A collaborative signal processing method between a direct sequence spread spectrum transceiver and an upper and lower computer

Abstract

This invention proposes a collaborative signal processing method for a direct sequence spread spectrum transceiver and its host computer. The method involves two parts: the transmitter and the receiver. This method fully utilizes the host computer's powerful computing power and memory space, enabling the transceiver to host more complex signal processing algorithms and facilitating updates and iterations. Furthermore, it maintains the high-speed, real-time data processing capabilities of the direct sequence spread spectrum transceiver without compromising performance.

Description

Technical Field

[0001] The present invention relates to the technical field of spread spectrum communication, and in particular to a method for collaboratively processing signals between a direct sequence spread spectrum transceiver and an upper and lower computer. Background Art

[0002] Spread spectrum communication, also known as spread spectrum communication, is a communication method that utilizes a radio frequency signal with a much wider bandwidth than the original signal (the signal generated by the source). In a spread spectrum communication system, the transmitting end uses a specific modulation method to expand the bandwidth of the original signal, generating a spread spectrum signal. The receiving end then processes the received spread spectrum signal to restore it to its original bandwidth. Bandwidth expansion is achieved using an independent code sequence (typically a pseudorandom code) through encoding and modulation methods, independent of the transmitted information data. The receiving end uses the same code sequence for coherent synchronization, despreading, and recovering the transmitted information data. Compared to non-spread spectrum communication (i.e., narrowband communication), spread spectrum communication offers advantages such as strong resistance to narrowband interference, improved eavesdropping resistance, improved multipath immunity, the ability to share the same frequency band with multiple users, and ranging capabilities. It is widely used in both military and civilian fields. Therefore, spread spectrum communication, along with fiber-optic communication and satellite communication, is considered one of the three high-tech communication transmission methods of the information age.

[0003] Direct Sequence Spread Spectrum Communication Systems (DS-SS), often referred to as direct sequence systems or DS-SS systems, multiply the information signal to be transmitted by a high-rate pseudorandom code waveform to directly control a parameter of the radio frequency signal, thereby expanding the bandwidth of the transmitted signal. The pseudorandom sequence used for spectrum spread is called a spreading code sequence. In direct sequence spread spectrum communication systems, the carrier is typically modulated using phase shift keying (PSK). To save transmit power and improve transmitter efficiency, spread spectrum communication systems often use balanced modulators. Balanced modulation with suppressed carrier is also beneficial for improving the anti-detection capabilities of spread spectrum signals.

[0004] With the advancement of semiconductor technology, direct sequence spread spectrum (DSSS) transceivers have become increasingly miniaturized, and their performance has continued to improve. The development of integrated circuits in the 1980s gradually made transceivers accessible to personal use. The advent of software-defined radio (SDRS) in the 1990s further advanced wireless communications and accelerated the development of digital wireless communication transceivers, including DSSS transceivers. Currently, DSSS transceiver designs both domestically and internationally primarily utilize a SDR architecture. SDR technology reduces hardware design and allows for different functions to be implemented without hardware modifications, requiring only software reprogramming and upgrades. Given the numerous functions required in spread spectrum communication, such as spread spectrum signal acquisition, signal tracking, carrier tracking, bit synchronization, frame synchronization, and pseudo-random code generation, and the high speed of the spread spectrum signal, DSSS transceivers require high-speed data processing capabilities. Therefore, DSPs and FPGAs are commonly used processors for implementing spread spectrum communication transceivers, both of which offer fast data processing capabilities.

[0005] While current software-defined radio (SDRS) architectures based on FPGAs or DSPs are experiencing increasing performance and shrinking size, they still have certain drawbacks in signal processing. For a complete DSSS transmitter, the information to be transmitted first undergoes source coding and channel coding to generate efficient and reliable digital source data. This source data undergoes waveform transformation and modulation to create a waveform suitable for channel transmission. This waveform is then multiplied with a pseudo-random code (spreading code) waveform for spread spectrum processing. After mixing, the signal passes through a transmit filter, power amplifier, and matching circuit to complete transmission. A complete DSSS receiver, on the other hand, follows a reverse process: the received signal passes through a receive filter, an RF amplifier, and a mixer before entering a despreader to generate the correct intermediate frequency (IF) signal. This IF signal is then demodulated by a demodulator to generate the baseband signal, which can then be decoded and analyzed. Current direct sequence spread spectrum communication transceivers implement almost all of the above-mentioned complete transmission and reception processes on FPGA or DSP. Therefore, the entire processing flow of the direct sequence spread spectrum signal is implemented on the lower computer. The upper computer is basically only responsible for transmitting the information to be transmitted and receiving the final decoded received information provided by the lower computer.

[0006] This signal processing method has the following drawbacks: (1) It wastes the resources of the host computer. The host computer usually has more memory and more powerful processors than the slave computer, which can implement more complex algorithms and perform more complex signal processing; (2) It increases the difficulty of iterative updates of the communication system. Although the rise of software radio allows developers to use software to program hardware circuits on DSP or FPGA to update or modify signal processing algorithms, many complex algorithms are still more difficult to program on the slave computer than on the host computer. The host computer can support many more advanced programming languages, which makes it easier to iterate and update the functions of the communication system. Summary of the Invention

[0007] To address technical issues or improve upon existing technologies, the present invention proposes a method for collaborative signal processing between a direct sequence spread spectrum transceiver and its host computer. This method fully utilizes the host computer's powerful computing power and memory space, enabling the transceiver to handle more complex signal processing algorithms and facilitating updates and iterations. Furthermore, it maintains the high-speed, real-time data processing capabilities of the direct sequence spread spectrum transceiver without compromising performance.

[0008] The present invention is implemented through the following technical solution. The present invention proposes a method for collaborative signal processing between a direct sequence spread spectrum transceiver and an upper and lower computer. The method acts on the transmitter side. The method includes the following steps:

[0009] Step 1: The direct sequence spread spectrum transmitter starts working;

[0010] Step 2: The host computer performs source encoding on the information to be sent according to the source encoding method selected by the user;

[0011] Step 3: The host computer performs channel coding on the source data according to the channel coding method selected by the user;

[0012] Step 4: The host computer digitally modulates the baseband signal according to the modulation mode and intermediate frequency selected by the user;

[0013] Step 5: The host computer transmits the modulated digital signal and the spread spectrum configuration information selected by the user to the slave computer;

[0014] Step 6: The lower computer performs spread spectrum processing on the digital modulated signal through the spread spectrum configuration information;

[0015] Step 7: The spread spectrum signal passes through the DA module and becomes an analog signal;

[0016] Step 8: After the analog signal is mixed, it passes through the transmit filter, power amplifier, and matching circuit to complete the spread spectrum signal transmission;

[0017] Step 9: The lower computer provides a transmission success signal to the upper computer and determines whether it is necessary to continue transmitting the signal. If necessary, it returns to step 2; otherwise, it ends.

[0018] Furthermore, in step 2, the source coding is to find a method based on the statistical characteristics of the source output symbol sequence to transform the source output symbol sequence into the shortest codeword sequence, so that the average amount of information carried by each codeword of the latter is maximized, while ensuring that the original symbol sequence can be restored without distortion.

[0019] Furthermore, in step 3, channel coding provides error detection and correction capabilities to the transmitted signal by adding error correction coding after source coding.

[0020] Furthermore, in step 4, digital modulation refers to the process of moving the spectrum of the digital baseband signal to the vicinity of the intermediate frequency signal to convert it into a digital bandpass signal. The purpose is to match the characteristics of the signal with the channel and improve the anti-interference ability of the signal when passing through the channel.

[0021] Furthermore, the spread spectrum processing in step 6 refers to the process of performing spectrum expansion on the intermediate frequency signal; specifically, it is as follows:

[0022] Step 1: Generate a pseudo-random code according to the primitive polynomial;

[0023] Step II, multiplying the intermediate frequency signal and the pseudo-random code waveform to obtain a composite code;

[0024] The process of generating the pseudo-random code in step I is completed by a shift register with an initial value. As long as the primitive polynomial is known, the tap position of the shift register can be known. Then, an initial value is attached to each shift register, and the required pseudo-random code can be obtained through circular shifting.

[0025] The present invention also proposes a method for collaboratively processing signals between a direct sequence spread spectrum transceiver and an upper and lower computer. The method operates on the receiver side and comprises the following steps:

[0026] Step 1: The direct sequence spread spectrum receiver starts working;

[0027] Step 2: The host computer transmits the despreading configuration information selected by the user to the despreading module of the slave computer;

[0028] Step 3: The received analog signal passes through the receiving filter, the RF amplifier and then the mixer;

[0029] Step 4: The signal after the mixer is converted into a digital signal before despreading through an AD module;

[0030] Step 5: The lower computer performs despreading processing on the input digital signal according to the despreading configuration information;

[0031] Step 6: The despread intermediate frequency signal is transmitted to the host computer via a high-speed bus;

[0032] Step 7: If there is a signal analysis algorithm, the host computer performs signal analysis on the intermediate frequency signal. If not, proceed to step 8.

[0033] Step 8: The host computer demodulates the intermediate frequency signal according to the signal demodulation method selected by the user;

[0034] Step 9: The host computer performs channel decoding on the baseband signal according to the channel decoding method selected by the user;

[0035] Step 10: The host computer decodes the source signal according to the source decoding method selected by the user;

[0036] Step 11: The host computer displays that the reception is complete and determines whether to continue decoding. If necessary, it returns to step 2; otherwise, it ends.

[0037] Furthermore, the despreading process in step 5 specifically includes the following steps:

[0038] Step 1: Capturing the spread spectrum signal;

[0039] Step II: tracking of spread spectrum signals;

[0040] The step I adopts a sliding correlation capture method, and the step II adopts a delay phase-locked loop to achieve tracking.

[0041] Furthermore, the signal analysis algorithm in step 7 generally refers to various algorithms for analyzing the received intermediate frequency signal.

[0042] The beneficial effects of the present invention are:

[0043] 1. The collaborative signal processing method between the upper and lower computers proposed in the present invention can effectively utilize the computing resources of the upper computer, reduce the computing and space burden of the lower computer, and optimize the resources of the entire communication system.

[0044] 2. The present invention moves complex signal processing to the host computer, allowing developers to use software that is easier to develop to develop the functions of the communication system, and also making it easier to transplant software functions.

[0045] 3. The present invention retains the signal processing of high-speed data in the lower computer, ensuring the communication system's ability to process broadband and high-speed direct sequence spread spectrum signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a flow chart of the collaborative signal processing between a direct-sequence spread spectrum transmitter and its upper and lower computers according to the present invention.

[0047] Figure 2 This is a flow chart of the collaborative signal processing between a direct-sequence spread spectrum receiver and its upper and lower computers according to the present invention.

[0048] Figure 3 This is the principle diagram of direct sequence spread spectrum.

[0049] Figure 4 This is a deconstruction diagram of the pseudo-code synchronization loop for direct sequence despreading. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0051] Direct sequence spread spectrum systems have many functions and require extensive data processing. The signals after spread spectrum transmission have a very high data rate. Signal processing is performed on an FPGA or DSP rather than being transferred to a host computer for further processing. This is due to the inherent latency and bandwidth limitations of communication between the host and the host computer. Therefore, large-bandwidth direct sequence spread spectrum signals can only be processed on the host computer. However, it is worth noting that the intermediate frequency (IF) digital signal before spreading is relatively low-speed data. This data is not processed on the host computer, but rather transmitted to the host computer via a high-speed bus for processing, without significantly impacting the overall performance of the transceiver. Furthermore, complex signal processing methods such as encoding / decoding, modulation / demodulation, optimization algorithms, heuristic algorithms, and deep learning-based algorithms are all performed on the pre-spread data. Therefore, this complex signal processing can be moved to the host computer, utilizing host computer resources while facilitating system software upgrades and updates, as the host computer has more mature programming software and languages. The spread spectrum / despreading processing of large bandwidth and high-speed data is handled by the lower computer. On the one hand, this is because the data processing function of this part is relatively simple to implement, and on the other hand, it can also ensure the real-time performance of the system in processing data.

[0052] See Figures 1-4 The present invention proposes a method for collaborative signal processing between a direct sequence spread spectrum transceiver and an upper and lower computer. The method operates on the transmitter side and comprises the following steps:

[0053] Step 1: The direct sequence spread spectrum transmitter starts working;

[0054] Step 2: The host computer performs source encoding on the information to be sent according to the source encoding method selected by the user;

[0055] The source coding method in step 2 refers to a transformation of source symbols to improve communication efficiency and to reduce or eliminate source redundancy. In step 2, the source coding method is to find a method based on the statistical characteristics of the source output symbol sequence to transform the source output symbol sequence into the shortest codeword sequence, so as to maximize the average information content carried by each codeword, while ensuring that the original symbol sequence can be restored without distortion.

[0056] Step 3: The host computer performs channel coding on the source data according to the channel coding method selected by the user;

[0057] The channel coding in step 3 is to improve the reliability of communication by adding error correction coding after source coding to provide error detection and correction capabilities to the transmitted signal. Common channel coding methods include Hamming coding, convolutional coding, and BCH coding.

[0058] Step 4: The host computer digitally modulates the baseband signal according to the modulation mode and intermediate frequency selected by the user;

[0059] In step 4, digital modulation is the process of shifting the spectrum of the digital baseband signal to near the intermediate frequency signal, converting it into a digital bandpass signal. The purpose is to match the characteristics of the signal with the channel and improve the signal's ability to resist interference when passing through the channel.

[0060] Step 5: The host computer transmits the modulated digital signal and the spread spectrum configuration information selected by the user to the slave computer;

[0061] Step 6: The lower computer performs spread spectrum processing on the digital modulated signal through the spread spectrum configuration information;

[0062] The spread spectrum processing in step 6 refers to the process of spreading the spectrum of the intermediate frequency signal; specifically:

[0063] Step 1: Generate a pseudo-random code according to the primitive polynomial;

[0064] Step II, multiplying the intermediate frequency signal and the pseudo-random code waveform to obtain a composite code;

[0065] The pseudo-random code generation process in step 1 is accomplished by using a shift register with an initial value. Knowing the primitive polynomial allows us to determine the tap positions of the shift register. By assigning an initial value to each shift register and performing a circular shift, we can obtain the desired pseudo-random code.

[0066] Step 7: The spread spectrum signal passes through the DA module and becomes an analog signal;

[0067] Step 8: After the analog signal is mixed, it passes through the transmit filter, power amplifier, and matching circuit to complete the spread spectrum signal transmission;

[0068] Step 9: The lower computer provides a transmission success signal to the upper computer and determines whether it is necessary to continue transmitting the signal. If necessary, it returns to step 2; otherwise, it ends.

[0069] The present invention also proposes a method for collaboratively processing signals between a direct sequence spread spectrum transceiver and an upper and lower computer. The method operates on the receiver side and comprises the following steps:

[0070] Step 1: The direct sequence spread spectrum receiver starts working;

[0071] Step 2: The host computer transmits the despreading configuration information selected by the user to the despreading module of the slave computer;

[0072] Step 3: The received analog signal passes through the receiving filter, the RF amplifier and then the mixer;

[0073] Step 4: The signal after the mixer is converted into a digital signal before despreading through an AD module;

[0074] Step 5: The lower computer performs despreading processing on the input digital signal according to the despreading configuration information;

[0075] The lower computer performs despreading processing on the input digital signal according to the despreading configuration information; the despreading processing in step 5 specifically includes the following steps:

[0076] Step 1: Capturing the spread spectrum signal;

[0077] Step II: tracking of spread spectrum signals;

[0078] Step I uses a sliding correlation capture method, and step II uses a delay-locked loop to achieve tracking. Steps I and II can also be achieved through a full digital pseudo-code synchronization loop without using different loops. Regardless of the method, the method of the present invention is applicable;

[0079] Step 6: The despread intermediate frequency signal is transmitted to the host computer via a high-speed bus;

[0080] Step 7: If there is a signal analysis algorithm, the host computer performs signal analysis on the intermediate frequency signal. If not, proceed to step 8.

[0081] The signal analysis algorithm in step 7 is a general term that refers to various algorithms that analyze the received intermediate frequency signal. For example, the spectrum analysis algorithm can obtain the frequency domain information of the received signal and observe its spectral components; the signal recognition algorithm based on deep learning can use deep learning methods to identify the modulation mode or certain characteristics of the signal; the resource allocation algorithm can allocate the current network resources according to the current signal characteristics; other more complex algorithms can be implemented in the host computer using mature algorithm programs;

[0082] Step 8: The host computer demodulates the intermediate frequency signal according to the signal demodulation method selected by the user;

[0083] Step 9: The host computer performs channel decoding on the baseband signal according to the channel decoding method selected by the user;

[0084] Step 10: The host computer decodes the source signal according to the source decoding method selected by the user;

[0085] Step 11: The host computer displays that the reception is complete and determines whether to continue decoding. If necessary, it returns to step 2; otherwise, it ends.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for collaborative signal processing between a direct sequence spread spectrum transceiver and an upper and lower computer, characterized in that: The method is applied to the transmitter side; the method comprises the following steps: Step 1: The direct sequence spread spectrum transmitter starts working; Step 2: The host computer performs source encoding on the information to be sent according to the source encoding method selected by the user; Step 3: The host computer performs channel coding on the source data according to the channel coding method selected by the user; Step 4: The host computer digitally modulates the baseband signal according to the modulation mode and intermediate frequency selected by the user; Step 5: The host computer transmits the modulated digital signal and the spread spectrum configuration information selected by the user to the slave computer; Step 6: The lower computer performs spread spectrum processing on the digital modulated signal through the spread spectrum configuration information; Step 7: The spread spectrum signal passes through the DA module and becomes an analog signal; Step 8: After the analog signal is mixed, it passes through the transmit filter, power amplifier, and matching circuit to complete the spread spectrum signal transmission; Step 9: The lower computer provides a transmission success signal to the upper computer and determines whether it is necessary to continue transmitting the signal. If necessary, it returns to step 2; otherwise, it ends.

2. The method according to claim 1, wherein: In step 2, the source coding is to find a method based on the statistical characteristics of the source output symbol sequence to transform the source output symbol sequence into the shortest codeword sequence, so that the average amount of information carried by each codeword of the latter is maximized, while ensuring that the original symbol sequence can be restored without distortion.

3. The method according to claim 2, wherein: In step 3, channel coding provides error detection and correction capabilities to the transmitted signal by adding error correction coding after source coding.

4. The method according to claim 3, wherein: In step 4, digital modulation refers to the process of shifting the spectrum of the digital baseband signal to near the intermediate frequency signal to convert it into a digital bandpass signal. The purpose is to match the characteristics of the signal with the channel and improve the anti-interference ability of the signal when passing through the channel.

5. The method according to claim 4, characterized in that: The spread spectrum processing in step 6 refers to the process of spreading the spectrum of the intermediate frequency signal; specifically: Step 1: Generate a pseudo-random code according to the primitive polynomial; Step II, multiplying the intermediate frequency signal and the pseudo-random code waveform to obtain a composite code; The process of generating the pseudo-random code in step I is completed by a shift register with an initial value. As long as the primitive polynomial is known, the tap position of the shift register can be known. Then, an initial value is attached to each shift register, and the required pseudo-random code can be obtained through circular shifting.

6. A method for collaborative signal processing between a direct sequence spread spectrum transceiver and an upper and lower computer, characterized in that: The method is applied to the receiver side and comprises the following steps: Step 1: The direct sequence spread spectrum receiver starts working; Step 2: The host computer transmits the despreading configuration information selected by the user to the despreading module of the slave computer; Step 3: The received analog signal passes through the receiving filter, the RF amplifier and then the mixer; Step 4: The signal after the mixer is converted into a digital signal before despreading through an AD module; Step 5: The lower computer performs despreading processing on the input digital signal according to the despreading configuration information; Step 6: The despread intermediate frequency signal is transmitted to the host computer via a high-speed bus; Step 7: If there is a signal analysis algorithm, the host computer performs signal analysis on the intermediate frequency signal. If not, proceed to step 8. Step 8: The host computer demodulates the intermediate frequency signal according to the signal demodulation method selected by the user; Step 9: The host computer performs channel decoding on the baseband signal according to the channel decoding method selected by the user; Step 10: The host computer decodes the source signal according to the source decoding method selected by the user; Step 11: The host computer displays that the reception is complete and determines whether to continue decoding. If necessary, it returns to step 2; otherwise, it ends.

7. The method according to claim 6, characterized in that: The despreading process in step 5 specifically includes the following steps: Step 1: Capturing the spread spectrum signal; Step II: tracking of spread spectrum signals; The step I adopts a sliding correlation capture method, and the step II adopts a delay phase-locked loop to achieve tracking.

8. The method according to claim 7, wherein: The signal analysis algorithm in step 7 generally refers to various algorithms for analyzing the received intermediate frequency signal.

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