponding effective subcarrier positions. The frequency domain pilot head is subjected to an inverse fast Fourier transform to generate a time domain pilot head to be transmitted, which serves as the pilot head.

3. The method according to claim 1, characterized in that, Adding a pilot header based on a ZC sequence to the data frame to form a frequency-hopping data transmission frame includes: According to the preset number of frequency hopping, the specified number of pilot headers, timing synchronization headers and data frames are spliced ​​together in a preset format to form a complete frequency hopping data transmission frame; The number of pilot heads is four times the preset number of frequency hopping plus one.

4. The method according to claim 1, characterized in that, The carrier synchronization processing for the digital signal, which involves scanning multiple frequency hopping points to filter for valid communication frequencies, includes: The receiving end performs carrier frequency scanning on multiple frequency hopping points with a preset number of pilot head times as the switching period; During the frequency dwell time at each frequency hopping point, frequency switching and AGC gain adjustment are performed using the first pilot head time, and carrier synchronization and carrier validity are performed using the subsequent pilot head time. A dual-peak detection mechanism based on dynamic threshold is used to determine whether the current frequency hopping point is a valid communication frequency point. If the current frequency hopping point is not a valid communication frequency point, then the next frequency hopping point is switched according to the switching cycle and a valid communication frequency point judgment is performed until the valid communication frequency point is determined.

5. The method according to claim 4, characterized in that, The method of using a dynamic threshold-based dual-peak detection mechanism to determine whether the current frequency hopping point is a valid communication frequency point includes: For the current frequency hopping point, perform a point-by-point sliding correlation operation on the digital signal based on a time window according to the local ZC sequence to obtain the correlation operation result; Compare the correlation calculation result with a preset minimum threshold. When the correlation calculation result exceeds the preset minimum threshold for the first time, it is considered that a first correlation peak is detected, and the first correlation peak information including the time point and the correlation power value is recorded. Calculate the decision threshold for the second relevant peak value based on the relevant power value; and determine the time range in which the second relevant peak value occurs based on the time point. If a second correlation peak value higher than the decision threshold is detected within the time range, the current frequency hopping point is considered a valid communication frequency point.

6. The method according to claim 5, characterized in that, The method further includes: After detecting the first correlation peak, the correlation calculation results are continuously monitored within the time window. If a new correlation peak with a higher correlation power value than the first correlation peak appears, the first correlation peak information is updated using the new correlation peak. The decision threshold and time range of the second relevant peak value are updated based on the updated first relevant peak value information.

7. The method according to claim 5, characterized in that, The calculation formula for the sliding correlation operation is as follows: in, Indicates the index of the starting sampling point of the current sliding window; Represents the complex conjugate operation; This indicates the offset of the sampling points within the sliding window, covering the local ZC sequence; S represents a digital signal; S represents a known reference template. Indicates the first The relevant calculation results corresponding to each initial sampling point.

8. The method according to claim 5, characterized in that, The formula for calculating the preset minimum threshold is: in, Indicates the first The relevant calculation results corresponding to each initial sampling point; Indicates the first The preset minimum threshold corresponding to each initial sampling point; This represents the noise figure.

9. The method according to claim 3, characterized in that, Determining the start position of the data frame based on the effective communication frequency point includes: Lock the effective communication frequency point and continuously perform sliding correlation detection on the digital signal to match the timing synchronization header in the frequency hopping data transmission frame; The starting position of the data frame is determined based on the position of the timing synchronization header.

10. The method according to any one of claims 1 to 9, characterized in that, The step of processing the data to be sent into data frames includes: The data to be transmitted is encoded and modulated to form the data frame; And / or, The step of processing the radio frequency signal into a digital signal includes: The radio frequency signal is down-converted, processed by an ADC, and then subjected to digital low-pass filtering to obtain the digital signal.

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