CN109246041B - R-CSK double-rate composite telegraph text signal broadcasting control method - Google Patents

R-CSK double-rate composite telegraph text signal broadcasting control method Download PDF

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CN109246041B
CN109246041B CN201811078853.1A CN201811078853A CN109246041B CN 109246041 B CN109246041 B CN 109246041B CN 201811078853 A CN201811078853 A CN 201811078853A CN 109246041 B CN109246041 B CN 109246041B
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signal
phase
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CN109246041A (en
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王盾
陈耀辉
李东俊
董启甲
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Space Star Technology Co Ltd
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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
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
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Abstract

The invention relates to a R-CSK double-rate composite telegraph text signal broadcasting control method, which comprises the following steps: firstly, on an in-phase I branch, DSSS direct sequence spread spectrum is carried out on basic text by adopting a preset keying modulation method, and an in-phase I branch baseband signal is constructed; meanwhile, on the orthogonal Q branch, a preset keying modulation method is adopted, and code shift keying modulation of repeated phase shift is carried out for multiple times aiming at the spread message to obtain a pseudorandom spread spectrum sequence, namely a baseband signal of the orthogonal Q branch, wherein the code phase of the pseudorandom spread spectrum sequence is controlled by the spread message; 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, power amplification processing is carried out to form a double-rate composite telegraph text signal which is sent to a transmitting antenna for broadcasting. The invention can effectively improve the information broadcasting rate and improve the signal broadcasting efficiency.

Description

R-CSK double-rate composite telegraph text signal broadcasting control method
Technical Field
The invention relates to a R-CSK double-rate composite telegraph text signal broadcasting control method, 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.
For communication and navigation systems using direct sequence spread spectrum signal systems, the rate of broadcast messages is generally less than the reciprocal of the spreading code period. For example, the spreading code period of the GPS L1C/a code in the united states is 1ms, and the rate of the navigation message is 50bps [ refer to ICD-GPS-200C ]; the spread spectrum code period of the WAAS satellite navigation satellite-based augmentation system is 1ms, and the speed of the navigation message is 500sps [ refer to RTCA DO-229D-2006 ]. If the broadcast rate of the telegraph text is increased, the code length of the spread code is shortened, or the polarity is overturned for a plurality of times in one code period, so that the relevant characteristics during signal receiving and tracking are reduced, and the signal receiving performance is damaged.
On the other hand, for the japanese QZSS quasi zenith satellite navigation system which also adopts a code shift keying modulation mode (CSK modulation mode for short) to broadcast messages, in order to provide necessary spreading code chips and code period time information for CSK demodulation, the QZSS system designs a special pilot channel which does not broadcast messages in an L6 signal which broadcasts CSK modulated messages, and the pilot channel signal and the message broadcast signal are combined in a TDM time division multiplexing mode and broadcast in the same carrier phase [ refer to IS-QZSS ver.1.6 ].
Document 1[ refer to chinese national invention patent acceptance number: 201810947305.1, baseband signals of different message rates modulated by BPSK carrier are respectively adopted on IQ orthogonal branches, the I branch modulates basic messages by DSSS direct sequence spread spectrum mode, the Q branch modulates spread messages by CSK code shift keying mode, and the two branches can be configured with different power ratios to meet the requirements of different message transmission rates. Document 2[ refer to chinese national invention patent acceptance number: 201811042847.0, it proposes a multiple-repeated phase-shift code shift keying modulation method (R-CSK modulation method for short), which generates phase shift according to the content of the transmission text, and repeatedly generates a pseudo-random sequence with the same phase shift for multiple times in an information transmission symbol time, so as to obtain higher effective information transmission rate.
On the basis of the dual-rate composite telegraph text broadcasting control method provided by the document 1, the invention introduces the code shift keying modulation method for repeatedly shifting the phase for many times, which is provided by the document 2, improves the conventional CSK modulation method adopted by the document 1, and can obtain better dual-rate composite telegraph text information transmission performance.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a double-rate composite telegraph text signal broadcasting control method which can effectively solve the requirement on multi-type telegraph text service in the application of communication and navigation systems.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for controlling the broadcasting of R-CSK dual-rate composite telegraph text signals is to realize the broadcasting of the dual-rate composite telegraph text signals by applying IQ two-path quadrature modulation, and comprises the following steps:
firstly, on an in-phase I branch, DSSS direct sequence spread spectrum is carried out on basic text by adopting a preset keying modulation method, and an in-phase I branch baseband signal is constructed;
meanwhile, on the orthogonal Q branch, a preset keying modulation method is adopted, and code shift keying modulation of repeated phase shift is carried out for multiple times aiming at the spread message to obtain a pseudorandom spread spectrum sequence, namely a baseband signal of the orthogonal Q branch, wherein the code phase of the pseudorandom spread spectrum sequence is controlled by the spread message;
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, power amplification processing is carried out to form a double-rate composite telegraph text signal which is sent to a transmitting antenna for broadcasting.
As a preferred technical scheme of the invention: in the R-CSK dual-rate composite telegraph text signal broadcasting method, the in-phase I branch baseband signal is constructed on the in-phase I branch according to the following method:
first, channel coding is performed on the basic text to obtain a coded bit stream DB(t)；
Then, according to the basic text spread spectrum code period clock and Chip clock provided by the time sequence generator, the basic text spread spectrum code generator generates the basic text spread spectrum code CB(t) using a predetermined key modulation method to obtain a bit stream D corresponding to the basic textB(t) performing direct sequence spread spectrum modulation to update the bit stream corresponding to the basic text to CB(t)·DB(t)；
Finally, the preset basic message power proportioning coefficient A is combinedIPress 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 R-CSK dual-rate composite telegraph text signal broadcasting method, the quadrature Q branch baseband signal is constructed on the quadrature Q branch as follows:
firstly, carrying out channel coding on an extended message to obtain a coded bit stream;
secondly, according to the spreading message symbol clock provided by the time sequence generator, the corresponding bit stream after the spreading message coding is processed by 1->KRbit serial/parallel conversion is carried out to obtain parallel data streams; wherein each KRBit parallel data duration (symbol time length) equal to N times spreading code period time of the spreading message;
then, according to the spread message spread spectrum code period clock provided by the time sequence generator, the phase selection module generates the phase offset corresponding to the parallel data stream;
finally, according to the spread message code period clock provided by the time sequence generator, the Chip clock and the phase offset corresponding to the parallel data stream, the spread message spread spectrum code generator adopts a preset keying modulation method to repeat the spread message spread spectrum code generated by the spread message spread spectrum code generator for multiple times to carry out code shift keying modulation, and a modulated spread message spread spectrum code signal is obtained
Figure BDA0001801400650000031
And combining with a preset expanded message power ratio coefficient AQPush-button
Figure BDA0001801400650000032
Obtaining a pseudorandom spreading sequence SQ(t), i.e. quadrature Q branch baseband signal SQ(t) wherein the code phase of the pseudorandom spreading sequence is controlled by the spreading text, (a)I)2+(AQ)2＝1。
As a preferred technical scheme of the invention: the spread message symbol clock is an integral multiple of the spread message code period clock and is synchronous with the spread message code period clock.
In addition, as a preferred embodiment of the present invention: the preset keying modulation method is BPSK binary phase shift keying carrier modulation or other multi-system orthogonal signal modulation modes with the same property.
Compared with the prior art, the R-CSK double-rate composite telegraph text signal broadcasting control method has the following excellent effects:
the R-CSK double-rate composite telegraph text signal broadcasting control method adopts IQ two-path quadrature modulation, wherein a BPSK (binary phase shift keying) carrier modulation is adopted on an in-phase I branch, and a baseband signal is a basic telegraph text which is subjected to DSSS (direct sequence spread spectrum); BPSK binary phase shift keying carrier modulation is adopted on the orthogonal Q branch, a baseband signal is a pseudorandom spread spectrum sequence which is subjected to code shift keying modulation of repeated phase shift for multiple times, and the code phase of the pseudorandom sequence is controlled by a broadcast spreading message; under the condition of the same spreading code length or period, a CSK modulation mode is adopted, and the telegraph text broadcasting rate higher than the DSSS direct sequence spread spectrum can be obtained; because the invention adopts code shift keying modulation of repeated phase shift for many times, compared with the conventional CSK modulation system, the demodulation performance of the receiver can be effectively improved under the condition of the same broadcast effective information rate; the CSK modulation information transmission rate can be improved, meanwhile, the signal power density of a receiving end is kept unchanged, and the software and hardware cost and the power consumption of the receiving end for demodulating CSK messages are prevented from being greatly increased; 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 design and the like.
Drawings
FIG. 1 is a block diagram of a broadcasting method in the R-CSK dual-rate composite telegraph text signal broadcasting control method of the present invention;
FIG. 2 is a timing relationship of components of an I-branch baseband signal;
FIG. 3 is a timing relationship of components of a Q branch baseband signal;
FIG. 4 is a constellation diagram of complex baseband signals;
FIG. 5 is a diagram of a basic text signal receiver;
FIG. 6 is a diagram of a coherent receiver for complex textual signals;
FIG. 7 is a diagram of a complex textual signal non-coherent receiver;
FIG. 8 is a diagram of a comb filter configuration;
FIG. 9 is a timing diagram of a conventional CSK modulation;
FIG. 10 is a graph comparing the effect of the R-CSK error rate of the present invention on the conventional CSK error rate.
Detailed Description
The following description will explain embodiments of the present invention in further detail with reference to the accompanying drawings.
In practical application, as shown in fig. 1, the R-CSK dual-rate composite telegraph text signal broadcasting control method of the invention realizes the broadcasting of the dual-rate composite telegraph text signal by applying IQ two-path quadrature modulation.
Firstly, on the in-phase I branch, DSSS direct sequence spread spectrum is carried out on basic text by adopting a preset keying modulation method, and an in-phase I branch baseband signal is constructed.
Meanwhile, on the orthogonal Q branch, a preset keying modulation method is adopted, and code shift keying modulation of repeated phase shift is carried out for a plurality of times aiming at the spread message, so as to obtain a pseudorandom spread spectrum sequence, namely a baseband signal of the orthogonal Q branch, wherein the code phase of the pseudorandom spread spectrum sequence is controlled by the spread message.
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:
first, channel coding is performed on the basic text to obtain a coded bit stream DB(t)；
Then, according to the basic message spread spectrum code period clock (in fig. 1, the basic message spread spectrum code period clock is short) and the Chip clock provided by the time sequence generator, the basic message spread spectrum code generator generates the basic message spread spectrum code CB(t) using a predetermined key modulation method to obtain a bit stream D corresponding to the basic textB(t) performing direct sequence spread spectrum modulation to update the bit stream corresponding to the basic text to CB(t)·DB(t)；
As shown in FIG. 2, the time sequence relation of each component of the in-phase I branch baseband signal is given, and the time length of the basic 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.
Finally, the preset basic message power proportioning coefficient A is combinedIPress 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:
firstly, carrying out channel coding on an extended message to obtain a coded bit stream;
secondly, according to the spreading message symbol clock provided by the time sequence generator, the corresponding bit stream after the spreading message coding is processed by 1->KRbit serial/parallel conversion is carried out to obtain parallel data streams; wherein each KRBit parallel data duration (symbol time length) equal to N times spreading code period time of the spreading message;
then, according to an extended message spread spectrum code period clock (referred to as an extended message code period clock in fig. 1 for short) provided by the timing generator, a phase selection module obtains a phase offset corresponding to the parallel data stream;
FIG. 3 shows the time sequence relationship of each component of the quadrature Q branch signal, extending the time length T of the telegraph symbol clockESEqual to the spread-spectrum code period of the spread-textECBy a factor of N, using KR-bit represents a symbol, extending the rate R at which the teletext information is broadcastE＝KR/TES，KR-the initial phase of the bit corresponding to the PRN is expressed as a decimal value range of
Figure BDA0001801400650000061
I.e. at most can represent
Figure BDA0001801400650000062
And (4) a phase. Without loss of generality, for convenience of subsequent description, N is set to 2, and the message spreading code period clock time length T is extendedEC1ms, using 4-bit to represent a symbol, expanding the broadcast rate R of the message informationE＝4/TESThe initial phase of 2kbps, 4-bit for PRN is expressed as a decimal value MRRepeating and modulating 2 same pseudo-random sequences (i.e. 4-bit text (m) corresponds to N prn (m) in fig. 3) with the same phase, connecting 2 pseudo-random sequences with the same initial phase in sequence to form a new modulation symbol, and completing multiple-time repeated phase-shifting code shift keying modulation. The correspondence between the 4-bit text (m) and the PRN (m) in FIG. 3 is only an embodiment of the present invention, and other correspondence relationships are also possible.
Finally, according to the spread message code period clock provided by the time sequence generator, the Chip clock and the phase offset corresponding to the parallel data stream, the spread message spread spectrum code generator adopts a preset keying modulation method to repeat the spread message spread spectrum code generated by the spread message spread spectrum code generator for multiple times to carry out code shift keying modulation, and a modulated spread message spread spectrum code signal is obtained
Figure BDA0001801400650000071
And combining with a preset expanded message power ratio coefficient AQPush-button
Figure BDA0001801400650000072
Obtaining a pseudorandom spreading sequence SQ(t), i.e. quadrature Q branch baseband signal SQ(t), wherein the code phase of the pseudorandom spreading sequence is controlled by the spreading text.
(AI)2+(AQ)2＝1
As shown in FIG. 4, the current setting is given
Figure BDA0001801400650000073
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 present example of the invention, the spreading text spreading code has a code length of 10230 chips. KRIs selected by
Figure BDA0001801400650000074
Limitation, KRThe maximum may be 13, i.e., the maximum symbol rate of the extended text in this example is 13 ksps. In order to ensure that the receiving end obtains the same message demodulation performance without considering the difference between the channel coding of the basic message and the channel coding of the extended message, a branch with high message rate is generally configured with higher signal broadcast power.
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.
The preset keying modulation method mentioned in the above method is BPSK binary phase shift keying carrier modulation, or other multi-system orthogonal signal modulation methods with the same property.
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, power amplification processing is carried out to form a double-rate composite telegraph text signal which is sent to a transmitting antenna for broadcasting.
The radio frequency transmission signal of the dual rate composite text signal is expressed herein as follows:
Figure BDA0001801400650000081
wherein, PsRepresenting the total power of the transmitted RF signal of the composite message, fcRepresenting the transmitted signal frequency.
In the R-CSK dual-rate composite telegraph text signal broadcasting control method, the basic telegraph text and the expanded telegraph text are respectively placed on orthogonal IQ branches, the broadcasting rate of the expanded telegraph text is increased only by increasing the power of the expanded telegraph text 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 code shift keying modulation technology of repeatedly shifting the phase for many times, the information broadcasting rate can be effectively improved, and the signal broadcasting efficiency is further improved.
Aiming at the designed R-CSK dual-rate composite telegraph text signal broadcasting control method, the invention further designs a composite signal receiving method, which comprises a basic telegraph text receiving method in the R-CSK dual-rate composite telegraph text signal, a coherent demodulation extended telegraph text receiving method in the R-CSK dual-rate composite telegraph text signal and an incoherent demodulation extended telegraph text receiving method in the R-CSK dual-rate composite telegraph text signal; the method for receiving the basic message in the R-CSK dual-rate composite message signal is shown in fig. 5 and specifically comprises 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 is judged by the basic text judgment module to output the basic text data bit.
As shown in fig. 6, the method for receiving coherent demodulation extended telegraph text in R-CSK dual-rate composite telegraph text signals specifically includes the following steps:
when demodulating the basic message, transmitting an extended message spread spectrum code periodic clock and a Chip clock which are obtained after synchronization and are synchronous with a received signal to an extended message spread spectrum code generator and a coherent matching filtering module, and transmitting an extended message symbol clock and the extended message spread spectrum code periodic clock to a comb filter; transmitting the Q branch baseband signal to a comb filter, and superposing N groups of pseudorandom sequence data in the same symbol into 1 group of pseudorandom sequence data by the comb filter;
the comb filter is shown in fig. 8: the comb filter delays the input data by N-1 times in sequence under the control of a periodic clock of the spread message spread spectrum code, and the periodic time T of the spread message spread spectrum code is delayed and expanded every timeECSecond, the N-1 time delay data and the input data are superposed and then sent to a data interception module; secondly, the data interception module intercepts input data stream under the control of an expanded message symbol clock and an expanded message spread spectrum code period clock, outputs data superposed for N times in the same symbol, and the data time length is the expanded message spread spectrum code period time TECAnd second. The intercepted data is sent to a coherent matched filtering module.
Then, the coherent matched filter module controls the received time length to be T under the control of the spread message symbol clock and the spread message spread spectrum code period clockECThe data block 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, correlation results are output to a correlation peak searching module, the phase of the local spread message spread spectrum code corresponding to the correlation peak is searched, and the phase is converted into bit data to be output;
and finally, the bit data output by the correlation peak searching module passes through a channel decoding module to obtain transmitted expanded text data.
The method for receiving the incoherent demodulation extended telegraph text in the R-CSK dual-rate composite telegraph text signal is shown in fig. 7, and specifically comprises the following steps:
when demodulating the basic message, transmitting an extended message spread spectrum code periodic clock and a Chip clock which are obtained after synchronization and are synchronous with a received signal to an extended message spread spectrum code generator and a non-coherent matched filtering module, and transmitting an extended message symbol clock and the extended message spread spectrum code periodic clock to a comb filter; the baseband IQ two-path signals are transmitted to a comb filter, and the comb filter superposes N groups of pseudo-random sequence data in the same symbol into 1 group of pseudo-random sequence data;
wherein the content of the first and second substances,the comb filter is constructed as shown in fig. 8: the comb filter delays the input data by N-1 times in sequence under the control of a periodic clock of the spread message spread spectrum code, and the periodic time T of the spread message spread spectrum code is delayed and expanded every timeECSecond, the N-1 time delay data and the input data are superposed and then sent to a data interception module; secondly, the data interception module intercepts input data stream under the control of an expanded message symbol clock and an expanded message spread spectrum code period clock, outputs data superposed for N times in the same symbol, and the data time length is the expanded message spread spectrum code period time TECAnd second. The intercepted data is transmitted to a non-coherent matched filtering module.
Then, the incoherent matched filter module takes the received time length as T under the control of the spread message symbol clock and the spread message spread spectrum code period clockECThe data block 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, correlation results are output to a correlation peak searching module, the phase of the local spread message spread spectrum code corresponding to the correlation peak is searched, and the phase is converted into bit data to be output;
and finally, the bit data output by the correlation peak searching module passes through a channel decoding module to obtain transmitted expanded text data.
In order to more intuitively embody the effectiveness of the R-CSK modulation adopted by the Q branch in comparison with the conventional CSK modulation provided by the present invention, fig. 10 is a graph comparing the effect of the information transmission error rate of the R-CSK of the present invention with the conventional CSK information error rate, theoretical calculation is performed for the error rate performance of the conventional CSK and the R-CSK under the condition that the transmission information rates are consistent, and the related symbols and the corresponding relations are agreed as follows:
FIG. 9 shows a timing diagram of a conventional CSK modulation in which the spreading code period time of the spreading code of the spreading message is TECChip length L and symbol time length TESWherein T isES＝TECWhen K-bit is used to represent a symbol, the system is M2KInformation rate RE＝K/TES(ii) a The initial phase of the K-bit corresponding to the PRN is shown as a decimal value ranging from M to 0,1, …,2K1, i.e. can represent at most 2KAnd-1 phase, and modulating the pseudo random sequence by an initial phase represented by a K-bit symbol to complete CSK modulation. In fig. 9, K ═ 2 is taken as an example, and correspondence between the 2-bit text (m) and the prn (m) is only one embodiment of the present invention, and other correspondence relationships may be used.
The coherent demodulation symbol error rate calculation formula of the conventional CSK modulation is as follows:
Figure BDA0001801400650000111
the formula converted into the bit error rate of the information is as follows:
Figure BDA0001801400650000112
in R-CSK, the spreading code period time of the spreading message is TECChip length L and symbol time length TES,RBy using KR-bit represents a symbol with repetition number N, K being satisfied to achieve a transmission rate consistent with the conventional CSKR＝NK,TES,R＝NTESThen carry M toR＝2NK＝MNInformation rate RE,R＝KR/TES,R＝NK/NTEC＝K/TES＝RE；
M of R-CSKRAnd substituting into a coherent demodulation symbol error rate calculation formula of CSK modulation to obtain a coherent demodulation symbol error rate calculation formula of R-CSK:
Figure BDA0001801400650000113
the formula converted into the bit error rate of the information is as follows:
Figure BDA0001801400650000114
in order to facilitate the calculation of the calculation,without loss of generality, K is 2 (i.e., M is 4), and N is 2 (i.e., M is 4)R16) was simulated, the effect is shown in fig. 10, and it can be seen that at the same information transmission rate and the same Eb/N0Under the condition of bit energy noise density ratio, the bit error rate of coherent demodulation information obtained by the R-CSK modulation method provided by the invention is lower than that obtained by a conventional CSK modulation method, and the transmission performance is better. The same conclusion can also be obtained from the information bit error rate calculation formula of the CSK modulation non-coherent demodulation. As can be deduced from fig. 10, the R-CSK modulation method proposed by the present invention requires less bit energy for information transmission under the condition of the same bit error rate of the information. Or, in other words, under the condition that the error rate of the information bits is the same as the energy of the information bits, the R-CSK modulation method provided by the invention can obtain a higher information transmission rate.
In the above example of the present invention, the basic text bit width is equal to the basic text spreading code period, and the extended text spreading code period is equal to the basic text spreading code period, which is just one example of the application of the present invention, and the basic text bit width, the basic text spreading code period, and the extended text spreading code period may be set to any relationship of coherent synchronization with each other
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 (4)

1. A R-CSK double-rate composite telegraph text signal broadcasting control method is characterized by comprising the following steps: the method for realizing the broadcasting of the double-rate composite telegraph text signal by using IQ two-path quadrature modulation comprises the following steps:
firstly, on an in-phase I branch, DSSS direct sequence spread spectrum is carried out on basic text by adopting a preset keying modulation method, and an in-phase I branch baseband signal is constructed;
meanwhile, on the orthogonal Q branch, a preset keying modulation method is adopted, and code shift keying modulation of repeated phase shift is carried out for multiple times aiming at the spread message to obtain a pseudorandom spread spectrum sequence, namely a baseband signal of the orthogonal Q branch, wherein the code phase of the pseudorandom spread spectrum sequence is controlled by the spread message;
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, power amplification processing is carried out to form a double-rate composite telegraph text signal which is sent to a transmitting antenna;
on the orthogonal Q branch, the baseband signal of the orthogonal Q branch is constructed according to the following method:
firstly, carrying out channel coding on an extended message to obtain a coded bit stream;
secondly, according to the spreading message symbol clock provided by the time sequence generator, the corresponding bit stream after the spreading message coding is processed by 1->KRbit serial/parallel conversion is carried out to obtain parallel data streams; wherein each KR-the bit parallel data duration, i.e. the symbol time length, is equal to N times the spreading code period time of the spreading message;
then, according to the extended message code period clock provided by the time sequence generator, the phase selection module generates the phase offset corresponding to the parallel data stream;
finally, according to the spread message code period clock provided by the time sequence generator, the Chip clock and the phase offset corresponding to the parallel data stream, the spread message spread spectrum code generator adopts a preset keying modulation method to repeat the spread message spread spectrum code generated by the spread message spread spectrum code generator for multiple times to carry out code shift keying modulation, and a modulated spread message spread spectrum code signal is obtained
Figure FDA0002728955610000011
And combining with a preset expanded message power ratio coefficient AQPush-button
Figure FDA0002728955610000012
Obtaining a pseudorandom spreading sequence SQ(t), i.e. quadrature Q branch baseband signal SQ(t) in which the code phase of the pseudorandom spreading sequence is subjected toExtended text control (A)I)2+(AQ)2＝1。
2. The R-CSK dual-rate composite telegraph text signal broadcasting control method as claimed in claim 1, characterized in that: on the in-phase I branch, an in-phase I branch baseband signal is constructed according to the following method:
first, channel coding is performed on the basic text to obtain a coded bit stream DB(t)；
Then, according to the basic text spread spectrum code period clock and Chip clock provided by the time sequence generator, the basic text spread spectrum code generator generates the basic text spread spectrum code CB(t) using a predetermined key modulation method to obtain a bit stream D corresponding to the basic textB(t) performing direct sequence spread spectrum modulation to update the bit stream corresponding to the basic text to CB(t)·DB(t)；
Finally, the preset basic message power proportioning coefficient A is combinedIPress SI(t)＝AI·CB(t)·DB(t) obtaining an in-phase I branch baseband signal SI(t)。
3. The R-CSK dual-rate composite telegraph text signal broadcasting control method as claimed in claim 1, characterized in that: the spread message symbol clock is an integral multiple of the spread message code period clock and is synchronous with the spread message code period clock.
4. The R-CSK dual-rate composite telegraph text signal broadcasting control method as claimed in claim 1, characterized in that: the preset keying modulation method is BPSK binary phase shift keying carrier modulation or other multi-system orthogonal signal modulation modes with the same property.
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