JP2008072212A - Mixed signal separator/extractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce an original signal continuously and faithfully. <P>SOLUTION: An extraction section 9 extracts a signal while sectioning for every block formed continuously and having an overlapped region on the time axis, and since a calculating section 11 detects the signal difference (Δϕ) in the overlapped region and supplies the calculation data of a combination to be continuous along with the signal difference (Δϕ) data to a coupling section 12, the coupling section 12 can perform corrected coupling such that the signal difference (Δϕ) becomes zero and an original signal having a signal waveform (frequency spectrum) faithful to the input signal can be reproduced and outputted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention receives a mixed signal including a plurality of incident signals (original signals) that arrive at the same time, separates the received mixed signals in units of blocks connected on the time axis, and separates the original signals in units of blocks. The present invention relates to a mixed signal separation / extraction apparatus that reproduces and extracts original signals that arrive after connecting the signals on the time axis.

  When a signal (mixed signal) in which a plurality of incident signals (original signals) are mixed is received by a plurality of sensors arranged at predetermined intervals, blind signal separation (BBS: Blind Source Separation) for the received signals, A technique for extracting an original signal from a mixed signal is known.

  In the blind signal separation, the mixed signal of the original signal received by each sensor is analog / digital (A / D) converted, and the original signal is separated and extracted for each sampling period (cycle) after the A / D conversion. Thus, the original signal included in the mixed signal received by the sensor can be reproduced and output by the connection based on the correlation between the sampling signals before and after each of the separated and extracted original signals.

  In blind signal separation, it is a condition that the reception time of the mixed signal at each sensor can be regarded as the same, and when the interval between the sensors is wide, there is a difference in reception time between the sensors that cannot be ignored. Therefore, in this case, a general blind signal separation method cannot be adopted.

  Therefore, an independent component analysis (ICA) method is known as a method for separating and extracting an original signal even when the interval between sensors is wide and a reception time difference occurs between sensors. (For example, refer to Patent Document 1).

  The separation and extraction of the original signal by independent component analysis is performed by decomposing the received signal at the sensor into frequency components, collecting all the frequency components, rearranging them, and returning them to time series data. The separation and extraction of the original signal depends only on the sex.

  In addition, in the independent component analysis, separation and extraction are performed by normalization processing as will be described later. Therefore, the signal level and frequency spectrum of the separated and extracted incident signal (original signal), that is, the amplitude and power can be arbitrarily determined. Sex is not maintained. In addition, since the order between the previous and next sampling periods is not maintained, even if all the frequency components are collected and rearranged as described above, and connected to return to time-series data, the incident signal (original signal) is faithfully reproduced. It has the property that a regenerated product cannot be obtained.

  FIG. 5 is a configuration diagram of a mixed signal separation / extraction apparatus for separating and extracting an original signal by conventional general blind signal separation. In blind signal separation, the number of sensors (for example, n = 4) can be separated and extracted up to the same number of incident signals (original signals) as the number of sensors (that is, m = 4).

  Therefore, in the following description, it is assumed that the same number (m = 4) of original signals as the number of sensors (n = 4) is separated and extracted from the received mixed signal. In the present specification, the sampling period is referred to as a block, and therefore, the division of the sampling period is referred to as a block.

  As shown in FIG. 5, the conventional mixed signal separating / extracting device receives a plurality of (four) sensors 1 (11) that respectively receive a mixed signal X of a plurality of incident signals (original signals) S (S1 to S4). To 14), band-limited filter 2 (21 to 24) for limiting the reception band of the mixed signal received by the plurality of sensors 1 (11 to 14), and band-limited filter 2 (21 to 24), respectively. A / D converter 3 (31 to 34) for A / D converting the band-limited mixed signal, and mixed signal X (X1 to X4) converted by this A / D converter 3 (31 to 34) As shown in FIG. 6, the extraction unit 4 (41 to 44) for extracting and extracting the data in units of a block b (sampling period t) having a predetermined time length and the extraction unit 4 (41 to 44) Data of block mixed signal X (X1-X4) is introduced sequentially The blind separation unit 5 that separates and outputs a plurality (four) of original signals Y2 (Y21 to Y24) for each block, and the plurality of separated original signals Y2 (Y21 to Y24) are sequentially introduced, and the first A plurality of first original signals Y2 separated in block b1 (first sampling period t1) and a plurality of second original signals Y2 separated in second block b2 (second sampling period t2) (following the first block) A calculation unit 6 that detects a correlation (for example, frequency correlation) with the original signal Y2 and calculates a combination that should be continued based on the detected correlation result, and is calculated by the calculation unit 6. A connecting unit 7 that extracts and generates a continuous original signal Q (Q1 to Q4) by connecting each of the plurality of first original signals Y2 with any of the plurality of second original signals Y2 by selective switching based on the combination; , The connecting portion 7 by a connecting extracted original signal Q (Q1 to Q4) and a D / A conversion section 8 which outputs the D / A conversion of the.

  The digitization sampling rate or the number of quantization precision bits in D / A conversion or A / D conversion is determined according to the required performance.

  As shown in FIG. 7, the structure of the blind separation unit 5 receives data extraction of the mixed signal for each block b corresponding to each sensor 1 (11 to 14) from the extraction unit 4 (41 to 44). From the covariance matrix generation circuit 51 that generates the variance matrix, the eigenvector calculation circuit 52 that calculates the eigenvector of the generated covariance matrix, and the mixed output of the extraction unit 4 (41 to 44) and the calculated eigenvector, Whitening / decorrelation and power normalization circuit 53 for whitening / decorrelation and power normalization and an output signal of whitening / decorrelation and power normalization circuit 53 are introduced, and the original signal Q (Q1˜ Q4), a separation matrix generation circuit 54 that generates a separation matrix W and outputs a separation signal Y1; a separation signal Y1 from the separation matrix generation circuit 54; and a whitening / decorrelation and power normalization circuit 53 Normalized signal And a respective block outputs the original signal to separate each Y2 (Y21~Y24) in b units, each supplied signal separation processing circuit 55. the coupling portion 7 and the calculating section 6 shown in FIG. 5.

JP 2003-92557 A

  As described above, in the conventional mixed signal separation / extraction apparatus, the separation / extraction processing of the original signal in each block b (that is, each sampling period t) is cut out in units of block b and performed individually. Accordingly, in the blind separation unit, signal separation processing is performed in units of each block b, and there is a time difference. Therefore, even one original signal to be extracted originally has a frequency spectrum, that is, phase characteristics, in signal processing in units of blocks. It is inevitable that differences (signal differences) occur in the amplitude and power characteristics.

  That is, the incident signal (original signal) received by the sensor has smooth continuity between the blocks b1 and b2, as shown in FIG. 8A, but is separated and extracted in units of blocks. Due to the difference in signal processing characteristics in FIG. 8, even if connected, as shown in FIG. 8 (b), the connection after separation and extraction is output with a loss of continuity.

  Therefore, when one original signal cut out in blocks and separated and extracted is connected to be separated and extracted as the original one original signal, it shifts in phase, amplitude, power, etc. between adjacent blocks (signal difference) And the fidelity of the signal waveform of the incident signal (original signal) received by the sensor is impaired.

  Therefore, the present invention corrects a signal difference (deviation) generated between blocks of the same original signal in the connection to the calculation result of the combination of the separated original signals between the preceding and following blocks b1 and b2 in the calculation unit, and more accurately An object of the present invention is to provide a mixed signal separating / extracting device capable of outputting a connected signal that is more faithful to an incident signal waveform.

  The mixed signal separating / extracting apparatus according to the present invention includes a plurality of sensors that respectively receive signals obtained by mixing a plurality of incident signals, and A / D conversion that performs A / D conversion on the signals received by the plurality of sensors. And an extraction unit that extracts the signal converted into a digital signal by the A / D conversion unit by dividing the signal into blocks that are sequentially formed with overlapping regions on the time axis, and an extraction unit that extracts the signal A separation unit that sequentially introduces the signals of each block, separates and outputs the original signal by blind signal separation, and introduces the original signal of each block separated and output by the separation unit, and has the overlapping region A combination of original signals to be connected by two adjacent blocks is calculated, and a first original signal separated by a preceding first block in the overlap region and a second block following the first block A calculation unit that calculates a signal difference in the overlapping region between the first original signal that is separated and the second original signal to be connected; a combination of the original signals to be connected calculated by the calculation unit; And a connection unit that connects the first original signal and the second original signal output from the separation unit based on the signal difference in an overlapping region to reproduce a continuous original signal. .

  As described above, the signal separation / extraction device of the present invention includes an extraction unit that extracts and extracts the mixed signal from the A / D conversion unit by sequentially dividing the mixed signal into blocks that have overlapping regions on the time axis. The unit includes a first original signal separated by a preceding first block, and a second original signal separated by a second block following the first block, of two adjacent blocks having overlapping regions. Between the signals to be connected to each other and the difference between the original signals to be connected in the overlap region (signal difference) is calculated and output. By correcting, the incident signal (original signal) can be separated and extracted faithfully.

  Hereinafter, an embodiment of a mixed signal separating / extracting apparatus according to the present invention will be described in detail with reference to FIGS. The same components as those of the conventional mixed signal separating / extracting apparatus shown in FIGS. 5 to 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 1 is a block diagram showing an embodiment of a mixed signal separating / extracting apparatus according to the present invention.

  That is, in FIG. 1, analog signals received by n sensors 1 (11 to 14), which are means for capturing signals to be separated, such as antennas and microphones, are passed through bandpass filters 2 (21 to 24). It is supplied to the A / D converter 3 (31 to 34), digitized (digitized), and supplied to the extraction unit 9 (91 to 94) for blocking.

  As shown in FIG. 2, the extraction unit 9 (91 to 94) extracts a mixed signal by cutting out blocks having overlapping areas (Δt) with blocks adjacent to each other on the time axis. The signal is supplied to a separation unit 10 that performs signal separation.

  As shown in FIG. 3, the separating unit 10 includes a covariance matrix generation circuit 101 corresponding to the conventional covariance matrix generation circuit 51 (shown in FIG. 7) and an eigenvector corresponding to the conventional eigenvector calculation circuit 52. A calculation circuit 102, a whitening / decorrelation and power normalization circuit 103, a separation matrix generation circuit 104 corresponding to the conventional separation matrix generation circuit 54, a mixing matrix generation circuit 105, and a signal separation processing circuit 106 It is configured.

  That is, the mixed signal of each block having an overlapping area between adjacent blocks while corresponding to each sensor 1 (11-14) from the extraction unit 4 (41-44) is the covariance matrix generation circuit 101 (1011-1014). ) To generate a covariance matrix.

  The generated covariance matrix is supplied to the eigenvector calculation circuit 102 (1021 to 1024) to calculate the eigenvector, and the calculated eigenvector is supplied to the whitening / decorrelation and power normalization circuit 103 (1031 to 1034). Then, whitening, decorrelation, and power normalization are performed based on the supplied eigenvectors and the output (mixed signal) X of the extraction unit 4 (41 to 44) and supplied to the separation matrix generation circuit 104.

  The separation matrix generation circuit 104 introduces each output data of the normalized whitening / decorrelation and power normalization circuit 103 (1031 to 1034), and the separation matrix W1 corresponding to the original signal Q (Q1 to Q4). And the separation output Y1 (Y11 to Y14) by the generated separation matrix W1 is supplied to the mixing matrix (A) generation circuit 105.

  The mixing matrix generation circuit 105 estimates the mixing matrix A (A1 to A4) by the inverse matrix operation of the separation matrix W1 with respect to the separation output Y1 (Y11 to Y14) from the separation matrix W1 from the separation matrix generation circuit 104, and the signal This is supplied to the separation processing circuit 106. The estimated mixing matrix A (A1 to A4) is determined by the arrangement and characteristics of the sensor 1 (11 to 14).

  The mixing matrix generation circuit 105 estimates the mixing matrix A from the separation matrix W1 generated by the separation matrix generation circuit 104, and can reduce the influence of the noise N on the original signal to be separated and extracted. The output X (X1 to X4) of the extraction unit 9 is represented by the product (X = S · A) of the mixed signal S (S1 to S4) that is an incident signal and the mixing matrix A.

  On the other hand, when the output of the blind separation process in the separation matrix generation circuit 104 is Y1 (Y11 to Y14), the waveform data Y1 of the blind separation process output is expressed as Y1 = W1 · X.

  Therefore, since the waveform data Y1 of the blind separation process in the separation matrix generation circuit 104 is ideally the original signal S (= Y1), S = W1 · X = W1 · A · S.

Here, if the mixing matrix A = W1 ⁻¹ , the mixing matrix A = W1 · W1 ⁻¹ · S = I · S = S. Here, I represents a unit matrix.

  Therefore, the mixing matrix generation circuit 105 generates an n × m mixing matrix A (A1 to A4) by inverse matrix operation of the separation matrix W1.

  The next signal separation processing circuit 106 performs a method of forming a plurality of adaptive nulls (for example, Non-Patent Document 1) on the separation coefficient W2 by signal separation processing using the n × m matrix mixing matrix A in the mixing matrix generation circuit 105. (See Adaptive Processing in Array Antennas, Science and Technology Publication 1998) by Nobuyoshi Kikuma, multiplying by the mixed signal X output from the extraction unit 9, which is the original signal, and outputting the result.

  That is, after the mixing matrix A (A1 to A4) is estimated by the mixing matrix generation circuit 105, the signal separation processing circuit 106 generates the separation matrix W2 from the mixing matrix A (A1 to A4) according to (1) below. To do. Further, since the separation output Y2 = W2 · X, a predetermined separation output Y2 (Y21 to Y24) can be obtained from the generated separation matrix W2 and the mixed signal X.

W2 = (A ^H · A) ⁻¹ · A ^H (1)
However, H shows complex conjugate transposition.

  As described above, the signal separation processing circuit 106 of the separation unit 10 generates the original signal from the mixing matrix A (A1 to A4) generated by the mixing matrix generation circuit 105 and the mixed signal X from the extraction unit 9 (91 to 94). Y2 (Y21 to Y24) is separated and extracted, and supplied to the connecting unit 7 and the calculating unit 11 shown in FIG.

  Unlike the conventional case (FIG. 7), the signal separation processing circuit 106 performs the signal separation processing of the original signal by the separation matrix (W2) by the mixed signal X and the mixing matrix A which are not normalized. The signal Y2 is obtained by maintaining and storing the waveform level (that is, amplitude level or power level) of the incident signal as it is. Therefore, according to the configuration of the separation unit 10, a natural demodulated output sound can be separated and output when the original signal is an analog modulated wave such as an AM signal or an SSB signal modulated with a sound signal or the like.

  The calculation unit 11 introduces the original signal Y2 (Y21 to Y24) in each block separated by the separation unit 10 (signal separation processing circuit 106), but is adjacent to the introduced original signal Y2 (Y21 to Y24). Including overlapping areas (overlapping areas) between blocks to be performed.

  Since the characteristics such as the frequency spectrum are common among the blocks in the overlapping region, the difference between the blocks (signal difference) caused by the signal processing of the separation and extraction after the block formation is the difference in the overlapping region (signal difference) Since it is nothing but a signal difference, the calculation unit 11 can detect a difference (signal difference) in the overlapping region and supply it to the linking unit 12 together with the data of the corresponding block.

The connection unit 12 that has received the data of the corresponding block together with the difference (signal difference) in the overlapping region from the calculation unit 11 is separated and extracted in adjacent blocks so that the difference (signal difference) becomes zero. Therefore, the connecting unit 12 can output a connected original signal faithful to the incident signal (original signal) waveform received by the sensor 1 (11-14) while correcting the original signal.
With respect to the above operation, the original signal before separation / extraction processing (FIG. 4 (a)) in the overlapping region shown in FIG. 4 and the original signal (FIG. 4 (b)) subjected to separation / extraction processing for each block unit after blocking. ) Will be further described.

Will be described with reference to FIG.

  That is, as described above, the calculation unit 11 has a signal difference such as a phase difference, a frequency difference, or an amplitude level difference between the blocks of the original signal Y2 (Y21 to Y24) that is common in the overlapping region (that is, for example, FIG. The phase difference Δφ as shown in FIG. 4B is detected, and the data of the difference (phase difference Δφ) is supplied to the connecting unit 12 together with the corresponding original signal Y.

  The connection unit 12 is supplied with the original signal Y2 to be combined and calculated by the calculation unit 11 and a signal difference (for example, phase difference Δφ) between the two original signals Y2 to be combined. From the calculation unit 11, a combination signal of two original signals combined and connected between blocks and a signal difference (for example, phase difference Δφ) between the original signals between adjacent blocks are connected between adjacent blocks. Are corrected and connected so that the deviation between the original signals (signal difference, that is, phase difference Δφ) becomes zero.

  By connecting the signal difference correction in the connecting unit 12 as described above, the original signals Q (Q1 to Q4) connected between the blocks eliminate the waveform difference based on the block difference, and the D / A converting unit 8 Since it supplies, the D / A conversion part 8 can output the connection signal by which the signal waveform received in the sensor 1 (11-14) was reproduced faithfully.

  In the above description, the phase difference between the original signals to be connected in the calculation unit 11 can be detected by a known phase discriminator, and the detection of the difference in amplitude level or the difference in power level is similarly known. An amplitude comparator or a power comparator can be employed.

  As described above, the mixed signal separating / extracting apparatus according to the present embodiment relates to blocks that are sequentially formed on the time axis, and the extraction unit 9 creates an overlapping area (overlapping area) between adjacent blocks. Since the calculation unit 11 calculates a signal difference between the original signals to be connected in the overlapping region and supplies the signal difference to the connection unit 12, the connection unit 12 is connected to each other in blocks. It is possible to perform a connection in which a signal difference between signals to be corrected is corrected, and a connection signal faithful to the received signal waveform can be stably output.

1 is a configuration diagram illustrating an embodiment of a mixed signal separation / extraction apparatus according to the present invention. It is explanatory drawing of blocking in the extraction part shown in FIG. It is a block diagram of the isolation | separation part shown in FIG. FIG. 4 (a) shows the incident signal of the overlapping area between adjacent blocks in the extraction unit, and FIG. 4 (b) separates the data of each block in the overlapping area shown in FIG. 4 (a) individually. It is the figure which showed the original signal after extracting. It is the block diagram which showed the conventional mixed signal separation / extraction apparatus. FIG. 6 is a diagram illustrating blocking (sampling period) in the extraction unit illustrated in FIG. 5. It is a block diagram of the isolation | separation part shown in FIG. FIG. 8A shows an incident signal between adjacent blocks in the extraction unit, and FIG. 8B shows a state after data of each adjacent block shown in FIG. It is the figure which showed the original signal.

Explanation of symbols

1 (11-14) Sensor 2 (21-24) Bandpass filter 3 (31-34) A / D converter 7 Connection unit 8 D / A conversion unit 9 (91-94) Extraction unit 10 Separation unit 101 Covariance Matrix generation circuit 102 Eigenvector calculation circuit 103 Whitening / decorrelation and power normalization circuit 104 Separation matrix generation circuit 105 Mixing matrix generation circuit 106 Signal separation processing circuit 11 Calculation unit 12 Connection unit

Claims (4)

A plurality of sensors each receiving a mixed signal of a plurality of incident signals;
An A / D converter for A / D converting each of the signals received by the plurality of sensors;
An extraction unit that extracts the signal converted into a digital signal by the A / D conversion unit by sequentially dividing the signal into blocks that have overlapping regions on the time axis;
A separation unit that sequentially introduces the signals of each block extracted by the extraction unit, separates and outputs the original signal by blind signal separation, and
The original signal of each block separated and output by the separation unit is introduced to calculate a combination of original signals to be connected by two adjacent blocks having the overlapping region, and the preceding first in the overlapping region. A signal difference in the overlap region between a first original signal separated by a block and a second original signal separated by a second block following the first block and to be connected to the first original signal is calculated. A calculation unit;
Based on the combination of the original signals to be connected calculated by the calculation unit and the signal difference in the overlapping region, the first original signal and the second original signal output from the separation unit are connected. A mixed signal separating / extracting device comprising: a connecting unit that reproduces a continuous original signal. The separation unit is
A blind separation matrix generation circuit for generating a blind separation matrix by introducing the signal of the block extracted in the extraction unit;
A mixing matrix generation circuit that generates a mixing matrix from the separation matrix generated in the blind separation matrix generation circuit;
A signal separation processing circuit that separates and outputs an original signal in the block by a signal separation process using the mixing matrix generated by the mixing matrix generation circuit and the signal extracted by the extraction unit. The mixed signal separation / extraction apparatus according to claim 1. The calculation unit outputs, as the signal difference, a difference in amplitude characteristics in the overlapping region between the first original signal and the second original signal to be combined, or a difference in power characteristics,
The connecting unit corrects the difference in amplitude characteristics or the difference in power characteristics based on the signal difference output from the calculating unit, and connects the first original signal and the second original signal. The mixed signal separation / extraction apparatus according to claim 1 or 2. The calculation unit outputs the phase difference in the overlap region of the first original signal and the second original signal to be combined as the signal difference,
The said connection part correct | amends the said phase difference based on the said phase difference supplied from the said calculation part, and connects the said 1st original signal and the said 2nd original signal. Item 3. The mixed signal separating / extracting device according to Item 2.

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