CN113452403B - Multi-carrier coherent acquisition method, device, electronic equipment and storage medium - Google Patents
Multi-carrier coherent acquisition method, device, electronic equipment and storage medium Download PDFInfo
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- CN113452403B CN113452403B CN202111009000.4A CN202111009000A CN113452403B CN 113452403 B CN113452403 B CN 113452403B CN 202111009000 A CN202111009000 A CN 202111009000A CN 113452403 B CN113452403 B CN 113452403B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
Abstract
The invention provides a multi-carrier coherent acquisition method, a device, electronic equipment and a storage medium, wherein the method comprises the following steps: receiving a multi-carrier direct sequence spread spectrum signal; dividing the baseband signal into multiple sub-carrier signals; for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering; after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier; performing code phase correlation after the Doppler shift compensation is completed; after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane; and judging whether the acquisition is successful or not based on the coherent accumulation plane. The invention can reduce the complexity of multi-carrier coherent acquisition without influencing the acquisition performance.
Description
Technical Field
The present invention relates to the field of signal transmission technologies, and in particular, to a method and an apparatus for multi-carrier coherent acquisition, an electronic device, and a storage medium.
Background
In most cases, non-coherent combining is adopted in the conventional multicarrier direct sequence spread spectrum communication system subcarrier combining, which brings about large combining loss to cause the reduction of the acquisition performance, and the fully coherent combining among the subcarriers introduces large operation complexity to cause the difficult support of a satellite receiver.
Disclosure of Invention
To solve the problems in the prior art, embodiments of the present invention provide a multi-carrier coherent acquisition method, apparatus, electronic device, and storage medium.
In a first aspect, an embodiment of the present invention provides a multi-carrier coherent acquisition method, including:
receiving a multi-carrier direct sequence spread spectrum signal;
converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion;
dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals;
for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering;
after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier;
after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift;
after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane;
and judging whether the acquisition is successful or not based on the coherent accumulation plane.
Further, the converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion specifically includes:
the multi-carrier direct sequence spread spectrum signal is converted into a digital signal by an analog-to-digital converter (AD), and then converted into a baseband signal through digital down-conversion.
Further, after the doppler shift compensation is completed, code phase correlation is performed to complete compensation of code phase shift, which specifically includes:
and after the Doppler shift compensation is completed, performing code phase correlation on the local PN code template and the receiving sequence to complete the compensation of the code phase shift.
Further, after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combining on each subcarrier to obtain a coherent accumulation plane, specifically including:
and after the code phase correlation is completed, performing secondary compensation on the code phase offset of each subcarrier, weighting and adding the results of the secondary compensation of each subcarrier, and solving the modulus square to obtain a coherent accumulation plane.
Further, the determining whether the acquisition is successful based on the coherent accumulation plane specifically includes:
judging based on the coherent accumulation plane, and if a correlation peak corresponding to the coherent accumulation plane exceeds a threshold value, considering that the acquisition is successful; and if the correlation peak corresponding to the coherent accumulation plane does not exceed the threshold value, the acquisition is considered to be failed.
In a second aspect, an embodiment of the present invention provides a multi-carrier coherent acquisition apparatus, including:
a receiving module, configured to receive a multi-carrier direct sequence spread spectrum signal;
the signal conversion module is used for converting the multi-carrier direct sequence spread spectrum signal into a digital signal and then converting the digital signal into a baseband signal through digital down-conversion;
the shunt module is used for dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals;
the processing module is used for multiplying any path of subcarrier signal by carrier frequency signals with different frequencies generated by the digital frequency synthesizer, and then carrying out root raised cosine matched filtering;
the Doppler shift compensation module is used for carrying out parallel search on each subcarrier after the root raised cosine matching filtering is finished and carrying out Doppler shift compensation on the frequency offset of each subcarrier;
a code phase correlation module, configured to perform code phase correlation after the doppler shift compensation is completed, so as to complete compensation of code phase shift;
the second compensation module is used for performing second compensation on the code phase offset of each subcarrier after the code phase correlation is completed, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane;
and the determining module is used for judging based on the coherent accumulation plane and determining whether the acquisition is successful.
Further, the signal conversion module is specifically configured to:
the multi-carrier direct sequence spread spectrum signal is converted into a digital signal by an analog-to-digital converter (AD), and then converted into a baseband signal through digital down-conversion.
Further, the code phase correlation module is specifically configured to:
and after the Doppler shift compensation is completed, performing code phase correlation on the local PN code template and the receiving sequence to complete the compensation of the code phase shift.
In a third aspect, an embodiment of the present invention further provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the program to implement the steps of the multi-carrier coherent acquisition method according to the first aspect.
In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the multi-carrier coherent acquisition method described in the first aspect above.
As can be seen from the foregoing technical solutions, the multi-carrier coherent acquisition method, apparatus, electronic device, and storage medium provided in the embodiments of the present invention receive a multi-carrier direct sequence spread spectrum signal; converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion; dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals; for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering; after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier; after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift; after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane; and judging whether the acquisition is successful or not based on the coherent accumulation plane. The invention can reduce the complexity of multi-carrier coherent acquisition without influencing the acquisition performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart illustrating a multi-carrier coherent acquisition method according to an embodiment of the present invention;
fig. 2 is a block diagram of MC-DSSS full coherent delay/doppler two-dimensional joint acquisition according to an embodiment of the present invention;
FIG. 3 is a diagram of a MC-DSSS signal delay/Doppler acquisition plan according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a multi-carrier coherent acquisition apparatus according to an embodiment of the present invention;
fig. 5 is a schematic physical structure diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments, but not all embodiments, of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The multi-carrier coherent acquisition method provided by the present invention will be explained and illustrated in detail by specific embodiments.
Fig. 1 is a flowchart illustrating a multi-carrier coherent acquisition method according to an embodiment of the present invention; as shown in fig. 1, the method includes:
step 101: a multi-carrier direct sequence spread spectrum signal is received.
Step 102: the multi-carrier direct sequence spread spectrum signal is converted into a digital signal, and then converted into a baseband signal through digital down-conversion.
Step 103: the down-converted baseband signal is divided into multiple subcarrier signals.
Step 104: for any path of subcarrier signals, firstly multiplying the subcarrier signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering.
Step 105: and after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier.
Step 106: and after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift.
Step 107: and after the code phase correlation is finished, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane.
Step 108: and judging whether the acquisition is successful or not based on the coherent accumulation plane.
In this embodiment, it should be noted that the low earth orbit satellite communication system generally refers to a large satellite communication system composed of a plurality of satellites and capable of processing information in real time. Low orbit satellites have a lower constellation orbit height and therefore have shorter link transmission delays and less energy loss than high orbit satellite constellations. The satellite communication constellation consisting of a plurality of satellites realizes real global coverage, so that the frequency reuse of communication is more effective. The low orbit satellite communication technology is not only a 'competitive field' of commercial aerospace technology, but also becomes an important 'lever' of main big world space and military games. However, since the communication distance between the satellite and the ground is long and the satellite-ground link environment is open, the satellite communication link is often subject to strong interference and is intercepted.
Spread spectrum communication (spread spectrum) is often adopted in satellite communication, and the communication mode can effectively improve the concealment of a satellite uplink and reduce the influence of interference on a satellite uplink communication signal. The idea is to spread the signal spectrum bandwidth under the condition that the power is kept constant, so that the power spectrum density of the signal is reduced until the signal is submerged under the noise and cannot be perceived. The concealment, interference rejection and spreading ratio of spread spectrum communications are closely related. The spread spectrum communication system of multi-carrier-direct sequence spread spectrum (MC-DSSS) can continuously perform spectrum spreading by using a plurality of carriers on the basis of direct sequence spread spectrum, thereby realizing deep spread spectrum and ensuring the concealment and reliability of communication signals.
In a multi-carrier-direct sequence spread spectrum communication system, the synchronization quality of the signal tends to be a bottleneck limiting the performance of the receiver. The acquisition is used as an important component of a spread spectrum receiver, determines the threshold of the receiver, and plays an indispensable role in completing the synchronization function of the receiver. From the structure of the whole receiver, the capture is not only the bottleneck of signal reception, but also the pass of signal access, if the capture can not be carried out normally, the receiver can think that the ground transmitter does not carry out the transmission of signals, thereby influencing the normal work of the subsequent receiving module and further causing the loss of the whole frame of signals.
In order to guarantee the safety and reliability of user information transmission, a multi-carrier-direct sequence spread spectrum communication system is adopted for information transmission. Compared with the traditional single carrier direct sequence spread spectrum, the multi-carrier direct sequence spread spectrum communication system has the natural advantages of parallel processing on the basis of obtaining equivalent spread spectrum gain, and obviously reduces the difficulty in realizing spread spectrum signal capture. In most cases, non-coherent combining is adopted in the conventional multicarrier direct sequence spread spectrum communication system subcarrier combining, which brings about large combining loss to cause the reduction of the acquisition performance, and the fully coherent combining among the subcarriers introduces large operation complexity to cause the difficult support of a satellite receiver. Therefore, a new multi-carrier coherent acquisition method needs to be explored to reduce the complexity of multi-carrier coherent acquisition without affecting the acquisition performance.
However, the multi-carrier coherent acquisition method provided by the embodiment of the present invention is based on the usage scenario of low earth orbit satellite anti-detection interference communication, and combines the application background that the satellite load resource of the low earth orbit satellite is limited and the communication requirements for user safety and reliability are high, so as to break through the technical bottleneck that the resource of the multi-carrier load receiver is limited under the conditions of large dynamic state and low signal-to-noise ratio, which is specifically as follows:
in the low-orbit satellite-ground communication link, the transmission distance between the satellite and the ground is long, the power of signals reaching a receiver is low through the transmission loss of the link between the satellite and the ground. The communication system of the deep spread spectrum can reduce the power spectral density of signals through the spread spectrum bandwidth, and ensure the reliability and the safety of the communication between the satellite and the ground under the condition of certain transmission power.
The capture is the bottleneck of multi-carrier deep spread spectrum signal access, the existing non-coherent capture of each carrier can introduce merging loss, the requirement of low signal-to-noise ratio capture is difficult to meet, and the coherent merging can introduce a large amount of operation complexity due to the merging precision requirement. The multi-carrier coherent acquisition method provided by the embodiment of the invention performs compensation (namely, first compensation and second layer compensation) with different precisions on the sub-carrier phase at different stages of acquisition, thereby avoiding high computation caused by unnecessary high precision, reducing the complexity of an algorithm and realizing the low complexity of a satellite receiver.
In the embodiment of the present invention, what needs to be solved is the waveform problem of the uplink and downlink signals, that is, what waveform the transceivers use for data transmission. The waveform design of the signal is closely related to the electromagnetic environment of the satellite-ground link, and a frequency band which is relatively open and has less interference is selected for data transmission. In order to reduce power spectral density and improve reliability and safety of information transmission, a multi-carrier-direct sequence spread spectrum signal is selected as a digital baseband transmission waveform. In order to prevent aliasing between the subcarriers and facilitate synchronization of the transceiver, the subcarriers are spaced apart by an interval equal to or greater than twice the chip rate.
Referring to fig. 2, the baseband data is divided into U paths (1, U) after direct sequence spreading, where U is the number of subcarriers of a multicarrier. The baseband data is multiplied by a different carrier on each path and modulated onto a different digital frequency. And adding the U paths into one path, and processing the path by a digital-to-analog converter (DA) for sending.
After being transmitted by a transmitter, the signal reaches a receiving end through a channel, and the specific flow of the receiving end is as follows:
1. first, a received analog signal is converted into a digital signal after being acquired and processed by an AD (analog-to-digital converter), and then is down-converted into a baseband signal.
2. The signals after down-conversion are divided into multiple paths, multiplied by carrier frequency signals (preferably, each carrier frequency is consistent with the originating terminal) with different frequencies generated by a DDS (digital frequency synthesizer), and then subjected to root raised cosine matched filtering. The function of the root raised cosine matched filter is that the root raised cosine matched filter can prevent signals from generating intersymbol interference and simultaneously filter the interference of other subcarrier signals.
3. After the root raised cosine matching filtering is completed, parallel searching is carried out on each subcarrier, and searching and compensation of Doppler frequency offset are carried out on a frequency offset channel of each subcarrier.
4. After Doppler frequency offset compensation on a frequency offset search channel is completed on a specific channel, a local PN code template is correlated with a receiving sequence, initial compensation of a spreading code phase is completed in the correlation process, and the compensation is only performed in a code phase coarse grid (coarse compensation) due to the fact that the code phase correlation has low requirement on compensation precision, namely the coarse search of transmission delay (code phase offset) is completed.
5. In the multi-carrier direct sequence spread spectrum communication system, because the frequency points of the sub-carriers are different, the phase difference accumulated by the transmission delay on the sub-carriers is different, and the phase difference caused by the transmission delay needs to be compensated when the sub-carriers are coherently combined, so that the loss of the coherent combination can be ensured to be minimum, and therefore, the transmission delay (code phase offset) needs to be subjected to second fine grid compensation before the sub-carriers are combined.
6. And carrying out coherent combination on each subcarrier to obtain a coherent accumulation plane.
7. And (4) judging the coherent accumulation plane.
In the embodiment, the loss caused by the combination among the subcarriers is avoided through the full coherent combination among the carriers, so that the performance of the spread spectrum capture of the multi-carrier direct sequence is improved; and meanwhile, twice compensation is carried out (namely, double-mesh division of a coarse mesh and a fine mesh is utilized), so that the calculation complexity of the satellite borrowing mobile phone is favorably reduced, the storage capacity of the satellite load is greatly relieved, and the hardware overhead is favorably saved.
As can be seen from the above technical solutions, the multi-carrier coherent acquisition method provided in the embodiments of the present invention receives a multi-carrier direct sequence spread spectrum signal; converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion; dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals; for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering; after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier; after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift; after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane; and judging whether the acquisition is successful or not based on the coherent accumulation plane. The invention can reduce the complexity of multi-carrier coherent acquisition without influencing the acquisition performance.
On the basis of the foregoing embodiment, in this embodiment, the converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion specifically includes:
the multi-carrier direct sequence spread spectrum signal is converted into a digital signal by an analog-to-digital converter (AD), and then converted into a baseband signal through digital down-conversion.
On the basis of the foregoing embodiment, in this embodiment, after the doppler shift compensation is completed, code phase correlation is performed to complete compensation of code phase shift, which specifically includes:
and after the Doppler shift compensation is completed, performing code phase correlation on the local PN code template and the receiving sequence to complete the compensation of the code phase shift.
In this embodiment, it should be noted that, for the local PN code template and the receiving sequence, the local PN code template refers to a pseudo-random code template known a priori and the same as the originating end, and the local PN code template and the receiving sequence are used to perform correlation operation, so that compensation of code phase offset can be completed; meanwhile, an efficient operation framework can be designed in a mode of correlating the local PN code template with the received sequence, and the signal sequence can be rapidly captured.
As can be seen from the foregoing technical solutions, in the multi-carrier coherent acquisition method provided in the embodiments of the present invention, after the doppler shift compensation is completed, the code phase correlation is performed on the local PN code template and the received sequence, so as to complete the compensation of the code phase shift, and the initial search of the code phase shift can be completed.
On the basis of the foregoing embodiment, in this embodiment, after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combining on each subcarrier to obtain a coherent accumulation plane specifically includes:
and after the code phase correlation is completed, performing secondary compensation on the code phase offset of each subcarrier, weighting and adding the results of the secondary compensation of each subcarrier, and solving the modulus square to obtain a coherent accumulation plane.
In this embodiment, it is understood that coherent combining for each subcarrier may be to perform weighted addition on the compensated results of each subcarrier and determine a modulo square of the compensated weighted addition result of each subcarrier, so as to obtain a coherent accumulation plane, as shown in fig. 3.
On the basis of the foregoing embodiment, in this embodiment, the determining based on the coherent accumulation plane to determine whether the acquisition is successful specifically includes:
judging based on the coherent accumulation plane, and if a correlation peak corresponding to the coherent accumulation plane exceeds a threshold value, considering that the acquisition is successful; and if the correlation peak corresponding to the coherent accumulation plane does not exceed the threshold value, the acquisition is considered to be failed.
In this embodiment, for example, a coherent accumulation plane is determined, if a correlation peak exceeds a capture threshold, the capture is considered to be successful, and if a capture result does not exceed the threshold, the capture is considered to be failed, and the capture operation is continuously performed.
In this embodiment, it should be noted that, regarding the capture threshold, there are two ways to determine the capture threshold in general, one is a constant threshold decision criterion, which means that the threshold is a fixed value and is a relatively simple processing way, but when the received noise power is uncertain or may change at any time, the constant threshold is difficult to adapt. The other is a variable threshold decision criterion, also called adaptive threshold decision criterion, which is a mechanism for flexibly adjusting the threshold according to the input data, and usually, the average value of the data is multiplied by a fixed threshold coefficient to be used as the final decision threshold.
In order to better understand the present invention, the following examples are further provided to illustrate the content of the present invention, but the present invention is not limited to the following examples.
1. Multi-carrier direct sequence spread spectrum transmissionEnd single carrier symbol rate of
Single carrier spreading ratio of 8192, single carrier chip rate of 2.048Mcps, and shaping coefficient
= 0.35, single carrier bandwidth of 2.76MHz, subcarrier spacing
= 4.096MHz, carrier number L =
And the radio frequency point is 2 GHz.
2. Analog signals of a receiving end are converted into digital signals after being acquired by AD, and the digital signals are converted into baseband signals through digital down-conversion.
3. The down-converted signal is divided into multiple paths, and the frequency is different from that generated by a DDS (digital frequency synthesizer)
、
、3
、…、L
) Multiplying the carrier frequency signals (each carrier frequency is consistent with the corresponding transmitting end), then carrying out root raised cosine matched filtering, and convolving with a root raised cosine forming filter.
4. After the root raised cosine matching filtering is completed, the frequency deviation of each subcarrier is compensated in each frequency deviation searching unit, and the frequency deviation corresponding to the frequency deviation searching unit is assumed to be
The frequency offset value of the compensation is
。
5. After completing Doppler frequency offset compensation on a frequency offset search channel on a specific channel, correlating a local PN code template with a receiving sequence to complete 'coarse search' of transmission time delay (code phase offset), wherein the search precision of the transmission time delay is
I.e. by
Tc is the duration of each spreading chip of the spread signal, and Rc is the chip rate Tc = 1/Rc.
6. Because the code phase precision required by the coherent combination of each subcarrier of the multiple carriers is higher than the code phase correlation, the transmission delay (code phase offset) of the subcarriers is secondarily compensated before the coherent combination of the subcarriers, and the compensation precision
。
7. And weighting and adding the acquired results after each subcarrier is compensated, and performing modular squaring on the summed result to obtain a coherent accumulation plane.
8. And judging the coherent accumulation plane, and if the correlation peak exceeds the capture threshold, considering that the capture is successful.
The embodiment of the invention provides a user uplink waveform design based on a multi-carrier direct sequence for the low-earth-orbit satellite communication requirement; the method can meet the requirement of low signal-to-noise ratio in low-orbit satellite communication, and reduce the complexity of multi-carrier coherent acquisition without influencing the acquisition performance.
Fig. 4 is a schematic structural diagram of a multi-carrier coherent acquisition apparatus according to an embodiment of the present invention, as shown in fig. 4, the apparatus includes: a receiving module 201, a signal converting module 202, a splitting module 203, a processing module 204, a doppler shift module 205, a code phase correlation module 206, a second compensation module 207, and a determining module 208, wherein:
the receiving module 201 is configured to receive a multicarrier direct sequence spread spectrum signal;
a signal conversion module 202, configured to convert the multicarrier direct sequence spread spectrum signal into a digital signal, and then convert the digital signal into a baseband signal through digital down-conversion;
a shunting module 203, configured to divide the baseband signal subjected to the down-conversion into multiple sub-carrier signals;
the processing module 204 is configured to multiply any one path of subcarrier signal with carrier frequency signals of different frequencies generated by the digital frequency synthesizer, and then perform root raised cosine matched filtering;
a doppler shift module 205, configured to perform parallel search on each subcarrier after the root raised cosine matched filtering is completed, and perform doppler shift compensation on the frequency shift of each subcarrier;
a code phase correlation module 206, configured to perform code phase correlation after the doppler shift compensation is completed, so as to complete compensation of code phase shift;
a second compensation module 207, configured to perform second compensation on the code phase offset of each subcarrier after the code phase correlation is completed, and perform coherent combining on each subcarrier to obtain a coherent accumulation plane;
a determining module 208, configured to make a decision based on the coherent accumulation plane, and determine whether acquisition is successful.
The multi-carrier coherent acquisition apparatus provided in the embodiment of the present invention may be specifically configured to execute the multi-carrier coherent acquisition method in the foregoing embodiment, and the technical principle and the beneficial effect thereof are similar, and reference may be specifically made to the foregoing embodiment, which is not described herein again.
Based on the same inventive concept, an embodiment of the present invention provides an electronic device, which specifically includes the following contents with reference to fig. 5: a processor 301, a communication interface 303, a memory 302, and a communication bus 304;
the processor 301, the communication interface 303 and the memory 302 complete mutual communication through the communication bus 304; the communication interface 303 is used for realizing information transmission between related devices such as modeling software, an intelligent manufacturing equipment module library and the like; the processor 301 is used for calling the computer program in the memory 302, and the processor executes the computer program to implement the method provided by the above method embodiments, for example, the processor executes the computer program to implement the following steps: receiving a multi-carrier direct sequence spread spectrum signal; converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion; dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals; for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering; after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier; after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift; after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane; and judging whether the acquisition is successful or not based on the coherent accumulation plane.
Based on the same inventive concept, yet another embodiment of the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, is implemented to perform the methods provided by the above method embodiments, for example, receiving a multi-carrier direct sequence spread spectrum signal; converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion; dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals; for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering; after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier; after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift; after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane; and judging whether the acquisition is successful or not based on the coherent accumulation plane.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods of the various embodiments or some parts of the embodiments.
In addition, in the present invention, terms such as "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
Moreover, in the present invention, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Furthermore, in the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. A multi-carrier coherent acquisition method, comprising:
receiving a multi-carrier direct sequence spread spectrum signal;
converting the multi-carrier direct sequence spread spectrum signal into a digital signal, and then converting the digital signal into a baseband signal through digital down-conversion;
dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals;
for any path of subcarrier signal, multiplying the subcarrier signal by carrier frequency signals with different frequencies generated by a digital frequency synthesizer, and then carrying out root raised cosine matched filtering;
after the root raised cosine matching filtering is finished, parallel searching is carried out on each subcarrier, and Doppler shift compensation is carried out on the frequency offset of each subcarrier;
after the Doppler shift compensation is completed, code phase correlation is carried out to complete the compensation of code phase shift;
after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane;
judging based on the coherent accumulation plane to determine whether the acquisition is successful;
wherein, after completing the doppler shift compensation, performing code phase correlation to complete the compensation of code phase shift, specifically comprising:
after the Doppler shift compensation is completed, performing code phase correlation on the local PN code template and the receiving sequence to complete the compensation of code phase shift;
after the code phase correlation is completed, performing second compensation on the code phase offset of each subcarrier, and performing coherent combining on each subcarrier to obtain a coherent accumulation plane, which specifically includes:
and after the code phase correlation is completed, performing secondary compensation on the code phase offset of each subcarrier, weighting and adding the results of the secondary compensation of each subcarrier, and solving the modulus square to obtain a coherent accumulation plane.
2. The method according to claim 1, wherein said converting the multi-carrier direct sequence spread spectrum signal into a digital signal and then into a baseband signal via digital down-conversion comprises:
the multi-carrier direct sequence spread spectrum signal is converted into a digital signal by an analog-to-digital converter (AD), and then converted into a baseband signal through digital down-conversion.
3. The multi-carrier coherent acquisition method according to claim 1, wherein said determining based on the coherent accumulation plane to determine whether the acquisition is successful comprises:
judging based on the coherent accumulation plane, and if a correlation peak corresponding to the coherent accumulation plane exceeds a threshold value, considering that the acquisition is successful; and if the correlation peak corresponding to the coherent accumulation plane does not exceed the threshold value, the acquisition is considered to be failed.
4. A multi-carrier coherent acquisition apparatus, comprising:
a receiving module, configured to receive a multi-carrier direct sequence spread spectrum signal;
the signal conversion module is used for converting the multi-carrier direct sequence spread spectrum signal into a digital signal and then converting the digital signal into a baseband signal through digital down-conversion;
the shunt module is used for dividing the baseband signals subjected to down-conversion into multiple paths of subcarrier signals;
the processing module is used for multiplying any path of subcarrier signal by carrier frequency signals with different frequencies generated by the digital frequency synthesizer, and then carrying out root raised cosine matched filtering;
the Doppler shift compensation module is used for carrying out parallel search on each subcarrier after the root raised cosine matching filtering is finished and carrying out Doppler shift compensation on the frequency offset of each subcarrier;
a code phase correlation module, configured to perform code phase correlation after the doppler shift compensation is completed, so as to complete compensation of code phase shift;
the second compensation module is used for performing second compensation on the code phase offset of each subcarrier after the code phase correlation is completed, and performing coherent combination on each subcarrier to obtain a coherent accumulation plane;
the determining module is used for judging based on the coherent accumulation plane and determining whether the acquisition is successful;
the code phase correlation module is specifically configured to:
after the Doppler shift compensation is completed, performing code phase correlation on the local PN code template and the receiving sequence to complete the compensation of code phase shift;
the second compensation module is specifically configured to: and after the code phase correlation is completed, performing secondary compensation on the code phase offset of each subcarrier, weighting and adding the results of the secondary compensation of each subcarrier, and solving the modulus square to obtain a coherent accumulation plane.
5. The multi-carrier coherent acquisition apparatus of claim 4, wherein the signal conversion module is specifically configured to:
the multi-carrier direct sequence spread spectrum signal is converted into a digital signal by an analog-to-digital converter (AD), and then converted into a baseband signal through digital down-conversion.
6. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the multi-carrier coherent acquisition method according to any of claims 1 to 3 when executing the program.
7. A non-transitory computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor implements the multi-carrier coherent acquisition method according to any of claims 1 to 3.
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