Method and device synchronization and resolve the phase ambiguity of signals communication systems

 

The invention relates to the field of digital technology and can be used for synchronization and how to resolve the phase ambiguity of the signals of communication systems. The technical result is the optimization of signal processing with the absolute phase shift keying (AFM) and the relative phase shift keying (there) and simplify hardware implementation. In the way the signal demodulator, differential decode, summarize the signals in-phase and quadrature channels, the signal is correlated with a unique word clock, then differentially encode that provides synchronization of the receiving side and removing the phase ambiguity for signals with AFM, and signals there exclude differential encoding. The device contains a serial connected coherent demodulator phase-shift keyed signals, a differential decoder, adder-phase and quadrature channels, the shift register of the correlator whose output is the output device, and a differential encoder, the input of which is connected to the outputs of the decoder, and outputs a differential encoder are output devices. 2 N. p. F.-ly, 2 ill., 1 PL.

The invention relates to the field of educa information in digital form is becoming increasingly used in communication systems. Currently, special attention is paid to the development of communication systems with multiple access on the basis of time-division channels (MDR). Typically, these systems use phase modulation methods. When this is used as an absolute phase shift keying (AFM), and the relative phase shift keying (there). Sometimes in one communication system is used and that, and another kind of manipulation. So in the "spade" in the information channels used four AFM and channel General alarm biphasic there [1, C. 201 and 202]. Each of these methods of manipulation has its own advantages and disadvantages.

For communication systems with AFM the main drawback is the "reverse work", when instead of the original transmitted information at the receiver side we get a distorted information due to the mixed phase of the recovered reference carrier wave in demodulateur device. Advantage communications systems with AFM in comparison with there is a higher immunity (the occurrence of a single error at the receiving side when a single failure in the communication line).

For communication systems with there main disadvantage is the appearance on the receiving side of pairwise errors of Edinaya is relative to the state of the previous symbol. The main advantage is the absence of "reverse work" due to the preliminary differential coding on the transmission side and differential decode it at the receiver side.

For synchronization and eliminate the "reverse work" in communication systems with AFM using a special combination packages, which, although they reduce the effectiveness of the communication system, but provide unambiguous subsequent recovery of the original information [5 - prototype]. If the communication system uses four AFM, after demodulateur devices the following combinations of information in the subchannel: AB,Andwhere a, b and,respectively the direct and inverse values of the characters in the subchannels.

According to the method prototype synchronization and dealing with ambiguity is performing the following operations:

- received signal demodulator (converted into digital form);

- correlate the received digital stream with possible code combinations of unique words synchronization (AB,

- according to the results of determination of type a unique word synchronization (phase ambiguities) in the signal lead information part type AV, i.e., eliminate the phase ambiguity.

The disadvantage of the prototype method is the complexity of the hardware implementation of personnel devices, packet synchronization and resolve the phase ambiguity.

Ambiguity (“reverse work”) currently eliminated by the use of correlators for each of the possible States code combination of synchroprint. The response of one or another of the correlator is used for generating control signals to disambiguate. Resulting in possible combinations AB,,And,transformed to the original combination AB.

One of the possible schemes of synchronization and ambiguity resolution, which is used in modern equipment for four AFM, shown in Fig.2 [5 - prototype]. The structure of the device consists of two N-bit shift register 4, the four correlator 5, four threshold circuit 7 and four digital adder 8, desipramine correlators by tripping on a unique word clock errors) and the bulkiness of the device. In communication systems with MDR transmitted, as a rule, batch, personnel, superlative signals, i.e., at the receiving side must be installed three sets of prototype devices.

The aim of the invention is the optimization of the method of signal processing with AFM and there and simplify the hardware implementation.

To achieve this goal it is proposed a method in which the signal demodulator and correlate with the unique word clock. According to the invention demodulated signal is entered, the operation of the differential decoding and summing the signals in-phase and quadrature channels, and after the correlation introduced by the operation of differential encoding, resulting in elimination of the phase ambiguity at AFM, for signals with there operation differential encoding rule out (transit mode).

A device that implements the proposed method contains a coherent phase demodulator signals and connected in series to the shift register and the correlator. According to the invention it is entered serially connected differential decoder and the adder-phase and quadrature channels, and a differential encoder, the second input is connected to the output of the correlator, and the present paper the rst inputs of the shift register is to the outputs of the adder. The outputs are the outputs of the differential encoder and the correlator.

The proposed method and the device for its realization, are not described in literature, clearly does not follow from the achievements of science and technology, so they satisfy the criteria of novelty and inventive step.

In Fig.1 shows the structural diagram of the device for the proposed method, Fig.2 is a structural diagram of a device prototype.

The proposed method performs the following sequence of operations:

signal demodulator;

- signal differential decode;

- summarize the signals in-phase and quadrature channels;

signal is correlated with a unique word clock;

- signal differential encode that provides synchronization of the receiving side and removing the phase ambiguity for signals with AFM;

- exclude differential encoding signals there.

The device according to the proposed method contains (Fig.1) connected in series coherent demodulator phase-shift keyed signals 1, the differential decoder 2, the adder-phase and quadrature channels 3, the shift register 4 and the correlator 5 and a differential encoder 6. The outputs of the decode is the device operates as follows.

Input intermediate frequency FFCfed to the demodulator 1, where it is converted into a digital stream accompanied by the clock frequency (for two-phase modulation And orfor four AB,And,). Next, the AFM signal is fed to a differential decoder 2, where the signal is transformed into the signal a' is for a two-phase signal and a' for the four signal, while only the unique word synchronization are transformed into permanent code combinations regardless of the ambiguity of the demodulator 1. Simultaneously transformed and information after the decoder 2.

Regular unique word synchronization subchannel and' and' are summed in the adder 3 to the stream in a' arrives at the shift register 4 and is further distinguished by a single correlator 5, the response of which to set the initial bits in the encoder 6 to restore the original (transmitted) information. When processing signals with there differential encoder 6 is translated in the transit mode.

Procedures differential encoding/decoding for signals FM and FM well known [1, C. 201 and 202], for signals TRELLIS < FM and Alacati procedures when FM, because manipulation codes are selected so that when the phase jumps of the recovered carrier demodulator 90 and 180change the values of only senior level in-phase and quadrature channels, they are subjected to procedures of differential encoding/decoding algorithms the four modulation (FM).

Consider the nature of the processing procedures AFM signals in a specific example for a single AFM. Let the transmitted original sequence

Then after the demodulator 1 received

Subject Tu and another sequence of operation of the differential decoding rule

get the

Distortion of the previous character before the code combination synchroprint after the demodulator 1 is called a single error in the code combinations after differential decoder 2, and the distortion of the character in the code combination causes a steam error that when a large capacity (30 to 40 characters) code words in sisterinacti as pseudonoise signal with a large base. Next, by using only one correlator allocated synchroprint transformed into the result of the operation of the differential decoding one code combination, a collapsible its duration to basic character and use for initial setup of the memory element (Ai-1) differential encoder. Set Ai-1=0 and subjected to an information sequence of operation of the differential encoding rule

,

where ai- the original meaning of the symbols in real time;

Ai-1- the character value in the preceding time;

andi- recoded value of the character at the moment.

Then after the encoder obtain the original sequence of characters

when any ambiguity information sequence after the demodulator 1.

Set symbol Ai-1=I for the operation of the differential coding results highlight synchroprint will give the inverse of the combination of the source sequence of symbols, i.e., it is necessary to have a priori information about the true value of the last character in the code combination Shin the encoding.

The table shows the results of processing the AFM signals when a single failure in the communication line.

The table shows that when there is a single failure in the communication line on the receiving side after the operation of the decoding arise pair of errors (see expression (1) and table) that when the encoding operation is reduced to a single error. It would seem that during the operation of the differential encoding with a single failure in the communication line with the dip AFM should be the inverse of the information sequence, but this does not happen because of the fact that when the previous operation of the decoding arise pair of errors. The first mistake would give the inverse of the information sequence, but following the second error source gives the combination, with the second error after the decoder is corrected in the encoder. The data obtained can be extended to the processing of signals from AFM higher multiplicity.

Thus, in the considered processing procedures AFM signals through the use of processing devices there signals were able to optimize the process, to simplify the technical implementation of the device and saved the>iterator

1. Spilker J. Digital satellite communications. - M.: Communication, 1979.

2. Kindlmann P. D. and Kuner E. B. high-speed correlator. “Research equipment”, 1968, No. 6.

3. Express information VINITI, series PI, 1974, No. 29, S. 8-12.

4. Single-chip correlator 64 bit words. Electronics, 1980, No. 23, S. 123 and 124.

5. Shunvoku Sasaki, Hiroshi Kurihara, Burst Codeword with arbitrary Length for Four-Phase CPSK/TDMA System. Fourth International Conference on Digital Satellite Communications, 23 - 25 October 1978, Montreal, p.327-332.

Claims

1. Synchronization method and resolve the phase ambiguity of the signals of communication systems in which the signal demodulator and correlate with the unique word clock, wherein the demodulated signal differential decode and summarize the signals in-phase and quadrature channels, and after correlation with a unique word signal differential encode than provide synchronization of the receiving side and eliminate the phase ambiguity for signals with absolute phase modulation, while for signals with a relative phase modulation operation of the differential encoding rule out (transit mode).

2. The device containing the demodulator and connected in series register add and the adder-phase and quadrature channels, the outputs of which are connected to the inputs of the shift register, and a differential encoder, and the outputs of the demodulator is connected to the inputs of the decoder, the outputs of which are connected to first inputs of the encoder to the second input of which is connected to the output of the correlator outputs of the device are the outputs of the encoder and the correlator.

 

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FIELD: radiophone groups servicing distant subscribers.

SUBSTANCE: proposed radiophone system has base station, plurality of distant subscriber stations, group of modems, each affording direct digital synthesizing of any frequency identifying frequency channel within serial time spaces, and cluster controller incorporating means for synchronizing modems with base station and used to submit any of modems to support communications between subscriber stations and base station during sequential time intervals.

EFFECT: enhanced quality of voice information.

12 cl, 11 dwg

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