JP4454473B2 - Equalizer, device and program using the same - Google Patents

Description

  The present invention relates to an equalizer for correcting distortion of a received signal caused by multipath of a propagation path by waveform equalization in digital transmission and digital broadcasting, an apparatus such as a receiver and a measuring instrument using the equalizer, and Regarding the program.

  FIG. 10 shows an example of a conventional equalizer. The equalizer 10 equalizes a received signal distortion due to multipath of a propagation path in a time domain, and feeds forward by a FIR (Finite-duration Impulse Response) filter 11 in the preceding stage. A tap is configured, and a feedback tap is configured by an IIR (Infinite-Duration Impulse Response) filter 13 including a subtractor 12 and an FIR filter 13 that feeds back an output to a subtracting terminal of the subtracter 12 in the subsequent stage. The equalizer 10 configured as described above feeds a multipath wave (hereinafter referred to as “pre-ghost”) that arrives in time before the main wave having the largest amplitude on the delay profile of the received signal. The multipath wave that arrives later in time than the main wave (hereinafter referred to as “rear ghost”) is equalized by a feedback tap (see Non-Patent Document 1).

Yoichi Sato, “Linear Equalization Theory, Adaptive Digital Signal Processing”, Maruzen Co., Ltd., May 31, 1990, p. 42-43

  When the multipath wave is equalized by the feedback tap, the coefficient set in the FIR filter 13 constituting the feedback tap is the same FIR type coefficient as the delay profile. On the other hand, when the multipath wave is equalized by the feed forward tap, the coefficient set in the FIR filter 11 constituting the feed forward tap is an IIR type impulse response. A tap length several times longer is required. Therefore, when equalizing the previous ghost, a tap length several times that of the subsequent ghost with the same delay time difference is required. In this case, when the tap length of the filter is increased, not only the hardware scale is increased, but also the time required for the filter processing is increased.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide an equalizer and an equalization program that can solve the above-described problems and can efficiently equalize a front ghost and a rear ghost with a short tap length filter. is there. The second object of the present invention is to provide an apparatus and a program such as a receiver including an equalizer and a delay profile measuring instrument that solve the above-mentioned problems.

The equalizer according to claim 1 of the present invention is an equalizer for equalizing distortion caused by multipath of a propagation path with respect to an input signal, and temporarily storing the input signal in a memory. and means for outputting the signal to, the output signal from the memory, to create a time-reversed signal of the input signal, it performs a filtering process on the time-reversed signal, the input signal generates a signal which equalizes the prior ghost included in the front to create a time-reversed signal of the signal obtained by equalizing the ghost, it applies a filtering process to the time-reversed signal of the signal obtained by equalizing the pre-ghost, After performing a series of processes for generating a signal obtained by equalizing a post-ghost included in the input signal, the signal subjected to the series of processes is input, and before and after of the signals in time Delete some signals and output Characterized in that and means.

An equalizer according to a second aspect of the present invention is an equalizer that equalizes distortion caused by multipath of a propagation path with respect to an input signal, and temporarily stores the input signal in a memory. And outputting the signal, filtering the input signal with respect to the signal output from the memory , generating a signal equalizing the post-ghost included in the signal, and generating the post-ghost create a time-reversed signal of the equalized signal, generating a time-reversed signal to subjected to filtering, signal equalization ghost before included in the input signal of the signal obtained by equalizing the post ghost Then , after performing a series of processes for creating a time-inverted signal of the signal obtained by equalizing the previous ghost, the signal subjected to the series of processes is input, and the time before and after the signal is input. How to delete some signals and output And characterized in that it comprises a door.

  The equalizer according to claim 3 of the present invention is the equalizer according to claim 1 or 2, wherein means for temporarily storing the input signal in a memory and outputting the signal is provided. After the signal output from the memory is subjected to a series of processes, the signal subjected to the series of processes is input, and a part of the signals before and after the time are input. And means for deleting and outputting.

  An equalizer according to a fourth aspect of the present invention is the equalizer according to any one of the first to third aspects, wherein the filter processing is performed by an IIR filter.

  A receiving apparatus according to a fifth aspect of the present invention includes the equalizer according to any one of the first to fourth aspects, and is configured to demodulate an output signal of the equalizer. .

  A delay profile measuring apparatus according to a sixth aspect of the present invention includes the equalizer according to any one of the first to fourth aspects, and is input to the equalizer based on a coefficient of a filter that performs equalization. The delay profile of the received signal is calculated.

  An equalization program according to a seventh aspect of the present invention is a program for equalizing a distortion caused by a multipath of a propagation path with respect to a signal input to an equalizer, and the computer constituting the equalizer A process for generating and outputting a time-inverted signal of the input signal, and a process for performing a filtering process on the time-inverted signal and equalizing and outputting a pre-ghost included in the input signal. A process for generating and outputting a time-reversed signal of the signal obtained by equalizing the previous ghost, and performing a filtering process on the time-reversed signal of the signal obtained by equalizing the previous ghost, and included in the input signal. And a process of outputting a signal obtained by equalizing the post-ghost.

  An equalization program according to an eighth aspect of the present invention is a program for equalizing distortion caused by a multipath of a propagation path with respect to a signal input to an equalizer, and is a computer constituting the equalizer In addition, a filtering process is performed on the input signal to output a signal obtained by equalizing the post-ghost included in the signal, and a time-inverted signal of the signal obtained by equalizing the post-ghost is generated and output. Processing, filtering the time-reversed signal of the signal obtained by equalizing the post-ghost, outputting the signal obtained by equalizing the pre-ghost included in the input signal, and equalizing the pre-ghost And generating and outputting a signal obtained by inverting the time of the signal.

  A delay profile measurement program according to a ninth aspect of the present invention is a program for inputting an observation signal from a propagation path, performing equalization processing on the signal with a filter, and measuring the delay profile of the propagation path. Further, each processing according to claim 7 or 8 and processing for calculating a delay profile of a propagation path from the coefficient of the filter are executed.

  According to the present invention, a means for generating and outputting a time-reversed signal and a means for performing a filtering process on the input signal to equalize a pre-ghost are combined, and the time-reversed signal is convolved with the time-reversed signal. Thus, the previous ghost can be equalized with a filter having a short tap length. In addition, a receiver, a delay profile measuring device, and the like using this equalizer can be realized.

Hereinafter, an equalizer according to the present invention and an apparatus using the equalizer will be described with reference to the drawings.
(Equalizer)
FIG. 1 is a block diagram showing a first embodiment of an equalizer according to the present invention. In the figure, 1 is an equalizer according to the present invention, 101 is a memory unit, 102 and 105 are time inversion units, 103 and 106 are subtractors, 104 and 107 are FIR filters, 108 is a time window processing unit, and 109 and 110 are Each of the IIR filter units is shown.

  The memory unit 101 receives an observation signal affected by the multipath of the propagation path, which is a signal input to the equalizer 1, and has a time length set separately by a flag from the coefficient calculation unit 2 described later. The observation signal is stored in the memory and the contents of the memory are output. The time reversing unit 102 reads a signal accumulated in the memory of the memory unit 101, and creates and outputs a signal obtained by inverting the read signal with respect to time. The subtractor 103 inputs the output of the time inverting unit 102 (time inverted signal) to the subtracted terminal, inputs the output of the FIR filter 104 to the subtracting terminal, and subtracts the signal of the subtracting terminal from the signal of the subtracted terminal. Output. The FIR filter 104 receives the output of the subtractor 103, convolves a separately set coefficient with the input signal, performs filter processing, and outputs the result to the subtraction terminal of the subtractor 103.

  Here, the subtractor 103 and the FIR filter 104 constitute an IIR filter unit 109 by combining them. The IIR filter unit 109 is supplied with a time-reversed signal input to the equalizer 1 and convolves the time-reversed signal with a time-reversed coefficient, which will be described separately, in the FIR filter 104, thereby pre-ghosting. It is configured to equalize.

  The time reversing unit 105 receives the signal output from the subtractor 103, and creates and outputs a signal that is time-reversed of the signal. The subtractor 106 inputs the output of the time inverting unit 105 (time inverted signal) to the subtracted terminal, inputs the output of the FIR filter 107 to the subtracting terminal, and subtracts the signal of the subtracting terminal from the signal of the subtracted terminal. Output. The FIR filter 107 receives the output of the subtractor 106, performs a filter process by convolving a separately set coefficient with the input signal, and outputs the result to the subtraction terminal of the subtractor 106.

  Here, the subtractor 106 and the FIR filter 107 are combined to constitute the IIR filter unit 110 in the same manner as the combination of the subtractor 103 and the FIR filter 104 described above. The IIR filter unit 110 is supplied with a signal obtained by converting the signal time-reversed by the time reversing unit 105 into a forward signal, and the FIR filter 107 converts the forward time signal described separately into the forward time signal. It is configured to equalize the post-ghost by convolving the coefficients.

  The time window processing unit 108 receives the signal from the subtractor 106, deletes a part of the signal before and after the signal in time, and only the signal near the center of the input signal in time. The extraction time window is applied to the input signal, and the extracted signal is output as an equalized signal.

Next, the operation of the equalizer 1 shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a diagram for explaining processing of a signal output from the memory unit 101. In this figure, N is the width of the time window of the time window processing unit 108, L1 and L2 are time widths, and the time obtained by adding L1, N, and L2 (L1 + N + L2) is the signal output from the memory unit 101. Each length is shown. The first signal output from the memory unit 101 is D _{1 to} D _{L1 + N + L2} , and the second signal is D _{1 + N to} D _{L1 + 2N + L2} . In the first signal, a signal that is correctly equalized among the signals output from the memory unit 101 is extracted by the time window of the time window processing unit 108 and is an N portion (the width of the time window that is output). Only D _{L1 + 1 to} D _{L1 + N} ). A portion having a width L1 from the front (D _{1 to} D _L1 ) and a portion having a width L2 from the rear (D _{L1 + N + 1 to} D _{L1 + N + L2} ) of the signal output from the memory unit 101 are signals having a width N in the center. Is used to equalize More specifically, the L1 width portion from the front of the signal output from the memory unit 101 is equal to the front ghost component included in the central N width portion in the IIR filter unit 109 that equalizes the previous ghost. It becomes a signal necessary for the conversion. On the other hand, the portion of the L2 width from the rear of the signal output from the memory unit 101 is used to equalize the post-ghost component included in the central N-width portion in the IIR filter unit 110 that equalizes the post-ghost. Necessary signal.

ここで、ａは１以上の整数である。マルチパスのＤＵ（Ｄｅｓｉｒｅｄ ｔｏ Ｕｎｄｅｓｉｒｅｄ）比にもよるが、ａは５倍程度（数倍）必要となる。つまり、ＦＩＲフィルタ１０４，１０７は、当該フィルタのタップ長よりも数倍長い信号を用いて前ゴースト成分、後ゴースト成分をそれぞれ等化する。 Next, the lengths of L1 and L2 will be described. When the tap length of the FIR filter 104 is M1, and the tap length of the FIR filter 107 is M2, the following equation is established.

Here, a is an integer of 1 or more. Although it depends on the multipath DU (Desired to Undesired) ratio, a is required to be about 5 times (several times). That is, the FIR filters 104 and 107 equalize the front ghost component and the rear ghost component using a signal several times longer than the tap length of the filter.

Note that the signal that is correctly equalized among the signals output from the memory unit 101 is only the N portion that is extracted and output by the time window of the time window processing unit 108, so the next (second time). The signal output from the memory unit 101 is a signal (D _{1 + N to} D _{L1 + 2N + L2} ) having a length (L1 + N + L2) delayed by N from the head (D ₁ ) of the signal output from the memory unit 101 in the previous time (first time). It becomes. In this case, the time window processing unit 108 of the equalizer 1 shown in FIG. 1 performs time window processing that deletes the L1 width portion from the beginning and the L2 width portion from the end of the input signal. Only the remaining central N-width portion is extracted and output.

  FIG. 2 is a block diagram showing a second embodiment of the equalizer according to the present invention. 1 is an equalizer according to the present invention, 101 is a memory unit, 111 and 113 are IIR filter units, 112 and 114 are time reversing units, and 108 is a time window processing unit. The equalizer 1 shown in FIG. 2 and the equalizer 1 shown in FIG. 1 are different in arrangement of the time reversing unit and the IIR filter unit, but basically have the same configuration, and thus detailed description will be made. Is omitted. In the equalizer 1 of FIG. 2, the front-stage IIR filter unit 111 equalizes the rear ghost, and the rear-stage IIR filter unit 113 equalizes the front ghost. Accordingly, the front-stage IIR filter unit 111 is configured to set a coefficient for equalizing the rear ghost, and the rear-stage IIR filter unit 113 is configured to set a coefficient for equalizing the front ghost. Is done.

  As described above, according to the equalizer 1 shown in FIGS. 1 and 2, the time inverting units 102, 105, 112, and 114 and the IIR filter units 109, 110, Since the signals are equalized by the configurations of 111 and 113, it is not necessary to configure a feedforward tap by an FIR filter having a long tap length. Accordingly, it is possible to realize the equalizer 1 that equalizes the previous ghost with a filter having a short tap length.

(Receiving machine)
FIG. 4 is a block diagram showing an embodiment of a receiver using the equalizer 1 according to the present invention. In FIG. 4, 20 is a receiver, 1 is an equalizer, 2 is a coefficient calculation unit, and 3 is a demodulation unit. The equalizer 1 is configured in the same manner as the equalizer 1 shown in FIGS. 1 and 2. The equalizer 1 receives the signal input to the receiver 20, equalizes the input signal, and performs coefficient calculation 2. The equalized signal is output to the demodulator 3. The coefficient calculation unit 2 calculates a coefficient of a filter for waveform equalization built in the equalizer 1 and outputs the coefficient to the equalizer 1. Detailed description of the coefficient calculation unit 2 will be described later. The demodulator 3 receives the signal output from the equalizer 1 and performs demodulation according to the format of the signal. The configuration of the demodulator 3 varies greatly depending on the format of the input signal, but the basic configuration of the equalizer 1 does not change with this configuration. For this reason, description of the structure of the demodulation part 3 is abbreviate | omitted here.

(Delay profile measuring instrument)
FIG. 5 is a block diagram showing a first embodiment of a delay profile measuring device using the equalizer 1 according to the present invention. In FIG. 5, 30 is a delay profile measuring device, 1 is an equalizer, 2 is a coefficient calculation unit, and 4 is a delay profile display unit. The equalizer 1 is configured in the same manner as the equalizer 1 shown in FIGS. 1 and 2, and receives the signal input to the delay profile measuring device 30, equalizes the input signal, and equalizes the input signal. The subsequent signal is output to the coefficient calculation unit 2. The coefficient calculation unit 2 calculates a coefficient of a filter for waveform equalization built in the equalizer 1 and outputs the coefficient to the equalizer 1 and the delay profile display unit 4. The delay profile display unit 4 inputs the coefficient of the equalizer 1 output from the coefficient calculation unit 2, and calculates the delay profile of the propagation path of the signal input to the delay profile measuring unit 30 based on the coefficient. ,indicate.

(Coefficient calculation unit)
Here, the operation of the coefficient calculation unit 2 shown in FIGS. 4 and 5 will be described with a detailed example. FIG. 6 is a block diagram showing an embodiment of the coefficient calculation unit 2, which is applied to a delay profile measuring device 30 for a digital signal using the OFDM method or a digital broadcast signal (hereinafter referred to as an OFDM signal). An example is shown. In FIG. 6, 1 is an equalizer, 2 is a coefficient calculation unit, 4 is a delay profile display unit, 201 is an FFT window processing unit, 202 is an FFT unit, 203 is a pilot equalization unit, 204 is an area determination unit, and 205 is Delay unit, 206, complex division unit, 207, error calculation unit, 208, FFT window error correction unit, 209, equalization residual calculation unit, 210, IFFT unit, 211, coefficient addition unit, 212, noise removal unit, 213 Denotes a noise threshold setting unit, 214 denotes a coefficient dividing unit, 215 denotes a time reversing unit, 216 denotes a delay unit, and 217 denotes a display determination unit.

  The coefficient calculation unit 2 substantially inputs the equalized signal output from the equalization unit 1. The FFT window processing unit 201 receives the signal input to the coefficient calculation unit 2, extracts and outputs a signal in the effective symbol period of the OFDM signal so that intersymbol interference does not occur in the signal after FFT. The FFT unit 202 performs FFT (Fast Fourier Transform) on the signal of the effective symbol period output from the FFT window processing unit 201, converts it into subcarrier data of the OFDM signal, and outputs it. Here, the subcarrier data output by the FFT unit 202 is defined as R (k, n). k is a carrier number and frequency, and n is an integer indicating the number of times the coefficient calculation unit 2 updates the coefficient of the equalization unit 1. Further, K is defined as the total number of subcarriers of the OFDM signal. For example, in the case of mode 3 of the terrestrial digital broadcasting system ISDB-T, K = 5617.

尚、ＦＦＴ窓処理部２０１から複素除算部２０６までの詳細な説明については、特開２００３−１４３０９９号公報「周波数特性算出回路およびそれを用いたキャンセラならびに装置」にも記載されているので、参照されたい。図６に示すＦＦＴ窓処理部２０１から複素除算部２０６までの構成の特徴は、データキャリアを含む全てのサブキャリアの周波数特性を算出できるところにある。 The pilot equalization unit 203 receives the signal output from the FFT unit 202, equalizes each subcarrier using the pilot signal included in the subcarrier of the OFDM signal, and outputs the equalized subcarrier. In the case of an OFDM signal that does not use a pilot signal, the pilot equalization unit 203 equalizes and outputs the input signal using the training signal used in that method. Here, the subcarrier data output by pilot equalization section 203 is defined as R _eq (k, n). The region determination unit 204 receives the signal output from the pilot equalization unit 203, performs region determination using the amplitude values of the real part and the imaginary part of the data R _eq (k, n) of each subcarrier, Data R _d (k, n) in which the amplitude and phase of the subcarrier are determined is output. The delay unit 205 receives the signal output from the FFT unit 202, delays the input signal by the processing time in the pilot equalization unit 203 and the region determination unit 204, and outputs the delayed signal. Complex division section 206 uses the signal output from area determination section 204 as the denominator and the signal output from delay section 205 as the numerator, and performs complex division on the data of each subcarrier and outputs the result. Assuming that the output of the complex division unit 206 is H (k, n), H (k, n) is calculated by the following equation.

The detailed description from the FFT window processing unit 201 to the complex division unit 206 is also described in Japanese Patent Laid-Open No. 2003-143099 “Frequency characteristics calculation circuit and canceller and apparatus using the same”. I want to be. A feature of the configuration from the FFT window processing unit 201 to the complex division unit 206 shown in FIG. 6 is that the frequency characteristics of all subcarriers including the data carrier can be calculated.

The error calculation unit 207 calculates the error SNR (n) of the output signal of the pilot equalization unit 203 based on the output signal of the region determination unit 204 by the following equation and outputs it.

  The FFT window error correction unit 208 receives the signal H (k, n) output from the complex division unit 206, and extracts the original effective symbol when the FFT window processing unit 201 extracts a signal in the effective symbol period of the OFDM signal. The error in the frequency characteristics generated in the subcarrier data H (k, n) of the output in the complex division unit 206 is corrected by the error from the position of the period, and the corrected result F (k, n) is output. The detailed description of the FFT window error correction unit 208 is also described in Japanese Patent Laid-Open No. 2000-295195 “OFDM Demodulator”.

The equalization residual calculation unit 209 receives the signal F (k, n) output from the FFT window error correction unit 208, and an equalization error component (hereinafter referred to as equalization residual) included in the input signal. Is calculated. When the output signal of the FFT window error correction unit 208 is F (k, n) and the equalization residual calculated by the equalization residual calculation unit 209 is E _eq (k, n), the equalization residual is given by Defined by

逆フーリエ変換を示す関数をＩＦＦＴ［］と定義し、ＩＦＦＴ部２１０の出力をｅ（ｋ，ｎ）として、ｅ（ｋ，ｎ）を次式で算出する。

ここで、ｅ（ｋ，ｎ）は周波数領域データをＩＦＦＴしたものであるから、時間領域のデータを示しており、ｅ（ｋ，ｎ）のｋは周波数ではなく時間を示している。ｋの時間間隔は、ＩＳＤＢ−Ｔのモード３の場合、周波数領域におけるｋの間隔が１０００／１００８（ｋＨｚ）であるから、その逆数をＩＦＦＴポイント数の８１９２で除算したものに等しく、６３／５１２（マイクロ秒）となる。また、振幅値の較正として、ＩＦＦＴに８１９２ポイント全てのデータを１として入力した場合にｋ＝０の位置に１が出力されるようなＩＦＦＴの関数を用いているとき、（６）式で算出したｅ（ｋ，ｎ）を８１９２／５６１７倍することにより、相対的な主波の振幅値が１となるように較正することができる。ここで、８１９２はＩＦＦＴポイント数、５６１７はＥ_ｅｑ（ｋ，ｎ）のデータ数である。 The IFFT unit 210 performs IFFT (inverse fast Fourier transform) on E _eq (k, n) output from the equalization residual calculation unit 209 and outputs the result. The number of data input to the FFT unit 202 and the IFFT unit 210 described above needs to be a power of two. In the case of ISDB-T mode 3 described above, since K = 5617, the smallest power of 2 greater than K is 8192. Accordingly, 0 is inserted into E _eq (k, n) having 5617 pieces of input carrier data, and 8192 pieces of data E (k, n) are created by the following equation.

A function indicating the inverse Fourier transform is defined as IFFT [], and the output of the IFFT unit 210 is e (k, n), and e (k, n) is calculated by the following equation.

Here, since e (k, n) is an IFFT of frequency domain data, it represents time domain data, and k in e (k, n) represents time, not frequency. In the case of ISDB-T mode 3, the time interval of k is equal to 1000/1008 (kHz), so that the reciprocal is divided by 8192 of the number of IFFT points. (Microseconds). When the IFFT function that outputs 1 at the position of k = 0 when all 8192 points of data are input as 1 as IFFT is used as the calibration of the amplitude value, it is calculated by the equation (6). By multiplying e (k, n) by 8192/5617, the relative amplitude value of the main wave can be calibrated. Here, 8192 is the number of IFFT points, and 5617 is the number of data of E _eq (k, n).

ここで、μは係数更新の重み付け係数である。 The coefficient adding unit 211 adds e (k, n) output from the IFFT unit 210 and c (k, n−1) output from the delay unit 216, which will be described later, by the following equation, and c ′ (k , N).

Here, μ is a coefficient update weighting coefficient.

ここで、ｂは１以上の実数である。通常、閾値Ｔ（ｎ）は、誤差算出部２０７により算出された誤差ＳＮＲ（ｎ）の１００倍程度が設定される。従って、ｂ＝１００程度の値が設定される。 The noise threshold setting unit 213 receives the error SNR (n) calculated by the error calculation unit 207 and calculates a threshold T (n) for setting in the noise removal unit 212. T (n) is calculated by the following equation.

Here, b is a real number of 1 or more. Usually, the threshold value T (n) is set to about 100 times the error SNR (n) calculated by the error calculation unit 207. Therefore, a value of about b = 100 is set.

The noise removing unit 212 regards a coefficient whose absolute value is smaller than the threshold T (n) calculated by the noise threshold setting unit 213 among c ′ (k, n) calculated by the coefficient adding unit 211 as noise. Replace with 0 and output. The threshold output from the noise threshold setting unit 213 is T (n), and the coefficient from which noise has been removed by the noise removal unit 212 is c (k, n). Noise removal in the noise removal unit 212 is performed as follows.

尚、（１０）式は、ＩＳＤＢ−Ｔのモード３のように、ＩＦＦＴ部２１０のポイント数が８１９２であり、ｋの４０９６以降の部分が前ゴーストであるとした場合の例である。 The coefficient dividing unit 214 divides the coefficient c (k, n) from which noise has been removed by the noise removing unit 212 into a coefficient for post-ghost equalization and a coefficient for pre-ghost equalization of the equalizer 1 respectively. Output. The coefficient c (k, n) calculated from the signal whose error has been corrected by the FFT window error correction unit 208 is adjusted so that the delay time difference from the main wave is 0 at the position where k = 0. Therefore, the coefficient dividing unit 214 converts the input coefficient c (k, n) into the coefficient c ₁ (k, n) for the post-ghost equalization and the coefficient c ₂ (the pre-ghost equalization coefficient c ₂ ( k, n).

The expression (10) is an example in the case where the number of points of the IFFT unit 210 is 8192 and the part after 4096 of k is a pre-ghost as in the mode 3 of ISDB-T.

The time reversing unit 215 inverts the time sequence of the coefficients c ₂ (k, n) for the previous ghost equalization output from the coefficient dividing unit 214, that is, the k sequence and outputs the result. When c ₂ (k, n) in the equation (10) is time-reversed, it is expressed as the equation (11)

The display determination unit 217 receives the error SNR (n) calculated by the error calculation unit 207, determines whether equalization by the equalizer 1 is correctly performed from the value of the error SNR (n), The display permission flag as the determination result is output to the equalizer 1 and the delay profile display unit 4. The correct equalization performed by the equalizer 1 means that the coefficient of the equalizer 1 correctly indicates the delay profile. Therefore, it is possible to determine whether the delay profile is correctly calculated by determining whether equalization is correctly performed. For example, the display determination unit 217 is configured to set a display permission flag and output it to the equalizer 1 and the delay profile display unit 4 when the expression (12) is satisfied.

Thus, the coefficient calculation unit 2 outputs the calculated coefficient to the equalizer 1 and the delay profile display unit 4. Specifically, the time reversal unit 215 of the coefficient calculation unit 2 outputs the previous ghost coefficient c ₂ ′ (k, n) to the previous ghost equalization filter 104 in the equalizer 1, and the coefficient division unit 214. Outputs the post-ghost coefficient c ₁ (k, n) to the post-ghost equalization filter 107 in the equalizer 1. The coefficient calculation unit 2 also outputs the calculated coefficient to the delay profile display unit 4. Specifically, the noise removing unit 212 provided in front of the coefficient dividing unit 214 branches the coefficient c (k, n), which is an output signal, and outputs it to the delay profile display unit 4.

  Further, the coefficient calculation unit 2 outputs the display permission flag determined by the display determination unit 217 to the equalization unit 1 and the delay profile display unit 4. The equalization unit 1 receives the display permission flag output from the coefficient calculation unit 2, acquires a new observation signal, and stores it in the memory. Then, the time reversing unit 102 of the equalizer 1 reads a new observation signal. This display permission flag is used for updating the observation signal for equalization. Further, the delay profile display unit 4 receives the display permission flag output from the coefficient calculation unit 2 and displays the delay profile.

ここで、ｈ（ｋ，ｎ）は、ｋ＝４０９６が遅延時間０、すなわち遅延プロファイルｈ（ｋ，ｎ）上の主波の位置となる。また、実施例に用いているＩＳＤＢ−Ｔのモード３では、ｋが１進むと時間が６３／５１２（≒０．１２３）マイクロ秒進む。尚、遅延プロファイルｈ（ｋ，ｎ）は主波が削除された形で算出される。従って、遅延プロファイルを表示する場合、遅延プロファイル表示部４は、ｋ＝４０９６すなわち遅延時間０の位置に主波となるべきインパルスを追加した形で表示する。係数算出部２のＩＦＦＴ部２１０の出力ｅ（ｋ，ｎ）が主波の振幅値が１となるように較正されている場合は、ｈ（４０９６，ｎ）＝１とすればよい。 (Delay profile display)
The delay profile display unit 4 inputs the coefficient c (k, n) branched and output by the noise removal unit 212 of the coefficient calculation unit 2, converts the coefficient c (k, n) into a delay profile, and displays the delay profile. . When the coefficient dividing unit 214 divides into a pre-ghost equalization coefficient and a post-ghost equalization coefficient as in equation (10), the delay profile display unit 4 also performs pre-ghost equalization as in equation (10). Are divided into a coefficient for use and a coefficient for post-ghost equalization. The delay profile h (k, n) divided into the order of the delay time after being divided into the front ghost and the rear ghost in the delay profile display unit 4 is expressed by the following equation.

Here, for h (k, n), k = 4096 is the delay time 0, that is, the position of the main wave on the delay profile h (k, n). Further, in the ISDB-T mode 3 used in the embodiment, when k increases by 1, the time advances by 63/512 (≈0.123) microseconds. The delay profile h (k, n) is calculated in a form in which the main wave is deleted. Therefore, when displaying the delay profile, the delay profile display unit 4 displays k = 4096, that is, an impulse to be the main wave added at the position of the delay time 0. When the output e (k, n) of the IFFT unit 210 of the coefficient calculation unit 2 is calibrated so that the amplitude value of the main wave becomes 1, h (4096, n) = 1 may be set.

(Embodiment 2 of delay profile measuring instrument)
FIG. 7 is a block diagram showing a second embodiment of the delay profile measuring device using the equalizer 1 according to the present invention. In this figure, 30 is a delay profile measuring device, 1 is an equalizer, 2 is a coefficient calculation unit, and 4 is a delay profile display unit. In FIG. 7, the same blocks as those in FIG. The difference between FIG. 7 and FIG. 5 is that the coefficient calculation unit 2 of the delay profile measuring device 30 shown in FIG. 7 inputs the two signals of the input signal and the output signal of the equalization unit 1 and the coefficient of the equalizer 1. Is to calculate. Specifically, the coefficient calculation unit 2 calculates the coefficient of the equalization unit 1 using an algorithm based on the least square error method (MMSE).

  As described above, according to the delay profile measuring device 30 including the equalizer 1 shown in FIG. 1 or FIG. 2, the coefficient calculation unit 2 uses the filter in the equalizer 1 to equalize the frequency characteristics of the observation signal. Are calculated by inputting the output signal of the equalizer 1. Then, the equalizer 1 performs equalization using the coefficient calculated by the coefficient calculation unit 2, and the delay profile display unit 4 inputs the coefficient to calculate the transfer function of the equalizer 1, The delay profile was calculated from the transfer function. As a result, even when the observed signal includes interference such as intersymbol interference and intercarrier interference, the delay profile can be accurately measured from the observed signal.

  Further, according to the delay profile measuring device 30 described above, the coefficient calculation unit 2 determines whether or not equalization by the equalizer 1 is correctly performed, and indicates a flag indicating that equalization is correctly performed. Are output to the equalizer 1 and the delay profile display unit 4. And the equalizer 1 will acquire a new observation signal, if the said flag is input. The acquired delay profile display unit 4 displays a delay profile when the flag is input. Thereby, a delay profile can be accurately measured from one observation signal. In addition, the delay profile measuring device 30 can be applied to a computer having a slow observation signal input update process.

  Next, a delay profile measuring device capable of accurately measuring a delay profile from an observation signal even in a multipath environment where the observation signal includes a front ghost and a rear ghost will be described. As described above, the delay profile measuring device 30 shown in FIGS. 5 and 7 can accurately determine the delay profile from the observation signal even when the observation signal includes interference such as intersymbol interference and intercarrier interference. Can be measured.

  However, when the observed signal contains both the front ghost and the back ghost, and the delay profile is calculated from the coefficient of the equalizer that equalizes in the time domain, the characteristics of the filter that equalizes the front ghost are convolved with the back ghost. Therefore, coefficients that do not exist in the actual delay profile appear in the coefficients of the filter that equalizes the post-ghost. For this reason, the coefficient of the filter for equalizing the post-ghost cannot be used as the post-ghost delay profile. Also, if the filter order is changed and a filter that equalizes the front ghost is connected before the filter that equalizes the rear ghost, the characteristics of the filter that equalizes the rear ghost are convoluted with the front ghost. Therefore, a coefficient that does not exist in the actual delay profile appears in the coefficient of the filter that equalizes the previous ghost. For this reason, the coefficient of the filter for equalizing the previous ghost cannot be used as it is as the delay profile of the previous ghost.

Hereinafter, a delay profile measuring device capable of accurately measuring a delay profile from an observation signal even in a multipath environment in which the observation signal includes a front ghost and a rear ghost will be described.
(Embodiment 3 of delay profile measuring instrument)
First, the configuration of the delay profile measuring device will be described. FIG. 8 is a block diagram showing a third embodiment of the delay profile measuring device. In FIG. 8, 30 is a delay profile measuring device, 1 is an equalizer, 2 is a coefficient calculation unit, 4 is a delay profile display unit, 14 is a pre-ghost equalization filter, 15 is a post-ghost equalization filter, and 41 is an image removal. , 42 is a delay profile calculation unit, and 43 is a data display unit. In FIG. 8, the same blocks as those in FIGS. 5 and 7 are denoted by the same reference numerals and description thereof is omitted. The main difference between FIG. 8 and FIG. 5 and FIG. 7 is that the delay profile display unit 4 in FIG. 8 inputs the pre-ghost equalization coefficient and the post-ghost equalization coefficient from the coefficient calculation unit 2 and The characteristic of the equalization filter is convolved with the post-ghost, thereby eliminating a coefficient (hereinafter referred to as an image) that does not exist in the actual delay profile that appears in the coefficient of the post-ghost equalization filter.

  Referring to FIG. 8, an observation signal affected by the multipath of the propagation path is input to delay profile measuring instrument 30. The equalizer 1 inputs the observation signal input to the delay profile measuring device 30. The equalizer 1 equalizes waveform distortion due to multipath included in the observation signal, and outputs the equalized signal. The equalizer 1 includes a pre-ghost equalization filter 14 and a post-ghost equalization filter 15. The pre-ghost equalization filter 14 equalizes and outputs the pre-ghost included in the input observation signal. The post-ghost equalization filter 15 equalizes and outputs the post-ghost included in the output signal of the pre-ghost equalization filter 14. The specific configuration and operation of the equalizer 1 are the same as those of the equalizer 1 shown in FIG. 1 and FIG. The pre-ghost equalizing filter 14 shown in FIG. 8 includes the time inverting unit 102, the subtractor 103, and the FIR filter 104 of the equalizer 1 shown in FIG. 1, and the post-ghost equalizing filter 15 is shown in FIG. The time inverting unit 105, the subtractor 106, and the FIR filter 107 are included. Further, the pre-ghost equalizing filter 14 is configured by the IIR filter unit 111 and the time reversing unit 112 of the equalizer 1 shown in FIG. 2, and the post-ghost equalizing filter 15 is the IIR filter unit 113 shown in FIG. And a time reversing unit 114.

The coefficient calculation unit 2 receives the equalized signal output from the equalizer 1 and calculates a difference (equalization residual) between the transfer function of the propagation path and the transfer function of the equalizer 1. Then, using the equalization residual, a new coefficient of the equalizer 1 is calculated so that the transfer function of the equalizer 1 becomes equal to the reciprocal of the transfer function of the propagation path, and the calculated coefficient is used as the equalizer 1 and Output to the delay profile display unit 4. The specific configuration and operation of the coefficient calculating unit 2 are the same as those of the coefficient calculating unit 2 of the delay profile measuring device 30 shown in FIGS. The coefficient calculation unit 2 shown in FIG. 6 outputs the coefficient c (k, n) to the delay profile display unit 4, but in the coefficient calculation unit 2 shown in FIG. 8, the time reversing unit 215 uses the pre-ghost equalization coefficient. The c ₂ ′ (k, n) and the coefficient dividing unit 214 branch the post-ghost equalization coefficient c ₁ (k, n), respectively, and output them to the delay profile display unit 4. Also, the coefficient calculation unit 2 divides the coefficient into a pre-ghost equalization coefficient and a post-ghost equalization coefficient, and outputs them to the pre-ghost equalization filter 14 and the post-ghost equalization filter 15, respectively.

  The delay profile display unit 4 calculates and displays the delay profile of the propagation path through which the observation signal has passed from the transfer function G (ω, n) of the equalizer 1. By the adaptive algorithm of the equalizer of the equalizer 1, the reciprocal of the obtained transfer function of the equalizer 1 becomes equal to the transfer function of the propagation path through which the observation signal has passed. Therefore, if the delay profile of the propagation path through which the observation signal passes is h (t, n), the inverse of the transfer function G (ω, n) of the equalizer 1 is the transfer function H (ω, n) of the propagation path. And h (t, n) obtained by performing inverse Fourier transform on the transfer function H (ω, n) of this propagation path is an impulse response of the propagation path, that is, a delay profile.

  The configuration and operation of the delay profile display unit 4 will be specifically described. The delay profile display unit 4 uses the coefficient of the equalizer 1 output from the coefficient calculation unit 2 to calculate and display the delay profile of the propagation path through which the observation signal has passed. The delay profile display unit 4 inputs the coefficient of the pre-ghost equalization filter 14 and the coefficient of the post-ghost equalization filter 15 output from the coefficient calculation unit 2 and branched. As shown in FIG. 8, when the equalizer 1 is configured to input the output of the filter 14 that equalizes the pre-ghost to the filter 15 that equalizes the post-ghost, the image removing unit 41 of the delay profile display unit 4. Inputs the pre-ghost equalization coefficient and the post-ghost equalization coefficient, multiplies the reciprocal of the frequency characteristic of the post-ghost equalization filter 15 by the frequency characteristic of the pre-ghost equalization filter 14, and calculates the delay profile. To the unit 42. In this calculation, the characteristic of the pre-ghost equalization filter 14 is convolved with the post-ghost, so that the coefficient that does not exist in the actual delay profile that appears in the coefficient of the post-ghost equalization filter 15 can be removed.

  The delay profile calculation unit 42 receives the pre-ghost equalization coefficient output from the coefficient calculation unit 2 to the equalizer 1, calculates the pre-ghost delay profile from the pre-ghost equalization coefficient, and the image removal unit The delay profile of the post-ghost is calculated from the output of 42. The delay profile calculation unit 42 combines the delay profile of the previous ghost and the delay profile of the subsequent ghost, and outputs the result to the data display unit 43 as a delay profile h (t, n).

  The data display unit 43 graphs the delay profile h (t, n) output from the delay profile calculation unit 42 with the horizontal axis as the delay time t, and outputs the graph to a display device such as a monitor. Further, the data display unit 43 can be configured not only to display the delay profile on a monitor or the like but also to output the measurement result to an external memory or the like.

（１４）式において、係数ｃ’’_１（ｋ，ｎ）は後ゴーストの周波数特性の逆数のインパルス応答を、係数ｃ’’_２（ｋ，ｎ）は前ゴーストの周波数特性の逆数のインパルス応答をそれぞれ示している。従って、係数ｃ’’（ｋ，ｎ）は、後ゴーストの周波数特性の逆数及び前ゴーストの周波数特性の逆数を乗算したものを逆フーリエ変換したものであり、本式により後ゴースト等化フィルタ１５の係数に現れるイメージを除去することができる。イメージ除去部４１は、算出した係数ｃ’’（ｋ，ｎ）を遅延プロファイル算出部４２へ出力する。 Next, the operation of the delay profile display unit 4 when a digital broadcast or digital transmission signal using an OFDM signal is used as an observation signal will be described. The delay profile display unit 4 includes a coefficient c (k, k) that includes both the coefficient of the pre-ghost equalization filter 14 and the coefficient of the post-ghost equalization filter 15 that are output and branched by the noise removal unit 212 of the coefficient calculation unit 2. n). The image removing unit 41 uses the expression (14) to calculate an image that is a coefficient that does not exist in the actual delay profile that appears in the coefficient of the post-ghost equalization filter 15 when the pre-ghost equalization filter 14 is convolved with the post-ghost. Remove.

In the equation (14), the coefficient c ″ ₁ (k, n) is the impulse response of the reciprocal of the frequency characteristic of the rear ghost, and the coefficient c ″ ₂ (k, n) is the impulse response of the reciprocal of the frequency characteristic of the front ghost. Respectively. Therefore, the coefficient c ″ (k, n) is obtained by performing inverse Fourier transform on the product of the inverse of the frequency characteristic of the rear ghost and the inverse of the frequency characteristic of the front ghost. The image appearing in the coefficient of can be removed. The image removing unit 41 outputs the calculated coefficient c ″ (k, n) to the delay profile calculating unit 42.

ここで、ｈ（ｋ，ｎ）は、ｋ＝４０９６が遅延時間０、すなわち遅延プロファイル上の主波の位置となる。また、本例に用いているＩＳＤＴ−Ｔのモード３では、ｋが１進むと時間が６３／５１２（≒０．１２３）マイクロ秒進む。尚、ｃ（ｋ，ｎ）は、主波の振幅が１となるように較正されているものとし、（１５）式では、ｈ（４０９６，ｎ）＝１としている。遅延プロファイル算出部４２は、（１５）式で算出した遅延プロファイルｈ（ｋ，ｎ）をデータ表示部４３へ出力する。 The delay profile calculation unit 42 receives the coefficient c (k, n) output from the equalizer 1 and the coefficient c ″ (k, n) output from the image removal unit 41, and receives the delay profile h (k , N) is calculated and output. The delay profile h (k, n) divided into the front ghost and the rear ghost and rearranged in the order of the delay time is expressed by the following equation.

Here, for h (k, n), k = 4096 is the delay time 0, that is, the position of the main wave on the delay profile. Further, in the ISDT-T mode 3 used in this example, the time advances by 63/512 (≈0.123) microseconds when k advances by 1. Note that c (k, n) is calibrated so that the amplitude of the main wave is 1, and h (4096, n) = 1 in the equation (15). The delay profile calculation unit 42 outputs the delay profile h (k, n) calculated by the equation (15) to the data display unit 43.

(Embodiment 4 of delay profile measuring instrument)
FIG. 9 is a block diagram showing a fourth embodiment of the delay profile measuring device. In FIG. 9, the same blocks as those in FIG. The difference between FIG. 9 and FIG. 8 is that the equalizer 1 shown in FIG. 9 is configured such that the front ghost equalizing filter 14 is connected after the rear ghost equalizing filter 15. The coefficient of the front ghost equalization filter 14 in this configuration is a form in which the characteristics of the rear ghost equalization filter 15 are convoluted. For this reason, the image removal unit 41 of the delay profile display unit 4 is configured to remove an image appearing in the coefficient of the pre-ghost equalization filter 14. The operation up to the image removal unit 41 of the delay profile display unit 4 is the same as the operation shown in FIG. That is, the removal of the image appearing in the coefficient of the pre-ghost equalization filter 24 by the image removal unit 41 is performed using the equation (14).

（１６）式で算出したｈ（ｋ，ｎ）も（１５）式と同様に、ｋ＝４０９６が遅延時間０、すなわち遅延プロファイル上の主波の位置となる。また、本例に用いているＩＳＤＴ−Ｔのモード３では、ｋが１進むと時間が６３／５１２（≒０．１２３）マイクロ秒進む。尚、ｃ（ｋ，ｎ）は、主波の振幅が１となるように較正されているものとし、（１６）式では、ｈ（４０９６，ｎ）＝１としている。遅延プロファイル算出部４２は、（１６）式で算出した遅延プロファイルｈ（ｋ，ｎ）をデータ表示部４３へ出力する。 In the delay profile measuring device 30 illustrated in FIG. 9, the delay profile calculation unit 42 includes the coefficient c (k, n) output from the coefficient calculation unit 2 and the coefficient c ″ (k, n) output from the image removal unit 41. n) is input, and the delay profile h (k, n) is calculated and output. The delay profile h (k, n) divided into the front ghost and the rear ghost and rearranged in the order of the delay time is expressed by the following equation.

Similarly to the equation (15), k (4096) is h (k, n) calculated by the equation (16), and the delay time is 0, that is, the position of the main wave on the delay profile. Further, in the ISDT-T mode 3 used in this example, the time advances by 63/512 (≈0.123) microseconds when k advances by 1. Note that c (k, n) is calibrated so that the amplitude of the main wave is 1, and h (4096, n) = 1 in the equation (16). The delay profile calculation unit 42 outputs the delay profile h (k, n) calculated by the equation (16) to the data display unit 43.

  As described above, according to the delay profile measuring device 30 shown in FIGS. 8 and 9, the image removal unit 41 of the delay profile display unit 4 is connected to the rear part in the equalizer 1 and the ghost equalization filter. 15 (the pre-ghost equalization filter 14 in the case of FIG. 9) is removed, and the delay profile calculation unit 42 calculates the delay profile based on the coefficient from which the image is removed. Thus, in FIG. 8, the problem associated with the characteristic of the front ghost equalization filter 14 being convoluted with the rear ghost, that is, the coefficient that does not exist in the actual delay profile is the coefficient of the rear ghost equalization filter 15. Appears, the problem that the coefficient cannot be used as it is for the calculation of the delay profile can be solved. Also in FIG. 9, the problem that the coefficient of the pre-ghost equalization filter 14 cannot be used for the calculation of the delay profile as it is can be solved with the same convolution. Therefore, even when interference such as intersymbol interference and intercarrier interference is included in the observed signal, in addition to being able to accurately measure the delay profile from the observed signal, the observed signal includes a front ghost and a rear ghost. Even in the included multipath environment, the delay profile can be accurately measured from the observation signal.

  The equalizer 1 includes a volatile storage medium such as a CPU and a RAM, a non-volatile storage medium such as a ROM, an input device such as a keyboard and a pointing device, a display device that displays images and data, and an external device. It is composed of a computer that has an interface for communicating with it. In this case, each process of the memory unit 101, the time reversing units 102, 105, 112, 114, the IIR filter units 109, 110, 111, 113, and the time window processing unit 108 executes a program describing the processing to the CPU. This is realized by These programs can also be stored and distributed in a storage medium such as a magnetic disk (floppy disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, or the like. Further, the receiver 20 and the delay profile measuring device 30 are also configured by a computer including a volatile storage medium such as a CPU and a RAM. In this case, each process of the equalizer 1, the coefficient calculation unit 2, the demodulation unit 3, and the delay profile display unit 4 is realized by causing the CPU to execute a program describing the process. These programs can also be stored and distributed in a storage medium such as a magnetic disk.

1 is a block diagram showing a first embodiment of an equalizer according to the present invention. FIG. It is a block diagram which shows the 2nd Example of the equalizer by this invention. It is a figure for demonstrating the output process in a memory part. It is a block diagram which shows one Example of the receiver using the equalizer by this invention. It is a block diagram which shows the 1st Example of the delay profile measuring device using the equalizer by this invention. It is a block diagram which shows one Example of a coefficient calculation part. It is a block diagram which shows the 2nd Example of the delay profile measuring device using the equalizer by this invention. It is a block diagram which shows the 3rd Example of the delay profile measuring device using the equalizer by this invention. It is a block diagram which shows the 4th Example of the delay profile measuring device using the equalizer by this invention. It is a block diagram which shows the example of the conventional equalizer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Equalizer 2 Coefficient calculation part 3 Demodulation part 4 Delay profile display part 11,13,104,107 FIR filter 12,103,106 Subtractor 14 Pre-ghost equalization filter 15 Post-ghost equalization filter 20 Receiver 30 Delay profile measuring device 101 Memory unit 102, 105, 112, 114, 215 Time inversion unit 108 Time window processing unit 109, 110, 111, 113 IIR filter unit 201 FFT window processing unit 202 FFT unit 203 Pilot equalization unit 204 Area determination Units 205 and 216 Delay unit 206 Complex division unit 207 Error calculation unit 208 FFT window error correction unit 209 Equalization residual calculation unit 210 IFFT unit 211 Coefficient addition unit 212 Noise removal unit 213 Noise threshold setting unit 214 Coefficient division unit 217 Display determination Part

Claims (8)

An equalizer for equalizing distortion caused by multipath of a propagation path with respect to an input signal,
Means for temporarily storing the input signal in a memory and outputting the signal;
For the signal output from the memory,
Create a time-inverted signal of the input signal ,
Filter the time-reversed signal to generate a signal that equalizes the previous ghost included in the input signal ,
Create a time-reversed signal of the signal that equalizes the previous ghost ,
Filtering is performed on the signal obtained by time-reversing the signal obtained by equalizing the pre-ghost, and a series of processes for generating a post-ghost equalized signal included in the input signal is performed. An equalizer, comprising: means for inputting an applied signal and deleting and outputting a part of the signal before and after the signal in time . An equalizer for equalizing distortion caused by multipath of a propagation path with respect to an input signal,
Means for temporarily storing the input signal in a memory and outputting the signal;
For the signal output from the memory,
Applying a filtering process to the input signal to generate a signal obtained by equalizing a post-ghost included in the signal ;
Create a time-reversed signal of the post-ghost equalized signal ,
Filtering the time-reversed signal of the post-ghost equalized signal to generate a signal equalizing the pre-ghost included in the input signal,
After performing a series of processes for creating a signal that is time-reversed of the signal obtained by equalizing the pre-ghost, the signal subjected to the series of processes is input, and part of the signal before and after in time An equalizer characterized by comprising: means for deleting and outputting the signal . The filtering, the equalizer according to claim 1 or 2, characterized by applying the IIR filter. A receiver comprising the equalizer according to any one of claims 1 to 3 and configured to demodulate an output signal of the equalizer. A configuration including the equalizer according to any one of claims 1 to 3 , wherein a delay profile of a signal input to the equalizer is calculated based on a coefficient of a filter that performs equalization. A delay profile measuring apparatus characterized by the above. For an input signal, a computer configured as an equalizer that equalizes distortion caused by multipath of a propagation path,
A process of temporarily storing the input signal in a memory and outputting the signal;
For the signal output from the memory,
Create a time-inverted signal of the input signal ,
Filter the time-reversed signal to generate a signal that equalizes the previous ghost included in the input signal ,
Create a time-reversed signal of the signal that equalizes the previous ghost ,
Filtering is performed on the signal obtained by time-reversing the signal obtained by equalizing the pre-ghost, and a series of processes for generating a post-ghost equalized signal included in the input signal is performed. An equalization program for executing a process of inputting a given signal, deleting a part of the signal before and after the signal, and outputting the signal . For an input signal, a computer configured as an equalizer that equalizes distortion caused by multipath of a propagation path,
A process of temporarily storing the input signal in a memory and outputting the signal;
For the signal output from the memory,
Applying a filtering process to the input signal to generate a signal obtained by equalizing a post-ghost included in the signal ;
Create a time-reversed signal of the post-ghost equalized signal ,
Filtering the time-reversed signal of the post-ghost equalized signal to generate a signal equalizing the pre-ghost included in the input signal,
After performing a series of processes for creating a signal that is time-reversed of the signal obtained by equalizing the pre-ghost, the signal subjected to the series of processes is input, and part of the signal before and after in time An equalization program for executing the process of deleting and outputting the signal of A computer configured as a delay profile measuring apparatus that inputs an observation signal from a propagation path, performs equalization processing on the signal by a filter, and measures a delay profile of the propagation path,
Each processing according to claim 6 or 7 ,
The delay profile measurement program for performing the process which calculates the delay profile of a propagation path from the coefficient of the said filter.

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