JP2005252826A - Quality measuring apparatus of ofdm broadcast wave - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide quality measuring apparatus of an OFDM broadcast wave in which circuit scale is reduced and the time required for measurement is also shortened. <P>SOLUTION: An FFT arithmetic circuit 1 performs an FFT arithmetic operation upon an OFDM broadcast wave to obtain an OFDM subcarrier, a scattered pilot carrier extracted from the OFDM subcarrier is divided by a reference scattered pilot carrier in a divider circuit 5 to remove and normalize modulation contents of each scattered pilot carrier, and a division output with respect to each scattered pilot carrier is averaged by an averaging processing circuit 6 for one valid symbol term. A square error based on an input/output difference of averaging processing is determined for each scattered pilot carrier by a square error calculation circuit 7, power of the determined square error is added for a predetermined symbol term, a calculated square error output is defined as a quality value by carriers, and a power sum output of the calculated square errors is defined as a total quality value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an OFDM broadcast wave quality measuring apparatus for measuring the quality of a terrestrial digital television broadcast wave.

  A modulation error ratio (also referred to as MER (Modulation Error Ratio)), which is one of the parameters indicating the quality of terrestrial digital television broadcast waves, is known, for example, in the European DVB standard and in the ETR-290 measurement guidelines. MER measurement of terrestrial digital television broadcast waves is specified. Based on this, the MER value measured by the MER measuring device for terrestrial digital television broadcast waves is used as an index of the quality of OFDM broadcast waves.

  A conventional MER measuring apparatus for OFDM broadcast waves is configured as shown in FIG. The OFDM broadcast wave is supplied to the FFT operation circuit 1 and the synchronization circuit 2, the position of the effective symbol interval of the OFDM broadcast wave is detected in the synchronization circuit 2, and the effective symbol interval information is supplied to the FFT operation circuit 1 as FFT time window information. Then, the FFT operation circuit 1 performs an FFT operation on the signal obtained by extracting the input OFDM broadcast wave through the FFT time window and demodulates it to obtain an OFDM subcarrier.

  Since the amplitude and phase of the input OFDM broadcast wave are unknown, the equalization circuit 35 receives the OFDM subcarrier demodulated by the FFT operation circuit 1 and determines the amplitude and phase of the scattered pilot carrier in the input OFDM broadcast wave. Processing to match the known amplitude and phase of the reference scattered pilot carrier is performed. In response to the OFDM subcarrier output from the equalization circuit 35, the hard decision circuit 37 performs a so-called hard decision process for determining a symbol value from a position on the complex plane for each of the input OFDM subcarriers.

  In the error calculation circuit 36, an error is obtained by subtracting the hard decision output from the hard decision circuit 37 from the position on the complex plane for each of the equalized OFDM subcarriers, and the error power sum obtained in the error calculation circuit 36 is obtained. Is calculated by the power sum calculation circuit 38.

  On the other hand, the power sum of the symbol values determined by the hard decision circuit 37 is obtained by the power sum calculation circuit 39, and the error power obtained by the power sum calculation circuit 38 and the decision symbol obtained by the power sum calculation circuit 39 The ratio of the value to the power sum is obtained by the MER value calculation circuit 40 as the MER value. Therefore, the MER value is obtained by the equation (1).

  However, when the above-described conventional OFDM broadcast wave MER measuring apparatus is used, the equalization process by the equalization circuit 35, the determination process by the hard decision circuit 37, and the error calculation process by the error calculation circuit 36 are applied to all OFDM subcarriers. In order to obtain the MER value, a large-scale circuit is required.

  An object of the present invention is to provide an OFDM broadcast wave quality measuring apparatus that requires only a small circuit scale.

  An OFDM broadcast wave quality measuring apparatus according to claim 1 according to the present invention includes an FFT operation means for performing an FFT operation on an OFDM broadcast wave, demodulating it, and outputting an OFDM subcarrier, and a scattered pilot carrier extracted from the OFDM subcarrier. Is divided by the reference scattered pilot carrier to remove and normalize the modulation contents of each scattered pilot carrier, and an average that averages the divided outputs for each scattered pilot carrier over one effective symbol period. Means for calculating, for each scattered pilot carrier, a square error based on the difference between the input and output of the averaging means, and an average for averaging the calculated square error over a period of one effective symbol or more. And the power of the calculated squared error averaged And a power sum calculating means for adding for a predetermined symbol period, an output from the averaging means and the value of the carrier-quality, characterized by the calculated power sum output and the value of Total Quality.

  An OFDM broadcast wave quality measurement apparatus according to claim 2 according to the present invention is an OFDM broadcast wave quality measurement apparatus, comprising: an effective symbol period length delay means for delaying an OFDM broadcast wave by one effective symbol period length; Subtracting means for subtracting an OFDM broadcast wave delayed by an effective symbol period from the wave, and detecting a noise interval by detecting a noise interval from the output of the subtracting means based on a threshold set at a predetermined level between the signal level and the noise level Noise power averaging means for averaging noise power over a period of time, and sum signal power in the sum signal section detected by detecting the sum signal section of the signal and noise following the noise section from the output of the subtraction means based on the threshold value Signal power averaging means that averages over the length of the noise interval, and the ratio of average noise power and average sum signal power And a dividing means for obtaining, characterized in that the value of the quality output of the divider means.

  According to a third aspect of the present invention, there is provided an OFDM broadcast wave quality measuring apparatus comprising: FFT calculation means for performing an FFT operation on an OFDM broadcast wave, demodulating and outputting an OFDM subcarrier; and a scattered pilot carrier extracted from the OFDM subcarrier. Is divided by the reference scattered pilot carrier to remove and normalize the modulation content of each scattered pilot carrier, and the difference between the divided output for each scattered pilot carrier and the reference scattered pilot carrier And an error power average calculating means for averaging the error power for each scattered pilot carrier minimized by the adaptive equalization means over a period of one effective symbol or more. Add error power over a given symbol period And a differential power sum calculation unit, the output of the error power average calculation means and the value of the carrier-quality, characterized by the output of the error power sum calculation means with the value of the overall quality of the OFDM broadcast waves.

  According to a fourth aspect of the present invention, there is provided an OFDM broadcast wave quality measuring apparatus comprising: FFT calculation means for performing an FFT operation on an OFDM broadcast wave, demodulating the OFDM broadcast wave, and outputting an OFDM subcarrier; Averaging means for averaging over a period, a dividing means for dividing the average power of each OFDM subcarrier into in-band and out-of-band, and a ratio between the level of the divided in-band power and the level of out-of-band power is obtained. Division means, and the division output is a quality value of the OFDM broadcast wave.

  According to the OFDM broadcast wave quality measuring apparatus of the first aspect of the present invention, an OFDM subcarrier is obtained from an OFDM broadcast wave by FFT, and a scattered pilot carrier extracted from the OFDM subcarrier is used as a reference scattered carrier. By dividing by the pilot carrier, the modulation content of each scattered pilot carrier is removed and normalized. The divided output for each scattered pilot carrier is averaged by the averaging means over one effective symbol period, and a square error based on the difference between the input and output of the averaging means is calculated for each scattered pilot carrier. The averaging error is averaged by the averaging means over a period in which the square error is one effective symbol or more. The averaged square error is used as a value for each carrier quality. The averaged square error power is added over a predetermined symbol period. The added power of the square error is used as a total quality value. In order to obtain the quality in this way, it is not necessary to perform an operation for obtaining the quality for all of the OFDM subcarriers, and the scale of the apparatus can be reduced.

  According to the OFDM broadcast wave quality measuring apparatus of the second aspect of the present invention, the OFDM broadcast wave delayed by one effective symbol period is subtracted from the OFDM broadcast wave, and the power of only the noise component obtained by the subtraction calculation power is reduced to noise. The power of the sum signal of the signal and noise obtained by subtraction outside the noise component interval is averaged over the period length of the component interval, and the ratio between the average sum signal power and the average noise power is averaged over the period length of the noise component interval. The division value is obtained as a quality value. In order to obtain the quality in this way, the FFT operation is not required and the apparatus scale is small. In addition, it is not necessary to perform the calculation for obtaining the quality for all the OFDM subcarriers, and the apparatus scale can be small.

  According to the OFDM broadcast wave quality measuring apparatus of the third aspect of the present invention, an OFDM subcarrier is obtained from the OFDM broadcast wave by FFT, and the scattered pilot carrier extracted from the OFDM subcarrier is used as the reference scattered carrier. By dividing by the pilot carrier, the modulation content of each scattered pilot carrier is removed and normalized. The error between the divided output for each scattered pilot carrier and the reference scattered pilot carrier is minimized by the adaptive equalization means, and the error power for each scattered pilot carrier minimized is a period of one effective symbol or more. The average value is used as a quality value for each carrier, the power of the averaged error is added over a predetermined symbol period, and the sum is used as the total quality value of the OFDM broadcast wave. In order to obtain the quality in this way, it is not necessary to perform an operation for obtaining the quality for all of the OFDM subcarriers, and the scale of the apparatus can be reduced.

  According to the OFDM broadcast wave quality measuring apparatus of claim 4 of the present invention, the power of each OFDM subcarrier obtained by performing an FFT operation on the OFDM broadcast wave is averaged over a predetermined period in the time direction, and each OFDM signal thus averaged is averaged. The power of the subcarrier is divided into in-band and out-of-band, and the ratio between the divided in-band power level and out-of-band power level is divided by the dividing means, and the divided output is the quality of the OFDM broadcast wave. Value. In order to obtain the quality in this way, it is not necessary to perform an operation for obtaining the quality for all of the OFDM subcarriers, and the scale of the apparatus can be reduced.

  Hereinafter, an OFDM broadcast wave quality measuring apparatus according to the present invention will be described with reference to embodiments.

  FIG. 1 is a block diagram showing a configuration of an OFDM broadcast wave quality measuring apparatus according to a first embodiment of the present invention.

  The OFDM broadcast wave quality measuring apparatus 10 according to the first embodiment of the present invention supplies the OFDM broadcast wave to the FFT operation circuit 1 and the synchronization circuit 2 as shown in FIG. The position of the effective symbol period of the wave is detected, the effective symbol period information is supplied to the FFT operation circuit 1 as FFT time window information, and the FFT operation circuit 1 extracts the input OFDM broadcast wave from the FFT time window. An OFDM operation is performed and demodulated to obtain an OFDM subcarrier.

  The OFDM subcarrier output from the FFT operation circuit 1 is supplied to the scattered pilot carrier extraction circuit 3, and the scattered pilot carrier is extracted from the OFDM subcarrier. The scattered pilot carrier extracted from the scattered pilot carrier extraction circuit 3 is as shown in equation (2).

Where r is the amplitude of the known scattered pilot carrier
α is the amplitude coefficient of the scattered pilot carrier of the input signal
φn is the known modulation phase of the nth scattered pilot carrier
θ is the phase rotation of the scattered pilot carrier of the input signal
Nn is a noise component included in the nth scattered pilot carrier
n is a natural number.

  The scattered pilot carrier extracted from the scattered pilot carrier extraction circuit 3 receives known amplitude information and phase information of the reference scattered pilot carrier output from the scattered pilot carrier phase information output circuit 4. Then, the division circuit 5 performs the division operation shown in the equation (3) to remove the modulation contents and normalize each scattered pilot carrier.

Here, modulation phase represented by .phi.n are different by the number of scattered pilot carriers, dividing the noisy component (2) of the scattered pilot carriers in e ^.phi.n hits the removal of the modulation content , R is the normalization. That is, as a result of the removal of the modulation content by performing the calculation of equation (3), the modulation phase that varies depending on the number of the scattered pilot carrier becomes a phase that is irrelevant to the modulation content. In Equation (3), since Nn is a noise component, it is set as a new noise component Nn ′ whose amplitude and phase have been changed by the operation of dividing Equation (2) by αe ^φn .

  The output from the division circuit 5 is averaged for each scattered pilot carrier in one effective symbol period in the averaging processing circuit 6. Nn ′ is a noise component, and if it follows a Gaussian distribution, the noise component Nn ′ becomes Nn′≈0 by the averaging process, and the output of the averaging processing circuit 6 is as shown in equation (4).

  Next, based on the difference between the output of the averaging processing circuit 6 and the output of the dividing circuit 5, that is, the division output averaged using the input / output values of the averaging processing circuit 6 and the division output before the averaging processing. A square error is obtained by the square error calculation circuit 7 for each scattered pilot carrier. The obtained square error is as shown in the equation (5), and represents a noise component in the OFDM broadcast wave, indicating the quality of each carrier.

  A simple quality value for each scattered pilot carrier can be obtained by performing the calculation of the above equation (5) for the designated scattered pilot carrier. Further, by averaging this value in the averaging processing circuit 9 over a period of one effective symbol or more, it is possible to obtain a value of improved accuracy and stable simple quality. Also, by performing the above calculation on all scattered pilot carriers in one symbol period, a distribution of simple quality values for one effective symbol period of OFDM broadcast waves is obtained, and the cause of quality degradation is estimated from this distribution. can do.

  When the distribution of simple quality values obtained from the equation (5) for all scattered pilot carriers within one effective symbol period of the OFDM broadcast wave 1 is as shown in FIG. The part affected by the carrier wave is shown, and the part b shows the part affected by the audio carrier wave in the analog broadcast wave. In the former case, the vicinity of the scattered pilot carrier number 30 corresponds to this, and in the latter case, the vicinity of the scattered pilot carrier number 210 corresponds to this.

  Similarly, when the distribution of the obtained simple quality values is as shown in FIG. 4, it is under the influence of frequency fading due to the multipath wave, and the increase and decrease depending on the frequency is periodically changed. Repeat. When the distribution of simple quality values is as shown in FIG. 5, the overall quality is deteriorated, and there is an OFDM broadcast wave that interferes with the entire band, or over the entire band. It is presumed that there is an equipment failure that generates noise.

  The square error processed in the averaging processing circuit 9 is supplied to the power sum calculation circuit 8, and the power of the averaged calculation square error is added over a predetermined symbol period, thereby obtaining a value of total simple quality.

  The simple quality value obtained by the OFDM broadcast wave quality measuring apparatus 10 can be supplied to the MER value conversion circuit 11 and converted into a MER value, as shown in FIG. The MER value conversion circuit 11 includes, for example, a storage device that stores a MER value corresponding to a quality value, and refers to the quality value obtained by the OFDM broadcast wave quality measurement device 10 to measure the quality of the OFDM broadcast wave. A simple MER value corresponding to the quality value obtained by the device 10 can be obtained from the storage device which is the MER conversion circuit 11. The MER value conversion circuit 11 may obtain a simple MER value by calculation based on the simple quality value obtained by the OFDM broadcast wave quality measuring apparatus 10.

  Next, an OFDM broadcast wave quality measuring apparatus according to a second embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration of an OFDM broadcast wave quality measuring apparatus according to the second embodiment of the present invention.

  The OFDM broadcast wave quality measuring apparatus 50 according to the second embodiment of the present invention supplies the OFDM broadcast wave to the effective symbol length delay circuit 12 and the subtraction circuit 13 as shown in FIG. 12, the OFDM broadcast wave is delayed by an effective symbol length period, and the OFDM broadcast wave delayed by the effective symbol length delay circuit 12 is subtracted from the OFDM broadcast wave by the subtraction circuit 13.

  The OFDM broadcast wave of the nth symbol is represented by equation (6).

Here, fn (t) is a signal component in the OFDM broadcast wave,
Nn (t) is a noise component in the FDM broadcast wave,
t is the time during the transmission symbol length (0 to T _ALL ) period of each symbol with the head of the guard interval set to 0. With respect to the signal delayed from the effective symbol length Ts output from the effective symbol length delay circuit 12, when Ts ≦ t ≦ T _ALL , the guard interval portion is output, so that the equation (7) is obtained.

When Ts ≦ t ≦ T _{ALL is not} satisfied (when 0 ≦ t <Ts in fn (t)), the signal delayed by the effective symbol length Ts output from the effective symbol length delay circuit 12 is expressed by equation (8). It becomes like this.

Therefore, Come to about subtraction result by the subtraction circuit 13 (difference), when the difference between the signal at time t is the Ts ≦ t ≦ T _ALL will as the equation (9). The difference when Ts ≦ t ≦ T _ALL is indicated by Δ1.

If the difference other than Ts ≦ t ≦ T _ALL is represented by Δ2, the difference Δ2 is expressed by the equation (10).

  The output from the subtracting circuit 13 detects this noise by detecting a threshold value circuit 14 in which a threshold value is set to a predetermined level between the signal level and the noise level, and a noise level lower than the threshold value set by the threshold value circuit 14. A noise signal averaging circuit 16 that averages the noise power over the period length of the noise section and a sum signal of a signal that is equal to or higher than a threshold value set by the threshold circuit 14 and noise and detects the sum signal following the noise section The sum signal power in the section is supplied to the signal power averaging circuit 15 that averages over the period length of the noise section, and the average of the noise power and the average of the signal power are obtained.

  Here, as a result of the subtraction in the subtraction circuit 13, only the noise component remains in the portion where the signal component is canceled by the subtraction in the subtraction circuit 13. As a result, the output of the subtraction circuit 13 is composed of a sum signal section that is a superposition signal of the signal and the noise component and a noise section that remains after the signal component is canceled by subtraction, and the sum signal level ≧ noise signal level. Typically, it is a concave shape with a level lowered in the noise interval, and the threshold value is set to a predetermined level between the sum signal level and the noise level.

  Therefore, the noise interval is detected by the interval less than the threshold, the noise interval length is equal to the guard interval interval length, the sum signal interval is detected by the interval above the threshold, and the output of the subtraction circuit 13 continues before and after the noise component interval. As a result, a sum signal interval occurs. The noise power averaging period in the noise power averaging circuit 16 is set to the noise interval length, and the averaging period of the sum signal power in the signal power averaging circuit 15 is similarly set to the noise interval length. The reason for combining the averaging periods is for the division described later.

  When the average power of the sum signal component is Ps and the average power of the noise component is Pn, when the average power of the equations (9) and (10) is obtained, the sum signal power changes between the previous symbol and the present. In addition, assuming that there is no change in noise power, equations (9) and (10) are as shown in equations (11) and (12).

  A ratio between the output of the signal power averaging circuit 15 and the output of the noise power averaging circuit 16 is obtained by the division circuit 17 and is set to a simple quality value. The ratio obtained in the divider circuit 17 is as shown in the equation (13).

  As is clear from equation (9), the signal component is removed by subtraction in the guard interval period to obtain only the noise component. As is clear from equation (10), the signal and noise are subtracted by subtraction outside the guard interval period. The sum signal, which is a superposition signal, is obtained, and the ratio of the average sum signal power and the average noise power is finally obtained from the ratio of the signal power averaged output and the noise power averaged output. Needless to say, it is compatible.

  A value based on the quality obtained by the division circuit 17 may be supplied to the MER value conversion circuit to obtain the MER value. Note that when the OFDM broadcast wave quality measuring apparatus 50 is used, since an OFDM broadcast wave demodulation operation is not required, an FFT operation circuit and a synchronization circuit are not required, and the configuration is simple.

  Next, an OFDM broadcast wave quality measuring apparatus according to a third embodiment of the present invention will be described. FIG. 7 is a block diagram showing a configuration of an OFDM broadcast wave quality measuring apparatus according to the third embodiment of the present invention.

  The OFDM broadcast wave quality measuring apparatus 60 according to the third embodiment of the present invention supplies the OFDM broadcast wave to the FFT operation circuit 1 and the synchronization circuit 2 as shown in FIG. The effective symbol interval is detected, and the effective symbol interval information is supplied to the FFT operation circuit 1 as FFT time window information. The FFT operation circuit 1 performs FFT on the signal extracted from the input OFDM broadcast wave by the FFT time window. An operation is performed to demodulate to obtain an OFDM subcarrier.

  The OFDM subcarrier output from the FFT operation circuit 1 is supplied to the scattered pilot carrier extraction circuit 3, and the scattered pilot carrier is extracted from the OFDM subcarrier.

  The scattered pilot carrier extracted from the scattered pilot carrier extraction circuit 3 receives known amplitude information and phase information of the reference scattered pilot carrier output from the scattered pilot carrier phase information output circuit 4. Then, division operation is performed in the division circuit 5, and the modulation content removal and normalization of each scattered pilot carrier are performed.

  A weight is added to the scattered pilot carrier that has been subjected to modulation content removal and normalization by the division circuit 5 by multiplying the weight value by the weight calculation circuit 21, and the reference scattered pilot carrier and weight are added by the error calculation circuit 22. An error with each scattered pilot carrier to which is added is detected. The error calculated by the error calculation circuit 22 is subjected to adaptive equalization processing by the adaptive equalization processing circuit 23, and the weight in the weight calculation circuit 21 is adjusted so that the error due to the calculation by the error calculation circuit 22 is minimized. . Here, the weight calculation circuit 21, the error calculation circuit 22, and the adaptive equalization processing circuit 23 constitute an adaptive equalization means.

  The error obtained by the error calculation circuit 22 is supplied to the error power average calculation circuit 25, and the error power for each scattered pilot carrier minimized is averaged over a period of one effective symbol or more, thereby simplifying the quality for each carrier. Get the value of. The output from the error power average calculation circuit 25 is supplied to the error power sum calculation circuit 24 and added over a predetermined symbol period, thereby obtaining a value of total simple quality from the sum.

  Based on the quality value obtained for each of the scattered pilot carriers of simple quality obtained by the error power average calculation circuit 25, a distribution over all the scattered pilot carriers is obtained, and from this, the OFDM broadcast wave quality measuring apparatus 10 Similarly to the case, the cause of quality deterioration can be estimated.

  It can also be used to grasp the convergence state of the error by error equalization processing.

  Next, an OFDM broadcast wave quality measuring apparatus according to a fourth embodiment of the present invention will be described. FIG. 8 is a block diagram showing a configuration of an OFDM broadcast wave quality measuring apparatus according to the fourth embodiment of the present invention.

  As shown in FIG. 8, the OFDM broadcast wave quality measuring apparatus 70 according to the fourth embodiment of the present invention supplies an OFDM broadcast wave to the FFT operation circuit 1 to obtain an OFDM subcarrier as frequency information and average it. The averaging circuit 28 averages the power of the OFDM subcarriers over a predetermined symbol period in the time direction for each OFDM subcarrier.

  The band of the OFDM broadcast wave is known (the band of one channel is 6 MHz), and the power level of each averaged OFDM subcarrier output from the averaging circuit 28 is determined as the in-band level acquisition circuit 29 and the out-of-band level. The power level supplied to the acquisition circuit 30 is divided into an in-band level and an out-of-band level, and the in-band level acquired by the in-band level acquisition circuit 29 and the band acquired by the out-of-band level acquisition circuit 30 The ratio with the outer level is obtained by the divider circuit 31 and is set as the quality value of the OFDM broadcast wave.

  As apparent from the above, when the power level of the averaged OFDM subcarrier is divided into the in-band and out-of-band levels, it is as shown in FIG. 9, and is divided into the in-band level e and the out-of-band levels d1 and d2. The ratio between the in-band level e and the out-of-band levels d1 and d2 becomes the quality value of the OFDM broadcast wave.

  Since the OFDM broadcast wave quality measuring device 70 measures the intermodulation of the OFDM broadcast wave, it can be used mainly for measuring the quality of the transmission output.

It is a block diagram which shows the structure of the quality measuring apparatus of the OFDM broadcast wave concerning the 1st Embodiment of this invention. It is a block diagram which shows the structure in the case of converting into a MER value the measured value by the OFDM broadcast wave quality measuring apparatus concerning the 1st Embodiment of this invention. It is a schematic diagram which shows an example of the measurement result of the quality measurement apparatus of the OFDM broadcast wave concerning the 1st Embodiment of this invention. It is a schematic diagram which shows the other example of the measurement result of the quality measuring apparatus of the OFDM broadcast wave concerning the 1st Embodiment of this invention. It is a schematic diagram which shows the further another example of the measurement result of the quality measurement apparatus of the OFDM broadcast wave concerning the 1st Embodiment of this invention. It is a block diagram which shows the structure of the quality measuring apparatus of the OFDM broadcast wave concerning the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the quality measuring apparatus of the OFDM broadcast wave concerning the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the quality measuring apparatus of the OFDM broadcast wave concerning the 4th Embodiment of this invention. It is a schematic diagram with which it uses for description of the measurement by the quality measuring apparatus of the OFDM broadcast wave concerning the 4th Embodiment of this invention. It is a block diagram which shows the structure of the conventional MER measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... FFT operation circuit 2 ... Synchronous circuit 3 ... Scattered pilot carrier extraction circuit 4 ... Scattered pilot carrier phase information output circuit 5, 17, 31 ... Dividing circuit 6, 9 ... Averaging processing circuit 7 ... Square error calculation Circuit 8 ... Power sum calculation circuit 10, 50, 60, 70 ... OFDM broadcast wave quality measuring device 12 ... Effective symbol length delay circuit 13 ... Subtraction circuit 14 ... Threshold circuit 15 ... Signal power averaging circuit 16 ... Noise power averaging Circuit 21 ... Weight calculation circuit 22 ... Error calculation circuit 23 ... Adaptive equalization processing circuit 24 ... Error power sum calculation circuit 25 ... Error power average calculation circuit 28 ... Averaging circuit 29 ... In-band level acquisition circuit 30 ... Out-of-band level acquisition circuit

Claims (4)

  An OFDM broadcast wave quality measurement apparatus, which performs FFT calculation on an OFDM broadcast wave, demodulates and outputs an OFDM subcarrier, and a scattered pilot carrier extracted from the OFDM subcarrier as a reference scattered pilot carrier Dividing means for removing and normalizing the modulation contents of each scattered pilot carrier by dividing by the above, averaging means for averaging the divided output for each scattered pilot carrier over one effective symbol period, and averaging means A square error calculation means for calculating a square error based on the difference between the input and output of each of the scattered pilot carriers, an averaging processing means for averaging the calculated square error over a period of one effective symbol or more, and averaging The power of the calculated calculated square error is shown for a predetermined symbol period. An OFDM broadcast wave quality measuring apparatus, comprising: an output from the averaging processing means as a value for each carrier quality, and a calculated power sum output as a total quality value. .   An OFDM broadcast wave quality measuring device, an effective symbol period length delay means for delaying an OFDM broadcast wave by one effective symbol period length, and a subtraction means for subtracting an OFDM broadcast wave delayed by an effective symbol period length from the OFDM broadcast wave; A noise power averaging means for detecting a noise interval from the output of the subtracting means based on a threshold set to a predetermined level between a signal level and a noise level, and averaging the noise power over the period of the detected noise interval; and based on the threshold Signal power averaging means for detecting the sum signal section of the signal and noise following the noise section from the output of the subtracting means and averaging the sum signal power in the sum signal section over the period length of the noise section; and average noise power And dividing means for obtaining a ratio of the average sum signal power, and setting the output of the dividing means as a quality value Quality measuring apparatus for OFDM broadcast wave and symptoms.   An OFDM broadcast wave quality measurement apparatus, which performs FFT calculation on an OFDM broadcast wave, demodulates and outputs an OFDM subcarrier, and a scattered pilot carrier extracted from the OFDM subcarrier as a reference scattered pilot carrier Dividing means that removes and normalizes the modulation content of each scattered pilot carrier by dividing by, and adaptive equalization that minimizes the error between the divided output for each scattered pilot carrier and the reference scattered pilot carrier Means, an error power average calculating means for averaging the error power for each scattered pilot carrier minimized by the adaptive equalization means over a period of one effective symbol or more, and the averaged error power over a predetermined symbol period With error power sum calculation means to add , The output of the error power average calculation means and the value of the specific carrier quality, OFDM broadcast wave quality measuring apparatus, characterized in that the value of the overall quality of the OFDM broadcast wave output of the error power sum calculation means.   An OFDM broadcast wave quality measurement apparatus, which performs FFT calculation on an OFDM broadcast wave, demodulates and outputs an OFDM subcarrier, and average means that averages the power of each OFDM subcarrier over a predetermined period in the time direction A dividing means for dividing the averaged power of each OFDM subcarrier into in-band and out-of-band; and a dividing means for obtaining a ratio between the divided in-band power level and out-of-band power level. An OFDM broadcast wave quality measuring apparatus, characterized in that an output is a quality value of the OFDM broadcast wave.

Images