CN112105958A - Bipolar CSK modulation composite telegraph text signal broadcasting method and device - Google Patents

Bipolar CSK modulation composite telegraph text signal broadcasting method and device Download PDF

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CN112105958A
CN112105958A CN202080002400.XA CN202080002400A CN112105958A CN 112105958 A CN112105958 A CN 112105958A CN 202080002400 A CN202080002400 A CN 202080002400A CN 112105958 A CN112105958 A CN 112105958A
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CN112105958B (en
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王盾
陈耀辉
李东俊
刘成
刘天雄
李申阳
陈思源
董启甲
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Space Star Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/243—Demodulation of navigation message
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/25—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS
    • G01S19/256—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS relating to timing, e.g. time of week, code phase, timing offset
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/35—Constructional details or hardware or software details of the signal processing chain
    • G01S19/36—Constructional details or hardware or software details of the signal processing chain relating to the receiver frond end
    • 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
    • H04B1/7097—Interference-related aspects
    • H04B1/711—Interference-related aspects the interference being multi-path interference
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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Abstract

The invention discloses a composite telegraph text signal broadcasting method and a composite telegraph text signal broadcasting device based on bipolar CSK modulation, wherein the method comprises the following steps: modulating the basic telegraph text on the in-phase I branch, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the I branch after channel coding, and constructing an in-phase I branch baseband signal; modulating the spread text on an orthogonal Q branch, arbitrarily taking 1 bit from a modulation symbol of the spread text after channel coding to form a serial data stream on the Q branch, forming a parallel data stream on the Q branch by the rest bits, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the Q branch, carrying out CSK-DSSS direct sequence spread spectrum on the parallel data stream on the Q branch, and constructing an orthogonal Q branch baseband signal by the two. And carrying out carrier IQ quadrature modulation on the basic text baseband signal of the in-phase I branch and the expanded text baseband signal of the quadrature Q branch to form a multi-rate composite text signal and broadcast the multi-rate composite text signal.

Description

Bipolar CSK modulation composite telegraph text signal broadcasting method and device
Technical Field
The invention relates to a composite text signal broadcasting method and device based on CSK modulation, and belongs to the technical field of communication and navigation signal design.
Background
In the design of modern communication and navigation systems, according to different application requirements, composite messages meeting different requirements are often required to be simultaneously broadcast in signals of the same frequency point. Such as: basic telegraph text is broadcasted according to a certain information rate to meet the requirements of the basic service performance or the open service performance of the system, and expanded telegraph text with the same or different information rates is broadcasted at the same time to meet the requirements of the additional service performance or the non-open service performance of the system. Because the expanded text message signal is not always completely disclosed, the system requires the designed composite text message signal, and can ensure that the basic text message user can perfectly receive the basic text message in the composite text message signal under the condition of not knowing whether the expanded text message signal exists or not.
The direct sequence spread spectrum signal system is a common information modulation mode in the communication and navigation fields. The BPSK-DSSS modulation signal has the advantages of being simple in receiving and processing, capable of obtaining carrier synchronization information and modulation symbol synchronization information required by signal demodulation by self, capable of completing signal propagation time measurement while receiving data and the like, and is widely used in the field of satellite navigation. For example, the GPS satellite navigation system in the united states and the beidou satellite navigation system in china. Correspondingly, the CSK-DSSS modulated signal based on code shift keying has the advantages of high information transmission efficiency, i.e., low required data demodulation threshold, although the receiving process is complicated and it is difficult to self-acquire the carrier synchronization information and modulation symbol synchronization information required for signal demodulation. In the current satellite navigation system, multi-frequency point multi-signal has become the mainstream design. After the navigation ranging requirements are met, under the condition that the signal broadcasting power is limited, the information broadcasting efficiency, namely the information transmission efficiency, is further improved, and the new requirements are met. For this reason, the japanese QZSS quasi zenith satellite navigation system introduces a CSK-DSSS direct sequence spread spectrum modulation signal for broadcasting system error correction information serving for high-precision positioning.
For the CSK-DSSS direct sequence spread spectrum modulation signal, the higher the modulation order, i.e. the more the bit number of the spread spectrum modulation symbol, the better the information transmission efficiency. At the same time, the greater the complexity of signal reception. For example, for a 6-bit modulation symbol, 64 sets of correlation values need to be matched and received simultaneously. If 1 bit is added, then 128 sets of correlation values are received for simultaneous matching. The signal reception complexity increases exponentially with the number of modulation symbol bits. One solution is to use the added 1-bit information to modulate the polarity of the CSK modulated signal, i.e. superimpose BPSK-DSSS modulation on the CSK modulated signal to form a bipolar CSK (antipodal CSK) modulated signal.
Compared with the K +1 bit conventional CSK modulation signal, the K bit bipolar CSK modulation signal has the same information transmission rate, the data demodulation thresholds in a coherent demodulation mode are almost consistent, and the signal receiving complexity can be reduced by half. However, the full-bit data of the bipolar CSK modulated signal, that is, the K + 1-bit data, can be received only by the coherent demodulation method, and the noncoherent demodulation method can receive only the K-bit number of the CSK modulation. Correspondingly, the conventional CSK modulation signal may receive the K +1 bit information in a coherent demodulation manner, or may receive the K +1 bit information in a non-coherent demodulation manner. Generally speaking, the coherent demodulation method has a lower demodulation threshold in the AGWN channel, and is suitable for a stable signal receiving environment; the noncoherent demodulation mode can receive signals without signal carrier phase synchronization, and is suitable for complex electromagnetic environments with more interference signals.
Considering the application requirements and application scenes of high-precision single-point positioning of a satellite navigation system, the requirements on a multi-rate composite message signal broadcasting mode are increasingly strong, and a bipolar CSK modulation composite message signal broadcasting method and a bipolar CSK modulation composite message signal broadcasting device are provided, so that the information transmission rate is further improved and the high-precision positioning service performance of the satellite navigation system is improved on the premise of keeping the signal receiving and processing complexity basically unchanged. The invention further improves the information transmission rate without increasing the complexity of signal receiving and processing, and the broadcast composite message signal also has the advantages of high efficiency, multipath interference resistance and the like.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a signal broadcasting method and device with good multipath interference suppression performance, which can further improve the information transmission efficiency and keep the complexity of signal receiving and processing basically unchanged under the condition that the signal power is limited, and meet the requirement of a communication and navigation system for broadcasting multi-type composite text services.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a bipolar CSK modulation composite telegraph text signal broadcasting method, which comprises the following steps:
modulating the basic telegraph text on the in-phase I branch, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the I branch after channel coding, and constructing an in-phase I branch baseband signal;
modulating an expanded message on an orthogonal Q branch, arbitrarily selecting 1 bit from an expanded message modulation symbol after channel coding to form a serial data stream on the Q branch, forming parallel data streams on the Q branch by the rest bits, carrying out BPSK-DSSS direct sequence spread on the serial data stream on the Q branch, carrying out CSK-DSSS direct sequence spread on the parallel data streams on the Q branch, and jointly constructing an orthogonal Q branch baseband signal by the serial data stream and the parallel data streams on the Q branch of the direct sequence spread;
and carrying out IQ quadrature modulation on the basic text baseband signal of the in-phase I branch and the expanded text baseband signal of the quadrature Q branch to obtain a carrier signal, carrying out power amplification processing, and broadcasting by a transmitting antenna.
As a preferred technical scheme of the invention: in the method for broadcasting the bipolar CSK modulated composite telegraph text signal, the in-phase I branch baseband signal is constructed according to the following method on the in-phase I branch:
channel coding is carried out on the basic text to obtain a coded bit stream DB(t)；
Generating a basic text spread spectrum code C by a basic text spread spectrum code generator according to a basic text spread spectrum code period clock and a Chip clock provided by a time sequence generatorB(t) a bit stream D corresponding to the obtained elementary textB(t) carrying out BPSK-DSSS direct sequence spread spectrum modulation, and updating bit stream corresponding to basic text to CB(t)·DB(t)；
Power proportioning coefficient A based on preset basic telegraph textIPress SI(t)＝AI·CB(t)·DB(t) obtaining an in-phase I branch baseband signal SI(t)。
As a preferred technical scheme of the invention: in the above method for broadcasting the bipolar CSK modulated composite teletext signal, the quadrature Q branch baseband signal is constructed as follows:
channel coding is carried out on the expanded text to obtain a coded expanded text modulation symbol, and the data bit width of the coded expanded text modulation symbol is (K)R+1) bits;
for spread text modulation symbols, optionally KRThe bits forming a parallel data stream DE,P(t) according to the spread telegraph symbol clock provided by the timing generator, by the phase selection module according to the parallel data stream DE,PK of (t)RBit information and generating K according to a preset phase mapping relationRThe phase offset of the spread spectrum code corresponding to the bit information;
according to the extended message code period clock, Chip clock and K provided by the time sequence generatorRThe spread spectrum code phase offset corresponding to the bit information is generated by the spread spectrum code generator with an initial phase KRSpread text spread spectrum code of phase offset corresponding to bit information to obtain parallel data stream DE,P(t) modulated CSK-DSSS direct sequence spread spectrum signal
Figure BDA0002737437090000041
Removing parallel data stream D for spread text modulation symbolsE,P(t) selected KRThe remaining 1 bit after the bit constitutes a serial data stream DE,S(t) from the serial data stream D, according to the spread telegraph symbol clock provided by the timing generatorE,S(t) for the spread spectrum signal
Figure BDA0002737437090000042
Carrying out BPSK-DSSS modulation, and updating bit stream corresponding to spread text modulation symbols to
Figure BDA0002737437090000043
Power proportioning coefficient A based on preset extension messageQPush-button
Figure BDA0002737437090000044
Obtaining quadrature Q branch baseband signal SQ(t) of (d). Wherein (A)I)2+(AQ)2＝1。
As a preferred technical scheme of the invention: the extended text symbol clock comprising:
the spread message symbol clock is synchronous with the spread message modulation symbol, and the period of the spread message symbol clock is equal to the duration of the spread message modulation symbol;
the spread message symbol clock is synchronous with the spread message code period clock, the spread message symbol clock period is equal to N times of the spread message code period, wherein N is an integer greater than or equal to 1;
when N is equal to 1, the duration time of the spread message modulation symbol is equal to the period time of the spread message code, one modulation symbol corresponds to a spread spectrum code sequence of one period, and a conventional CSK-DSSS direct sequence spread spectrum modulation signal is obtained;
and when N is larger than 1, the duration of the modulation symbol of the spread message is equal to N times of the cycle time of the spread message code, one modulation symbol corresponds to the spread spectrum code sequence of N cycles, and CSK-DSSS direct sequence spread spectrum modulation, namely R-CSK-DSSS direct sequence spread spectrum modulation signal with repeated phase shifting is obtained.
As a preferred technical scheme of the invention: the phase selection module is configured with a spread spectrum code phase offset table and the number of phase offsets
Figure BDA0002737437090000045
The phase offset of the spreading code, i.e. the initial phase of the spreading code sequence, is phiiWherein Z is an integer of 1 or more, and i is 0 to M-1. And when the Z is more than 1, the generated phase offsets are not continuous with each other and are spaced by the Z, and the CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase or the R-CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase is obtained.
The invention also provides a bipolar CSK modulation composite telegraph text signal broadcasting device, which comprises:
the first modulation unit is used for modulating the basic telegraph text on the in-phase I branch, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the I branch after channel coding, and constructing an in-phase I branch baseband signal;
the second modulation unit is used for modulating the expanded message on the orthogonal Q branch, randomly taking 1 bit from the modulation symbol of the expanded message after channel coding to form a serial data stream on the Q branch, forming a parallel data stream on the Q branch by the rest bits, carrying out BPSK-DSSS direct sequence spread on the serial data stream on the Q branch, carrying out CSK-DSSS direct sequence spread on the parallel data stream on the Q branch, and jointly constructing an orthogonal Q branch baseband signal by the serial data stream and the parallel data stream on the Q branch of the direct sequence spread;
the carrier modulation unit is used for carrying out IQ quadrature modulation on the basic text baseband signal of the in-phase I branch and the extended text baseband signal of the quadrature Q branch to obtain a carrier signal;
and the sending unit is used for carrying out power amplification processing on the carrier signal and broadcasting the carrier signal by the transmitting antenna.
As a preferred technical solution of the present invention, in a bipolar CSK modulation composite telegraph text signal broadcasting device according to an embodiment of the present invention, the first modulation unit includes:
a coding subunit, configured to perform channel coding on the basic text to obtain a coded bit stream DB(t)；
A first spread spectrum modulation subunit for generating a basic text spread spectrum code C by the basic text spread spectrum code generator according to the basic text spread spectrum code period clock and the Chip clock provided by the time sequence generatorB(t) a bit stream D corresponding to the obtained elementary textB(t) carrying out BPSK-DSSS direct sequence spread spectrum modulation, and updating bit stream corresponding to basic text to CB(t)·DB(t)；
A baseband signal generating subunit for generating a power ratio coefficient A based on a preset basic messageIPress SI(t)＝AI·CB(t)·DB(t) obtaining an in-phase I branch baseband signal SI(t)。
As a preferred technical solution of the present invention, in the bipolar CSK modulation composite telegraph text signal broadcasting device according to the embodiment of the present invention, the second modulation unit includes:
a coding subunit, configured to perform channel coding on the extension message to obtain a coded extension message modulation symbol, where a data bit width of the coding subunit is (K)R+1) bits;
a phase shift subunit for modulating the symbol for the spread text, optionally KRThe bits forming a parallel data stream DE,P(t) according to the spread telegraph symbol clock provided by the timing generator, by the phase selection module according to the parallel data stream DE,PK of (t)RBit information and generating K according to a preset phase mapping relationRThe phase offset of the spread spectrum code corresponding to the bit information;
a second spread spectrum modulation subunit for providing a spread message code period clock, a Chip clock, and K according to the time sequence generatorRThe spread spectrum code phase offset corresponding to the bit information is generated by the spread spectrum code generator with an initial phase KRSpread text spread spectrum code of phase offset corresponding to bit information to obtain parallel data stream DE,P(t) modulated CSK-DSSS direct sequence spread spectrum signal
Figure BDA0002737437090000061
A third spread spectrum modulation subunit for removing the parallel data stream D for the spread text modulation symbolE,P(t) selected KRThe remaining 1 bit after the bit constitutes a serial data stream DE,S(t) from the serial data stream D, according to the spread telegraph symbol clock provided by the timing generatorE,S(t) for the spread spectrum signal
Figure BDA0002737437090000062
Carrying out BPSK-DSSS modulation, and updating bit stream corresponding to spread text modulation symbols to
Figure BDA0002737437090000063
A baseband signal generating subunit for generating a power ratio coefficient A based on the preset extended messageQPush-button
Figure BDA0002737437090000064
Obtaining quadrature Q branch baseband signal SQ(t) of (d). Wherein (A)I)2+(AQ)2＝1。
As a preferred embodiment of the present invention, the extended text-symbol clock includes:
the spread message symbol clock is synchronous with the spread message modulation symbol, and the period of the spread message symbol clock is equal to the duration of the spread message modulation symbol;
the spread message symbol clock is synchronous with the spread message code period clock, the spread message symbol clock period is equal to N times of the spread message code period, wherein N is an integer greater than or equal to 1;
when N is equal to 1, the duration time of the spread message modulation symbol is equal to the period time of the spread message code, one modulation symbol corresponds to a spread spectrum code sequence of one period, and a conventional CSK-DSSS direct sequence spread spectrum modulation signal is obtained;
and when N is larger than 1, the duration of the modulation symbol of the spread message is equal to N times of the cycle time of the spread message code, one modulation symbol corresponds to the spread spectrum code sequence of N cycles, and CSK-DSSS direct sequence spread spectrum modulation, namely R-CSK-DSSS direct sequence spread spectrum modulation signal with repeated phase shifting is obtained.
As a preferred technical scheme of the invention: the phase selection module is configured with a spread spectrum code phase offset table and the number of phase offsets
Figure BDA0002737437090000071
The phase offset of the spreading code, i.e. the initial phase of the spreading code sequence, is phiiWherein Z is an integer of 1 or more, and i is 0 to M-1. And when the Z is more than 1, the generated phase offsets are not continuous with each other and are spaced by the Z, and the CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase or the R-CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase is obtained.
Compared with the prior art, the bipolar CSK modulation composite telegraph text signal broadcasting method has the following excellent effects:
the invention discloses a bipolar CSK modulation composite telegraph text signal broadcasting method, which adopts IQ two-path carrier quadrature modulation, wherein a baseband signal on an in-phase I branch is a BPSK-DSSS direct sequence spread spectrum modulation signal, and can provide required carrier synchronization and modulation symbol synchronization information for signal receiving and processing; the baseband signal on the orthogonal Q branch is a bipolar CSK modulation signal which is subjected to two-stage direct sequence spread spectrum of CSK-DSSS and BPSK-DSSS, and higher information transmission rate can be provided for broadcast signals. Compared with the unipolar conventional CSK-DSSS direct sequence spread spectrum modulation signal, under the conditions of the same data transmission rate and the same signal receiving data demodulation threshold, the bipolar CSK-DSSS direct sequence spread spectrum modulation signal adopted by the invention has the advantage of halving the signal receiving and processing complexity, can greatly reduce the cost of a user receiver, and is beneficial to application and popularization.
By configuring the multiple proportion of the clock period of the expanded message symbol and the code period of the expanded message, the bipolar CSK modulation composite message signal broadcasting method can realize the R-CSK-DSSS direct sequence spread spectrum modulation of repeated phase shift. Compared with the conventional CSK-DSSS modulation signal with single phase shift, the invention has the advantages of low signal receiving data demodulation threshold or low information receiving processing complexity under the condition that the signal broadcasting power spectral density is the same as the data transmission rate.
By configuring a spread spectrum code phase offset table in a phase selection module, the bipolar CSK modulation composite message signal broadcasting method can realize phase discontinuous CSK-DSSS or R-CSK-DSSS direct sequence spread spectrum modulation. Compared with the conventional CSK-DSSS or R-CSK-DSSS direct sequence spread spectrum modulation with continuous phases, when the delay time of the multipath interference signal is between two specified phases, the signal of the invention can not generate related peak side lobe interference, can eliminate the inter-symbol interference problem caused by the related peak side lobe interference, and has the advantage of improving the signal demodulation performance of a receiver.
Because the basic message and the expanded message are respectively placed on the orthogonal IQ branch, different power ratios can be configured for the basic message signal and the expanded message signal with different message rates, and the signal broadcasting efficiency is improved; because IQ branches are orthogonal, the phase difference of carriers is 90 degrees, and the influence of high-power expanded message signals on the receiving performance of basic message signals can be effectively avoided; BPSK signals are broadcast on the I branch, which not only can provide synchronous information required by CSK demodulation for the Q branch, but also can effectively broadcast basic telegraph text; because the basic text signal and the spread text signal are different in spread spectrum code and orthogonal in carrier, a system user only needing to receive the basic text does not need to consider the existence of the spread text, the design of the basic text receiver can be simplified, and the cost of the basic text receiver is reduced.
The method is suitable for the fields of communication, navigation system signal design and the like.
Drawings
Fig. 1 is a composite teletext signal propagation example 1 according to the invention;
fig. 2 is a composite teletext signal propagation example 2 according to the invention;
FIG. 3 is a schematic diagram of the timing relationship of I branch baseband signals;
fig. 4 is a diagram illustrating initial phase mapping relationship between CSK modulation symbol information and spreading code sequence;
FIG. 5 is a diagram illustrating timing relationships of baseband signals of the Q branch;
FIG. 6 is a schematic diagram of a complex baseband signal constellation;
FIG. 7 is an example of a complex textual signal coherent receiver in accordance with the present invention;
fig. 8 is an example of a complex textual signal non-coherent receiver in accordance with the present invention.
Detailed Description
The following description will explain embodiments of the present invention in further detail with reference to the accompanying drawings.
In practical application, the composite telegraph text signal broadcasting example 1 based on the invention shown in fig. 1 can be adopted, the composite telegraph text signal broadcasting example 2 based on the invention shown in fig. 2 can also be adopted, and IQ two-way quadrature modulation is applied to realize the broadcasting of the multi-rate composite telegraph text signal.
Modulating the basic telegraph text on the in-phase I branch, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the I branch after channel coding, and constructing an in-phase I branch baseband signal;
modulating an expanded message on an orthogonal Q branch, arbitrarily selecting 1 bit from an expanded message modulation symbol after channel coding to form a serial data stream on the Q branch, forming parallel data streams on the Q branch by the rest bits, carrying out BPSK-DSSS direct sequence spread on the serial data stream on the Q branch, carrying out CSK-DSSS direct sequence spread on the parallel data streams on the Q branch, and jointly constructing an orthogonal Q branch baseband signal by the serial data stream and the parallel data streams on the Q branch of the direct sequence spread;
the construction of the in-phase I branch baseband signal and the quadrature Q branch baseband signal is implemented by the following methods, respectively.
The specific method for constructing the in-phase I branch baseband signal is as follows:
channel coding is carried out on the basic text to obtain a coded serial data stream DB(t)；
Generating a basic text spread spectrum code C by a basic text spread spectrum code generator according to a basic text spread spectrum code period clock and a Chip clock provided by a time sequence generatorB(t) a bit stream D corresponding to the obtained elementary textB(t) carrying out BPSK-DSSS direct sequence spread spectrum modulation, and updating bit stream corresponding to basic text to CB(t)·DB(t)；
As shown in FIG. 3, the time sequence relation of the I branch baseband signal is given, and the time length of the basic telegraph text clock is TBS1ms, the information of the basic text is formed into a rate R after block coding and channel codingB＝1/TBSBit stream D of 1kbps and with a value of plus or minus 1B(t) of (d). Basic text spreading code CB(T) code rate of 10.23MHz, basic text spread spectrum code period time length TBC1ms, and takes positive and negative 1. The correspondence between the text and the pseudo-random sequence is 1->“PRN(0)+”,-1->"PRN (0) -", where "PRN (0) +" denotes a positive-polarity pseudo-random sequence whose initial phase is 0, and "PRN (0) -" denotes a negative-polarity pseudo-random sequence whose initial phase is 0.
Power proportioning coefficient A based on preset basic telegraph textIPress SI(t)＝AI·CB(t)·DB(t) obtaining an in-phase I branch baseband signal SI(t)。
For the construction of the quadrature Q branch baseband signal, the specific method is as follows:
channel coding is carried out on the expanded text to obtain a coded expanded text modulation symbol, and the data bit width of the coded expanded text modulation symbol is (K)R+1) bits;
for spread text modulation symbols, optionally KRThe bits forming a parallel data stream DE,P(t) according to the spread telegraph symbol clock provided by the timing generator, by the phase selection module according to the parallel data stream DE,PK of (t)RBit information and generating K according to a preset phase mapping relationRThe phase offset of the spread spectrum code corresponding to the bit information;
according to the extended message code period clock, Chip clock and K provided by the time sequence generatorRThe spread spectrum code phase offset corresponding to the bit information is generated by the spread spectrum code generator with an initial phase KRSpread text spread spectrum code of phase offset corresponding to bit information to obtain parallel data stream DE,P(t) modulated CSK-DSSS direct sequence spread spectrum signal
Figure BDA0002737437090000101
FIG. 4 shows the initial phase mapping relationship between CSK modulation symbol information and spreading code sequence, KRNumber of phase offsets of spreading codes corresponding to bit modulation symbol information
Figure BDA0002737437090000102
The phase offset of the spreading code, i.e. the initial phase of the spreading code sequence, is phiiWherein Z is an integer of 1 or more, and i is 0 to M-1. And when the Z is more than 1, the generated phase offsets are not continuous with each other and are spaced by the Z, and the CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase or the R-CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase is obtained. Without loss of generality, for convenience of the following description, K is set in FIG. 4RThe spacing Z is 64, 6.
Removing parallel data stream D for spread text modulation symbolsE,P(t) selected KRThe remaining 1 bit after the bit constitutes a serial data stream DE,S(t) from the serial data stream D, according to the spread telegraph symbol clock provided by the timing generatorE,S(t) for the spread spectrum signal
Figure BDA0002737437090000103
Carrying out BPSK-DSSS modulation, and updating bit stream corresponding to spread text modulation symbols to
Figure BDA0002737437090000104
FIG. 5 shows the timing relationship of the Q branch baseband signal, extending the time length T of the telegraph symbol clockES,REqual to the spread-spectrum code period of the spread-textECN times of (K)R+1) bit represents an extended text modulation symbol, the rate of broadcast of extended text information RE,R＝(KR+1)/TES,R. Without loss of generality, for convenience of subsequent explanation, the clock time length T of the spreading code period of the extended text is setEC1ms, the time length T of the telegraph symbol clock is expandedES,REqual to the spread-spectrum code period of the spread-textEC2, i.e. N is 2, the telegraphic symbol clock time length T is extendedES,R2ms, 7 bits is used to represent an extended text modulation symbol (K)R6), the teletext information dissemination rate R is extendedE,R＝(KR+1)/TES,R＝7/TES,R＝3.5kbps，KRThe bit message value range is 0-63, the phase interval Z is 64 chips, and the corresponding phase offset is the initial phase phi of the pseudo-random sequenceiRepeatedly modulating 2 same pseudo-random sequences with the same phase (namely 6-bit telegram (i) corresponds to N PRNs (i) in the graph of FIG. 5), sequentially connecting the 2 pseudo-random sequences with the same phase offset, and finishing R-CSK-DSSS direct sequence spread spectrum modulation with discontinuous phases; the remaining 1-bit text and the pseudo-random sequence PRN (i x Z) after the direct sequence spread spectrum modulation of the R-CSK-DSSS with discontinuous phase are in the corresponding relation of 1->“PRN(i*Z)+”,-1->And performing BPSK-DSSS modulation by using "PRN (i x Z) -", wherein "PRN (i x Z) +" represents a positive-polarity pseudo-random sequence with an initial phase of i x Z, and "PRN (i x Z) -" represents a negative-polarity pseudo-random sequence with an initial phase of i x Z.
The correspondence between the 6-bit telegram (i) and the PRN (i × Z) in fig. 5 is only an embodiment of the present invention, and other correspondence relationships are also possible.
Power proportioning coefficient A based on preset extension messageQPush-button
Figure BDA0002737437090000111
Obtaining quadrature Q branch baseband signal SQ(t) of (d). Wherein (A)I)2+(AQ)2＝1。
As shown in FIG. 6, the current setting is given
Figure BDA0002737437090000112
In this case, the constellation of the complex baseband signal is only an example, and the power matching relationship is not limited to this correspondence.
In the embodiment of the invention, an extended message symbol clock is synchronous with an extended message modulation symbol, and the period of the extended message symbol clock is equal to the duration of the extended message modulation symbol;
the spread message symbol clock is synchronous with the spread message code period clock, the spread message symbol clock period is equal to N times of the spread message code period, wherein N is an integer greater than or equal to 1;
when N is equal to 1, the duration time of the spread message modulation symbol is equal to the period time of the spread message code, one modulation symbol corresponds to a spread spectrum code sequence of one period, and a conventional CSK-DSSS direct sequence spread spectrum modulation signal is obtained;
and when N is larger than 1, the duration of the modulation symbol of the spread message is equal to N times of the cycle time of the spread message code, one modulation symbol corresponds to the spread spectrum code sequence of N cycles, and CSK-DSSS direct sequence spread spectrum modulation, namely R-CSK-DSSS direct sequence spread spectrum modulation signal with repeated phase shifting is obtained.
In the embodiment of the invention, the phase interval Z is an integer which is more than or equal to 1, when Z is more than 1, the generated phase offsets are not continuous, the interval is Z, and the CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase or the R-CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase is obtained.
In the example of the present invention, in order to ensure that the receiving end obtains the same message demodulation performance, a branch with a high message rate is generally configured with higher signal broadcast power, without considering the difference between the channel coding of the basic message and the channel coding of the extended message.
The two branches use different spreading code sequences. When the message rates are different, the IQ branch can allocate different transmission powers, so that the basic message and the extended message received by the receiving end have the same receiving performance. The spread spectrum codes and messages of the two paths of the broadcast signal IQ are kept synchronous with each other.
For the in-phase I branch baseband signal SI(t) and quadrature Q branch baseband signal SQThe complex expression of (t) is as follows:
S(t)＝SI(t)+jSQ(t)
wherein j is an imaginary number.
Then, IQ quadrature modulation is carried out on the in-phase I branch baseband signal and the quadrature Q branch baseband signal to obtain an intermediate frequency carrier signal, up-conversion processing is carried out on the intermediate frequency carrier signal to obtain a radio frequency carrier signal, and finally, multi-rate composite message signals are formed through power amplification processing and sent to a transmitting antenna.
Here the radio frequency transmit signal of the multirate composite text signal is expressed as follows:
Figure BDA0002737437090000121
wherein, PsRepresenting the total power of the transmitted RF signal of the composite message, fcRepresenting the transmitted signal frequency.
In the bipolar CSK modulation composite message signal broadcasting method, the basic message and the expanded message are respectively placed on orthogonal IQ branches, the broadcasting speed of the expanded message is increased only by increasing the power of the expanded message signal, and the signal broadcasting efficiency is improved; IQ branches are orthogonal, and the phase difference of carriers is 90 degrees, so that the influence of high-power expanded message signals on the receiving performance of basic message signals can be effectively avoided; the BPSK signal broadcast on the I branch can not only provide the Q branch with the synchronous information required by CSK demodulation, but also effectively broadcast the basic telegraph text; by adopting the discontinuous configuration code shift keying modulation technology of phase with repeated or zero repeated times, namely non-repeated phase shift, the information broadcasting rate can be effectively improved, the signal broadcasting efficiency is further improved, and simultaneously the multipath interference signals are effectively inhibited; by adopting the bipolar CSK to modulate the composite text signal, the information transmission rate is further improved and the high-precision positioning service performance of the satellite navigation system is improved on the premise of keeping the complexity of signal receiving and processing basically unchanged.
Aiming at the bipolar CSK modulation composite telegraph text signal broadcasting method, the invention further designs and provides an example of a composite telegraph text signal receiver based on the invention, which comprises an example of a composite telegraph text signal coherent receiver based on the invention and an example of a non-coherent receiver.
An example of a coherent receiver for complex message signals according to the present invention is shown in fig. 7, wherein the basic message receiving method specifically includes the following steps:
a radio frequency carrier signal received by a receiver antenna is processed by a radio frequency Front-End (RF Front-End) to output a digital intermediate frequency signal; firstly, the digital intermediate frequency signal and a carrier frequency-mixing copied by a carrier ring output orthogonal IQ two-path baseband signal, and the IQ two-path baseband signal respectively carries out correlation operation with a basic message spread spectrum code copied by a basic message spread spectrum code generator to obtain IQ two-path correlation results; then IQ two-path correlation results are used as the input of a phase discrimination filtering module, the phase discrimination filtering module calculates a Carrier phase discrimination error and a Code phase discrimination error and filters the phase discrimination error, the filtering results are respectively used for adjusting Carrier NCO (Carrier NCO) and Code NCO (Code NCO), so that the Carrier output by the Carrier NCO is consistent with a receiving Carrier, a basic text spread spectrum Code copied by a basic text spread spectrum Code generator under the control of the Code NCO is consistent with the receiving basic text spread spectrum Code, and the Carrier and the spread spectrum Code in a receiving signal at the next moment are still thoroughly stripped in a tracking loop; and meanwhile, the correlation result output by the I branch correlator outputs basic text data bits through polarity judgment and channel decoding.
The coherent demodulation method of the extended telegraph text specifically comprises the following steps:
when demodulating the basic text, transmitting an extended text spread spectrum code periodic clock and a Chip clock which are obtained after synchronization and are synchronous with a received signal to an extended text spread spectrum code generator, transmitting an extended text symbol clock and the extended text spread spectrum code periodic clock to an M-system orthogonal modulation signal coherent demodulation module, and controlling the received Q-branch baseband by the M-system orthogonal modulation signal coherent demodulation module under the control of the extended text symbol clock and the extended text spread spectrum code periodic clockThe signal and the spread message spread spectrum code generated by the spread message spread spectrum code generator under the control of the spread message spread spectrum code period clock and the Chip clock are subjected to correlation matching calculation to obtain M correlation results r0,r1,…,rM-1Outputting the data to a maximum absolute value selection module;
then, the maximum absolute value selection module selects M input correlation results r0,r1,…,rM-1Taking absolute value, then selecting maximum value of M correlation results absolute value to obtain KRThe serial number j of the maximum absolute value of the bit, and the polarity a of the original correlation result corresponding to the maximum absolute valuemaxIs a reaction of KRBit maximum absolute value number j and absolute value maximum correlation value polarity amaxOutputting to a channel decoding module;
finally, the channel decoding module is used for decoding the serial number j corresponding to the input maximum absolute value and the polarity a of the maximum correlation value of the absolute valuemaxAnd decoding to obtain the transmitted expanded text data.
An example of a composite message signal non-coherent receiver according to the present invention is shown in fig. 8, wherein the basic message receiving method specifically includes the following steps:
a radio frequency carrier signal received by a receiver antenna is processed by a radio frequency Front-End (RF Front-End) to output a digital intermediate frequency signal; firstly, the digital intermediate frequency signal and a carrier frequency-mixing copied by a carrier ring output orthogonal IQ two-path baseband signal, and the IQ two-path baseband signal respectively carries out correlation operation with a basic message spread spectrum code copied by a basic message spread spectrum code generator to obtain IQ two-path correlation results; then IQ two-path correlation results are used as the input of a phase discrimination filtering module, the phase discrimination filtering module calculates a Carrier phase discrimination error and a Code phase discrimination error and filters the phase discrimination error, the filtering results are respectively used for adjusting Carrier NCO (Carrier NCO) and Code NCO (Code NCO), so that the Carrier output by the Carrier NCO is consistent with a receiving Carrier, a basic text spread spectrum Code copied by a basic text spread spectrum Code generator under the control of the Code NCO is consistent with the receiving basic text spread spectrum Code, and the Carrier and the spread spectrum Code in a receiving signal at the next moment are still thoroughly stripped in a tracking loop; and meanwhile, the correlation result output by the I branch correlator outputs basic text data bits through polarity judgment and channel decoding.
The extended text incoherent demodulation method specifically comprises the following steps:
when demodulating the basic text, transmitting an extended text spread spectrum code period clock and a Chip clock which are obtained after synchronization and are synchronous with a received signal to an extended text spread spectrum code generator, transmitting the extended text symbol clock and the extended text spread spectrum code period clock to an M-system orthogonal modulation signal incoherent demodulation module, carrying out correlation matching calculation on the received IQ two paths of baseband signals and the extended text spread spectrum code generated by the extended text spread spectrum code generator under the control of the extended text symbol clock and the extended text spread spectrum code period clock by the M-system orthogonal modulation signal incoherent demodulation module to obtain M correlation results of IQ two paths, and carrying out modulus extraction on the IQ two paths of corresponding correlation results to obtain M correlation results r0,r1,…,rM-1And outputting the data to a maximum value selection module;
then, the maximum value selection module selects M input correlation results r0,r1,…,rM-1Selecting the maximum value of M correlation results to obtain KRBit maximum value number j, KRThe bit maximum value serial number j is output to a channel decoding module;
finally, the channel decoding module is based on the input KRAnd decoding the bit maximum value serial number j to obtain the transmitted expanded text data.
Compared with the prior art, the bipolar CSK modulation composite telegraph text signal broadcasting method has the following excellent effects:
the invention discloses a bipolar CSK modulation composite telegraph text signal broadcasting method, which adopts IQ two-path carrier quadrature modulation, wherein a baseband signal on an in-phase I branch is a BPSK-DSSS direct sequence spread spectrum modulation signal, and can provide required carrier synchronization and modulation symbol synchronization information for signal receiving and processing; the baseband signal on the orthogonal Q branch is a bipolar CSK modulation signal which is subjected to two-stage direct sequence spread spectrum of CSK-DSSS and BPSK-DSSS, and higher information transmission rate can be provided for broadcast signals. Compared with the unipolar conventional CSK-DSSS direct sequence spread spectrum modulation signal, under the conditions of the same data transmission rate and the same signal receiving data demodulation threshold, the bipolar CSK-DSSS direct sequence spread spectrum modulation signal adopted by the invention has the advantage of halving the signal receiving and processing complexity, can greatly reduce the cost of a user receiver, and is beneficial to application and popularization.
By configuring the multiple proportion of the clock period of the expanded message symbol and the code period of the expanded message, the bipolar CSK modulation composite message signal broadcasting method can realize the R-CSK-DSSS direct sequence spread spectrum modulation of repeated phase shift. Compared with the conventional CSK-DSSS modulation signal with single phase shift, the invention has the advantages of low signal receiving data demodulation threshold or low information receiving processing complexity under the condition that the signal broadcasting power spectral density is the same as the data transmission rate.
By configuring a spread spectrum code phase offset table in a phase selection module, the bipolar CSK modulation composite message signal broadcasting method can realize phase discontinuous CSK-DSSS or R-CSK-DSSS direct sequence spread spectrum modulation. Compared with the conventional CSK-DSSS or R-CSK-DSSS direct sequence spread spectrum modulation with continuous phases, when the delay time of the multipath interference signal is between two specified phases, the signal of the invention can not generate related peak side lobe interference, can eliminate the inter-symbol interference problem caused by the related peak side lobe interference, and has the advantage of improving the signal demodulation performance of a receiver.
Because the basic message and the expanded message are respectively placed on the orthogonal IQ branch, different power ratios can be configured for the basic message signal and the expanded message signal with different message rates, and the signal broadcasting efficiency is improved; because IQ branches are orthogonal, the phase difference of carriers is 90 degrees, and the influence of high-power expanded message signals on the receiving performance of basic message signals can be effectively avoided; BPSK signals are broadcast on the I branch, which not only can provide synchronous information required by CSK demodulation for the Q branch, but also can effectively broadcast basic telegraph text; because the basic text signal and the spread text signal are different in spread spectrum code and orthogonal in carrier, a system user only needing to receive the basic text does not need to consider the existence of the spread text, the design of the basic text receiver can be simplified, and the cost of the basic text receiver is reduced.
The method is suitable for the fields of communication, navigation system signal design and the like.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims (10)

1. A method of bipolar CSK modulated composite teletext signal dissemination, the method comprising:
modulating the basic telegraph text on the in-phase I branch, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the I branch after channel coding, and constructing an in-phase I branch baseband signal;
modulating an expanded message on an orthogonal Q branch, arbitrarily selecting 1 bit from an expanded message modulation symbol after channel coding to form a serial data stream on the Q branch, forming parallel data streams on the Q branch by the rest bits, carrying out BPSK-DSSS direct sequence spread on the serial data stream on the Q branch, carrying out CSK-DSSS direct sequence spread on the parallel data streams on the Q branch, and jointly constructing an orthogonal Q branch baseband signal by the serial data stream and the parallel data streams on the Q branch of the direct sequence spread;
and carrying out IQ quadrature modulation on the basic text baseband signal of the in-phase I branch and the expanded text baseband signal of the quadrature Q branch to obtain a carrier signal, carrying out power amplification processing, and broadcasting by a transmitting antenna.
2. The bipolar CSK modulated composite teletext signal propagation method according to claim 1, wherein said constructing an in-phase I branch baseband signal comprises:
channel coding is carried out on the basic text to obtain a coded serial data stream DB(t)；
Generating a basic text spread spectrum code C by a basic text spread spectrum code generator according to a basic text spread spectrum code period clock and a Chip clock provided by a time sequence generatorB(t) a bit stream D corresponding to the obtained elementary textB(t) performing BPSK-DSSS direct sequenceSpread spectrum modulation, updating bit stream corresponding to basic text to CB(t)·DB(t)；
Power proportioning coefficient A based on preset basic telegraph textIPress SI(t)＝AI·CB(t)·DB(t) obtaining an in-phase I branch baseband signal SI(t)。
3. The bipolar CSK modulated composite teletext signal propagation method of claim 1, wherein said constructing a quadrature Q-branch baseband signal comprises:
channel coding is carried out on the expanded text to obtain a coded expanded text modulation symbol, and the data bit width of the coded expanded text modulation symbol is (K)R+1) bits;
for spread text modulation symbols, optionally KRThe bits forming a parallel data stream DE,P(t) according to the spread telegraph symbol clock provided by the timing generator, by the phase selection module according to the parallel data stream DE,PK of (t)RBit information and generating K according to a preset phase mapping relationRThe phase offset of the spread spectrum code corresponding to the bit information;
according to the extended message code period clock, Chip clock and K provided by the time sequence generatorRThe spread spectrum code phase offset corresponding to the bit information is generated by the spread spectrum code generator with an initial phase KRSpread text spread spectrum code of phase offset corresponding to bit information to obtain parallel data stream DE,P(t) modulated CSK-DSSS direct sequence spread spectrum signal
Figure FDA0002737437080000021
Removing parallel data stream D for spread text modulation symbolsE,P(t) selected KRThe remaining 1 bit after the bit constitutes a serial data stream DE,S(t) from the serial data stream D, according to the spread telegraph symbol clock provided by the timing generatorE,S(t) for the spread spectrum signal
Figure FDA0002737437080000022
Carrying out BPSK-DSSS modulation, and updating bit stream corresponding to spread text modulation symbols to
Figure FDA0002737437080000023
Power proportioning coefficient A based on preset extension messageQPush-button
Figure FDA0002737437080000024
Obtaining quadrature Q branch baseband signal SQ(t); wherein (A)I)2+(AQ)2＝1。
4. The bipolar CSK modulated composite teletext signal propagation method according to claim 1 or 3, wherein the extended teletext symbol clock comprises:
the spread message symbol clock is synchronous with the spread message modulation symbol, and the period of the spread message symbol clock is equal to the duration of the spread message modulation symbol;
the spread message symbol clock is synchronous with the spread message code period clock, the spread message symbol clock period is equal to N times of the spread message code period, wherein N is an integer greater than or equal to 1;
when N is equal to 1, the duration time of the spread message modulation symbol is equal to the period time of the spread message code, one modulation symbol corresponds to a spread spectrum code sequence of one period, and a conventional CSK-DSSS direct sequence spread spectrum modulation signal is obtained;
and when N is larger than 1, the duration of the modulation symbol of the spread message is equal to N times of the cycle time of the spread message code, one modulation symbol corresponds to the spread spectrum code sequence of N cycles, and CSK-DSSS direct sequence spread spectrum modulation, namely R-CSK-DSSS direct sequence spread spectrum modulation signal with repeated phase shifting is obtained.
5. The bipolar CSK modulated composite textual signal dissemination method of claim 1 or 3 wherein the phase selection module is configured with a spread spectrum code phase offset table, number of phase offsets
Figure FDA0002737437080000031
The phase offset of the spreading code, i.e. the initial phase of the spreading code sequence, is phiiWherein Z is an integer of 1 or more, and i is 0 to M-1.
And when the Z is more than 1, the generated phase offsets are not continuous with each other and are spaced by the Z, and the CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase or the R-CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase is obtained.
6. A bipolar CSK modulated composite teletext signal dissemination device, the device comprising:
the first modulation unit is used for modulating the basic telegraph text on the in-phase I branch, carrying out BPSK-DSSS direct sequence spread spectrum on the serial data stream on the I branch after channel coding, and constructing an in-phase I branch baseband signal;
the second modulation unit is used for modulating the expanded message on the orthogonal Q branch, randomly taking 1 bit from the modulation symbol of the expanded message after channel coding to form a serial data stream on the Q branch, forming parallel data streams on the Q branch by the rest bits, carrying out BPSK-DSSS direct sequence spread on the serial data stream on the Q branch, carrying out CSK-DSSS direct sequence spread on the parallel data streams, and jointly constructing an orthogonal Q branch baseband signal by the serial data stream on the Q branch and the parallel data streams of the direct sequence spread;
the carrier modulation unit is used for carrying out IQ quadrature modulation on the basic text baseband signal of the in-phase I branch and the extended text baseband signal of the quadrature Q branch to obtain a carrier signal;
and the sending unit is used for carrying out power amplification processing on the carrier signal and broadcasting the carrier signal by the transmitting antenna.
7. The bipolar CSK-modulated composite textual signal dissemination device of claim 6, wherein the first modulation unit comprises:
a coding subunit, configured to perform channel coding on the basic text to obtain a coded bit stream DB(t)；
First spread spectrum modulationA sub-unit for generating a basic message spreading code C by the basic message spreading code generator according to the basic message spreading code period clock and Chip clock provided by the timing generatorB(t) a bit stream D corresponding to the obtained elementary textB(t) carrying out BPSK-DSSS direct sequence spread spectrum modulation, and updating bit stream corresponding to basic text to CB(t)·DB(t)；
A baseband signal generating subunit for generating a power ratio coefficient A based on a preset basic messageIPress SI(t)＝AI·CB(t)·DB(t) obtaining an in-phase I branch baseband signal SI(t)。
8. The bipolar CSK-modulated composite textual signal dissemination device of claim 6 wherein the second modulation unit comprises:
a coding subunit, configured to perform channel coding on the extension message to obtain a coded extension message modulation symbol, where a data bit width of the coding subunit is (K)R+1) bits;
a phase shift subunit for modulating the symbol for the spread text, optionally KRThe bits forming a parallel data stream DE,P(t) according to the spread telegraph symbol clock provided by the timing generator, by the phase selection module according to the parallel data stream DE,PK of (t)RBit information and generating K according to a preset phase mapping relationRThe phase offset of the spread spectrum code corresponding to the bit information;
a second spread spectrum modulation subunit for providing a spread message code period clock, a Chip clock, and K according to the time sequence generatorRThe spread spectrum code phase offset corresponding to the bit information is generated by the spread spectrum code generator with an initial phase KRSpread text spread spectrum code of phase offset corresponding to bit information to obtain parallel data stream DE,P(t) modulated CSK-DSSS direct sequence spread spectrum signal
Figure FDA0002737437080000041
Third spread spectrum modulationA subunit for removing the parallel data stream D for the spread text modulation symbolsE,P(t) selected KRThe remaining 1 bit after the bit constitutes a serial data stream DE,S(t) from the serial data stream D, according to the spread telegraph symbol clock provided by the timing generatorE,S(t) for the spread spectrum signal
Figure FDA0002737437080000042
Carrying out BPSK-DSSS modulation, and updating bit stream corresponding to spread text modulation symbols to
Figure FDA0002737437080000043
A baseband signal generating subunit for generating a power ratio coefficient A based on the preset extended messageQPush-button
Figure FDA0002737437080000044
Obtaining quadrature Q branch baseband signal SQ(t); wherein (A)I)2+(AQ)2＝1。
9. The bipolar CSK modulated composite textual signal dissemination device of claim 6 or 8, wherein the extended textual symbol clock comprises:
the spread message symbol clock is synchronous with the spread message modulation symbol, and the period of the spread message symbol clock is equal to the duration of the spread message modulation symbol;
the spread message symbol clock is synchronous with the spread message code period clock, the spread message symbol clock period is equal to N times of the spread message code period, wherein N is an integer greater than or equal to 1;
when N is equal to 1, the duration time of the spread message modulation symbol is equal to the period time of the spread message code, one modulation symbol corresponds to a spread spectrum code sequence of one period, and a conventional CSK-DSSS direct sequence spread spectrum modulation signal is obtained;
and when N is larger than 1, the duration of the modulation symbol of the spread message is equal to N times of the cycle time of the spread message code, one modulation symbol corresponds to the spread spectrum code sequence of N cycles, and CSK-DSSS direct sequence spread spectrum modulation, namely R-CSK-DSSS direct sequence spread spectrum modulation signal with repeated phase shifting is obtained.
10. The bipolar CSK modulated composite textual signal dissemination device of claim 6 or 8, wherein the phase selection module is configured with a spreading code phase offset table, number of phase offsets
Figure FDA0002737437080000051
The phase offset of the spreading code, i.e. the initial phase of the spreading code sequence, is phiiWherein Z is an integer of 1 or more, and i is 0 to M-1. And when the Z is more than 1, the generated phase offsets are not continuous with each other and are spaced by the Z, and the CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase or the R-CSK-DSSS direct sequence spread spectrum modulation signal with discontinuous phase is obtained.
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CN114624746B (en) * 2022-03-07 2023-01-17 北京凯芯微科技有限公司 CSK modulation symbol decoding method, device, chip and satellite receiver

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