CN105337634A - Spread spectrum communication method and spread spectrum communication device based on two-dimensional baseband direct sequence spread spectrum - Google Patents

Spread spectrum communication method and spread spectrum communication device based on two-dimensional baseband direct sequence spread spectrum Download PDF

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CN105337634A
CN105337634A CN201410381693.3A CN201410381693A CN105337634A CN 105337634 A CN105337634 A CN 105337634A CN 201410381693 A CN201410381693 A CN 201410381693A CN 105337634 A CN105337634 A CN 105337634A
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spread spectrum
branch road
module
code sequence
base band
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CN105337634B (en
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康家方
王红星
毛忠阳
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School Of Aeronautical Combat Service Naval Aeronautical University Of People's Liberation Army
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Abstract

The invention provides a spread spectrum communication method and a spread spectrum communication device based on two-dimensional baseband direct sequence spread spectrum. A baseband transmission part contains two first and second parallel direct sequence spread spectrum transmission branches, wherein a spread spectrum code sequence adopted by second branch spread spectrum modulation is Hilbert transform of the spread spectrum code sequence adopted by first branch spread spectrum modulation, or a forming function used for forming a second branch baseband is the Hilbert transform of the forming function used for forming a first branch baseband, and first and second branch spread spectrum modulation signals are output after being superposed; and a receiving end adopts a matched filtering method to carry out non-interference demodulation on the received signals. The communication method and the communication device provided by the invention can be used for spreading the spatial dimension of a baseband signal of a traditional direct sequence spread spectrum communication system from 1 to 2, so that the communication capacity and the communication rate are doubled, and the potential application fields comprise military satellite communication, confidential radio communication, Beidou satellite navigation communication systems, etc.

Description

Based on spectrum spread communication method and the communicator of 2 dimension baseband direct sequence spread spectrums
Technical field
The present invention relates to radio communication technology, more specifically, the present invention relates to a kind of spectrum spread communication method based on 2 dimension baseband direct sequence spread spectrums and communicator, belong to technical field of information transmission.
Background technology
A characteristic feature of spread spectrum system is that the bandwidth be transmitted shared by signal energy must be greater than bandwidth corresponding to information bit rate (be generally much larger than), and it has been generally acknowledged that transmission bandwidth and information bit rate have nothing to do, this viewpoint is all clearly refer in the documents and materials such as the classical works " IntroductiontoSpreadSpectrumCommunications " of patent disclosed in the U.S. " METHODANDAPPARATUSFORSELECTINGASPREADINGCODEINASPECTRUMS PREADCOMMUNICATIONSYSTEM " (see U.S.Patent5515396) and RogerL.
Resistant DS Spread Spectrum System (DSSS) is a kind of typical spread spectrum communication system, it is also called direct sequence modulating system or pseudonoise system (PN system), there is anti-interference, that Anti TBIgG, ability of anti-multipath are strong feature, be all widely used at numerous areas such as global positioning satellite, Beidou navigation, satellite communication, military radio communication, surveies of deep space.The information spreading code that direct sequence spread spectrum will send expands to a very wide frequency band and gets on, and at receiving terminal, carries out relevant treatment, and then recover primary data information (pdi) with the spreading code identical with transmitting terminal to the spread-spectrum signal received.A characteristic feature of this system is that the bandwidth of modulated spread-spectrum signal and modulation intelligence bit rate have nothing to do, and from the angle of spectrum utilization, the spectrum efficiency of this system is extremely low.
As everyone knows, under the prerequisite not increasing Signal transmissions bandwidth, increase signal space dimension and can improve information transfer efficiency; Meanwhile, the orthogonal or accurate orthogonal property between signal is utilized can to realize the noiseless demodulation of multi-dimensional modulation signal.As can be seen from the physical layer general principle of direct sequence spread spectrum communication system, traditional direct sequence spread spectrum transmission system only has 1 signal dimension in base band, and its message capacity and transmission rate are also just restricted.If under the prerequisite not increasing Signal transmissions bandwidth, the signal space dimension be associated with spreading code in direct sequence spread spectrum communication system can be increased, just can significantly improve message capacity and the transmission rate of direct sequence spread spectrum communication system.
Summary of the invention
Based on the basic physical layer principle of Direct Sequence Spread Spectrum Communication, from the angle of expansion modulation signal Spatial Dimension, realize the 2 dimension baseband direct sequence spread spectrum transmission based on single spreading code, improve message capacity and the transmission rate of direct sequence spread spectrum transmission system.The invention provides a kind of spectrum spread communication method based on 2 dimension baseband direct sequence spread spectrums and communicator.
According to an aspect of the present invention, a kind of spectrum spread communication method based on 2 dimension baseband direct sequence spread spectrums is provided:
Radiating portion: first serioparallel exchange preliminary treatment is carried out to pre-adjusting information, secondly base-band digital modulation is carried out to pretreated information, then direct sequence spread spectrum modulation is carried out to base-band digital modulation signal, it is shaping that signal after modulating direct sequence spread spectrum again carries out base band, and the signal after shaping is carried out up-conversion and exported by antenna.
Receiving unit: first receive modulated signal by antenna, and carry out down-conversion to received signal; Then carry out despreading demodulation processing to received signal, obtain demodulating information, finally parallel-serial conversion process is carried out to demodulating information.
It is characterized in that: baseband transmission comprises first, second two parallel transmission branch roads, wherein, second branch road spread spectrum code sequence is the orthogonal transform form of the first branch road spread spectrum code sequence, or the second branch road base band shaping function and the first branch road base band shaping function mutually orthogonal; First, second branch road spread spectrum code sequence described is the spread spectrum code sequence that the modulation of first, second branch road direct sequence spread spectrum adopts respectively, and first, second branch road base band shaping function described is the shaping function of the shaping employing of first, second branch road base band respectively.
When the second branch road spread spectrum code sequence is the orthogonal transform form of the first branch road spread spectrum code sequence, after the modulation of first, second branch road direct sequence spread spectrum, first branch road modulated spread spectrum signal is superposed, then to carry out base band shaping with signal.Further, described orthogonal transform is Hilbert transform; First, second branch road demodulation of receiving unit all adopts matched filtering demodulation method, the template signal that first, second flow adaptation demodulation by filter adopts be respectively first, second branch road spread spectrum code sequence base band shaping after the waveform signal that obtains.
When the second branch road spread spectrum code sequence is identical with the first branch road spread spectrum code sequence, the second branch road base band shaping function and the first branch road base band shaping function mutually orthogonal; After first, second branch road base band is shaping, signal is superposed, then carry out up-conversion to signal.Further, the second branch road base band shaping function is the Hilbert transform of the first branch road base band function; First, second branch road demodulation of receiving unit all adopts matched filtering demodulation method, and the template signal that first, second branch road demodulation module matched filtering adopts is respectively the waveform signal that first, second branch road spread spectrum code sequence obtains after first, second branch road shaping function is shaping.
According to a further aspect in the invention, a kind of frequency spreading device based on 2 dimension baseband direct sequence spread spectrums is provided, comprises transmitter unit and receiving element:
Transmitter unit, for completing 2 dimension baseband direct sequence band spectrum modulation, and launches output by modulation signal frequency conversion; Comprise: information source module, for providing system pre-adjusting information; Serioparallel exchange pretreatment module, for carrying out serioparallel exchange preliminary treatment to the pre-adjusting information of serial; Digital baseband modulation module, carries out digital baseband modulation for pretreated pre-adjusting information; Direct sequence spread spectrum modulation module, for carrying out direct sequence spread spectrum modulation to digital baseband modulation signal; Base band forming module, shaping for carrying out base band to digital modulated spread spectrum signal; Laminating module, for synthesizing a road and signal by arm modulation Signal averaging; Up-conversion output module, for carrying out up-conversion to base-band spread-spectrum modulation signal, and is exported the signal after frequency conversion by antenna transmission.
Receiving element, for receiving modulated signal, and carrying out demodulation process to received signal, obtaining demodulating information; Comprising: down-conversion receiver module, for receiving modulated signal by antenna, and carrying out down-conversion to received signal; Demodulation module, for carrying out demodulation to received signal, obtains demodulating information; Parallel-serial conversion processing module, for carrying out parallel-serial conversion process to parallel demodulation information; Stay of two nights module, receives or stores demodulating information.
It is characterized in that: digital modulation module comprises first, second digital modulation module, direct sequence spread spectrum module comprises first, second direct sequence spread spectrum module, and demodulation module comprises first, second demodulation module; Second spread spectrum code sequence is identical with the first spread spectrum code sequence, or the orthogonal transform form of the first spread spectrum code sequence, and first, second spread spectrum code sequence described is the spread spectrum code sequence that first, second direct sequence spread spectrum module adopts respectively.
When the second spread spectrum code sequence is the orthogonal transform form of the first spread spectrum code sequence, laminating module input is connected with first, second direct sequence spread spectrum module, and output is connected with base band forming module.Further, described orthogonal transform is Hilbert transform, first, second demodulation module adopts matched filtering demodulation technology, the template signal that first, second mode transfer Block-matching filtering adopts be respectively first, second spread spectrum code sequence base band shaping after the waveform signal that obtains.
When the second spread spectrum code sequence is identical with the first spread spectrum code sequence, base band forming module comprises first, second base band forming module further, laminating module input is connected with first, second base band forming module, output is connected with up-conversion output module, first shaping function and the second shaping function mutually orthogonal, first, second shaping function described be respectively first, second base band forming module adopt shaping function.Further, second shaping function is the Hilbert transform of the first base band function, first, second demodulation module adopts matched filtering demodulation technology, and the template signal that first, second mode transfer Block-matching filtering adopts is respectively the waveform signal that spread spectrum code sequence obtains after first, second shaping function is shaping.
Accompanying drawing explanation
Referring to accompanying drawing, the specific embodiment of the invention and embodiment are described further, wherein:
Fig. 1 is the spread spectrum communication system transmitter unit Structure and Process based on 2 dimension baseband direct sequence spread spectrums.
Fig. 2 is the spread spectrum communication system receiving element Structure and Process based on 2 dimension baseband direct sequence spread spectrums.
Fig. 3 is the normalization time-domain response of base band shaping function h (t).
Fig. 4 is the Hilbert transform of base band shaping function h (t) normalization time-domain response waveform.
Fig. 5 is system error performance simulation curve.
As shown in the figure, in order to more clearly state embodiments of the invention structure, specific structure and module are marked in the drawings, this is only signal needs, be not intended to limit the invention in this ad hoc structure, module or environment, these devices and module can carry out adjusting or revising by those of ordinary skill in the art according to specific needs, and the adjustment carried out or amendment are still included in accompanying right.
Embodiment
In the following description, multiple different aspect of the present invention will be described, but, for those skilled in the art, can only utilize part or all structure of the present invention or flow process to implement the present invention.In order to the definition explained, set forth specific number, configuration and order, but clearly, also can implement the present invention when there is no these specific detail.Concrete technology due to the present invention's employing is the basic fundamental (as serioparallel exchange, direct sequence spread spectrum, Hilbert transform, matched filtering demodulation etc.) that those of ordinary skill in the art know, in order to not obscure the present invention, will no longer be described in detail for numerous known feature.
(1) based on the concrete implementation step of spectrum spread communication method of 2 dimension baseband direct sequence spread spectrums:
According to an aspect of the present invention, provide a kind of spectrum spread communication method based on 2 dimension baseband direct sequence spread spectrums, Fig. 1, Fig. 2 are spread spectrum communication system transmitter unit and the receiving element structure flow chart of tieing up the direct serial spread spectrum of base band based on 2 respectively.As can be seen from the figure, the method implementation step comprises: the modulation of presetting information serioparallel exchange, first, second digital baseband and direct sequence spread spectrum, the digital modulated spread spectrum signal base band of first, second branch road be shaping, superpose, up-conversion exports; Receive down-conversion, first, second branch road demodulation, parallel-serial conversion.
Particularly, the concrete implementation step based on the spectrum spread communication method of 2 dimension baseband direct sequence spread spectrums is:
1. serioparallel exchange.According to the pre-adjusting information of serial that information source module provides, serioparallel exchange is carried out to pre-adjusting information and obtains a i, b ii=0,1,2 ... two-way walks abreast pre-adjusting information, for the ease of setting forth, and might as well by a ibranch road is called the first branch road, b ibranch road is called that the second branch road is pre-, a i, b irepresent the pre-adjusting information of first, second branch road respectively.
2. digital baseband modulation.According to the concrete digital baseband modulation system that system adopts, respectively to a i, b icarry out digital baseband modulation, obtain first, second branch road numeral baseband modulation signal a (t), b (t).
3. direct sequence spread spectrum modulation.Utilize the spread spectrum code sequence that length is K respectively i=1,2 ..., K, carries out direct sequence spread spectrum modulation to first, second branch road numeral baseband modulation signal, obtains first, second branch road numeral base-band spread-spectrum modulation signal a c(t), b c(t).
4. base band is shaping.Utilize base band shaping function h respectively 1(t), h 2t (), to first, second branch road numeral base-band spread-spectrum modulation signal a c(t), b ct () carries out base band shaping, obtains first, second branch road base-band spread-spectrum modulation signal s a(t), s b(t).
5. time domain superposition.Time domain superposition is carried out to first, second tributary signal that back obtains, obtains a road and signal.
6. up-conversion launches output.After shaping to base band and signal carries out up-conversion, and is exported by antenna by the signal after frequency conversion.
7. down-conversion receives.Receive modulated signal by antenna, and down-conversion is carried out to it, obtain Received signal strength r (t)=s (t)+n (t), n (t) and represent noise jamming.
8. demodulation.According to the digital baseband modulation system of transmitting terminal, utilize spread spectrum code sequence respectively i=1,2 ..., K, and base band shaping function h 1(t), h 2t (), r (t) carries out demodulation to received signal, obtains first, second branch road demodulating information a ' i, b ' i.
9. parallel-serial conversion.To first, second branch road parallel demodulation information a ' iwith b ' icarry out parallel-serial conversion, obtain final demodulating information.
The feature of communication means is, at base band transmitting two paths modulated spread spectrum signal simultaneously, need meet a condition in following two conditions:
Condition 1): step 3. in, second branch road band spectrum modulation adopt spread spectrum code sequence i=1,2 ..., K is that the first branch road band spectrum modulation adopts spread spectrum code sequence i=1,2 ..., the orthogonal transform form of K;
Condition 2): step 4. in, the shaping function h of the shaping employing of the second base band 2the shaping function h of (t) and the shaping employing of the first base band 1t () is mutually orthogonal.
Satisfy condition 1) when:
When first, second base band shaping function is identical, i.e. h 1(t)=h 2time (t), also can ensure base band shaping after code element modulated spread spectrum signal mutually orthogonal, that is:
∫ - T g 2 T s + T g 2 S a ( t ) S b ( t ) dt = 0 - - - ( 1 )
In formula, T srepresent code-element period, T gcode element expansion time after expression base band is shaping.
When first, second base band shaping function is different, can be obtained by the autocorrelation performance of spread spectrum code sequence:
∫ - T g 2 T s + T g 2 S a ( t ) S b ( t ) dt ≈ 0 - - - ( 2 )
Satisfy condition 2) when:
When first, second base-band spread-spectrum code sequence is identical or the second base-band spread-spectrum code sequence is the orthogonal transform form of the first base-band spread-spectrum code sequence, according to the autocorrelation performance of orthogonal function and spread spectrum code sequence, can obtain:
∫ - T g 2 T s + T g 2 S a ( t ) S b ( t ) dt ≈ 0 - - - ( 3 )
Further, the shaping symbol time expansion T caused of base band is considered gcause the intersymbol interference problem of code element before and after between branch road, due to Direct Sequence Spread Spectrum Communication spreading factor K (namely spread code length) usually comparatively large (tens, hundreds of even thousands of), and above-mentioned intersymbol interference is band spectrum modulation chip carries out causing when base band is shaping, its value relative to whole code element energy almost can ignore.
Being analyzed as can be seen from above, meeting under described arbitrary condition, two branch road band spectrum modulation code elements all can be made to be in quasi-orthogonal state, is also the necessary condition ensureing system transfers performance.
As everyone knows, Hilbert transform is a kind of orthogonal transform, carries out Hilbert transform can obtain another discrete series to discrete series, carries out Hilbert transform can obtain another continuous function to continuous function.This characteristic is applied in the present invention, both can obtain and the first branch road spread spectrum code sequence i=1,2 ..., the Hilbert transform sequence that K is mutually orthogonal can obtain again and the first branch road base band shaping function h 1t shaping function h that () is mutually orthogonal 2(t).The natural characteristic of Hilbert transform can bring the transmission performance of near ideal to system.Especially, the time domain waveform of raised cosine shaping function and Hilbert transform thereof respectively as shown in Figure 3, Figure 4.
A kind of modulation system often has multiple demodulation method, and when two paths of signals meets orthogonal or accurate orthogonal property, matched filtering is a kind of simple, efficient demodulation method, is also one of demodulation method of extensive use in communication system.Based on the fundamental characteristics of modulation signal of the present invention, the method for matched filtering demodulation can be adopted.
Particularly, step 8. in, adopt the demodulation method of matched filtering, the template signal that the first demodulation flow adaptation filtering adopts is spread spectrum code sequence i=1,2 ..., K is through shaping function h 1waveform signal t () is shaping after, the template signal that the second demodulation flow adaptation filtering adopts is spread spectrum code sequence i=1,2 ..., K is through shaping function h 2waveform signal t () is shaping after.
It should be noted that, consider the complexity issue that system realizes, when satisfying condition 1), first, second base band shaping function h 1(t), h 2t () is identical, now can by step 4. with step 5. order exchange, and by step 4. in first, second two base band shaping to merge into a base band shaping, obtain base-band spread-spectrum modulation signal after shaping.
(2) based on the concrete implementation step of frequency spreading device of 2 dimension baseband direct sequence spread spectrums
According to a further aspect in the invention, a kind of frequency spreading device based on 2 dimension baseband direct sequence spread spectrums is provided.Transmitter unit comprises information source module, serioparallel exchange module, digital baseband modulation module (comprising first, second digital baseband modulation module), direct sequence spread spectrum modulation module (comprising first, second direct sequence spread spectrum modulation module), base band forming module, laminating module, up-conversion transmitter module; Receiving element comprises reception down conversion module, demodulation module (comprising first, second demodulation module), parallel serial conversion module and stay of two nights module.Fig. 1, Fig. 2 tie up spread spectrum communication system transmitter unit and the receiving element Structure and Process of the direct serial spread spectrum of base band based on 2.
Wherein, transmitter unit has been used for 2 dimension baseband direct sequence band spectrum modulation, and output is launched in modulation signal frequency conversion; Comprise: information source module, for providing system pre-adjusting information; Serioparallel exchange module, for carrying out serial conversion to the pre-adjusting information of serial, obtaining the first branch road and the second branch road two-way and to walk abreast pre-adjusting information; Digital baseband modulation module, comprises first, second digital baseband modulation module, is respectively used to carry out digital baseband modulation to the pre-adjusting information of first, second branch road, obtains first, second branch road numeral baseband modulation signal; Direct sequence spread spectrum modulation module, comprises first, second direct sequence spread spectrum modulation module, is respectively used to carry out direct sequence spread spectrum modulation to digital baseband modulation signal, obtains first, second branch road numeral modulated spread spectrum signal; Base band forming module, shaping for carrying out base band to digital modulated spread spectrum signal; Laminating module, for being superposed by first, second branch road base-band spread-spectrum modulation signal, obtains a road and signal; Up-conversion transmitter module, for carrying out up-conversion to the signal after the shaping superposition of base band, and is exported the signal after frequency conversion by antenna transmission.
Receiving element for receiving modulated signal, and carries out demodulation process to received signal, obtains demodulating information; Comprising: down-conversion receiver module, for receiving modulated signal by antenna, and carrying out down-conversion to received signal; Demodulation module, comprises first, second branch road demodulation module, is respectively used to first, second arm modulation information of demodulation, obtains first, second branch road demodulating information; Parallel serial conversion module, for carrying out parallel-serial conversion to first, second branch road demodulating information, obtains the serial data identical with transmitter unit streamed; Stay of two nights module, receives or stores demodulating information.
The specific implementation process of the frequency spreading device transmitter unit based on 2 dimension baseband direct sequence spread spectrums provided by the invention is as follows:
1. serioparallel exchange.Based on serioparallel exchange pretreatment module, according to the pre-adjusting information of serial that information source module provides, serioparallel exchange is carried out to pre-adjusting information and obtains a i, b ii=0,1,2 ... two-way walks abreast pre-adjusting information, for the ease of setting forth, and might as well by a ibranch road is called the first branch road, b ibranch road is called that the second branch road is pre-, a i, b irepresent the pre-adjusting information of first, second branch road respectively.
2. digital baseband modulation.Based on first, second digital baseband modulation module, according to the concrete digital baseband modulation system that system adopts, respectively to a i, b icarry out digital baseband modulation, obtain first, second branch road numeral baseband modulation signal a (t), b (t).
3. direct sequence spread spectrum modulation.Based on first, second direct sequence spread spectrum modulation module, utilize the spread spectrum code sequence that length is K respectively i=1,2 ..., K, carries out direct sequence spread spectrum modulation to first, second branch road numeral baseband modulation signal, obtains first, second branch road numeral base-band spread-spectrum modulation signal a c(t), b c(t).
4. base band is shaping.Based on base band forming module, utilize base band shaping function h respectively 1(t), h 2t (), to first, second branch road numeral base-band spread-spectrum modulation signal a c(t), b ct () carries out base band shaping, obtains first, second branch road base-band spread-spectrum modulation signal s a(t), s b(t).
5. time domain superposition.Based on time domain laminating module, time domain superposition is carried out to first, second tributary signal that back obtains, obtains a road and signal.
6. up-conversion launches output.Based on up-conversion output module, up-conversion is carried out to base-band spread-spectrum modulation signal s (t), and the signal after frequency conversion is exported by antenna.
Frequency spreading device receiving element specific works process based on 2 dimension baseband direct sequence spread spectrums provided by the invention is as follows:
1. down-conversion receives.Based on down-conversion receiver module, receive modulated signal by antenna, and down-conversion is carried out to it, obtain Received signal strength r (t)=s (t)+n (t), n (t) and represent noise jamming.
2. demodulation.Based on first, second branch road demodulation module, according to the digital baseband modulation system of transmitting terminal, utilize spread spectrum code sequence respectively i=1,2 ..., K, and base band shaping function h 1(t), h 2t (), r (t) carries out demodulation to received signal, obtains first, second branch road demodulating information a ' i, b ' i.
3. parallel-serial conversion.Based on parallel serial conversion module, to first, second branch road parallel demodulation information a ' iwith b ' icarry out parallel-serial conversion, obtain final demodulating information.
Be characterised in that at base band transmitting two paths modulated spread spectrum signal simultaneously, a condition in following two conditions need be met:
Condition 1): in the transmitter unit course of work 3, the spread spectrum code sequence that the second branch road band spectrum modulation adopts i=1,2 ..., K is that the first branch road band spectrum modulation adopts spread spectrum code sequence i=1,2 ..., the orthogonal transform form of K;
Condition 2): in the transmitter unit course of work 4, the shaping function h of the shaping employing of the second base band 2the shaping function h of (t) and the shaping employing of the first base band 1t () is mutually orthogonal.
Above-mentioned two conditions can guarantee that two branch road band spectrum modulation code elements are in quasi-orthogonal state, are also the prerequisites ensureing system transfers performance.
Further, adopt the process means of Hilbert transform, make condition 1) in, the spread spectrum code sequence that the second branch road direct sequence spread spectrum modulation adopts i=1,2 ..., K is that the first branch road direct sequence spread spectrum modulation adopts spread spectrum code sequence i=1,2 ..., the Hilbert transform of K; Make condition 2) in, the shaping function h of the shaping employing of the second base band 2t () is the first base band shaping employing shaping function h 1the Hilbert transform of (t).
Further, first, second branch road demodulation module of receiving terminal all adopts matched filtering demodulation detection technique, and the template signal that the first demodulation module matched filtering adopts is spread spectrum code sequence i=1,2 ..., K is through shaping function h 1waveform signal t () is shaping after, the template signal that the second demodulation module matched filtering adopts is spread spectrum code sequence i=1,2 ..., K is through shaping function h 2waveform signal t () is shaping after.
It should be noted that, in order to make the structure of communicator simple as far as possible, when satisfying condition 1), the shaping function that first, second branch road base band forming module adopts is identical, now 5. 4. implementation step sequentially can be exchanged with implementation step, and by step 4. in first, second two base band forming modules merge into a base band forming module, obtain base-band spread-spectrum modulation signal after shaping.
Embodiment:
In order to implementation step of the present invention is better described, represent good characteristic of the present invention simultaneously, below in conjunction with accompanying drawing, communication system provided by the present invention is described further.Obviously, described embodiment is only a part of embodiment of the present invention, instead of whole embodiment.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Tie up the spectrum spread communication method of baseband direct sequence spread spectrums and the implementation step of communicator according to based on 2, it is as follows that communication system parameter is set:
Spread spectrum code sequence: m sequence;
Digital baseband modulation system: binary pulse amplitude modulation(PAM) (BPAM);
Direct sequence spread spectrum modulation system: (primitive polynomial is x in 127 direct sequence spread spectrum modulation 7+ x 3+ 1);
Base band shaping function: raised cosine filter shaping (forming coefficients: 0.25, over-sampling rate: 8);
Channel condition: additive white Gaussian noise channel (AWGN);
Demodulation mode: matched filtering demodulation;
Transmission conditions: first, second branch road spread spectrum code sequence identical ( i=1,2 ..., 127), the second branch road base band shaping function is the Hilbert transform (h of the first branch road shaping function 2(t)=Hilbert{h 1(t) }, Hilbert{} represents Hilbert transform operator);
Information source: pseudorandom information source;
Transmission information amount: 2 × 10 7bit.
Concrete implementation step is as follows:
1. serioparallel exchange.Pre-for serial pseudorandom adjusting information is converted to first, second two branch roads to walk abreast pre-adjusting information.
2. binary pulse amplitude modulation(PAM).Respectively BPAM modulation is carried out to the pre-adjusting information of first, second branch road, obtain first, second branch road numeral baseband modulation signal.
3. direct sequence spread spectrum modulation.Utilize length be 127 m sequence, respectively direct sequence spread spectrum modulation is carried out to first, second branch road numeral baseband modulation signal, obtains first, second branch road numeral base-band spread-spectrum modulation signal.
4. base band is shaping.Utilize raised cosine filter shaping function and its Hilbert transform respectively, base band carried out to first, second branch road numeral base-band spread-spectrum modulation signal shaping, obtain first, second branch road base-band spread-spectrum modulation signal.
5. superpose.Time domain superposition is carried out to shaping first, second branch road base-band spread-spectrum modulation signal obtained of base band, obtains roadbed band and a signal.
6. up-conversion launches output.Up-conversion is carried out to base band and signal, and the signal after frequency conversion is exported by antenna.
7. channel adds and makes an uproar.To the interpolation white Gaussian noise that transmits.
7. down-conversion receives.Receive modulated signal by antenna, and down-conversion is carried out to it, obtain Received signal strength.
8. demodulation.Adopt the waveform signal of m sequence after raised cosine filter shaping function and its Hilbert transform are shaping as template signal respectively, carry out first, second flow adaptation demodulation by filter to received signal, obtain first, second branch road demodulating information.
9. parallel-serial conversion.Parallel-serial conversion is carried out to first, second branch road parallel demodulation information, obtains final demodulating information.
Fig. 4 is the ber curve figure of system under Gaussian white noise channel condition obtained by Bit Error Code Statistics.As can be seen from error rate result, the theoretical error rate that the statistics error rate is almost modulated with BPAM is completely the same.Compared with traditional direct sequence spread spectrum communication system, spectrum spread communication method provided by the invention and communicator not spread spectrum communication bandwidth, do not reduce transmission performance prerequisite under, transmission rate be doubled, this result presentation the invention provides the superiority of communication means and communicator.
Beneficial effect:
Generally speaking, for direct sequence spread spectrum communication system provided by the invention and communication means, compared with prior art, there is following beneficial effect:
1. message capacity is large, transmission rate is high.
Compared with traditional direct sequence spread spectrum modulator approach, not expanding system transmission bandwidth, do not reduce system transfers performance prerequisite under, the signal space dimension of baseband direct sequence spread spectrum communication is brought up to 2 by 1 by the present invention, the message capacity of direct sequence spread spectrum modulating system and transmission rate are improved greatly, original twice can be reached.
2. Project Realization is simple, hardware cost is low.
Communication means provided by the invention obtains on the basis of existing, ripe signal of communication processing method, do not relate to complicated algorithm, under existing hardware technology level, can directly be realized by integrated chip, special requirement is not had to hardware performance, has the advantages that Project Realization is simple, hardware cost is low.
3. applied range.
Communication system provided by the invention and communication means have important using value and realistic meaning, can directly apply to the upgrading of existing direct sequence spread spectrum communication system and the development of direct sequence spread spectrum communication system of future generation.Potential application also comprises: military satellite communication, radio security communication, Beidou satellite navigation, mobile CDMA communication etc.
Finally it should be noted that, above embodiment and embodiment are intended to technical scheme of the present invention instead of the restriction to technical method are described, the present invention can extend in application other amendment, change, application and embodiment, and therefore think that all such amendments, conversion, application and embodiment are all within spirit of the present invention and teachings.

Claims (12)

1. based on a spectrum spread communication method for 2 dimension baseband direct sequence spread spectrums,
Radiating portion: first preliminary treatment is carried out to pre-adjusting information, secondly base-band digital modulation is carried out to pre-adjusting information, then direct sequence spread spectrum modulation is carried out to base-band digital modulation signal, it is shaping that signal after modulating direct sequence spread spectrum again carries out base band, and the signal after shaping is carried out up-conversion and exported by antenna;
Receiving unit: first receive modulated signal by antenna, and carry out down-conversion to received signal; Then carry out despreading demodulation processing to received signal, obtain demodulating information;
It is characterized in that: baseband transmission comprises first, second two parallel transmission branch roads, wherein, second branch road spread spectrum code sequence is the orthogonal transform form of the first branch road spread spectrum code sequence, or the second branch road base band shaping function and the first branch road base band shaping function mutually orthogonal; First, second branch road spread spectrum code sequence described is the spread spectrum code sequence that the modulation of first, second branch road direct sequence spread spectrum adopts respectively, and first, second branch road base band shaping function described is the shaping function of the shaping employing of first, second branch road base band respectively.
2. communication means according to claim 1, it is characterized in that, second branch road spread spectrum code sequence is the orthogonal transform form of the first branch road spread spectrum code sequence, after the modulation of first, second branch road direct sequence spread spectrum, first branch road modulated spread spectrum signal is superposed, then to carry out base band shaping with signal.
3. communication means according to claim 1, is characterized in that, the second branch road spread spectrum code sequence is identical with the first branch road spread spectrum code sequence, the second branch road base band shaping function and the first branch road base band shaping function mutually orthogonal; After first, second branch road base band is shaping, signal is superposed, then carry out up-conversion to signal.
4. the communication means according to claim 1,2, is characterized in that, the second branch road spread spectrum code sequence is the Hilbert transform of the first branch road spread spectrum code sequence.
5. the communication means according to claim 1,3, is characterized in that, the second branch road base band shaping function is the Hilbert transform of the first branch road base band function.
6. the communication means according to claim 1,2,4, it is characterized in that, first, second branch road demodulation all adopts matched filtering demodulation method, the template signal that first, second flow adaptation demodulation by filter adopts be respectively first, second branch road spread spectrum code sequence base band shaping after the waveform signal that obtains.
7. the communication means according to claim 1,3,5, it is characterized in that, first, second branch road demodulation all adopts matched filtering demodulation method, and the template signal that first, second branch road demodulation module matched filtering adopts is respectively the waveform signal that first, second branch road spread spectrum code sequence obtains after first, second shaping function is shaping.
8., based on a frequency spreading device for 2 dimension baseband direct sequence spread spectrums, comprise information source module, serioparallel exchange pretreatment module, digital modulation module, direct sequence spread spectrum module, base band forming module, laminating module, up-conversion output module, down-conversion receiver module, demodulation module, parallel-serial conversion processing module, stay of two nights module;
It is characterized in that: digital modulation module comprises first, second digital modulation module, direct sequence spread spectrum module comprises first, second direct sequence spread spectrum module, and demodulation module comprises first, second demodulation module; Second spread spectrum code sequence is identical with the first spread spectrum code sequence, or the orthogonal transform form of the first spread spectrum code sequence, and first, second spread spectrum code sequence described is the spread spectrum code sequence that first, second direct sequence spread spectrum module adopts respectively;
When the second spread spectrum code sequence is the orthogonal transform form of the first spread spectrum code sequence, laminating module input is connected with first, second direct sequence spread spectrum module, and output is connected with base band forming module;
When the second spread spectrum code sequence is identical with the first spread spectrum code sequence, base band forming module comprises first, second base band forming module further, laminating module input is connected with first, second base band forming module, output is connected with up-conversion output module, first shaping function and the second shaping function mutually orthogonal, first, second shaping function described be respectively first, second base band forming module adopt shaping function.
9. communicator according to claim 4, is characterized in that, the second spread spectrum code sequence is the orthogonal transform form of the first spread spectrum code sequence, and described orthogonal transform is Hilbert transform.
10. communicator according to claim 4, is characterized in that, the second spread spectrum code sequence is identical with the first spread spectrum code sequence, and the second shaping function is the Hilbert transform of the first base band function.
11. communicators according to claim 4,5, it is characterized in that, first, second demodulation module adopts matched filtering demodulation technology, the template signal that first, second mode transfer Block-matching filtering adopts be respectively first, second spread spectrum code sequence base band shaping after the waveform signal that obtains.
12. communicators according to claim 4,6, it is characterized in that, first, second demodulation module adopts matched filtering demodulation technology, and the template signal that first, second mode transfer Block-matching filtering adopts is respectively the waveform signal that spread spectrum code sequence obtains after first, second shaping function is shaping.
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