JPH09247219A - Signal discrimination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate a signal with high accuracy by a method having provision for the configuration of transmission and reception terminal equipments flexibly by setting each of plural threshold levels to a value denoting a center of an area providing an eye aperture corresponding to individually to all signal points in each of areas of an eye pattern of a base band signal. SOLUTION: Each of plural comparator means 111 -11M discriminates a relation of quantity between each instantaneous value of each of signal points of a base band signal obtained by demodulating a modulation wave and each of plural threshold levels corresponding to the signal points and provides an output of the results. A symbol generating means 13 obtains symbols in the order of time series of transmission information. Each of the plural threshold levels is set to a value denoting a center of an area providing an eye aperture corresponding to individually to all signal points in an area of an eye pattern of the base band signal obtained in advance in response to reference transmission information consisting of all bit pattern series to be included as transmission information. Thus, possibility of occurrence of a bit error due to added noise is minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal deciding device which takes in a baseband signal output in a symbol unit by a demodulator adapted to a digital modulation system and decides a symbol indicated by the baseband signal.

[0002]

2. Description of the Related Art In recent years, in a wireless communication system, a multi-value digital modulation system is often applied in order to adapt to an increasing amount of transmission information and the number of terminals while making effective use of a limited radio frequency. There is. In such a wireless communication system, for example, in a mobile communication system to which a 4-level FSK modulation method is applied, a baseband signal obtained by demodulating a received wave at a receiving end has a transmission characteristic of a wireless transmission line. In addition to the distortion generated according to the fluctuation of the transmission characteristic or the transmission characteristic, the noise component superimposed on the wireless transmission path is included. Therefore, in the latter stage of the demodulator, a signal determiner for determining which symbol value the instantaneous value of the baseband signal indicates is generally provided, and the bit error rate caused by the above-mentioned distortion and noise is reduced. Is suppressed.

FIG. 8 is a diagram showing a configuration example of a conventional signal judging device. In the figure, the baseband signal is provided from the comparator 51 ₁ to to 51 the first input of the ₃ (not shown) demodulator, a second input respectively to the input threshold value A of the comparators, B, C are given . The outputs of the comparators 51 _{1 to} 51 ₃ are connected to the first to third inputs of the determination circuit 52, respectively. A symbol clock is applied to the clock input of the determination circuit 52 from a clock recovery circuit (not shown),
A symbol value having a word length of 2 bits is obtained at the output of the determination circuit.

In the signal deciding device having such a configuration, the received wave input to the demodulator is 4-valued FSK modulated according to the transmission information, and the demodulator gives a base under the demodulation processing adapted to this modulation method. The band signal is a for a regular signal point
Instantaneous values a, b, c, d satisfying the inequality of>b>c> d
In the case of taking the above, the above-mentioned threshold values A, B and C are, as shown by the dotted line on the horizontal axis of FIG. 9, A = (a + b) / 2 ... (1) B = (b + c) / 2 ... (2) C = (c + d) / 2 (3) It is set to a constant value shown by each equation. In FIG. 9, the abscissa axis represents the time t normalized by a cycle equal to the reciprocal of the transmission rate in symbol units, and the ordinate axis represents the instantaneous value S of the baseband signal.

Further, comparator 51 _{1-51 3,} the instantaneous value S and the threshold values A of the respective baseband signals, B, determines the magnitude relation between C. Further, the determination circuit 52 fetches the results of these determinations in synchronization with the above-mentioned symbol clock, and S> A ... (4) A ≧ S> B ... (5) B ≧ S> C. .. (6) C ≧ S ... As symbol values corresponding to those that hold among the inequalities of (7), for example, “11”, “10”, “01”,
The code word "00" is output.

[0006]

However, in such a conventional example, when intersymbol interference occurs due to the transfer characteristics of a filter or the like provided at the transmitting end or the receiving end, the time series order is used. The symbol values S indicating the same signal point are not necessarily the same depending on the permutation of the signal points taken. Therefore, there is a high possibility that the determination results obtained in the outputs of the comparators 51 _{1 to} 51 ₃ include an error and the determination results obtained in the outputs of the determination circuit 52 also include an error.

It is an object of the present invention to provide a signal determiner that flexibly adapts to the configuration of the transmitting end and the receiving end to accurately determine a signal.

[0008]

FIG. 1 is a block diagram showing the principle of the first aspect of the present invention.

According to the first aspect of the present invention, different instantaneous values are individually obtained corresponding to the signal points arranged in the signal space, and the modulated wave generated under the signal arrangement in the signal space is demodulated. A given baseband signal and a plurality of threshold values individually corresponding to these signal points are used to determine the magnitude relationship in parallel, and a plurality of comparison means for outputting the results of these determinations, and a plurality of comparison means. Symbol value generation that obtains symbol values that indicate transmission information in chronological order by capturing the output results and encoding these results based on the signal constellation and the correspondence relationship between the signal constellation and instantaneous values And a plurality of threshold values in the signal determiner including
A series of information that can be included as transmission information through a transmitter that generates a modulated wave or a transmitter that has characteristics equivalent to that transmitter and a receiver that demodulates or a receiver that has characteristics equivalent to that receiver. Set to the value that indicates the center of the area that provides the eye aperture individually corresponding to all the signal points in the area of the eye pattern of the baseband signal obtained in advance according to the reference transmission information that consists of the permutation of all bit patterns It is characterized by being done.

FIG. 2 is a principle block diagram of the invention described in claims 2 to 4. According to the invention described in claim 2, different instantaneous values are individually obtained corresponding to the signal points arranged in the signal space, and the modulated wave generated under the signal arrangement in the signal space is demodulated and given. A delay unit 21 that sequentially delays the baseband signal by a unit of an integer fraction of the symbol period over a plurality of stages, and among taps included in the delay unit 21 other than a specific tap in the middle, For the permutation of the instantaneous values of the baseband signal obtained by the above, it is obtained based on actual measurement or simulation under the transmission characteristics of the transmission line, and the noise margin is maximum for each signal point, or the error rate is Of the baseband signal obtained in parallel with the storage unit 23 in which the threshold value expected to be the smallest is stored in advance and the taps of the delay unit 21 other than the specific tap. By the threshold variable setting means 25 that refers to the storage means 23 based on the permutation of values and obtains the threshold value corresponding to the permutation, the instantaneous value of the baseband signal given through a specific tap, and the threshold variable setting means 25. the obtained results magnitude relationship between the individual threshold determined in parallel, a plurality of comparing means 27 ₁ ~ 27 _N for outputting the results of these determination, output by the plurality of comparison means 27 ₁ ~ 27 _N And symbol value generation means 29 for obtaining the symbol values indicating the transmission information in chronological order by encoding these results based on the signal arrangement and the correspondence between the signal arrangement and the instantaneous values. Is characterized by.

According to a third aspect of the present invention, in the signal determiner according to the second aspect, the storage means 23 stores a quantum value obtained for a momentary value of the baseband signal under a predetermined companding characteristic. The threshold value obtained for the permutation of the coded values is stored corresponding to the permutation, and the variable threshold setting means 25 quantizes the instantaneous value of the baseband signal obtained in parallel with taps other than the specific tap. , And means for referring to the storage means 23 based on the permutation of the quantized values obtained based on the quantization.

The invention according to claim 4 is the signal judging device according to claim 2 or 3, wherein the delay means 21 is provided.
Is the transmission characteristic of each individual symbol value that precedes and follows the symbol giving that symbol value and is actually formed between the transmitter that generates the modulated wave and the receiver that demodulates. , The number of symbols that can be regarded as an allowable degree of possible intersymbol interference is equal to or more than the sum of “1”, and a specific tap is sandwiched between its preceding symbol and its succeeding symbol. It is characterized in that it is set in the stage corresponding to the symbol.

In the signal judging device according to the invention described in claim 1, the plurality of comparing means 11 _{1 to} 11 _M individually correspond to the instantaneous value and the signal point of the baseband signal given by demodulating the modulated wave. The symbol value generating means 13 outputs these results by discriminating the magnitude relationship with the plurality of thresholds, and the symbol value generating means 13 outputs these results based on the signal constellation and the correspondence relation between the signal constellation and the instantaneous value of the baseband signal. Is encoded to obtain a symbol value indicating the transmission information in time series. In addition, these plural threshold values are transmitted through a transmitter that performs the above-described modulation or a transmitter that has a characteristic equivalent to that transmitter, and a receiver that performs demodulation or a receiver that has a characteristic equivalent to that receiver. , An eye aperture individually corresponding to all the signal points in the eye pattern area of the baseband signal previously obtained according to the reference transmission information consisting of a sequence of all bit patterns that can be included as transmission information. Is set to a value indicating the center of the area.

Since such an eye pattern is obtained under the condition that intersymbol interference occurs in a wireless transmission system including an actual transmitter and receiver, a bit error occurs due to noise added in the wireless transmission line. The chances are minimal. In the signal determiner according to the second aspect of the present invention, the delay means 21 sequentially delays the baseband signal over a plurality of stages in units of an integer fraction of the symbol period. The storage unit 23, with respect to the permutation of the instantaneous values of the baseband signal obtained in parallel with the taps other than the specific tap among the taps included in the delay unit 21, the transmission characteristic of the transmission line and the transmission characteristic thereof. A threshold that is obtained in advance based on actual measurement or simulation with respect to variations in transmission characteristics and is expected to have the maximum noise margin or the smallest error rate for each signal point is stored in advance.

The threshold variable setting means 25 refers to the storage means 23 based on the permutation of the instantaneous values of the baseband signal obtained in parallel with the taps other than the specific tap described above, and obtains the threshold value corresponding to the permutation. . Comparison means 27 _1-27
N discriminates in parallel the magnitude relation between the instantaneous value of the baseband signal given from the delay means 21 through the specific tap and the individual threshold values thus obtained, and the results of these discriminations are shown. Output. The symbol value generation means 29
In addition to the above-mentioned signal arrangement, by encoding these results based on the correspondence between the signal arrangement and the instantaneous value, the symbol value indicating the transmission information in chronological order is obtained.

That is, for each symbol to be subjected to signal determination, there is a possibility of a determination error due to intersymbol interference with respect to a combination of instantaneous values of baseband signals indicating symbols preceding and following the symbol. A small threshold is set dynamically. Therefore, the bit error rate can be suppressed small while flexibly adapting to the actual transmission specification of the transmission path.

According to a third aspect of the signal judging device of the present invention, in the signal judging device of the second embodiment, the storage means 23 stores the instantaneous value of the baseband signal under a predetermined companding characteristic. The threshold value obtained for the permutation of the quantized values of is stored. Further, the threshold variable setting means 25
Quantizes the instantaneous value of the baseband signal obtained in parallel with taps other than the specific tap of the delay means 21, and refers to the storage means 23 based on the permutation of the quantized values obtained based on the quantization. To do.

That is, since the number of combinations of threshold values stored in the storage means 23 decreases under the above-described companding characteristic, the scale of hardware and power consumption can be reduced. In the signal determiner according to the invention described in claim 4, in the signal determiner according to claims 2 and 3, the delay means 21 precedes and follows the symbol giving the symbol for each symbol value, and A number of stages equal to the sum of "1" and the number of symbols that can be regarded as an allowable degree of intersymbol interference that may occur under actual transmission characteristics between a transmitter that performs modulation and a receiver that performs demodulation is set. Have. Further, the specific tap of the delay unit 21 is set at the stage corresponding to the symbol sandwiched between the preceding symbol and the following symbol described above.

That is, based on only the instantaneous value of the baseband signal, which is the main cause of intersymbol interference, the number of stages of the delay means 21 and the threshold value, the required number N of the comparison means 25 _{1 to} 25 _N , and the symbol value are combined. Since the amount of information to be encoded by the generation unit 29 is optimized, the scale of hardware is reduced and responsiveness is improved.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a diagram showing an embodiment corresponding to the invention described in claim 1. In FIG. In the figure, parts having the same functions and configurations as those shown in FIG. 8 are designated by the same reference numerals, and the description thereof will be omitted here. Differs from the conventional example shown in this embodiment and FIG. 8 is a threshold A _F applied to the other input of the comparator 51 ₁ ~51 _3, B _F, is in the value of C _F, the basic configuration and operation Is the same as that of the conventional example, the description thereof will be omitted here.

Regarding the correspondence relationship between this embodiment and the block diagram shown in FIG. 1, the comparators 51 _{1 to} 51 ₃ correspond to the comparing means 11 _{1 to} 11 _M , and the judging circuit 52 corresponds to the symbol value generating means 13. Corresponding to. Hereinafter, the above-mentioned thresholds A _F , B _F ,
A procedure for _obtaining the value of C _F will be described. (1) A transmitter and a receiver (or a transmitter and a receiver having characteristics equivalent to those of the transmitter and the receiver) respectively configuring the transmitter and the receiver of the wireless transmission system to which the present embodiment is applied. A pseudo line having a transmission characteristic equivalent to (or considered equivalent to) an actual wireless transmission line is formed between the antenna terminals.

(2) The transmission information consisting of all bit strings that can be actually transmitted is given to the modulation input of the transmitter. (3) As shown in FIG. 4, an eye pattern is obtained by giving a baseband signal (hereinafter, referred to as “test signal”) obtained at the output of the demodulator mounted on the receiver to the memory scope.

(4) With respect to the eye apertures h _A , h _B and h _C which the eye pattern thus obtained has corresponding to each symbol, the maximum value M and the minimum value m of the symbol value S of the test signal are obtained. And are individually requested. In the following,
For the sake of simplicity, such maximum and minimum values are associated with the thresholds A _F , B _F , and C _F by adding subscripts “A”, “B”, and “C”, respectively.

[0025] (5) In _{addition, A F = (M A +} m A) / 2 B F = (M B + m B) / 2 C F = (M C + m C) based on the equation / 2 threshold A _F , B _F , C _F.

That is, the thresholds A _F , B _F , and C _F are, as shown in the above-mentioned procedures (1) and (2), transmitters and receivers (or equivalent characteristics thereof) that constitute the wireless transmission system. It becomes a value indicating the midpoint of the eye aperture of the eye pattern according to the transmission information consisting of all bit strings actually transmitted via the transmitter and the receiver). Therefore, according to the present embodiment, the maximum noise margin is ensured for the noise component that is superimposed on the wireless transmission path while allowing the intersymbol interference that actually occurs in the transmitter and the receiver. Signal determination is performed more accurately than the conventional example that was set to a constant value shown by the above-mentioned formulas (1) to (3),
Transmission quality is improved.

In the above-described embodiment, the threshold value is set based on the actually measured eye pattern, but the present invention is not limited to the threshold value set in this way. For example, a transmitter and a receiver may be used. When the characteristic of 1 can be simulated, an eye pattern may be obtained based on computer simulation or the like, and a threshold value adapted to the eye pattern may be similarly obtained.

In the above embodiment, the eye pattern is measured through the memory scope. However, if the history of changes in the instantaneous value of the baseband signal can be reliably obtained, an oscilloscope, a wave memory, etc. It is possible to use any of the measuring devices described above. Furthermore, in the above-described embodiment, the threshold value is determined based only on the instantaneous value of the baseband signal at the identification time that gives each symbol, but the present invention is not limited to such instantaneous value, and its reference time. The threshold value may be set by weighting based on the distribution of the instantaneous values at times other than.

FIG. 5 is a diagram showing an embodiment corresponding to the invention described in claims 2 to 4. In the figure, parts having the same functions and configurations as those shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted here. The difference between the present embodiment and the embodiment shown in FIG. 3 is that comparators 40 ₁ to 40 ₃ are provided instead of the comparators 51 _{1 to} 51 ₃ .
The point is that the threshold value setting unit 41 is provided in the preceding stage of these comparators.

In the threshold value setting section 41, the baseband signal is connected to the first inputs of the ROMs 44 _{1 to} 44 ₃ via the A / D converter (A / D) 42 and the delay circuit 43 which are connected in cascade. Of the three taps of the delay circuit, the two taps adjacent to the central tap are each ROM 44 ₁
To 44 ₃ a second input of the is connected to the third input. The input terminal of the first stage of the delay circuit 43 is connected to the fourth inputs of the ROMs 44 _{1 to} 44 ₃ and the symbol clock is given to the clock inputs of the delay circuit and the A / D converter 42. The central tap of the delay circuit 43 is connected to the first inputs of the comparators 40 ₁ to 40 ₃ , and the outputs of the ROMs 44 _{1 to} 44 ₃ are connected to the second inputs of these comparators, respectively.

Regarding the correspondence relationship between this embodiment and the block diagram shown in FIG. 2, the A / D converter 42 and the delay circuit 43 correspond to the delay means 21, and the ROMs 44 _{1 to} 44 ₃ correspond.
Corresponds to the storage means 23 and the threshold variable setting means 25,
The comparators 40 ₁ to 40 ₃ correspond to the comparison means 27 _{1 to} 27 _N ,
The determination circuit 52 corresponds to the symbol value generation means 29. FIG. 6 is a diagram (1) for explaining the operation of this embodiment.

FIG. 7 is a diagram for explaining the operation of this embodiment.
(2). The operation of this embodiment will be described below with reference to FIGS. In this embodiment, for simplicity,
It is assumed that a 4-level FSK modulation scheme having a signal space diagram similar to that of the embodiment corresponding to the invention described in claim 1 is applied. Individual symbols (hereinafter,
It is called "evaluated symbol". In general, the main component of intersymbol interference associated with) is due to a predetermined number of symbol sequences (hereinafter referred to as “reference symbol sequence”) that are adjacent before and after the evaluation symbol along the time axis. Yes, the correlation with a symbol that is further away from the reference symbol sequence along the time axis is so small that it can be ignored. Note that in the following, for the sake of simplicity, the evaluated symbol serving as a reference that gives such a reference symbol sequence is referred to as a “reference symbol”.

The number of stages of the delay circuit 43 is obtained in advance based on the actual transmission characteristics or the simulated transmission characteristics of the wireless transmission system to which this embodiment is applied when the intersymbol interference occurs in the above-mentioned form. It is preset to a value equal to the predetermined number. Regarding the error component accompanying the baseband signal due to such intersymbol interference, generally, the waveform of the baseband signal having the symbol value S sharply changes along the time axis (see FIG. 6 (1 ), As large as in Fig. 7 (1), and smaller in the opposite case when it changes gently (Fig. 6 (2)).
, FIG. 7 (2)).

Therefore, the instantaneous values V _P , V _Q , V _R , and V _S of the baseband signal having such an error individually taken for all the evaluated symbols are intersymbol interference in the above-described form. In general, in the sequence of symbol values recognized by the modulator according to the transmission information to be actually transmitted, the sequence of instantaneous values of the baseband signal indicating the reference symbol sequence (hereinafter referred to as “reference instant”). Value sequence ”)). In the following, for the sake of simplicity, the timing at which the instantaneous values V _P , V _Q , V _R , and V _S are given is limited to the regular time (hereinafter referred to as “identification time”) at which each symbol should be given. limit.

[0035] For example, ROM 44 ₁ to to 44 _3, corresponding individually to all of the reference instantaneous value sequence described above, the instantaneous value V _P obtained in advance by actual measurement or simulation, V _Q,
Of V _R, V _S, the instantaneous value V _P, V _Q, the minimum instantaneous value V _Pm is the minimum value of V _R, V _Qm, and V _Rm, instantaneous value V _Q, V _R, the maximum value of V _S some maximum instantaneous value _{V QM, V RM, A C} = (V Pm + V QM) against the _{V SM / 2 ··· (8)} B C = (V Qm + V RM) / 2 ··· (9) C _C = (V _Rm + V _SM ) / 2 (10) The threshold value given by each equation is stored in advance. In these equations, the instantaneous value of the baseband signal that does not correspond to the reference symbol of the reference symbol sequence that gives each reference instantaneous value sequence among the instantaneous values V _P , V _Q , V _R , and V _S Normal instantaneous values are applied in the absence of intersymbol interference. The above-mentioned thresholds _AC , _BC , _CC are expressed by the above equation (8)-
In some cases, correction may be made from the value obtained in (10).

The A / D converter 42 generates digital information by A / D converting the analog baseband signal supplied from the demodulator, and the delay circuit 43 converts the digital information into such digital information at every symbol clock cycle. Add delay to 4 stages. Therefore, in the delay circuit 43,
In addition to the input and output of the first stage, the above-mentioned reference instantaneous value sequences are obtained at the outputs of the third and fourth stages by updating for each cycle of the symbol clock, and the output of the second stage is covered. An evaluated instantaneous value indicating the symbol value of the evaluation symbol (reference symbol) is obtained.

The ROMs 44 _{1 to} 44 ₃ are updated at the cycle of the symbol clock by sequentially reading the contents of the storage area corresponding to the address indicated by the reference instantaneous value sequence thus obtained, The threshold values shown in equations (8) to (10) are sequentially given to the comparators 40 ₁ to 40 ₃ . The comparators 40 ₁ to 40 ₃ determine the magnitude relationship between these threshold values and the evaluated instantaneous value obtained from the delay circuit 43, and also provide the determination circuit 52 with the results of these determinations.

As described above, according to the present embodiment, the reference instantaneous value sequence, which is a main factor of intersymbol interference, is sequentially monitored, and the threshold value dynamically updated corresponding to the reference instantaneous value sequence is sequentially updated. It is given to the comparators 40 ₁ to 40 ₃ . That is, in the same manner as the embodiment corresponding to the invention described in claim 1,
Since a large noise margin is secured for the noise component that is superimposed on the wireless transmission path while allowing inter-code interference that actually occurs in the transmitter and receiver, compared to the conventional example in which a fixed threshold value was set. Signal is accurately determined and transmission quality is improved.

In the present embodiment, the number of stages of the delay circuit 43 is set to an instantaneous value indicating the evaluated symbol under the actual or simulated transmission characteristics of the wireless transmission system to which the present embodiment is applied. Although it is set to a value that gives a reference symbol sequence that gives a main component of the accompanying intersymbol interference, the present invention is not limited to such a number of stages, and if the bit error rate surely decreases as compared with the conventional example. Any number of stages may be set, and it is also possible to set the number of stages to the minimum value as long as desired transmission quality is obtained under the error correction processing adapted to the channel coding method.

Further, in the above-described embodiment, the processing for making signal determination while dynamically setting the threshold value is all performed in the digital domain, but the present invention is not limited to such a configuration, and for example, delay The circuit 43 and the comparators 40 ₁ to 40 ₃ may be configured to perform equivalent processing in the analog area.
Further, in the above-described embodiment, the instantaneous value of the baseband signal given through the delay circuit 43 is given to the ROMs 44 _{1 to} 44 ₃ without any processing, but the present invention has such a configuration. For example, the lower bits of the digital signal indicating the instantaneous value may be rounded and provided to these ROMs.

Further, in the above-described embodiment, the ROM 44
Although _{1-44 3} threshold adapted to the reference instantaneous value column are stored is pre-calculated, are suppressed to an extent increasing with an acceptable calculation accuracy and decrease the hardware scale and power consumption of the operational speed Then, instead of these ROMs, a circuit for performing an equivalent operation in the analog domain or the digital domain may be provided.

[0042]

As described above, according to the first aspect of the present invention, the probability of occurrence of bit error due to noise added in an actual radio transmission system in which intersymbol interference occurs is minimized. According to the second aspect of the invention, the bit error rate can be suppressed small while flexibly adapting to the actual transmission identification of the transmission path.

According to the third aspect of the invention, the scale of the hardware and the power consumption can be reduced. According to the invention described in claim 4, the hardware scale of the signal determiner according to claims 1 to 3 is minimized. Therefore, in the wireless transmission system to which these inventions are applied, the transmission quality and reliability are improved without complicating the configuration and increasing the cost.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the invention according to claim 1;

FIG. 2 is a principle block diagram of the invention according to claims 2 to 4;

FIG. 3 is a diagram showing an embodiment corresponding to the invention described in claim 1;

FIG. 4 is a diagram illustrating a procedure for obtaining a threshold value.

FIG. 5 is a diagram showing an embodiment corresponding to the invention described in claims 2 to 4;

FIG. 6 is a diagram (1) for explaining the operation of the present embodiment.

FIG. 7 is a diagram (2) explaining the operation of the present embodiment.

FIG. 8 is a diagram showing a configuration example of a conventional signal determiner.

FIG. 9 is a diagram showing threshold values set in a conventional example.

[Explanation of symbols]

 11, 27 comparison means 13, 29 symbol value generation means 21 delay means 23 storage means 25 threshold variable setting means 40, 51 comparator 41 threshold setting section 42 A / D converter (A / D) 43 delay circuit 44 ROM 52 judgment circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Inoue 2-3-9 Shin-Yokohama, Kohoku-ku, Yokohama-shi, Kanagawa Fujitsu Digital Technology Co., Ltd. (72) Shigeyuki Yoshioka Shin-Yokohama, Kohoku-ku, Yokohama, Kanagawa 3-9 No. 9 Fujitsu Digital Technology Stock Association In-house

Claims (4)

[Claims] 1. A baseband signal given by demodulating a modulated wave generated under the signal arrangement in the signal space, taking different instantaneous values individually corresponding to the signal points arranged in the signal space. , A plurality of comparing means for discriminating in parallel the magnitude relationship with a plurality of thresholds individually corresponding to these signal points and outputting the results of these discriminations, and taking in the results output by the plurality of comparing means. Symbol value generation means for obtaining symbol values indicating transmission information in chronological order by encoding these results based on the signal constellation and the correspondence between the signal constellation and the instantaneous value. In the signal determiner, the plurality of thresholds have a transmitter that generates the modulated wave or a transmitter that has a characteristic equivalent to that of the transmitter and a receiver that performs the demodulation or a characteristic that is equivalent to that of the receiver. Through the receiver, in the area of the eye pattern of the baseband signal previously obtained according to the reference transmission information consisting of a sequence of all the bit patterns of the series that may be included as the transmission information, of the signal point A signal determiner characterized in that it is set to a value indicating the center of a region that gives an eye aperture corresponding to each individually. 2. A baseband signal obtained by demodulating a modulated wave generated under the signal arrangement in the signal space, taking different instantaneous values individually corresponding to the signal points arranged in the signal space. A delay unit that sequentially delays a unit of an integer fraction of a symbol period over a plurality of stages, and a baseband obtained in parallel with taps other than a specific tap in the taps included in the delay unit. With respect to the permutation of the instantaneous values of the signals, it is determined in advance based on actual measurement or simulation under the transmission characteristics of the transmission line, and the noise margin is maximum for each of the signal points,
Alternatively, a storage unit in which a threshold value expected to minimize the error rate is stored in advance, and among the taps of the delay unit, in a permutation of the instantaneous values of the baseband signal obtained in parallel with the taps other than the specific tap. Based on the storage means, based on the threshold value variable setting means for obtaining a threshold value corresponding to the permutation, the instantaneous value of the baseband signal given through the specific tap, the threshold value obtained by the threshold value variable setting means In parallel to determine the magnitude relationship with each of the plurality of comparing means for outputting the results of these determinations, the results output by the plurality of comparing means is taken in, the signal arrangement, the signal arrangement and the Symbol value generation means for obtaining these symbol values indicating the transmission information in chronological order by encoding these results based on the correspondence with the instantaneous value. Signal determiner for. 3. The signal determiner according to claim 2, wherein the storage unit obtains a permutation of quantized values obtained under a predetermined companding characteristic with respect to an instantaneous value of the baseband signal. The threshold values are stored corresponding to the permutations, and the variable threshold setting means quantizes the instantaneous value of the baseband signal obtained in parallel with taps other than the specific tap, and obtains it based on the quantization. A signal determiner comprising means for referring to the storage means based on the permutation of the quantized values. 4. The signal determiner according to claim 2 or 3, wherein the delay means is, for each symbol value, a transmitter that precedes and follows a symbol giving the symbol value, and generates a modulated wave. Based on the transmission characteristics of the transmission path that is actually formed between the receiver and the receiver that performs demodulation, the number of symbols that can be regarded as an extent to which the possible intersymbol interference is tolerable and the sum of "1" or more. A signal determiner having an equal number of stages, wherein a specific tap is set in a stage corresponding to a symbol sandwiched between its preceding symbol and its succeeding symbol.