CN110336582A - The solution of wideband signaling transmission system direct expansion OQPSK extends to demodulating algorithm - Google Patents

The solution of wideband signaling transmission system direct expansion OQPSK extends to demodulating algorithm Download PDF

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Publication number
CN110336582A
CN110336582A CN201910663781.5A CN201910663781A CN110336582A CN 110336582 A CN110336582 A CN 110336582A CN 201910663781 A CN201910663781 A CN 201910663781A CN 110336582 A CN110336582 A CN 110336582A
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signal
frequency
oqpsk
center
groups
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CN110336582B (en
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崔霞霞
王赛宇
李静芳
王立辉
李新玲
何朝玉
王少飞
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CETC 54 Research Institute
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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
    • 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
    • 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
    • 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
    • H04L27/22—Demodulator circuits; Receiver circuits

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

The invention discloses the solutions of wideband signaling transmission system direct expansion OQPSK a kind of to extend to demodulating algorithm, the characteristics of this method is according to the direct expansion OQPSK modulated signal Q ratio I delay half-chip time, the corresponding frequency expansion sequence CQ ' for generating local pseudo-random sequence generator is also delayed half-chip time (frequency expansion sequence that CI, CQ are respectively the road I and Q signal) than CI.In frequency expansion sequence tracking phase, by I, Q two-way spread-spectrum signal respectively to CI, CQ ' frequency expansion sequence is related adds up, export two groups of signals, clocking error calculated according to the respective advanced, lag of two groups of signals and middle branch signal jointly, realizes frequency expansion sequence tracking.Wherein two groups of middle branch signals control carrier wave digital controlled oscillator for calculating frequency error and generate corresponding carriers frequency deviation, track input signal carrier wave, output signal of the middle branch signal as despread-and-demodulation.The despreading and demodulation of wideband signaling transmission system direct expansion OQPSK modulated signal may be implemented in the present invention.

Description

The solution of wideband signaling transmission system direct expansion OQPSK extends to demodulating algorithm
Technical field
The present invention relates to the solutions of wideband signaling transmission system direct expansion OQPSK to extend to demodulation field, especially suitable for using straight Connect spread spectrum and the despreading and demodulation of communication system that OQPSK modulation system combines.
Background technique
The communication system combined using Direct-Spread and OQPSK modulation system, when transmitting in a communication link, two-way letter Number Q ratio I is delayed the half-chip time, and the frequency deviation of carrier wave is also established on the delay relationship of two paths of signals in transmission process.And General despread-and-demodulation algorithm, two-way frequency expansion sequence are not present delay relationship, two paths of signals I and Q and two-way frequency expansion sequence CI and The directly related cumulative realization frequency expansion sequence acquisition and tracking of CQ, middle branch export (ICI) and (QCQ) as demodulation input data, Inherently there is deviation using the despread signal that this general-purpose algorithm exports, if two paths of signals I ratio Q is delayed half before de-spreading Chip delay, despread signal will be not present deviation, but equally destroy the frequency deviation information of transmission, the frequency deviation calculated according to this Error amount is unable to characterize practical frequency deviation, consequence caused by this frequency difference be it is very serious, can not only signal-to-noise ratio be caused to decline, and And can also cause signal distortion, influence system worked well.For this status, it to be computed correctly frequency offset error value, it is necessary to protect The frequency deviation information in complex channel is stayed, therefore two paths of signals cannot be delayed, need for frequency expansion sequence to be delayed, further according to the spy of complex channel Point, using two-way spread-spectrum signal, related four cumulative road signals carry out frequency spreading tracking and demodulation respectively to two-way frequency expansion sequence.
Summary of the invention
Deficiency present in demodulation is extended to solve the prior art in the solution of direct expansion OQPSK, the present invention provides a kind of complete New frequency expansion sequence tracking and demodulation method, the characteristics of transmission according to OQPSK modulated signal complex channel, using despreading front signal with The related cumulative signal exported carries out frequency expansion sequence tracking and demodulation to two-way frequency expansion sequence respectively.
The technical solution adopted by the present invention are as follows:
A kind of solution of wideband signaling transmission system direct expansion OQPSK extends to demodulating algorithm, comprising the following steps:
(1) the signaling moiety base-band spread-spectrum signal of signal is subjected to spread spectrum sequence using matched filter mode together with frequency sweep Column capture, obtains I, Q two-way spread-spectrum signal；
(2) by I, Q two-way spread-spectrum signal after capture, respectively to local frequency expansion sequence CI, CQ ' sliding it is related and at one It adds up in symbol, obtains two groups of signal ICI、QCIAnd ICQ '、QCQ ', every group of signal generates advanced, lag respectively and middle branch is defeated Signal out, and clocking error is calculated according to principle sooner or later, local clock is finely tuned in real time according to clocking error；
(3) two groups of middle branch output signal (I after being finely adjustedCI)center、(QCI)center、(ICQ ')centerAnd (QCQ ')center, using formula sign (ICI)center*(QCI)center-sign(QCQ ')center*(ICQ ')centerError is calculated, according to Control errors carrier wave digital controlled oscillator generates corresponding frequency deviation, and the carrier frequency of two groups of middle branch output signals is compensated using frequency deviation Partially, using compensated two groups of middle branch output signals as the output signal of signaling despread-and-demodulation；
The solution for completing wideband signaling transmission system direct expansion OQPSK extends to demodulation.
Wherein, frequency expansion sequence CQ ' ratio CI locally generated in step (2) delay one half chip period.
Wherein, (I is used in step (2)CI)、(QCI) and (ICQ ')、(QCQ ') two groups of signals advanced, lag branch: (ICI)early、(ICI)late、(QCI)early、(QCI)late、(ICQ ')early、(ICQ ')late、(QCQ ')early(QCQ ')lateIt carries out local The adjustment of clock.
Compared with the background technology, the present invention, it has the advantages that
(1) do not increased according to the transmission feature of direct expansion OQPSK using completely new frequency spreading tracking algorithm and demodulating algorithm On the basis of adding complexity, the stability of system work ensure that；
(2) direct expansion is combined with OQPSK modulation system, ensure that the high reliability and Gao Baomi of wideband signaling transmission Property.
Specific embodiment
The solution of wideband signaling transmission system direct expansion OQPSK extends to demodulating algorithm, comprising steps of
(1) signaling moiety base-band spread-spectrum signal is realized into frequency expansion sequence using matched filter mode together with frequency sweep first Capture；
When system frequency deviation is larger, it may appear that the phenomenon that can not normally capturing, it is necessary to using frequency sweep cooperation capture work. The stepping and frequency deviation region of frequency sweep are rationally set according to the bit rate of broadband signalling, using frequency expansion sequence capture result as measurement standard Adjust the frequency deviation value of frequency sweep, the big frequency deviation of compensation system.
Capture portion use frequency expansion sequence be not delayed half-chip processing, when system frequency deviation is larger, capture match with frequency sweep Work is closed, big frequency deviation is compensated, realizes capture.If frequency expansion sequence has captured, frequency sweep keeps current frequency offset, no longer works；If Frequency expansion sequence does not capture, continues the step change by frequency sweep, until frequency expansion sequence is completed to capture.
(2) I, Q two-way spread-spectrum signal after capturing are related simultaneously to I branch and Q branch frequency expansion sequence CI, CQ ' sliding respectively It adds up in a symbol, obtains two groups of signal (ICI)、(QCI) and (ICQ ')、(QCQ '), every group of signal generates advanced, stagnant respectively Afterwards with middle branch output signal, clocking error is calculated according to principle sooner or later, local clock is finely tuned in real time, realizes and receives The precise synchronization of signal and local frequency expansion sequence；CQ ' ratio CI delay one half chip period；
General algorithm CQ ratio CI is not delayed one half chip period, only with (ICI)、(QCQ) one group of signal it is advanced, stagnant System clock is adjusted with middle branch afterwards, the present invention uses (ICI)、(QCI) and (ICQ ')、(QCQ ') two groups of signals it is advanced, stagnant Branch afterwards: (ICI)early、(ICI)late、(QCI)early、(QCI)late、(ICQ ')early、(ICQ ')late、(QCQ ')early(QCQ ')late Tracking and clock adjustment for frequency expansion sequence, (ICI) and (QCQ ') for determining a need for the spread spectrum of restarting step (1) Sequence capturing.
(3) two groups of middle branch output signals after accurate clock synchronizes are realized, using formula sign (ICI)center* (QCI)center-sign(QCQ ')center*(ICQ ')centerError is calculated, for controlling carrier wave digital controlled oscillator and generating respective tones Partially, the carrier wave frequency deviation that two groups of middle branch output signals are compensated using frequency deviation, by compensated two groups of middle branch output signals Output signal as signaling despread-and-demodulation；
According to the transmission feature of direct expansion OQPSK complex channel, (ICI)、(QCI)、(ICQ ') and (QCQ ') middle branch export use Frequency offset error signal is extracted in demodulation.It extracts signal to error by loop filter to be filtered, output result send numerical control to shake It swings device and makees that its frequency control word is cumulative, the sine wave freuqency output of digital controlled oscillator is controlled, to play to carrier wave real-time tracking Purpose.
Using the middle branch after completing frequency expansion sequence capture, tracking and demodulate as the output signal of signaling despread-and-demodulation. The signal is for determining whether demodulation locks.If the signal is judged as demodulation locking, the frequency sweep in step (1) will no longer work Make, step (1), (2), (3) work on；If the signal is judged as demodulating unlocked, frequency sweep in step (1) will continue Conversion frequency, step (1), (2), (3), which all reset, restarts work, until the signal is judged as demodulation locking.

Claims (3)

1. a kind of solution of wideband signaling transmission system direct expansion OQPSK extends to demodulating algorithm, which comprises the following steps:
(1) the signaling moiety base-band spread-spectrum signal of signal frequency expansion sequence is carried out using matched filter mode to catch together with frequency sweep It obtains, obtains I, Q two-way spread-spectrum signal；
(2) by I, Q two-way spread-spectrum signal after capture, respectively to local frequency expansion sequence CI, CQ ' sliding it is related and in a symbol It is interior cumulative, obtain two groups of signal ICI、QCIAnd ICQ '、QCQ ', every group of signal generates advanced, lag respectively and middle branch output is believed Number, and clocking error is calculated according to principle sooner or later, local clock is finely tuned in real time according to clocking error；
(3) two groups of middle branch output signal (I after being finely adjustedCI)center、(QCI)center、(ICQ ')centerAnd (QCQ ')center, using formula sign (ICI)center*(QCI)center-sign(QCQ ')center*(ICQ ')centerError is calculated, according to Control errors carrier wave digital controlled oscillator generates corresponding frequency deviation, and the carrier frequency of two groups of middle branch output signals is compensated using frequency deviation Partially, using compensated two groups of middle branch output signals as the output signal of signaling despread-and-demodulation；
The solution for completing wideband signaling transmission system direct expansion OQPSK extends to demodulation.
2. the solution of wideband signaling transmission system direct expansion OQPSK according to claim 1 extends to demodulating algorithm, feature exists In: locally generated frequency expansion sequence CQ ' ratio CI delay one half chip period in step (2).
3. the solution of wideband signaling transmission system direct expansion OQPSK according to claim 1 extends to demodulating algorithm, feature exists In: (I is used in step (2)CI)、(QCI) and (ICQ ')、(QCQ ') two groups of signals advanced, lag branch: (ICI)early、 (ICI)late、(QCI)early、(QCI)late、(ICQ ')early、(ICQ ')late、(QCQ ')early(QCQ ')lateCarry out the tune of local clock It is whole.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113141195A (en) * 2021-04-06 2021-07-20 重庆邮电大学 Demodulation method for dispreading in direct sequence spread spectrum system and storage medium

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Publication number Priority date Publication date Assignee Title
CN101286759A (en) * 2008-04-22 2008-10-15 北京航空航天大学 Quick synchronous device for space based spread-spectrum communications
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
CN108880609A (en) * 2018-06-25 2018-11-23 南京理工大学 PN synchronization method based on burst spread-spectrum signal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101286759A (en) * 2008-04-22 2008-10-15 北京航空航天大学 Quick synchronous device for space based spread-spectrum communications
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
CN108880609A (en) * 2018-06-25 2018-11-23 南京理工大学 PN synchronization method based on burst spread-spectrum signal

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113141195A (en) * 2021-04-06 2021-07-20 重庆邮电大学 Demodulation method for dispreading in direct sequence spread spectrum system and storage medium

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