CN113225103A - Spread spectrum signal synchronizer - Google Patents
Spread spectrum signal synchronizer Download PDFInfo
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- CN113225103A CN113225103A CN202110484643.8A CN202110484643A CN113225103A CN 113225103 A CN113225103 A CN 113225103A CN 202110484643 A CN202110484643 A CN 202110484643A CN 113225103 A CN113225103 A CN 113225103A
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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
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
Abstract
The invention discloses a spread spectrum signal synchronizing device, and belongs to the technical field of spread spectrum communication. The device comprises an I-path signal capturing unit, a Q-path signal capturing unit, a delay unit, a de-spreading unit, a code generator, a code clock unit, a flow control unit and a tracking and synchronizing control unit. The invention adopts different spread spectrum codes aiming at the frame structure segmentation, the modulation mode is 2BPSK, the I and Q signals have different spread spectrum codes and fixed time delay, can realize the signal synchronization function which is not possessed by the common modem, and is an important improvement to the prior art.
Description
Technical Field
The present invention relates to the field of spread spectrum communication technologies, and in particular, to a spread spectrum signal synchronization apparatus, which can be used in a spread spectrum communication system under BPSK modulation.
Background
The spread spectrum communication technology is one of the most advanced radio communication technologies in the information society at present, has strong anti-interference capability, low interception probability, good communication confidentiality and good code division multiple access communication capability, and has wide application prospect in military or civil communication systems. In the design implementation of a spread spectrum communication system, the synchronization technology is a key point and a difficult point in the spread spectrum communication system. Especially, for a spread spectrum system with a special structure in which different spreading codes are adopted in frame structure segments, the modulation mode is 2BPSK, and the spreading codes of the two paths of signals I and Q are different and have fixed time delay, the synchronization processing is a big difficulty. Currently, there is no signal synchronization scheme for such spread spectrum systems in the prior art.
Disclosure of Invention
In order to solve the problems mentioned in the background section above, the present invention provides a spread spectrum signal synchronization apparatus, which can implement the synchronization of spread spectrum signals of a spread spectrum system in which different spreading codes are adopted in frame structure segments, the modulation mode is 2BPSK, and the spreading codes of two paths of I and Q signals are different and have a fixed delay.
The purpose of the invention is realized as follows:
a spread spectrum signal synchronization device comprises an I-path signal acquisition unit, a Q-path signal acquisition unit, a delay unit, a de-spread unit, a code generator, a code clock unit, a flow control unit and a tracking and synchronization control unit;
the I/Q path signal capturing unit comprises an I/Q path PN sequence generator, an I/Q path PN sequence memory, an I/Q path signal shift register, an I/Q path signal power calculator and an I/Q path signal power comparator; the I/Q path PN sequence generator is used for generating an I/Q path captured local code sequence, the I/Q path PN sequence memory is used for loading the local code sequence, the I/Q path signal shift register is used for completing shift storage and reading of I/Q path data, the I/Q path signal power calculator is used for completing power statistics of I/Q path signals, and the I/Q path signal power comparator is used for completing comparison operation of an I/Q path signal power value and a threshold value and outputting an enabling signal to the code generator and the flow control unit;
the code clock unit is used for generating a clock of a local code word and transmitting the clock to the code generator, and the code generator is used for generating descrambling code words of the I path signal and the Q path signal and transmitting the descrambling code words to the despreading unit;
the despreading unit comprises an I-path signal descrambling unit, a Q-path signal descrambling unit, an I-path signal accumulation unit and a Q-path signal accumulation unit; the I/Q path signal descrambling unit adopts descrambling codes generated by the code generator to descramble I/Q path input signals, and the I/Q path signal accumulation unit is used for integrating and accumulating the signals subjected to I/Q path despreading and outputting accumulation completion enabling signals of each symbol to the synchronous control unit;
the tracking and synchronization control unit is used for completing the tracking of the code chip and the starting of the code generator and carrying out deviation adjustment on the code clock unit; the synchronous enabling unit is used for outputting a synchronous enabling signal to the process control unit;
the flow control unit is used for controlling the starting of the capture code; when the enable signal of the I/Q path signal power comparator and the enable signal of the tracking and synchronous control unit are not high level at the same time, the flow control unit outputs an enable signal started by the capture code;
the method comprises the following steps that an externally input signal is divided into two paths, wherein one path of signal passes through an I path capturing unit and a Q path capturing unit to complete signal capturing, and in the capturing process, the initial position of a signal frame header and the position mark of effective data are obtained by loading local code words and performing relevant operation on the input signal; the other path of signal passes through a delay unit, the delayed signal enters a de-spread unit, the de-spread unit carries out de-scrambling and accumulation through a de-scrambling code word generated by a code generator and the I/Q path of signal to obtain an advanced signal, a current signal and a delayed signal, wherein the advanced signal and the delayed signal are fed back to a tracking and synchronous control unit to carry out code tracking processing, the current signal is an original signal and is directly output to realize the synchronization of the spread spectrum signal.
The invention has the following beneficial effects:
(1) the invention adopts a kind of signals of different spreading codes at different positions according to the transmission frame structure to complete the acquisition of the signals.
(2) The invention adopts different spread spectrum codes and a class of delayed signals aiming at two paths of signals of a transmission frame I, Q, thereby completing the synchronization of the signals.
(3) The invention adopts the strategy of accessing the code word by the high-power clock, thereby reducing the processing delay of the signal.
Drawings
Fig. 1 is an electrical schematic diagram of spread spectrum signal synchronization in an embodiment of the present invention.
Fig. 2 is an electrical schematic diagram of the I-path signal capture unit of fig. 1.
Fig. 3 is an electrical schematic diagram of the Q-path signal capture unit of fig. 1.
Fig. 4 is an electrical schematic diagram of the despreading unit of fig. 1.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the accompanying drawings and the detailed description.
As shown in fig. 1, a spread spectrum signal synchronization apparatus includes an I-path signal capturing unit, a Q-path signal capturing unit, a delay unit, a despreading unit, a code generator unit, a code clock unit, a flow control unit, and a tracking and synchronization control unit. The system comprises an I-path signal capturing unit, a Q-path signal capturing unit, a delay unit, a de-spreading unit, a code generator unit, a code clock unit, a flow control unit and a tracking and synchronizing control unit, wherein the I-path signal capturing unit captures a signal synchronization head by using a code word of the I-path signal synchronization head, the Q-path signal capturing unit captures the signal synchronization head by using a code word of the Q-path signal synchronization head, the delay unit is used for completing the delay processing of signals, the de-spreading unit is used for completing the de-spreading processing of the I-path signals and the Q-path signals, the code generator unit is used for generating de-scrambling code words of the I-path signals and the Q-path signals, the code clock unit is used for generating a local code word clock, the flow control unit is used for controlling the starting of a capturing code, and the tracking and synchronizing control unit is used for completing the tracking of a code chip and the starting of the code generator.
As shown in fig. 2, the I-channel signal capturing unit is composed of an I-channel PN sequence generating unit, an I-channel PN sequence storing unit, an I-channel signal shift registering unit, an I-channel signal power calculating unit, and an I-channel signal power comparing unit. The I path PN sequence generating unit is used for generating an I path captured local code sequence, the I path PN sequence storage unit stores PN code words of the PN sequence generating unit in an RAM (random access memory) by adopting a high-power clock, the I path signal shifting register unit adopts a shifting register form to finish shifting and reading of I path input signals so as to finish correlation operation with the local PN sequence, the I path signal power calculating unit is used for performing integral accumulation operation on correlated data to finish power statistics, and the I path signal power comparing unit is used for performing comparison operation on a calculated power value and a preset power threshold value.
As shown in fig. 3, the Q-path signal capturing unit is composed of a Q-path PN sequence generating unit, a Q-path PN sequence storing unit, a Q-path signal shift registering unit, a Q-path signal power calculating unit, and a Q-path signal power comparing unit. The Q-path PN sequence generating unit is used for generating a Q-path captured local code sequence, the Q-path PN sequence storage unit stores PN code words of the PN sequence generating unit in an RAM (random access memory) by adopting a high-power clock, the Q-path signal shifting register unit adopts a shifting register form to complete shifting reading of Q-path input signals so as to complete correlation operation with the local PN sequence, the Q-path signal power calculating unit performs integral accumulation operation on correlated data to complete power statistics, and the Q-path signal power comparing unit performs comparison operation on a calculated power value and a preset power threshold value.
As shown in fig. 4, the despreading unit is composed of an I-path signal descrambling unit, a Q-path signal descrambling unit, an I-path leading branch signal accumulating unit, an I-path lagging branch signal accumulating unit, an I-path current branch signal accumulating unit, a Q-path leading branch signal accumulating unit, a Q-path lagging branch signal accumulating unit, and a Q-path current signal accumulating unit. The I path signal descrambling unit descrambles the I path input signal by using a scrambling code generated by the code generator, the Q path signal descrambling unit descrambles the Q path input signal by using the scrambling code generated by the code generator, the I path lead, lag and current signal accumulation units are respectively used for finishing the accumulation of lead and lag generated after the I path signal is descrambled and the accumulation of the current branch signal, and the Q path lead, lag and current signal accumulation units are respectively used for finishing the accumulation of lead and lag generated after the Q path signal is descrambled and the accumulation of the current branch signal.
The device comprises the following steps:
(1) the input signal is divided into two paths, wherein one path of signal completes the capture of the signal through an I path capture unit and a Q path capture unit at the same time;
(2) the other path of signal of the input signal branch passes through a signal delay unit, so that the delay value is the same as the capture delay, and the delayed data passes through a de-spread unit to complete de-spread processing of the signal under the action of a code generator and a flow control unit;
(3) the code tracking processing is completed by the leading branch and the lagging branch generated by the despreading unit, and the flow control unit controls the normal starting of each functional module to be finished, so that the synchronization process of the whole spread spectrum signal is completed.
In short, the invention adopts different spreading codes aiming at the frame structure segmentation, the modulation mode is 2BPSK, the spreading codes of the two paths of signals of I and Q are different, and the spreading system has fixed time delay, can realize the signal synchronization function which is not possessed by the common modem, and is an important improvement to the prior art.
Claims (1)
1. A spread spectrum signal synchronization device is characterized by comprising an I-path signal acquisition unit, a Q-path signal acquisition unit, a delay unit, a de-spread unit, a code generator, a code clock unit, a flow control unit and a tracking and synchronization control unit;
the I/Q path signal capturing unit comprises an I/Q path PN sequence generator, an I/Q path PN sequence memory, an I/Q path signal shift register, an I/Q path signal power calculator and an I/Q path signal power comparator; the I/Q path PN sequence generator is used for generating an I/Q path captured local code sequence, the I/Q path PN sequence memory is used for loading the local code sequence, the I/Q path signal shift register is used for completing shift storage and reading of I/Q path data, the I/Q path signal power calculator is used for completing power statistics of I/Q path signals, and the I/Q path signal power comparator is used for completing comparison operation of an I/Q path signal power value and a threshold value and outputting an enabling signal to the code generator and the flow control unit;
the code clock unit is used for generating a clock of a local code word and transmitting the clock to the code generator, and the code generator is used for generating descrambling code words of the I path signal and the Q path signal and transmitting the descrambling code words to the despreading unit;
the despreading unit comprises an I-path signal descrambling unit, a Q-path signal descrambling unit, an I-path signal accumulation unit and a Q-path signal accumulation unit; the I/Q path signal descrambling unit adopts descrambling codes generated by the code generator to descramble I/Q path input signals, and the I/Q path signal accumulation unit is used for integrating and accumulating the signals subjected to I/Q path despreading and outputting accumulation completion enabling signals of each symbol to the synchronous control unit;
the tracking and synchronization control unit is used for completing the tracking of the code chip and the starting of the code generator and carrying out deviation adjustment on the code clock unit; the synchronous enabling unit is used for outputting a synchronous enabling signal to the process control unit;
the flow control unit is used for controlling the starting of the capture code; when the enable signal of the I/Q path signal power comparator and the enable signal of the tracking and synchronous control unit are not high level at the same time, the flow control unit outputs an enable signal started by the capture code;
the method comprises the following steps that an externally input signal is divided into two paths, wherein one path of signal passes through an I path capturing unit and a Q path capturing unit to complete signal capturing, and in the capturing process, the initial position of a signal frame header and the position mark of effective data are obtained by loading local code words and performing relevant operation on the input signal; the other path of signal passes through a delay unit, the delayed signal enters a de-spread unit, the de-spread unit carries out de-scrambling and accumulation through a de-scrambling code word generated by a code generator and the I/Q path of signal to obtain an advanced signal, a current signal and a delayed signal, wherein the advanced signal and the delayed signal are fed back to a tracking and synchronous control unit to carry out code tracking processing, the current signal is an original signal and is directly output to realize the synchronization of the spread spectrum signal.
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Citations (4)
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| US5301206A (en) * | 1992-02-07 | 1994-04-05 | Victor Company Of Japan, Inc. | Spread spectrum communication system |
| WO2000039940A1 (en) * | 1998-12-23 | 2000-07-06 | Cadence Design Systems Inc. | Code tracking loop for a spread-spectrum receiver |
| CN107359901A (en) * | 2017-08-03 | 2017-11-17 | 中国电子科技集团公司第五十四研究所 | A kind of synchronization timing device and method for the incoherent band spectrum modulation of satellite channel |
| CN109586761A (en) * | 2018-11-09 | 2019-04-05 | 北京航天万源科技有限公司 | A kind of trace demodulation method of high dynamic spread spectrum signal |
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|---|---|---|---|---|
| US5301206A (en) * | 1992-02-07 | 1994-04-05 | Victor Company Of Japan, Inc. | Spread spectrum communication system |
| WO2000039940A1 (en) * | 1998-12-23 | 2000-07-06 | Cadence Design Systems Inc. | Code tracking loop for a spread-spectrum receiver |
| CN107359901A (en) * | 2017-08-03 | 2017-11-17 | 中国电子科技集团公司第五十四研究所 | A kind of synchronization timing device and method for the incoherent band spectrum modulation of satellite channel |
| CN109586761A (en) * | 2018-11-09 | 2019-04-05 | 北京航天万源科技有限公司 | A kind of trace demodulation method of high dynamic spread spectrum signal |
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