A hybrid capture method, device and system for spread spectrum baseband

Abstract

The present invention relates to the field of wireless spread spectrum communication technology, and specifically discloses a hybrid capture method for spread spectrum baseband, comprising: step S1: acquiring the current communication environment of the digital baseband; step S2: determining the current capture mode of the digital baseband according to the current communication environment of the digital baseband; step S3: controlling the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture. The present invention also discloses a hybrid capture device and system for spread spectrum baseband. The hybrid capture method for spread spectrum baseband provided by the present invention can select the capture mode according to the user's specific requirements for capture success rate and capture time, thereby having better adaptability.

Description

Technical Field

[0001] The present invention relates to the field of wireless spread spectrum communication technology, and in particular to a hybrid capture method for spread spectrum baseband, a hybrid capture device for spread spectrum baseband, and a hybrid capture system for spread spectrum baseband comprising the hybrid capture device for spread spectrum baseband. Background Art

[0002] Direct sequence spread spectrum can widen the frequency band of data through high-speed pseudo-code information at the transmitting end, which can reduce the spectral density of the signal or transmit it under noise, thereby improving the concealment of the transmission; it can also widen the spectrum of narrowband noise introduced into the channel at the receiving end, thereby improving the system's ability to resist narrowband noise interference. Therefore, direct sequence spread spectrum is widely used in wireless communication systems, making the communication system have good anti-interference, anti-fading capabilities and a certain degree of concealment.

[0003] Common capture methods include serial capture, parallel capture, matched filter capture and PMF-FFT capture methods. The first three are based on time domain capture. The PMF-FFT capture method captures from both the time domain and the frequency domain, making the capture more accurate. The serial capture method is small in area and slow in speed. The parallel capture method is fast, but consumes more area. The matched filter method is used more because it neutralizes the parallel and serial methods. The PMF-FFT method captures from a two-dimensional perspective and has better accuracy. With the development of artificial intelligence, there are now some methods that combine artificial intelligence neural networks for capture, but they are only in the simulation stage, mainly used for matched filtering. In the case of large frequency deviation, the PMF-FFT method will be used to implement it.

[0004] In the capture of spread spectrum codes, matched filtering is commonly used. However, currently, only a single capture method is used. In a good environment, the energy value needs to be calculated, which increases power consumption and prolongs the capture time. In a bad environment, the capture may fail. Summary of the invention

[0005] In view of the defects and shortcomings in the prior art, the present invention provides a hybrid capture method for spread spectrum baseband, which can select the capture mode according to the user's specific requirements for capture success rate and capture time, thereby having better adaptability.

[0006] As a first aspect of the present invention, a hybrid acquisition method for spread spectrum baseband is provided, the hybrid acquisition method for spread spectrum baseband comprising:

[0007] Step S1: Acquire the current communication environment of the digital baseband;

[0008] Step S2: determining a current acquisition mode of the digital baseband according to the current communication environment of the digital baseband;

[0009] Step S3: controlling the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture.

[0010] Further, the determining the current acquisition mode of the digital baseband according to the current communication environment of the digital baseband further includes:

[0011] In the initial state, the current capture mode of the digital baseband is defaulted to an adaptive threshold matched filter capture method;

[0012] If the current communication environment of the digital baseband is good, the current acquisition mode of the digital baseband is switched to a fixed threshold matched filter acquisition method;

[0013] If the current communication environment of the digital baseband is poor, the current acquisition method of the digital baseband is switched to the PMF-FFT acquisition method.

[0014] Furthermore, the adaptive threshold matched filter capture method includes:

[0015] Step S11: the digital baseband acquires data with a length four times that of the spread spectrum code;

[0016] Step S12: sampling the data of four times the spread spectrum code length every four sampling points to extract down-sampled data;

[0017] Step S13: performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data, and comparing the accumulated value data with an adaptive threshold value;

[0018] Step S14: determine whether the maximum value in the accumulated value data is greater than the adaptive threshold value; if so, proceed to step S15; otherwise, proceed to step S16;

[0019] Step S15: Select four data points before and after the maximum value;

[0020] Step S16: Wait for the next clock, wait for new data input, and return to step S11;

[0021] Step S17: Determine whether the four data point values ​​before and after the maximum value are all less than the adaptive threshold value; if so, proceed to step S18, otherwise, proceed to step S19;

[0022] Step S18: the digital baseband captures data successfully once;

[0023] Step S19: Wait for the next clock, wait for new data input, and return to step S11;

[0024] Repeat the data capture operation of step S11 to step S19 within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the data capture operation.

[0025] Further, the correlating operation of the down-sampled data with a known spread spectrum code to obtain accumulated value data includes:

[0026] Assuming that the data of four times the length of the spread spectrum code input by the digital baseband is signal_in_data(n), n is the length of the input data, then the data after downsampling is signal_sample_data(4n), assuming that the code sequence of the known spread spectrum code is PN(n), and the accumulated value data output after the relevant operation is signal_out(m), m refers to the length of the accumulated value data, and the calculation formula of the accumulated value data signal_out(m) is as follows:

[0027]

[0028] Furthermore, the calculation process of the adaptive threshold value includes:

[0029] Dividing the downsampled data signal_sample_data (4n) into two paths to obtain two paths of divided data;

[0030] According to the divided two paths of data, the energy value signal_energy(n) of the downsampled data signal_sample_data(4n) is calculated. The calculation formula of the energy value signal_energy(n) is as follows:

[0031] signal_energy(n) 2 =[signal_sample_data_i(4n)] 2 +[signal_sample_data_q(4n)] 2

[0032] Among them, signal_sample_data_i(4n) is the first data after division, and signal_sample_data_q(4n) is the second data after division;

[0033] The adaptive threshold value is obtained by multiplying the energy value signal_energy(n) of the downsampled data by the threshold coefficient ratio.

[0034] Furthermore, the method for determining the maximum value and the four data points before and after the maximum value in the accumulated value data includes:

[0035] First, set a register max and a register POS for storing the maximum value and its position, and clear them to zero;

[0036] Second, determine whether the input accumulated value data is greater than the maximum value in the register max; if so, update the maximum value in the register max to the accumulated value data input this time; otherwise, return to re-enter the new accumulated value data;

[0037] Third, repeat the above judgment process until the accumulated value data calculated this time is traversed, and the last updated maximum value in the register max is obtained, which is the maximum value in the accumulated value data, and the position of the last updated maximum value in the register max is output to the register POS;

[0038] Finally, according to the position of the last updated maximum value in the register max, four data points before and after the last updated maximum value are selected.

[0039] Furthermore, the fixed threshold matched filter capture method includes:

[0040] Step S21: the digital baseband acquires data with a length four times that of the spread spectrum code;

[0041] Step S22: sampling the data of four times the spread spectrum code length every four sampling points to extract down-sampled data;

[0042] Step S23: performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data, and comparing the accumulated value data with a fixed threshold value;

[0043] Step S24: determine whether the maximum value in the accumulated value data is greater than a fixed threshold value; if so, proceed to step S25; otherwise, proceed to step S26;

[0044] Step S25: the digital baseband captures data successfully once;

[0045] Step S26: Wait for the next clock, wait for new data input, and return to step S21;

[0046] Repeat the data capture operation of step S21 to step S26 within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the data capture operation.

[0047] Further, the PMF-FFT acquisition method includes:

[0048] The digital baseband acquires data of four times the length of the spread spectrum code;

[0049] Sampling the data of four times the length of the spread spectrum code once every four sampling points, and extracting down-sampled data;

[0050] The down-sampled data is correlated with a known spread spectrum code, and partially matched filtered to obtain accumulated value data;

[0051] Cache the accumulated value data;

[0052] The cached accumulated value data is padded with zeros to perform FFT operation, and the maximum value after FFT operation is compared with the threshold value;

[0053] If the maximum value after FFT operation is greater than the threshold value, the digital baseband captures data successfully once; otherwise, wait for the next clock and wait for new data input;

[0054] The above-mentioned PMF-FFT capture operation is repeated within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the PMF-FFT capture operation.

[0055] As a second aspect of the present invention, a hybrid acquisition device for spread spectrum baseband is provided, the hybrid acquisition device for spread spectrum baseband comprising:

[0056] An acquisition module, used to acquire the current communication environment of the digital baseband;

[0057] A determination module, configured to determine a current acquisition mode of the digital baseband according to a current communication environment of the digital baseband;

[0058] The control module is used to control the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture.

[0059] As a third aspect of the present invention, a hybrid capture system for spread spectrum baseband is provided, wherein the hybrid capture system for spread spectrum baseband comprises an MCU and a digital baseband, wherein the MCU comprises the hybrid capture device for spread spectrum baseband as described above, and wherein the MCU controls the digital baseband to perform data capture according to a current capture mode.

[0060] The hybrid capture method for spread spectrum baseband provided by the present invention has the following advantages: the capture mode can be selected according to the user's specific requirements for capture success rate and capture time, and the capture mode can be improved according to the needs in different situations, so that the capture has better adaptability, reduces the capture time, improves the capture success rate, and reduces the design area. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0062] Figure 1 A flow chart of a hybrid acquisition method for spread spectrum baseband provided by the present invention.

[0063] Figure 2 The present invention provides a flowchart of the MCU controlling three capture methods.

[0064] Figure 3 The present invention provides a flowchart of the adaptive threshold matched filter capture method.

[0065] Figure 4 A schematic diagram of dividing the downsampled data into two paths for calculation provided by the present invention.

[0066] Figure 5 A flow chart for determining the maximum value and the four data points before and after it in the accumulated value data provided by the present invention.

[0067] Figure 6 The present invention provides a flow chart of the fixed threshold matched filter capture method.

[0068] Figure 7 The present invention provides a flow chart of the PMF-FFT capture method.

[0069] Figure 8 A principle block diagram of a hybrid acquisition system for spread spectrum baseband provided by the present invention.

[0070] Fig. 9 Another principle block diagram of the hybrid acquisition system for spread spectrum baseband provided by the present invention. DETAILED DESCRIPTION

[0071] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0072] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0073] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0074] In this embodiment, a hybrid acquisition method for spread spectrum baseband is provided. Figure 1 The flowchart of the hybrid acquisition method for spread spectrum baseband provided by the present invention. Figure 1 As shown, the hybrid acquisition method for spread spectrum baseband includes:

[0075] Step S1: Acquire the current communication environment of the digital baseband;

[0076] Step S2: determining a current acquisition mode of the digital baseband according to the current communication environment of the digital baseband;

[0077] Step S3: controlling the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture.

[0078] The hybrid capture method for spread spectrum baseband provided by the present invention can select the capture mode according to the user's specific requirements for capture success rate and capture time, and improve the capture mode according to the needs in different situations, thereby making the capture more adaptable, reducing the capture time, improving the capture success rate, and reducing the design area.

[0079] Preferably, if Figure 2As shown, the user configures the capture mode to the baseband through the MCU according to the actual situation, and the baseband receives the configuration transmitted by the MCU and selects the capture mode set by the user. The current capture mode of the digital baseband is determined according to the current communication environment of the digital baseband, and further includes:

[0080] In the initial state, the current capture mode of the digital baseband is defaulted to an adaptive threshold matched filter capture method;

[0081] If the current communication environment of the digital baseband is good, the current acquisition mode of the digital baseband is switched to a fixed threshold matched filter acquisition method;

[0082] It should be noted that when environmental conditions are good and communication can be established directly without the need for excessive baseband processing, a fixed threshold method is used directly. This capture method directly compares the baseband data with the threshold value, greatly simplifying the data processing process. There is no need to perform additional FFT operations or calculate threshold values, and direct comparison can be performed, reducing capture time.

[0083] If the current communication environment of the digital baseband is poor, the current acquisition method of the digital baseband is switched to the PMF-FFT acquisition method.

[0084] It should be noted that in harsh environments where stable communication needs to be established, the PMF-FFT capture method can be selected. This capture method introduces the frequency domain and operates on data in both the time and frequency domains, greatly improving the success rate of capture.

[0085] In the process of adaptive and fixed threshold capture, the present invention improves the capture mode to make the capture situation more consistent with the hybrid capture situation.

[0086] The adaptive threshold capture method is a capture method that the system automatically enters. In actual use, more attention is paid to its capture success rate. Generally speaking, when the user does not set it, the capture success rate is required to be high, and the capture time has a high tolerance. In view of this situation, this article improves the common capture method. The common capture method is to search for the point where the maximum value is located and compare it with the threshold value within the range of 2 times the spread spectrum code length. If more than 5 or more of the 6 related values ​​are greater than the threshold value, it is considered that the capture is completed. In order to improve the capture success rate, this article makes improvements. After searching for the maximum value, a certain number of values ​​will be taken forward and backward within the maximum value range, and the maximum value needs to be greater than the threshold value. And the surrounding data is required to be lower than the threshold value, then it is considered that the capture is completed.

[0087] In the process of fixed threshold capture, more relaxed capture conditions are adopted. During use, this article requires that more than 4 captures out of 6 capture operations are successful, and the capture is considered completed. In addition, unlike the adaptive threshold, the fixed threshold does not need to calculate the energy value and then perform operations. It directly compares the threshold value and the related value, thus further speeding up the capture speed and better meeting the needs of users.

[0088] For the PMF-FFT capture method, because of the introduction of FFT capture in the frequency domain, more emphasis is placed on the success rate of capture.

[0089] There are three capture methods in the present invention, and the specific implementation process is as follows:

[0090] Preferably, if Figure 3 As shown, the adaptive threshold matched filter capture method includes:

[0091] Step S11: the digital baseband acquires data with a length four times that of the spread spectrum code;

[0092] Step S12: sampling the data of four times the spread spectrum code length every four sampling points to extract down-sampled data;

[0093] Step S13: performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data, and comparing the accumulated value data with an adaptive threshold value;

[0094] It should be noted that the adaptive threshold value here is continuously adjusted according to the input signal.

[0095] Step S14: determine whether the maximum value in the accumulated value data is greater than the adaptive threshold value; if so, proceed to step S15; otherwise, proceed to step S16;

[0096] Step S15: Select four data points before and after the maximum value;

[0097] Step S16: Wait for the next clock, wait for new data input, and return to step S11;

[0098] Step S17: Determine whether the four data point values ​​before and after the maximum value are all less than the adaptive threshold value; if so, proceed to step S18, otherwise, proceed to step S19;

[0099] It should be noted that the position where the maximum value is located is searched forward and backward for 4 data and compared with the obtained adaptive threshold value. Only when these 4 data are lower than the threshold value, it is considered that the capture is successful.

[0100] Step S18: the digital baseband captures data successfully once;

[0101] Step S19: Wait for the next clock, wait for new data input, and return to step S11;

[0102] Repeating the data capturing operation of step S11 to step S19 for a period of time;

[0103] When the number of successful data captures by the digital baseband reaches a preset number, the digital baseband completes data capture and sends a capture completion indication pulse;

[0104] When the number of successful data captures by the digital baseband does not reach a preset number, the digital baseband fails to capture data and returns to restart the data capture operation.

[0105] For example, the data capture operation of step S11 to step S19 is repeated six times. If more than five of the six capture operations are successful, it means that the capture is completed, and a capture completion indication pulse is sent after the capture is completed; if the capture fails, it returns to start again.

[0106] Preferably, the correlating operation of the down-sampled data with a known spread spectrum code to obtain accumulated value data includes:

[0107] Assuming that the data of four times the length of the spread spectrum code input by the digital baseband is signal_in_data(n), n is the length of the input data, and n is a positive integer, the data after downsampling is signal_sample_data(4n), assuming that the code sequence of the known spread spectrum code is PN(n), and the accumulated value data output after the relevant operation is signal_out(m), m refers to the length of the accumulated value data, and the calculation formula of the accumulated value data signal_out(m) is as follows:

[0108]

[0109] Specifically, the down-sampled data is correlated with the known spread spectrum code. First, the input signal is placed in a shift register for storage. If the length of the input PN code is N, after 4N clock cycles (this is due to the insertion of 0 at the transmitting end), the register is completely filled with the input data. Then, the input flow data is correlated with the known PN code. Since the PN code is a set of known data, correlating it is actually converting it into addition and subtraction. An adder is used instead of a multiplier. The adder or subtractor is selected by judging the highest bit. When the highest bit is 0, the adder is used. When the highest bit is 1, the subtractor is used. Moreover, since addition and subtraction are pure combinational logic, the output of the correlation value starts from the beginning of data input. Since the transmission data is inserted with 0 at the transmitting end, a 4N-bit register is needed here to store the input data, and then addition and subtraction are performed on it. Since addition and subtraction may overflow, it needs to be expanded after each addition, and the highest bit is expanded as the sign bit. Since overflow may occur, it is necessary to judge based on the highest and second highest bits of the number after the addition. If the highest and second highest bits are different and the highest bit is 1, then all 0s are output. If the highest bit is 0, then all 1s are output. This completes the relevant operations.

[0110] Preferably, the calculation process of the adaptive threshold value includes:

[0111] In actual use, the downsampled data signal_sample_data (4n) is divided into two paths, I and Q, such as Figure 4 As shown, two paths of data are obtained after division;

[0112] According to the divided two paths of data, the energy value signal_energy(n) of the downsampled data signal_sample_data(4n) is calculated. The calculation formula of the energy value signal_energy(n) is as follows:

[0113] signal_energy(n) 2 =[signal_sample_data_i(4n)] 2 +[signal_sample_data_q(4n)] 2

[0114] Among them, signal_sample_data_i(4n) is the first data after division, and signal_sample_data_q(4n) is the second data after division;

[0115] The adaptive threshold value is obtained by multiplying the energy value signal_energy(n) of the downsampled data by the threshold coefficient ratio, wherein the threshold coefficient ratio is obtained by simulation by the designer according to the actual situation.

[0116] The above is the theoretical formula for calculating the energy value. It mainly calculates the energy value of the input signal. For the energy value signal_energy(n), it is necessary to perform square root operations. In order to shorten the capture time in the present invention, an approximate algorithm is used in the actual operation. Approximate algorithms can be used for calculations to reduce area consumption and save calculation time. Specifically, it is simplified to a*max{I,Q}+b*min{I,Q}, where a can be further simplified to 1, and b can be simplified to 1 / 4+1 / 8. In actual operations, 1 / 4 and 1 / 8 are actually shift operations, so multiplication operations are not required, which greatly reduces area and time consumption. Then the calculated value is multiplied by the threshold coefficient ratio as the captured threshold value. In the case of a fixed threshold, the input threshold value is directly compared with the accumulated value data.

[0117] Preferably, if Figure 5 As shown, the method for determining the maximum value and the four data points before and after the maximum value in the accumulated value data includes:

[0118] First, set a register max and a register POS for storing the maximum value and its position, and clear them to zero;

[0119] Second, determine whether the input accumulated value data is greater than the maximum value in the register max; if so, update the maximum value in the register max to the accumulated value data input this time; otherwise, return to re-enter the new accumulated value data;

[0120] Third, repeat the above judgment process until the accumulated value data calculated this time is traversed, and the last updated maximum value in the register max is obtained, which is the maximum value in the accumulated value data, and the position of the last updated maximum value in the register max is output to the register POS;

[0121] Finally, according to the position of the last updated maximum value in the register max, four data points before and after the last updated maximum value are selected.

[0122] Preferably, if Figure 6 As shown, the fixed threshold matched filter capture method includes:

[0123] Step S21: the digital baseband acquires data with a length four times that of the spread spectrum code;

[0124] Step S22: sampling the data of four times the spread spectrum code length every four sampling points to extract down-sampled data;

[0125] Step S23: performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data, and comparing the accumulated value data with a fixed threshold value;

[0126] Step S24: determine whether the maximum value in the accumulated value data is greater than a fixed threshold value; if so, proceed to step S25; otherwise, proceed to step S26;

[0127] Step S25: the digital baseband captures data successfully once;

[0128] Step S26: Wait for the next clock, wait for new data input, and return to step S21;

[0129] Repeat the data capture operation of step S21 to step S26 within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the data capture operation.

[0130] For example, the data capture operation of step S21 to step S26 is repeated six times. If more than four of the six capture operations are successful, it means that the capture is completed, and a capture completion indication pulse is sent after the capture is completed; if the capture fails, it returns to start again.

[0131] Preferably, if Figure 7 As shown, the PMF-FFT acquisition method includes:

[0132] The digital baseband acquires data of four times the length of the spread spectrum code;

[0133] Sampling the data of four times the length of the spread spectrum code once every four sampling points, and extracting down-sampled data;

[0134] The down-sampled data is correlated with a known spread spectrum code, and partially matched filtered to obtain accumulated value data;

[0135] It should be noted that the spread spectrum code in actual operation is 1 or -1 data, so the correlation operation can be converted into addition and subtraction operations to correlate the input data, and the data after the matched filtering is completed can be used for the next step of capture.

[0136] Cache the accumulated value data;

[0137] The cached accumulated value data is padded with zeros to perform FFT operation, and the maximum value after FFT operation is compared with the threshold value;

[0138] If the maximum value after FFT operation is greater than the threshold value, the digital baseband captures data successfully once; otherwise, wait for the next clock and wait for new data input;

[0139] The above-mentioned PMF-FFT capture operation is repeated within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the PMF-FFT capture operation.

[0140] For example, repeat the above PMF-FFT capture operation six times. If more than four of the six capture operations are successful, it means the capture is completed. After the capture is completed, a capture completion indication pulse will be sent; if the capture fails, it returns and starts again.

[0141] In PMF-FFT, the PMF filter is a matched filter. Here, N partial matched filters are used, and the total length is N*M (where M refers to the length of each matched filter). The matched filter part is similar to the adaptive threshold operation. The local pseudo code does not change, the input signal is constantly updated, and the local code chip is correlated. Then, the output of the matched filter is padded with zeros and then FFT operation is performed. There are M PMF filters in total, each segment is N in length, and the data length of each signal code period is L=MN.

[0142] As another embodiment of the present invention, a hybrid acquisition device for spread spectrum baseband is provided, and the hybrid acquisition device for spread spectrum baseband includes:

[0143] An acquisition module, used to acquire the current communication environment of the digital baseband;

[0144] A determination module, configured to determine a current acquisition mode of the digital baseband according to a current communication environment of the digital baseband;

[0145] The control module is used to control the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture.

[0146] The hybrid capture device for spread spectrum baseband provided by the present invention can select the capture mode according to the user's specific requirements for capture success rate and capture time, and improve the capture mode according to the needs in different situations, so that the capture has better adaptability, reduces the capture time, improves the capture success rate, and reduces the design area.

[0147] As another embodiment of the present invention, a hybrid acquisition system for spread spectrum baseband is provided, which is applied to a spread spectrum circuit receiver, referring to Figure 8-9 As shown, the hybrid capture system for spread spectrum baseband includes an MCU and a digital baseband, the MCU includes the hybrid capture device for spread spectrum baseband mentioned above, and the MCU controls the digital baseband to capture data according to the current capture mode.

[0148] like Figure 8-9 As shown, first the user sends data to the target register through the MCU, and determines the capture method used by the receiver and the spread spectrum code of the transmitter for capture according to the actual situation. At the beginning of reception, the input signal is received by the RF front end, and the amplitude of the received signal is controlled by AGC to make it meet the range of the ADC, and then the signal is obtained by ADC sampling output. The sampled signal is captured. After the capture is completed, a capture success indication pulse is output. After the data is captured, it is sent to the tracking module for synchronization processing to obtain the best sampled signal. The rate, modulation method, data length, etc. of the transmitted information are extracted according to the demodulated data, and then sent to the subsequent modules for processing according to the specific demodulation method, so as to complete the data reception.

[0149] The hybrid acquisition system for spread spectrum baseband provided by the present invention includes the above-mentioned hybrid acquisition device for spread spectrum baseband, and therefore has the beneficial results of the hybrid acquisition device for spread spectrum baseband, which will not be repeated here.

[0150] In summary, the hybrid capture method for spread spectrum baseband provided by the present invention improves the common capture method and improves the flexibility and effect of capture. The common capture schemes are all single when the hybrid threshold judgment method is used for capture, either the capture effect is good and the time is long, or the capture time is short and the effect is poor, and the choice space for users is small. The scheme proposed in this article provides users with a choice of schemes. Under good environmental conditions, the four-matching filter and fixed threshold method can be used to achieve fast capture; under harsh environmental conditions, the PMF-FFT capture method can be used to achieve better capture, reducing the probability of false alarms and missed alarms; in normal mode, the capture method of matched filtering plus adaptive threshold is used, taking into account the capture success rate and capture time, so that the scheme achieves a capture with higher adaptability and better capture effect. Moreover, when the scheme is implemented specifically, the original scheme of directly selecting the maximum value and threshold comparison is improved, and the forward and backward search judgment capture method is adopted to reduce the situation of misjudgment. Therefore, the scheme has higher flexibility and better capture effect.

[0151] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A hybrid acquisition method for spread spectrum baseband, characterized in that: The hybrid acquisition method for spread spectrum baseband comprises: Step S1: Acquire the current communication environment of the digital baseband; Step S2: determining a current acquisition mode of the digital baseband according to the current communication environment of the digital baseband; Step S3: controlling the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture; Wherein, determining the current acquisition mode of the digital baseband according to the current communication environment of the digital baseband further includes: In the initial state, the current capture mode of the digital baseband is defaulted to an adaptive threshold matched filter capture method; If the current communication environment of the digital baseband is good, the current acquisition mode of the digital baseband is switched to a fixed threshold matched filter acquisition method; If the current communication environment of the digital baseband is poor, the current acquisition method of the digital baseband is switched to the PMF-FFT acquisition method.

2. The hybrid acquisition method for spread spectrum baseband according to claim 1, characterized in that: The adaptive threshold matched filtering capture method comprises: Step S11: the digital baseband acquires data with a length four times the length of the spread spectrum code; Step S12: sampling the data whose length is four times the length of the spread spectrum code every four sampling points, and extracting down-sampled data; Step S13: performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data, and comparing the accumulated value data with an adaptive threshold value; Step S14: determine whether the maximum value in the accumulated value data is greater than the adaptive threshold value; if so, proceed to step S15; otherwise, proceed to step S16; Step S15: Select four data points before and after the maximum value; Step S16: Wait for the next clock, wait for new data input, and return to step S11; Step S17: Determine whether the four data point values ​​before and after the maximum value are all less than the adaptive threshold value; if so, proceed to step S18, otherwise, proceed to step S19; Step S18: the digital baseband captures data successfully once; Step S19: Wait for the next clock, wait for new data input, and return to step S11; Repeat the data capture operation of step S11 to step S19 within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the data capture operation.

3. The hybrid acquisition method for spread spectrum baseband according to claim 2, characterized in that: The step of performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data includes: Assume that the data of the digital baseband input whose length is four times the length of the spread spectrum code is signal_in_data(n), n is the length of the input data, then the data after downsampling is signal_sample_data(4n), and the code sequence of the known spread spectrum code is PN(n). The accumulated value data output after the relevant operation is signal_out(m), m refers to the length of the accumulated value data, and the calculation formula of the accumulated value data signal_out(m) is as follows:

4. The hybrid acquisition method for spread spectrum baseband according to claim 3, characterized in that: The calculation process of the adaptive threshold value includes: Dividing the downsampled data signal_sample_data (4n) into two paths to obtain two paths of divided data; According to the divided two paths of data, the energy value signal_energy(n) of the downsampled data signal_sample_data(4n) is calculated. The calculation formula of the energy value signal_energy(n) is as follows: signal_energy(n) 2 =[signal_sample_data_i(4n)] 2 +[signal_sample_data_q(4n)] 2 Among them, signal_sample_data_i(4n) is the first data after division, and signal_sample_data_q(4n) is the second data after division; The adaptive threshold value is obtained by multiplying the energy value signal_energy(n) of the downsampled data by the threshold coefficient ratio.

5. The hybrid acquisition method for spread spectrum baseband according to claim 2, characterized in that: The method for determining the maximum value and the four data points before and after the maximum value in the accumulated value data includes: First, set a register max and a register POS for storing the maximum value and its position, and clear them to zero; Second, determine whether the input accumulated value data is greater than the maximum value in the register max; if so, update the maximum value in the register max to the accumulated value data input this time; otherwise, return to re-enter the new accumulated value data; Third, repeat the above judgment process until the accumulated value data calculated this time is traversed, and the last updated maximum value in the register max is obtained, which is the maximum value in the accumulated value data, and the position of the last updated maximum value in the register max is output to the register POS; Finally, according to the position of the last updated maximum value in the register max, four data points before and after the last updated maximum value are selected.

6. The hybrid acquisition method for spread spectrum baseband according to claim 1, characterized in that: The fixed threshold matched filter capture method comprises: Step S21: the digital baseband acquires data with a length four times the length of the spread spectrum code; Step S22: sampling the data having a length four times the length of the spread spectrum code every four sampling points, and extracting down-sampled data; Step S23: performing a correlation operation on the down-sampled data and a known spread spectrum code to obtain accumulated value data, and comparing the accumulated value data with a fixed threshold value; Step S24: determine whether the maximum value in the accumulated value data is greater than a fixed threshold value; if so, proceed to step S25; otherwise, proceed to step S26; Step S25: the digital baseband captures data successfully once; Step S26: Wait for the next clock, wait for new data input, and return to step S21; Repeat the data capture operation of step S21 to step S26 within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the data capture operation.

7. The hybrid acquisition method for spread spectrum baseband according to claim 1, characterized in that: The PMF-FFT acquisition method includes: The digital baseband acquires data having a length four times the length of the spread spectrum code; Sampling the data having a length four times the length of the spread spectrum code once every four sampling points, and extracting down-sampled data; The down-sampled data is correlated with a known spread spectrum code, and partially matched filtered to obtain accumulated value data; Cache the accumulated value data; The cached accumulated value data is padded with zeros to perform FFT operation, and the maximum value after FFT operation is compared with the threshold value; If the maximum value after FFT operation is greater than the threshold value, the digital baseband captures data successfully once; otherwise, wait for the next clock and wait for new data input; The above-mentioned PMF-FFT capture operation is repeated within a period of time; when the number of successful data captures by the digital baseband reaches a preset number of times, the digital baseband completes data capture and sends a capture completion indication pulse; when the number of successful data captures by the digital baseband does not reach the preset number of times, the digital baseband fails to capture data and returns to restart the PMF-FFT capture operation.

8. A hybrid acquisition device for spread spectrum baseband, used to implement the hybrid acquisition method for spread spectrum baseband according to any one of claims 1 to 7, characterized in that: The hybrid acquisition device for spread spectrum baseband comprises: An acquisition module, used to acquire the current communication environment of the digital baseband; A determination module, configured to determine a current acquisition mode of the digital baseband according to a current communication environment of the digital baseband; The control module is used to control the digital baseband to capture data according to the current capture mode of the digital baseband, so that the digital baseband completes data capture.

9. A hybrid acquisition system for spread spectrum baseband, characterized in that: The hybrid capture system for spread spectrum baseband includes an MCU and a digital baseband, the MCU includes the hybrid capture device for spread spectrum baseband according to claim 8, and the MCU controls the digital baseband to capture data according to the current capture mode.

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