CN1205135A - Tranmission system with improved lock detection - Google Patents

Abstract

In order to find the position of the boundary between transmitted codewords, in a receiver a reliability measure for two possible positions are compared. If a relative difference measure of these reliability measure exceeds a predetermined threshold value, the reliability measure indicating the largest reliability corresponds to the correct position of the boundary between the codewords.

Description

Transmission system with improved lock-in detection

The present invention relates to a kind of transmission system, it comprises a transmitter that is used for sending to a receiver through transmission medium numerical chracter, this receiver is furnished with a decoder and is used for producing symbol after the decoding from the input signal of receiver, this input signal have in a plurality of possible characteristics of signals, select, a predetermined characteristics of signals; This receiver comprises that characteristic determines device, and this characteristic determines that device is used for determining this predetermined characteristics of signals by determining the reliability of the symbol after the decoding from the signal that is received; This characteristic determine device also further be used for obtaining presenting first characteristics of signals the numerical chracter of being deciphered at least the first sequence and present second sequence of the numerical chracter of being deciphered of secondary signal characteristic.

The invention still further relates to a kind of transmission method and one is used for receiving and has at a plurality of possible characteristics of signals signal that select, a predetermined characteristics of signals.

The paper of writing at M.Moeneclay and P.Sanders according to a kind of transmission system of preamble " based on the viterbi decoder node of syndrome synchronously and abandon lock-in detection " (Syndrome-based Viterbi decoder Node Synchronisation andOut-of lock Detection) describe, this paper is seen GLOBECOM ' 90 minutes, roll up 1, the 604 to 608 pages.

DVB (digital video broadcasting) is the new European standard of a regulation digital video transmission.This standard to describe originating point code scheme and channel coding schemes.For satellite-based transmission (DVB-S), originating point code with adopt Reed Solomon code (RS sign indicating number) as outer sign indicating number, and adopt that ratio is 1/2, the convolution code of k=7 is relevant as a kind of like this concatenated coding scheme of ISN.The ratio of this convolution code can increase by contraction.Between RS encoder and convolution coder, introduced a digital multiplexer and burst error has been dispersed in the different Read-Solomon code words with it.

Because a DVB signal can carry various types of videos and sound signal, so a such DVB signal can have a large amount of characteristics of signals.These characteristics of signals in receiver side in advance and do not know.The example of characteristics of signals has, the fixed phase of the carrier phase under the QPSK modulation case, the actual speed rate of the convolution code that is adopted and the original position of contractible graph.In non-DVB system (its adopts block code as ISN) situation, the position on the border between two code words is a further characteristics of signals.For the characteristics of signals of the reality of determining received signal, receiver comprises and is used for determining that from the signal that receives the characteristic of this characteristics of signals determines device.

The characteristics of signals that adopts in order to find is attempted all possibilities till finding correct characteristics of signals.Existed at present some kinds to determine that whether a characteristics of signals of being attempted now is the method for correct characteristics of signals.

Determine that whether a characteristics of signals of being attempted now is that the first method of correct characteristics of signals is exactly to come symbol after the recompile decoding and the symbol of relatively input and the symbol of recompile according to the characteristics of signals that is presented.The if symbol error rate is less, and then selected characteristics of signals may be correct.If error rate is higher, then selected characteristics of signals is incorrect, and must attempt next characteristic.A shortcoming of said method is exactly the needed additional realization complexity of recompile.

Determine that whether a characteristics of signals of being attempted now is that the second method of correct characteristics of signals is exactly to numerical chracter (its reliability measurements usually is ready-made in the receiver side) reliability measurements of employing after the decoding.In the transmission system according to the above-mentioned meeting paper of mentioning, the reliability measurements that is adopted is the growth of road through measuring in the viterbi decoder that is used for ISN is deciphered.In this transmission system, attempt first characteristics of signals, with this reliability measurements and a threshold ratio.Attempt the secondary signal characteristic subsequently, threshold ratio is therewith again with this reliability measurements.When in two kinds of situations, reliability measurements has all surpassed this threshold value, all is incorrect with regard to these two characteristics of signals of decidable.

The existing problem of the above-mentioned transmission system of mentioning is that this reliability measurements changes with the characteristics of signals of signal transmitted.Reliability measurements is strong variations with the rate variation of ISN.Simulation shows, supposes the reliability measurements of a decoder of a speed 3/8 improperly, and is bigger than the reliability measurements of a decoder correctly supposing a speed 1/2.Also have reliability measurements also to be subjected to influence on signal-to-noise ratio (SNR).Everything all requires all threshold level all to be set to and relevant values such as the speed of ISN, signal to noise ratio.

The purpose of this invention is to provide a kind of transmission system (can adopt constant threshold level therein) according to preamble.

In order to reach this purpose, the present invention is characterised in that, if the relative difference of the reliability measurements of first and second sequences of the symbol behind the coding surpasses a predetermined value, then characteristic determines that the corresponding characteristics of signals of sequence of the symbol after device handle and the decoding with high reliability is designated as correct characteristics of signals.

Compare by a relative difference and a threshold value reliability measurements, rather than with reliability measurements itself and a threshold ratio, whether in determining two relevant characteristics of signals one when correct, it is important having only relative difference.The actual speed rate of this relative difference and signal to noise ratio and supposition is irrelevant.Therefore a fixing threshold value just can choose.

A kind of embodiment of the present invention is characterised in that, transmitter comprises that one is used for according to an encoder that comes the coded digital symbol among a plurality of sign indicating numbers, be characterised in that this sign indicating number that characteristics of signals comprises that at least encoder adopts and further characteristics of signals, and be characterised in that characteristic determines that device uses identical but different with dark one deck characteristic at least yard at least the first and second sequences that obtain symbol by supposition.

By the identical situation of the speed of comparison code only, just can avoid the correlation of reliability measurements and speed can cause that the relative difference of measured value is mistakenly above threshold value.

A further embodiment of the present invention is characterised in that reliability measurements is to be directly proportional with the needed time of predetermined growth of the path metric relevant with the corresponding sequence of digital signal that will obtain.

Pre-determine and increase the seeking time of wanting by determining to obtain of path metric, a reliability measurements of the signal of being deciphered can obtain the most apace.The precision of reliability measurements depends on the desired growth of path metric.If the growth of desired path metric is fixed, a given precision just can guarantee.If path metric increases fast, pre-determine growth with and subsequent reliability measurements, just can obtain very fast.

Realize to determine the method for this method of reliability measurements, exactly the quantity of the desired symbol period that overflows of the register (path metric is stored in wherein) that obtains a fixed qty is counted.

Explain the present invention with reference to the accompanying drawings, wherein:

Fig. 1 shows one first embodiment according to a kind of transmission system of the present invention, has wherein adopted a parity check code;

Fig. 2 shows a transmitter 2 that adopts in a kind of transmission system according to one second embodiment, adopted the encoding scheme of a cascade therein;

Fig. 3 shows a receiver 6 that adopts in a kind of transmission system according to one second embodiment of the present invention, adopted the encoding scheme of a cascade therein;

Fig. 4 shows the embodiment that the characteristic that adopts is determined device in the receiver system according to Fig. 3;

Fig. 5 shows a flow chart of the operation of the state machine 52 among Fig. 4;

In the transmission system according to Fig. 1, incoming symbol is applied to an odd even encoder 4 of transmitter 2.The output of transmitter 2 is connected to receiver 8 through transmission medium 6.

The input of receiver 6 is connected to the input of odd even decoder 16 and an input of clock recovery circuitry 10.In one first output of odd even decoder 16, the output symbol of decoding just can obtain.One second output of odd even decoder 16, it transmits the signal of an indication parity error, is connected to error counter 15.The output of error counter 15 is connected to the input that characteristic is determined device 14.

An output of clock recovery circuitry 10 is connected to an input of 7/8/9 frequency divider 12.Characteristic determines that one first output of device 14 is connected to a control input of 7/8 frequency divider 12.An output of frequency divider 12 is connected to the input that resets of odd even decoder 16.

In transmission system, adopt parity code (1 parity bit and 7 data bit) to encode by odd even encoder 4 at the source of input symbol according to Fig. 1.These coded positions send to receiver 10 by transmitter 2.The characteristics of signals that receiver will be determined here is two borders between code word.An optional position on decoder 16 these borders of supposition.After each 8 bit group, odd even decoder 16 is resetted to start the decoding to a new code word by a pulse from 7/8 frequency divider 12.7/8/9 frequency divider 12 receives a bit clock from clock recovery circuitry 10.When each parity error produces, this situation is informed error counter 15, error counter 15 is used for the quantity of parity error is counted.The quantity of the parity error that error counter 15 is write down here is exactly reliability measurements according to the present invention.Characteristics of signals is determined device 14, after a predetermined time cycle, reads the quantity of the mistake that is write down, and it is stored in the buffer memory.Thereafter characteristics of signals determines that device 14 sends a control signal to frequency divider 12 and impels it to carry out 7 frequency divisions, rather than 8 frequency divisions.This just impels odd even decoder 16 to carry previous clock-reset, and causes the moving an of bit of codeword boundary.Thereafter, the quantity of the parity error that error counter 15 was write down in the predetermined time cycle determines that by characteristic device 14 reads.

Characteristic determines that device 14 calculates a relative measurement difference DELTA of actual count value and previously stored value.Promptly calculate according to following formula: $\mathrm{\&Delta;}=\frac{\mathrm{ABS}({\mathrm{COUNT}}_1-{\mathrm{COUNT}}_2)}{\mathrm{MIN}({\mathrm{<figure-callout\; id="1"\; label="COUNT"\; filenames="97191256001416.png,97191256001517.png"\; state="\{\{state\}\}">COUNT</figure-callout>}}_1,{\mathrm{COUNT}}_2)}--------\left(1\right)$

In (1), COUNT ₁Be the count value of being stored, and COUNT ₂It is the value of actual count.ABS represents the absolute value of its variable, and MIN represents the minimum value of its variable.If Δ is less than a predetermined threshold value, the codeword boundary of attempting with regard to decidable is not correct codeword boundary, codeword boundary is moved thereafter again and the quantity of mistake is counted again.If Δ is less than this predetermined threshold value, that codeword boundary according to the present invention with regard to the corresponding smallest error counting of decidable is correct codeword boundary.If the count value of being stored is that minimum count value,, then controls frequency divider and carry out 9 frequency divisions for codeword boundary is moved back into previous position.The device that is used to produce characteristics of signals informs also that in the output of receiver correct codeword boundary finds.

In the transmitter 2 according to Fig. 2, the source symbol is applied to a Reed Solomon Coding device 20.The output of Reed Solomon Coding device is connected to an input of multiplexer 22.The output of multiplexer 22 is connected to an input of convolution coder 24.The output of convolution coder 24 is connected to an input of qpsk modulator 26.In the output of qpsk modulator 26, can obtain the output signal of transmitter.

In transmitter 2, adopt a kind of encoding scheme of so-called cascade according to Fig. 2.The advantage of this scheme is the ratio E of BER slope of a curve as energy per bit and noise density _b/ N ₀Function and increase fast, cause E in appropriateness _b/ N ₀The time low-down error probability.In the transmitter according to Fig. 2, the source symbol adopts Reed Solomon code to encode.For digital video broadcasting transmission, only sign indicating number is that (204,188, T=8) sign indicating number promptly has the Reed Solomon code of 204 symbols to Reed Solomon code RS, and wherein 188 is data symbol.Has unknown position and the quantity T of repairable symbol error equals 8.Can be before being applied to RS (255,239) encoder to the symbol that will encode, by increase by 51 bytes (all being set to 0) shortens RS (255,239, T=8) Reed Solomon code obtain RS (204,188, T=8) yard.

In order to reduce the quantity of the code word that can not correct, the symbol of RS coding is multiplexing burst error is dispersed in more than on the RS code word by multiplexer 22.Thereafter the symbol after multiplexing is encoded by convolution coder 24.

Convolution coder is used for according to speed 1/2, and k=7 convolution code (its speed can increase by contraction) is to the encoding symbols after multiplexing.Possible speed has 1/2,2/3,3/4,4/5,5/6 and 7/8 (generally being N/N+1).The encoder of the convolution coder that is used to shrink is known those of ordinary skill in the art.The the 6th to 9 page of the file that operates in Qualcomm company of convolution coder " multi-code velocity viterbi decoder, Q1650 k=7 " has explanation.This theme also relates in many textbooks.

In order to send, modulate according to the QPSK modulation scheme in the coded identification of the output of convolution coder 24.

In the receiver 6 according to Fig. 3, input signal is applied to a demodulator 30.An output of demodulator 30 is connected to separate shrinks unit 32.Separate the output of shrinking unit 32 and be connected to a viterbi decoder 34.One first output of viterbi decoder 34 is connected to an input of demodulation multiplexer 36.The output of demodulation multiplexer 36 is connected to an input of read-solomon decoder 38.Symbol after the output of read-solomon decoder 38 can obtain deciphering.

One second output of viterbi decoder 34 transmits an indication keeps the buffer memory of a path metric in viterbi decoder the signal that overflows, and it is connected to and overflows counter 42.An output of overflowing counter 42 is connected to the input that characteristic is determined device 44.Characteristic is determined one first output of device 44, transmits signal INV, and it is connected to one first input of demodulator 30.Characteristic is determined one second output of device 44, transmits signal SH, and it is connected to one second input of demodulator 30.Characteristic determines that one the 3rd output of device 44 is connected to a control input of a 2N-2/2N-1/2N frequency divider 40, and the output of 2N-2/2N-1/2N frequency divider 40 is connected to the input that resets of separating contraction unit 32.

In the receiver 2 of Fig. 3, the signal that is received carries out demodulation by demodulator 30.Signal after the demodulation is sent to viterbi decoder 34 through separating contraction unit 32.Because viterbi decoder adopts soft decoding information, the signal of demodulator is an amplitude limit not, but it is represented with the precision of a few bits (3-4).To have speed be 1/2 code in order to regain, and separates to shrink unit 32 and add the symbol that is shunk element deletion in convolution coder 24.Because the symbol that is inserted into is unknown, so the value of these symbols is being provided with corresponding to the level of logical zero with on corresponding to a level between the logical one level.This just causes viterbi decoder 34 to think that these symbols are insecure.Symbol after first output of viterbi decoder 34 can obtain deciphering.Symbol after this decoding is by demodulation multiplexer 36 demultiplexings.Symbol behind the demultiplexing is by the output symbol of read-solomon decoder 38 decodings with acquisition receiver 6.

In one second output of viterbi decoder, the signal that indication keeps the register of a status quantitavie to overflow in viterbi decoder 34.It is indifferent to the sort of status quantitavie of employing, because all status quantitavies all have the identical order of magnitude.42 pairs in counter overflows to be counted, and if the quantity of overflowing when surpassing a predetermined value notification characteristic determine device.

In order to shrink reset pulse of unit 32 generations to separating, characteristic determines that device produces a control signal to the 2N-2/2N-1/2N frequency divider.By select dividing a frequency 2N-2,2N-1 or 2N just may postpone, keep or separate in advance the original position of shrinkage operation.Be applied to and separate the speed that the control signal RATE that shrinks unit 32 is used for stipulating the convolution code that will decipher, and determine to separate the operation of shrinking unit 32 at this signal thereafter.The control signal INV and the SH that are applied to demodulator are used for introducing respectively spectrum inversion and phase shift.Can require spectrum inversion because might be on transmission channel frequency spectrum because mix with the oscillator signal an of this locality and be inverted, this local oscillator signal has the frequency higher than the frequency of the signal of wanting conversion.By being inverted this frequency spectrum again, just can obtain having a signal of the frequency spectrum identical with the signal that is sent.The uncertainty of phase in-migration processing by the phase place of the reference carrier that carrier recovery circuit produced carried out in requirement.This phase shift can be by the mutual quadrature component of output place of exchange demodulator, introduces in conjunction with the change of the symbol of one of quadrature component possibly.

Determining in the device 44 that according to the characteristic of Fig. 3 one first input that transmits signal OVF is connected to a measuring unit 50.An output of measuring unit 50 is connected to an input of a register 56 and one first input that is connected to a calculator/comparator 54.An output of register 56 is connected to one second input of calculator/comparator 54.

An output of calculator/comparator 54 is connected to one first input of state machine 52.One first output of state machine 52 transmits the inverted INV signal of output signal frequency that is used to make demodulator.One second of state machine 52 output transmits a signal SH who is used to make the output signal phase shift of demodulator.One the 3rd of state machine 52 output transmits one and is used to make and is shrinking the signal SKIP that moves on the symbol period separating contractible graph that unit 32 applies by separating.One the 4th of state machine 52 output transmits a signal RATE who is used to be provided with the speed of the convolution code that will adopt.One the 5th output of state machine 52 is connected to measuring unit 50, and one the 6th output of state machine 52 is connected to an input of calculator/comparator 54.

State machine 52 arrives a needed time of predetermined count value by signal NEXT instruction indication measurement unit 50 measurement counter 42.This Measuring Time be with viterbi decoder 34 in measure to increase and be inversely proportional to.Thereafter this time can be regarded the reliability measurements of the reliability of the symbol after indication is deciphered as.This time is by counting and can measure at an easy rate the quantity of symbol period.If arrived predetermined count value, calculator/comparator calculates the relative difference between time of a Measuring Time (it is stored in the register 56) and actual measurement.Can observe state machine and before measuring unit 50 starts measurement, change at least one in the characteristics of signals.Can find the relative difference of a suitable measured value according to following formula: ${\mathrm{\&Delta;}}_m=\frac{\mathrm{ABS}(T_1-T_2)}{\mathrm{MIN}({\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="97191256001416.png,97191256001517.png"\; state="\{\{state\}\}">T</figure-callout>}}_1,T_2)}------------\left(2\right)$

In (2), T ₁Be the time value that is stored in the register 56, and T ₂It is actually determined value.Calculated Δ _mValue after, Δ _mValue and a threshold ratio.Result relatively sends the control signal that state machine 52 is sent by this state machine with response to.Response ratio as a result the time, state machine takes appropriate measures, this will explain hereinafter.

In flow chart according to Fig. 5, the instruction of numbering has the connotation of following table: all initialization of variable that number title connotation 60 BEGIN are all, and program start.62 SET NEXT PUNCTURING separate contraction unit 32 and are apprised of individual the overflowing the needed time of P that one yard speed of following RATE, the 64 WAIT FOR MEASUREMENT measuring units 50 that will adopt are instructed to measure the status quantitavie in the viterbi decoder 34.90 ° of the phase place phase shifts of the signal after the 66 SHIFT PHASE demodulation.68 WAIT FOR MEASUREMENT measuring units 50 are instructed to measure individual the overflowing the needed time of N of the status quantitavie in the viterbi decoder 34.Whether 70 DIFF=TRUE verification difference surpasses threshold value, or whether the quantity of trial OR TRIES＞2N-1 is above 4N-2 time.Whether all enable positions of 72 ALL POS TRIED verification contractible graphs all attempted.74 INVERT SPECTRUM are inverted the frequency spectrum of the signal after the demodulation.75 NEXT POSITION attempt the next one possibility enable position of contractible graph.Whether 76 DIFF=TRUE verification differences surpass threshold value.78 LOCK DETECTED notice is to the detection of locking situation.

According to Fig. 4, in the instruction 60 of flow chart, all variablees all are set to their initial value and start-up routine.In instruction 62, the shrinkage of the sign indicating number that decipher is set to the next one (or initial value).This is by finishing to separating contraction unit 32 transmission signal RATE.In instruction 64, start the measurement of reliability measurements.After reliability measurements has been determined and has been stored in register 56, in instruction 66,90 ° of the phase shifts of the phase place of the signal after the demodulation by sending signal SH.In instruction 68, determine the reliability measurements of the phase place of up-to-date selection.Can observe the phase limit that will attempt is possible at 0 ° and 90 °.If actual phase place is 180 ° or 270 °, symbols streams will be squeezed.A kind of so inverted bit stream can be deciphered very ideally by viterbi decoder.Read-solomon decoder also can be discerned inverted bit stream.If detect an inverted bit stream, the unique measure that adopt is inverted bit stream in the output of read-solomon decoder exactly.

In instruction 70, read the result's of the comparison that expression finished by calculator/comparator a signal.If this as a result the indication measurement difference surpassed threshold value, program just advance to the instruction 76.Attempted 4N-2 time (to a non-inverted frequency spectrum of restituted signal, 2N-1 time if adopt same shrinkage; To an inverted frequency spectrum of the signal of institute's demodulation, 2N-1 time), program also advances to instruction 76.In instruction 76, determining to seek is still must advance to instruction 62 and to adopt a new shrinkage in instruction 78 terminations.

If the various conditions in instruction 70 do not satisfy, in instruction 72, whether all enable positions (2N-1) were all attempted to current shrinkage in verification.If not, then select next enable position, and program advances to instruction 64.For the place that begins with contractible graph moves a symbol, send signal SKIP.If the comparative result in instruction 72 indicates all positions all to attempt, the frequency spectrum of the signal of demodulation is squeezed by sending signal INV in instruction 74.After execution command 74, program advances to instruction 64.

Can be observed the situation that conceivable meeting exists spectrum inversion not take place.Obviously, needn't attempt spectrum inversion.In this situation, instruction 72,74 and 75 can be save, and instructs the value 4N-2 in 70 to replace with 2N-1.

Claims (10)

1, transmission system, it comprises a transmitter that is used for sending to a receiver through transmission medium numerical chracter, this receiver is furnished with a decoder and is used for producing symbol after the decoding from the input signal of receiver, this input signal have in a plurality of possible characteristics of signals, select, a predetermined characteristics of signals; This receiver comprises that characteristic determines device, and this characteristic determines that device is used for determining this predetermined characteristics of signals by determining the reliability of the symbol after the decoding from the signal that is received; This characteristic determines that device also further is used for obtaining representing second sequence of numerical chracter of the decoding of at least the first sequence of numerical chracter of decoding of first characteristics of signals and expression secondary signal characteristic; It is characterized in that, if the relative difference of the reliability measurements of first and second sequences of the symbol behind the coding surpasses a predetermined value, characteristic determines that device then is designated as correct characteristics of signals to the characteristics of signals corresponding with the sequence of symbol after the decoding with high reliability.

According to the transmission system of claim 1, it is characterized in that 2, transmitter comprises that one is used for according to an encoder that comes the coded digital symbol among a plurality of sign indicating numbers; Be that also characteristics of signals comprises this sign indicating number that adopted by encoder and further characteristics of signals at least, and be that characteristic determines that device uses identical by supposition but different with this further characteristic at least sign indicating numbers obtains at least the first and second sequences of symbol.

3, according to the transmission system of one of claim 1 or 2, it is characterized in that this at least further characteristic be included in the position of the predetermined symbol in the sequence of coded symbol.

4, according to claim 1, one of 2 or 3 transmission system, it is characterized in that this at least further characteristic comprise received a, fixed phase of the signal of in-phase modulation at least.

5, according to claim 1,2, one of 3 or 4 transmission system, it is characterized in that this at least further characteristic comprise the indication whether a frequency spectrum that indicates received signal is squeezed.

6,, it is characterized in that reliability measurements is to be directly proportional with the needed time of predetermined growth of the path metric relevant with the corresponding sequence of numerical chracter that will obtain according to the transmission system of above-mentioned arbitrary claim.

7, receiver comprises a decoder, be used for producing symbol after the decoding from the input signal of receiver, this input signal have in a plurality of possible characteristics of signals, select, a predetermined characteristics of signals; This receiver comprises that characteristic determines device, is used for determining this predetermined characteristics of signals by determining the reliability of the symbol after the decoding from the signal that is received; This characteristic determines that device also further is used for obtaining representing second sequence of numerical chracter of the decoding of at least the first sequence of numerical chracter of decoding of first characteristics of signals and expression secondary signal characteristic; It is characterized in that, if the relative difference of the reliability measurements of first and second orders of the symbol behind the coding surpasses a predetermined value, then characteristic determines that the corresponding characteristics of signals of sequence of the symbol after device handle and the decoding with high reliability is designated as correct characteristics of signals.

8, according to the receiver of claim 7, it is characterized in that characteristics of signals comprises this at least sign indicating number and a further characteristic, according to this sign indicating number input signal is encoded, and be characterised in that this characteristic determine device be used for by supposition adopt sign indicating numbers identical but that this further characteristic is different at least produce symbol at least the first and second in proper order.

9, receiver according to Claim 8, it is characterized in that this characteristic determine device be used for determining corresponding to and the normalization difference between the reliability measurements of this further characteristic decoding symbol inequality at least.

10, transmission method comprises through transmission medium sending numerical chracter, from this transmission medium receiving inputted signal, produces symbol after the decoding from input signal; This input signal has that select, a predetermined characteristics of signals in a plurality of possible characteristics of signals; This method is also determined this predetermined characteristics of signals by the reliability of definite symbol of being deciphered from the signal that is received, be that also this method comprises one first sequence that produces numerical chracter expression first characteristics of signals, decoding at least and one second sequence representing the numerical chracter secondary signal characteristic, that decipher; And be that also this method comprises, if the relative difference of the reliability measurements of first and second sequences of the symbol behind the coding surpasses a predetermined value, then the characteristics of signals corresponding with the sequence of symbol after the decoding with this high reliability is designated as correct signal.

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