JP4926307B2 - Digital broadcast receiving apparatus and delay profile creating method - Google Patents

Description

  The present invention relates to a digital broadcast receiving apparatus and a delay profile creating method for receiving a digital broadcast wave using an OFDM (Orthogonal Frequency Division Multiplexing) system.

In the OFDM scheme, information to be transmitted is allocated to a plurality of subcarriers and digitally modulated on each subcarrier. Examples of the digital modulation method include a QPSK (Quadrature Phase Shift Keying) method, a QAM (Quadrature Amplitude Modulation) method, a multilevel PSK (Phase Shift Keying) method, and the like.
Further, a known signal is multiplexed on a specific subcarrier, and on the receiving side, the subcarrier is demodulated using this known signal.
On the other hand, subcarriers that multiplex known signals are orthogonally transformed by inverse Fourier transform processing and frequency-converted to a desired transmission frequency before being transmitted. A transmission unit on which the inverse Fourier transform process is performed is called a symbol.
The last part of the signal after the inverse Fourier transform process is copied and added to the head of the symbol. This added portion is called a guard interval, and even if there is an incoming wave having a delay time equal to or shorter than the guard interval length, a signal can be reproduced without interference between symbols on the receiving side.

As a known signal inserted in advance in a transmission signal, a scattered pilot (SP) is taken as an example of the ISDB-T system which is a domestic terrestrial digital broadcast and the DVB-T system adopted in Europe. There is a signal (hereinafter referred to as SP signal). This SP signal is periodically inserted into the transmission signal.
The reception side has in advance the value of each SP signal periodically inserted into the transmission signal as a known SP signal, and the amplitude of each SP signal is obtained by dividing the received SP signal by the known SP signal. And a phase fluctuation amount (hereinafter referred to as transmission path characteristics) can be estimated (hereinafter referred to as transmission path estimation).
In addition, by performing inverse Fourier transform on the value of the transmission path characteristic, a delay profile indicating the intensity of the received signal for each arrival time can be obtained. Here, the delay profile obtained from the transmission path characteristic value is referred to as an SP-based delay profile.

  Another method for obtaining the delay profile is to use the power spectrum of the received signal (see, for example, Patent Document 1). In this method, a received signal is squared in the frequency domain, converted into a power dimension, and then subjected to inverse Fourier transform to obtain a delay profile. Here, this delay profile is called a power-based delay profile.

In the power-based delay profile, when the effective symbol length is Ts, the maximum delay time in which an incoming wave can be detected is Ts / 2, which is a time range longer than ± Ts / 6 in the SP-based delay profile.
However, the power-based delay profile has a problem that the relative time difference between the preceding wave and the delayed wave with respect to the main wave cannot be obtained, and the preceding wave and the delayed wave cannot be distinguished. In addition, when there are a plurality of incoming waves, there is a problem that intermodulation occurs due to interference between the incoming waves, and an incoming wave that does not exist originally appears on the delay profile.

On the other hand, Patent Document 2 discloses an OFDM wave delay profile measuring apparatus that uses a combination of a delay profile based on the transfer function method corresponding to the SP base delay profile described above and a delay profile based on the power spectrum method corresponding to the power base delay profile. It is disclosed. In this apparatus, by using both delay profiles, in the delay profile measurement method, the length of the maximum delay time in which the delay wave can be measured, the time resolution in which the delay wave can be measured, the level in which the delay wave can be measured, The accuracy of the delay wave level and the false pulse response can be eliminated.
However, since the incoming wave that appears only in the delay profile (SP-based delay profile) by the transfer function method is output as a measurement result as it is, the pseudo arrival that occurs when the mobile body equipped with the receiving device moves at high speed There was a problem that the waves could not be deleted.

In the OFDM receiver described in Patent Document 3, erroneous control during high-speed movement is prevented by determining a pseudo-arrival wave that is generated when the mobile body on which it is mounted moves at high speed.
However, there is a problem that the time range in which an incoming wave can be detected is limited to ± Ts / 6, and an incoming wave with a long delay time may be erroneously controlled.
Further, the receiving apparatus described in Patent Document 3 does not have a function of outputting an accurate delay profile in which a pseudo incoming wave does not appear.

  The present invention has been made to solve the above-described problems, and is an environment in which a mobile body equipped with the mobile device moves at high speed, or has a time range in which an incoming wave can be detected with an SP-based delay profile. An object of the present invention is to provide a digital broadcast receiving apparatus and a delay profile creating method capable of providing an error-free delay profile to eliminate erroneous control and improving reception performance even when there are exceeding arriving waves.

JP 2005-268831 A JP 2006-93760 A JP 2008-72224 A

  A digital broadcast receiver according to the present invention includes a Fourier transform unit that performs Fourier transform on a received orthogonal frequency division multiplex signal for each transmission unit, and subcarrier power data that is calculated from data Fourier-transformed by the Fourier transform unit. A power calculation unit, a first inverse Fourier transform unit that generates a first delay profile by performing an inverse Fourier transform on the subcarrier power data calculated by the subcarrier power calculation unit, and a Fourier transform performed by the Fourier transform unit A pilot signal extraction unit that extracts a pilot signal from data, a division unit that calculates transmission path characteristic data for the pilot signal of each transmission unit by dividing the pilot signal extracted by the pilot signal extraction unit by a known value; For the pilot signal of each transmission unit calculated by the division unit A second delay profile is generated by performing an inverse Fourier transform on the time direction interpolation unit for interpolating transmission line characteristic data in the time direction and the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit. Main wave arrival times of the second inverse Fourier transform unit, the first delay profile generated by the first inverse Fourier transform unit, and the second delay profile generated by the second inverse Fourier transform unit The arrival time detection time of the first delay profile is offset so as to match, and the second delay profile has a value equal to or greater than a predetermined threshold in the first delay profile with the arrival wave detection time offset. Leave the value corresponding to the arrival time, replace the value corresponding to the arrival time less than the threshold with a value that is not treated as an arrival wave, and delay the received orthogonal frequency division multiplexed signal. In which and a delay profile combining unit for outputting as a profile.

  According to the present invention, even in an environment in which a mobile body equipped with the mobile body moves at high speed, or when there is an incoming wave exceeding the detection time range in the second delay profile (SP-based delay profile), As a delay profile of the received orthogonal frequency division multiplexing signal, an error-free delay profile can be provided to eliminate erroneous control and improve reception performance.

It is a figure which shows the arrangement pattern of SP signal in a transmission signal. It is a figure which shows the estimation result of the transmission-line characteristic of SP signal interpolated in the time direction. It is a figure which shows the estimation result of the transmission-line characteristic of SP signal interpolated by the time direction and the frequency direction. It is a figure which shows an example of SP base delay profile. It is a figure which shows the estimation result of the transmission line characteristic containing an error by the interpolation of time direction. It is a figure which shows SP base delay profile and the pseudo incoming wave which arises in this. It is a figure which shows an example of the malfunction by the delay wave beyond the detection range by SP base delay profile. It is a figure which shows an example of a power base delay profile. It is a block diagram which shows the structure of the digital broadcast receiver by Embodiment 1 of this invention. 3 is a flowchart showing a flow of operations by a delay profile synthesis unit according to the first embodiment. 6 is an explanatory diagram illustrating delay profile synthesis processing according to Embodiment 1. FIG. 10 is a flowchart showing a flow of operation by a delay profile synthesis unit according to the second embodiment. FIG. 10 is an explanatory diagram for explaining delay profile synthesis processing according to Embodiment 3; It is a block diagram which shows the structure of the digital broadcast receiver by Embodiment 4 of this invention. It is a block diagram which shows the structure of the digital broadcast receiver by Embodiment 5 of this invention.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
First, an SP signal, an SP base delay profile, and a power base delay profile to be inserted into an OFDM transmission signal will be described.
FIG. 1 is a diagram showing an arrangement pattern of SP signals in a transmission signal. Black circle symbols in FIG. 1 indicate SP signals, and white circle symbols indicate signals such as data. As shown in FIG. 1, the SP signals are distributed for every 4 symbols in the time direction and every 12 carriers in the frequency direction, and for each symbol so that their insertion positions are the same frequency position in a 4-symbol period. It is arranged while shifting 3 carriers at a time. On the receiving side, the received SP signal is divided by a known SP signal to estimate the channel characteristics of each SP signal.

FIG. 2 is a diagram showing the estimation result of the transmission path characteristic of the SP signal interpolated in the time direction. The black circle symbol in FIG. 2 indicates the estimated value of the transmission path characteristic of the SP signal, and the black triangle symbol is The estimated value of the transmission path characteristic interpolated in the time direction is shown, and the white circle symbol indicates a signal such as data.
FIG. 3 is a diagram showing the estimation results of the SP signal transmission path characteristics interpolated in the time direction and the frequency direction, and the black circle symbols in FIG. 3 indicate the SP signal transmission path characteristic estimation values. The black triangle symbol indicates the estimated value of the transmission path characteristic interpolated in the time direction, and the black square symbol indicates the estimated value of the transmission path characteristic interpolated in the frequency direction.

The estimated values of the SP signal transmission path characteristics are interpolated in the time direction as shown in FIG. 2, and then further interpolated in the frequency direction as shown in FIG. It is possible to obtain road characteristics.
Here, as shown in FIG. 2, by interpolating the SP channel transmission path estimation values dispersed and arranged in units of 12 carriers in the time direction, the transmission path estimation values are dispersed by 3 carriers in the frequency direction. For this reason, the time range in which the transmission path characteristics can be estimated is expanded from Ts / 12 to Ts / 3, and even in an environment where the arrival time difference of the incoming waves is large, the transmission path is correctly within the expanded time range. The characteristics can be estimated.

  FIG. 4 is a diagram illustrating an example of an SP-based delay profile. By performing inverse Fourier transform on the above-described transmission path characteristic value, a delay profile (SP base delay profile) indicating the intensity of each received signal as shown in FIG. 4 is obtained. As shown in FIG. 4, in digital broadcasting using an OFDM signal, the main wave is an incoming wave having the highest level among a plurality of incoming waves included in the received signal. In addition, due to multipath included in the received signal, wraparound in retransmission, a main wave delay wave or a preceding wave (not shown in FIG. 4) is generated. In an environment in which a moving body (for example, a vehicle) on which a receiving device is mounted moves at a high speed, the received signal of the receiving device undergoes Doppler fluctuations, and the transmission path characteristics for each symbol vary.

  FIG. 5 is a diagram showing estimation results of transmission path characteristics including errors by interpolation in the time direction. The black circle symbol in FIG. 5 indicates the estimated value of the transmission path characteristics of the SP signal, and the cross symbol is the time direction. The estimated values of the transmission path characteristics including errors are shown by interpolation, and white circles indicate signals such as data. The maximum frequency (also referred to as the maximum Doppler frequency) of transmission path characteristic fluctuation due to Doppler fluctuation exceeds 1 / ((Ts + Tg) / 8) (Hz), which is the maximum frequency that can be interpolated by interpolation in the time direction. Then, as shown in FIG. 5, the transmission path characteristic includes an error, and interpolation in the time direction cannot be performed correctly. Here, Ts is the effective symbol length, Tg is the guard interval length, and the above equation indicating the maximum frequency that can be interpolated by interpolation is derived from the sampling theorem and the SP signal interpolated in a 4-symbol period. The

  FIG. 6 is a diagram showing an SP base delay profile and a pseudo incoming wave generated in the SP base delay profile. FIG. 6 shows the SP base delay profile obtained from the estimation result of the transmission path characteristics in which the interpolation in the time direction is erroneously performed as shown in FIG. 5 due to the high-speed movement of the mobile body equipped with the receiving apparatus. As described above, an arrival wave that does not exist originally appears on the delay profile as a pseudo arrival wave within a time range of ± Ts / 6 in which the arrival wave can be detected. If the receiving apparatus performs erroneous control due to this pseudo incoming wave, the reception performance deteriorates as a result.

In the SP-based delay profile, if there is an incoming wave with a delay time exceeding the time range of ± Ts / 6, which is the detection range of the incoming wave, the following problems occur.
FIG. 7 is a diagram illustrating an example of a problem caused by a delayed wave exceeding the detection range in the SP base delay profile. As shown in FIG. 7, in the SP-based delay profile, if there is an arrival wave with a delay time exceeding the time range of ± Ts / 6, the arrival wave is within the detection range from the original delay time on the delay profile. It appears as a return signal that returns as a signal. For this reason, the arrival wave that was originally a delayed wave becomes like a preceding wave with respect to the main wave, and the preceding wave and the delayed wave cannot be distinguished.
On the other hand, in the power-based delay profile, the time range in which an incoming wave can be detected is up to Ts / 2, but only the relative time difference between the delayed wave and the preceding wave with respect to the main wave can be obtained. For this reason, as shown in FIG. 8, in the power-based delay profile, it is not possible to distinguish between the preceding wave and the delayed wave. In addition, when there are a plurality of incoming waves, in the power-based delay profile, cross-modulation occurs due to interference between the incoming waves, and an originally existing incoming wave appears on the delay profile.

  In Patent Document 1, since the power-based delay profile is used, the above-described problem occurs. The apparatus of Patent Document 2 uses a combination of an SP base delay profile and a power base delay profile, but uses an incoming wave that appears only in the SP base delay profile as a detection result. For this reason, the pseudo arrival wave on the SP-based delay profile that occurs during high-speed movement cannot be removed. Furthermore, the receiving apparatus described in Patent Document 3 prevents false control by determining a pseudo incoming wave that occurs during high-speed movement, but has a limitation that the detection range of the incoming wave is ± Ts / 6, and delay There is a possibility that erroneous control is performed for an incoming wave having a long time.

  Therefore, in the first embodiment of the present invention, the error signal included in the SP base delay profile is canceled using the power base delay profile, and the SP base delay profile in which the error signal is canceled is used as an advantage of both delay profiles. Generates a new so-called synthesized delay profile. By doing this, even in a high-speed moving environment or when there is an incoming wave whose delay time exceeds the detection range, the newly generated delay profile has no error and depends on the previous delay profile. Accurate reception operation is possible without erroneous control. Details will be described below.

  FIG. 9 is a block diagram showing the configuration of the digital broadcast receiving apparatus according to Embodiment 1 of the present invention. A digital broadcast receiving apparatus 1 according to Embodiment 1 is a receiving apparatus that receives a digital broadcast wave using the OFDM method, and as shown in FIG. 9, a Fourier transform unit 2, a pilot signal extraction unit 3, a known signal, Generation unit 4, division unit 5, time direction interpolation unit 6, frequency direction interpolation unit 7, equalization unit 8, subcarrier power calculation unit 9, first inverse Fourier transform unit 10a, second inverse Fourier transform unit 10b and a delay profile synthesis unit 11.

  The Fourier transform unit 2 is a configuration unit that generates a frequency axis signal by cutting out a time axis signal (a signal of a transmission unit) of one symbol period from a received signal and performing a Fourier transform. Perform transform (FFT; Fast Fourier Transform). By performing the Fourier transform, the received time axis signal is converted into a signal for each subcarrier which is a carrier unit of the frequency axis signal.

  The pilot signal extracting unit 3 is a component that extracts the SP signal inserted at a predetermined subcarrier position from the signal for each subcarrier obtained by the Fourier transform unit 2. The known signal generation unit 4 is a component that generates a known value of the SP signal corresponding to a predetermined subcarrier position from which the SP signal is extracted by the pilot signal extraction unit 3. The SP signal having a known value is the value of the SP signal at the time of transmission, and is hereinafter referred to as a known SP signal. The divider 5 is a component that obtains a transmission line characteristic value by dividing the value of the SP signal extracted by the pilot signal extractor 3 by the value of the known SP signal corresponding thereto.

  In the OFDM signal, since the SP signal is distributed and inserted every 12 carriers, it is necessary to perform interpolation processing in order to obtain the transmission path characteristics of all the subcarriers. First, since the SP signal is arranged at intervals of 4 symbols in the time direction in the OFDM signal, interpolation processing is performed in the time direction. The time direction interpolation unit 6 is a component that interpolates the transmission path characteristic value generated by the division unit 5 in the time direction, and uses linear interpolation or a FIR (Finite impulse response) filter of a plurality of symbols. Interpolate in the time direction. By performing interpolation processing in the time direction, a transmission path characteristic signal for every three carriers is obtained in the frequency direction as shown in FIG.

  The frequency direction interpolation unit 7 performs a frequency direction interpolation process on the transmission line characteristic signal obtained by the time direction interpolation unit 6 using a linear interpolation or a FIR filter of a plurality of symbols. Part. By performing this frequency direction interpolation processing, the transmission path characteristics of all subcarriers can be obtained as shown in FIG. The equalization unit 8 equalizes the received signal by dividing the signal for each subcarrier obtained by the Fourier transform unit 2 by the transmission path characteristic value for each subcarrier obtained by the frequency direction interpolation unit 7. It is a component. A signal reproduction unit is provided at the subsequent stage of the equalization unit 8, and the signal reproduction unit reproduces original transmission data from the equalization result obtained by the equalization unit 8.

  The subcarrier power calculation unit 9 is a component that calculates subcarrier power from the signal for each subcarrier obtained by the Fourier transform unit 2. The first inverse Fourier transform unit 10 a is a component that generates a power-based delay profile (first delay profile) from the calculation result of the subcarrier power calculation unit 9. The second inverse Fourier transform unit 10b generates an SP-based delay profile (second delay profile) using the result of performing the inverse Fourier transform on the transmission path characteristic signal obtained by the time direction interpolation unit 6. It is a component.

  The delay profile synthesizing unit 11 is a component that inputs a power base delay profile from the first inverse Fourier transform unit 10a and inputs an SP base delay profile from the second inverse Fourier transform unit 10b. Of these, the SP base delay profile value corresponding to the arrival time having a value equal to or greater than the threshold value is left, and other SP base delay profile values are replaced with the minimum value to generate a new delay profile.

  In general, reflection or attenuation is performed from the time a signal is transmitted from a transmitting station until it is received by a receiving device, and a plurality of arriving waves reach the receiving device by being simultaneously transmitted from a plurality of transmitting sites. It becomes the signal of the path. Data indicating the arrival time and intensity (D / U ratio) of each incoming wave included in the multipath signal is called a delay profile. In the delay profile, the strongest incoming wave is called the main wave, the incoming wave that arrives later than the main wave is called the delayed wave, and the incoming wave that arrives earlier than the main wave is called the preceding wave.

Next, the operation will be described.
First, the subcarrier power calculation unit 9 squares the I axis (real axis) and Q axis (imaginary axis) of the frequency axis signal (complex signal) for each subcarrier obtained by the Fourier transform unit 2. Addition is performed, and the addition result is input to the I axis of the inverse Fourier transform by the first inverse Fourier transform unit 10a, and zero is input to the Q axis.
The first inverse Fourier transform unit 10a performs the inverse Fourier transform, squares the I-axis and the Q-axis after the inverse Fourier transform, and adds the result as a power-based delay profile (first delay profile). Output to the profile composition unit 11.
The power-based delay profile is characterized in that the main wave is the center, the time range in which the incoming wave can be detected is from 0 to Ts / 2, and both the delayed wave and the preceding wave appear symmetrically around the main wave. Note that the power-based delay profile obtained here may be used after being smoothed.

The second inverse Fourier transform unit 10b performs inverse Fourier transform on the output (complex signal) of the time direction interpolation unit 6, squares the I axis and Q axis of the output of the inverse Fourier transform, and adds the result. The SP base delay profile (second delay profile) is output to the delay profile synthesis unit 11. The center position of the time range in which the incoming wave can be detected in the SP-based delay profile is called a demodulation reference point. That is, in the SP base delay profile, it is possible to detect an incoming wave in a range up to ± Ts / 6 with the demodulation reference point as the center. Note that the SP-based delay profile obtained here may be used after being smoothed.
The order of each data in the delay profiles of both the power-based delay profile and the SP-based delay profile is called an index, and each index corresponds to the arrival time.

FIG. 10 is a flowchart showing an operation flow by the delay profile synthesis unit of the first embodiment, and FIG. 11 is an explanatory diagram for explaining delay profile synthesis processing. A new delay profile generation process will be described with reference to FIG.
The delay profile synthesis unit 11 detects the index of the main wave of the SP base delay profile (step ST1). Since the main wave has the largest value in the delay profile, the index corresponding to the largest value is detected as the main wave index among the data of the SP-based delay profile.

  Next, the delay profile synthesis unit 11 calculates a main wave offset value corresponding to the difference between the main wave index of the SP base delay profile and the index of the center (demodulation reference point) of the SP base delay profile (step ST2). ). In FIG. 11A, α, which is an index difference between the center (demodulation reference point) of the SP base delay profile indicated by a broken line and the main wave, is the main wave offset value. Therefore, the delay profile synthesizing unit 11 obtains a value obtained by subtracting the index of the center (demodulation reference point) of the SP base delay profile from the main wave index of the SP base delay profile as the main wave offset value α. Note that, as shown in FIG. 11B, in the power-based delay profile, the main wave is always the center of the delay profile.

  Subsequently, the delay profile synthesis unit 11 offsets the index of the power-based delay profile (step ST3). Here, the index of the power-based delay profile is offset by the amount corresponding to the main wave offset value α to replace each data. In this manner, as shown in FIG. 11C, the main wave index of the SP-based delay profile is matched with the main wave index of the power-based delay profile.

  The delay profile synthesizing unit 11 reads the power-based delay profile value obtained by offsetting the index in step ST3 one by one (step ST4), compares the value with a predetermined threshold (threshold), and determines whether or not the read value is smaller than the threshold. Is determined (step ST5). If the read value is equal to or greater than the threshold value (step ST5; NO), no processing is performed on the SP-based delay profile data corresponding to the arrival time (index) of the read value, and the process of step ST7 is performed. Migrate to

  On the other hand, if the read value is smaller than the threshold value (step ST5; YES), the delay profile synthesis unit 11 replaces the data of the SP base delay profile corresponding to the arrival time (index) of this read value with 0 (or incoming wave data). (Replaced with the smallest value that is not treated as) (step ST6).

  Depending on the number of points of the inverse Fourier transform, the delay time between the SP base delay profile and the power base delay profile may not uniquely correspond. In this case, the closest delay time (index) value is selected and replaced with 0 or the minimum value. Also, if there is no SP-based delay profile value for the corresponding delay time, no processing is performed. This is because the power-based delay profile has a delay time range (detection time range) up to Ts / 2, while the SP-based delay profile is ± Ts / 6.

  Each time the above-described process is executed, the delay profile synthesis unit 11 determines whether or not the processing has been completed for all indexes of the power-based delay profile (step ST7). Here, if the processing has not been completed for all the indexes of the power-based delay profile (step ST7; NO), the process returns to step ST4, the value corresponding to the next index of the power-based delay profile is read, and step ST4. To step ST7.

When the above processing is completed for all indexes of the power-based delay profile (step ST7; YES), the delay profile combining unit 11 sets the value corresponding to the value that does not satisfy the threshold in the power-based delay profile to 0 or the minimum value. The permuted SP-based delay profile is output as a so-called combined composite delay profile, where the advantages of both delay profiles are.
That is, even if the original SP base delay profile includes a pseudo incoming wave, the advantage of the power base delay profile in which the pseudo incoming wave does not appear is used to eliminate the SP incoming delay pseudo incoming wave. Thus, the delay profile shown in FIG. 11D can be obtained as the combined delay profile, and the pseudo arrival wave does not appear.
In addition, the power-based delay profile cannot distinguish between the preceding wave and the delayed wave, but by using the SP-based delay profile that can distinguish these, the combined delay profile has a preceding wave and a delayed wave as shown in FIG. Can distinguish waves.
Furthermore, when there are a plurality of incoming waves, the power-based delay profile becomes intermodulation, and there is a drawback that an originally existing incoming wave appears on the delay profile, but it does not appear in the combined delay profile. Thus, in the first embodiment, the delay profile can be obtained more accurately than in the conventional technique.

As described above, according to the first embodiment, the Fourier transform unit 2 that performs Fourier transform on the received OFDM signal for each transmission unit, and subcarrier power data is calculated from the data that is Fourier transformed by the Fourier transform unit 2. A subcarrier power calculation unit 9 that performs inverse Fourier transform on the subcarrier power data to generate a power-based delay profile, and a pilot signal from data Fourier-transformed by the Fourier transform unit 2. A pilot signal extracting unit 3 for extracting, a dividing unit 5 for dividing the pilot signal by a known value to calculate transmission line characteristic data for the pilot signal of each transmission unit, and transmission line characteristic data for the pilot signal of each transmission unit The time direction interpolation unit 6 for interpolating in the time direction and the transmission path characteristic data interpolated in the time direction The second inverse Fourier transform unit 10b that generates an SP-based delay profile by Fourier transform, and the arrival wave of the power-based delay profile so that the arrival times of the main wave of the power-based delay profile and the SP-based delay profile match. While offsetting the detection time, a value corresponding to the arrival time of a value greater than or equal to a predetermined threshold in the power-based delay profile in which the detection time of the incoming wave is offset among the SP-based delay profile is left, and the arrival time of a value less than the threshold And a delay profile synthesis unit 11 that outputs a delay profile of the received OFDM signal by replacing the value corresponding to 1 with a value not treated as an incoming wave (0 or a minimum value not treated as an incoming wave).
In this way, by deleting the pseudo-arrival wave of the SP-based delay profile using the power-based delay profile, a delay profile that combines the advantages of both the power-based delay profile and the SP-based delay profile is obtained. Even in a high-speed moving environment, an accurate arrival time and accurate power delay profile can be obtained.

Embodiment 2. FIG.
The basic structure of the digital broadcast receiving apparatus according to the second embodiment is the same as that of the first embodiment, but the method for creating a composite delay profile is different.
Therefore, the configuration of the digital broadcast receiving apparatus according to the second embodiment will be described in detail below with reference to FIG. 9 shown in the first embodiment and the details of the composite delay profile creation process according to the second embodiment. .

FIG. 12 is a flowchart showing a flow of operations performed by the delay profile synthesis unit according to the second embodiment of the present invention, and a new delay profile generation process will be described with reference to FIG.
The delay profile synthesis unit 11 detects the index of the main wave of the SP base delay profile (step ST1a). Since the main wave has the largest value in the delay profile, the index corresponding to the largest value is detected as the main wave index among the data of the SP-based delay profile.

  Next, the delay profile synthesis unit 11 calculates a main wave offset value corresponding to the difference between the main wave index of the SP base delay profile and the index of the center (demodulation reference point) of the SP base delay profile (step ST2a). ). Here, a value obtained by subtracting the index of the center (demodulation reference point) of the SP base delay profile from the index of the main wave of the SP base delay profile is obtained as the main wave offset value α.

  Subsequently, the delay profile synthesis unit 11 offsets the index of the power-based delay profile (step ST3a). Here, the index of the power base delay profile is offset by the amount of the main wave offset value α to replace each data, and the main wave indexes of the SP base delay profile and the power base delay profile are matched.

  The delay profile synthesizing unit 11 reads the power-based delay profile value obtained by offsetting the index in step ST3a one index at a time (step ST4a), and the SP base corresponding to the read value and the arrival time (index) of the read value. The delay profile value is multiplied (step ST5a).

Depending on the number of points of the inverse Fourier transform, the delay time between the SP base delay profile and the power base delay profile may not uniquely correspond. In this case, the closest delay time (index) value is selected and multiplied.
Also, if there is no SP-based delay profile value for the corresponding delay time, no processing is performed. This is because in the power-based delay profile, the delay time range (detection time range) is up to Ts / 2, while the SP-based delay profile is ± Ts / 6.

  Each time the above-described processing is executed, the delay profile combining unit 11 determines whether or not the processing has been completed for all indexes of the power-based delay profile (step ST6a). Here, if the processing has not been completed for all indexes of the power-based delay profile (step ST6a; NO), the process returns to step ST4a, and a value corresponding to the next index of the power-based delay profile is read, and step ST4a To step ST6a are repeated.

  When the above processing is completed for all indexes of the power base delay profile (step ST6a; YES), the delay profile synthesis unit 11 multiplies the values of the corresponding indexes between the power base delay profile and the SP base delay profile. The result is output as a delay profile of the received OFDM signal.

By generating the delay profile in this way, even if the SP-based delay profile includes a pseudo incoming wave, the pseudo-incoming wave does not appear in the power-based delay profile. The level can be reduced.
In addition, the power-based delay profile cannot distinguish between the preceding wave and the delayed wave, but it is also possible to distinguish these by combining with the SP-based delay profile.
Further, when there are a plurality of incoming waves, the power-based delay profile has cross-modulation, and there is a disadvantage that an incoming wave that does not exist originally appears on the delay profile, but an incoming wave that does not exist in the SP-based delay profile. Therefore, the level of the incoming wave can be reduced by combining by multiplication.
Thus, in the second embodiment, the delay profile can be obtained more accurately than in the conventional technique. In addition, since it is not necessary to compare the value of the power-based delay profile with a predetermined threshold, and it is not necessary to adjust the threshold, the apparatus configuration can be simplified as compared with the first embodiment.

As described above, according to the second embodiment, the Fourier transform unit 2 that performs Fourier transform on the received OFDM signal for each transmission unit, and subcarrier power data is calculated from the data that is Fourier transformed by the Fourier transform unit 2. A subcarrier power calculating unit 9, a first inverse Fourier transform unit 10 a that generates a power-based delay profile by performing inverse Fourier transform on the subcarrier power data, and a pilot signal from data Fourier transformed by the Fourier transform unit 2. A pilot signal extracting unit 3 for extracting; a dividing unit 5 for dividing the extracted pilot signal by a known value to calculate transmission path characteristic data for the pilot signal of each transmission unit; and a transmission path for the pilot signal of each transmission unit Time direction interpolation unit 6 for interpolating characteristic data in the time direction and transmission interpolated in the time direction The second inverse Fourier transform unit 10b that generates an SP base delay profile by performing inverse Fourier transform on the characteristic data, and the power base delay profile so that the arrival times of the main waves of the power base delay profile and the SP base delay profile match. The detection time of the incoming wave is offset, and the power-based delay profile offset from the detection time of the incoming wave is multiplied by the corresponding arrival time value of the SP-based delay profile, and output as the delay profile of the received OFDM signal A delay profile synthesizing unit 11.
In this way, by combining the power base delay profile value and the SP base delay profile, the error signal included in the power base delay profile and the error signal included in the SP base delay profile cancel each other, and a high-speed moving environment is obtained. Even so, it is possible to detect an accurate arrival time delay profile. Moreover, since it is not necessary to provide a threshold value, the apparatus configuration is simplified as compared with the first embodiment.

Embodiment 3 FIG.
The basic structure of the digital broadcast receiving apparatus according to the third embodiment is the same as that of the first embodiment, but the method for creating a composite delay profile is different.
Therefore, the configuration of the digital broadcast receiving apparatus according to the third embodiment will be described in detail below with reference to FIG. 9 shown in the first embodiment and the details of the composite delay profile creation process according to the third embodiment. .

FIG. 13 is an explanatory diagram for explaining delay profile synthesis processing according to Embodiment 3 of the present invention. As described with reference to FIG. 7 in the first embodiment, when the arrival time of the incoming wave exceeds ± Ts / 6 from the demodulation reference point, the SP-based delay profile turns back as a delayed wave, The delayed wave turns back as a preceding wave and appears on the delay profile. FIG. 13A shows a case where a preceding wave earlier than the time range of −Ts / 6 from the demodulation reference point is turned back and appears on the delay profile like a delayed wave.
On the other hand, as shown in FIG. 13C, the power-based delay profile has a time range in which an incoming wave can be detected up to Ts / 2, but the relative time difference between the delayed wave and the preceding wave with respect to the main wave is obtained. I can't. For this reason, in the incoming wave detected in the time range of ± Ts / 2 from the center (main wave) of the power-based delay profile, the preceding wave and the delayed wave cannot be distinguished.

Therefore, as shown in FIG. 13B, the delay profile synthesis unit 11 according to the third embodiment sets the delay profile contents in the detection time range of ± Ts / 6 with the demodulation reference point in the SP base delay profile as the center. A delay profile (third delay profile) copied before and after the detection time range of the initial SP base delay profile is created.
Since this delay profile coincides with the time range of ± Ts / 2 from the center of the power-based delay profile, the delay profile of the received OFDM signal is determined in the same manner as in the first embodiment or the second embodiment. Can be created.

That is, as in the first embodiment, the power-based delay profile in the time range of ± Ts / 2 from the center is offset (the SP-based delay profile and the main wave index are matched), and the offset-based power-based delay profile is processed. Is read one index at a time, compared with a predetermined threshold (threshold), and the value of the SP base delay profile corresponding to the read value index smaller than the threshold is replaced with 0 or the minimum value. The delay profile of the OFDM signal.
Further, as in the second embodiment, the power base delay profile value in the time range of ± Ts / 2 from the center is offset processed (the SP base delay profile and the main wave index are matched), and the offset processed power base A delay profile of the received OFDM signal is obtained by reading the value of the delay profile one index at a time and multiplying the read value by the SP base delay profile value corresponding to the arrival time (index) of the read value. And

  By combining the detection time range of the SP-based delay profile with the power-based delay profile, it is possible to correctly detect an incoming wave exceeding ± Ts / 6 that is reflected on the SP-based delay profile. There is also an advantage that the maximum detectable delay time can be extended to ± Ts / 2.

As described above, according to the third embodiment, the delay profile synthesis unit 11 determines the delay profile contents in the detection time range of the incoming wave in the SP-based delay profile output from the second inverse Fourier transform unit 10b. A delay profile of the received OFDM signal is generated using a delay profile copied before and after the detection time range and a power-based delay profile in a time range of ± Ts / 2 from the center.
By doing this, the same effects as those of the first embodiment or the second embodiment can be obtained, and the detection time range of the incoming wave in the SP-based delay profile can be expanded three times.

Embodiment 4 FIG.
FIG. 14 is a block diagram showing a configuration of a digital broadcast receiving apparatus according to Embodiment 4 of the present invention. In the configuration from the first embodiment to the third embodiment, the two inverse Fourier transform units, the first inverse Fourier transform unit 10a and the second inverse Fourier transform unit 10b, are provided. As shown in FIG. In addition, the digital broadcast receiving apparatus 1B according to the fourth embodiment includes only one inverse Fourier transform unit 10. That is, when the signal selection unit 12 switches between the output of the subcarrier power calculation unit 9 and the output of the time direction interpolation unit 6 and inputs the output to the inverse Fourier transform unit 10, one inverse Fourier transform unit 10 has the power. A base delay profile is generated and an SP base delay profile is generated. The memory unit 13 is a storage unit that stores the delay profile generated by the inverse Fourier transform unit 10, and the stored delay profile is appropriately read by the delay profile synthesis unit 11. In FIG. 14, the same components as those in FIG.

Next, the operation will be described.
The signal selection unit 12 selects the output of the subcarrier power calculation unit 9 and the output of the time direction interpolation unit 6 for the same received signal, and inputs them to the inverse Fourier transform unit 10.
The inverse Fourier transform unit 10 performs an inverse Fourier transform on the output signal of the subcarrier power calculation unit 9 and the output signal of the time direction interpolation unit 6 input via the signal selection unit 12, respectively, Each of the Q axes is squared and added to be stored in the memory unit 13 as a power base delay profile and an SP base delay profile.
At this time, as shown in the third embodiment, the inverse Fourier transform unit 10 obtains a profile obtained by copying the content of the detection time range of the SP base delay profile before and after the time series with respect to the SP base delay profile. It may be created and stored in the memory unit 13.
The delay profile synthesizing unit 11 uses the power-based delay profile and the SP-based delay profile stored in the memory unit 13 in the same manner as in any one of the first to third embodiments to receive the received OFDM signal. Create a delay profile.

  As described above, according to the fourth embodiment, the Fourier transform unit 2 that performs Fourier transform on the received OFDM signal for each transmission unit, and subcarrier power data is calculated from the data that is Fourier transformed by the Fourier transform unit 2. The subcarrier power calculating unit 9 for outputting, the pilot signal extracting unit 3 for extracting the pilot signal from the data Fourier-transformed by the Fourier transform unit 2, and dividing the extracted pilot signal by a known value to each transmission unit A division unit 5 that calculates transmission line characteristic data for each pilot signal, a time direction interpolation unit 6 that outputs the transmission line characteristic data for pilot signals of each transmission unit in the time direction, and a subcarrier power calculation unit 9 And the signal selection unit 12 that selects the output data of the time direction interpolation unit 6 by switching, and the signal selection unit 12 selects Inverse Fourier transform unit 10 that performs inverse Fourier transform on force data, and a power-based delay profile obtained by performing inverse Fourier transform on the output data of subcarrier power calculation unit 9 by inverse Fourier transform unit 10, and a time direction interpolation unit A memory unit 13 that stores an SP base delay profile obtained by performing inverse Fourier transform on the output data of 6, and the delay profile combining unit 11 reads the power base delay profile and the SP base delay profile read from the memory unit 13. Is output as a delay profile of the received OFDM signal. With this configuration, the number of inverse Fourier transform units can be reduced from two to one, and the circuit can be reduced.

Embodiment 5 FIG.
FIG. 15 is a block diagram showing a configuration of a digital broadcast receiving apparatus according to Embodiment 5 of the present invention. The digital broadcast receiving apparatus 1C according to the fifth embodiment has a Fourier transform timing generation unit 14 added to the configuration of the fourth embodiment. The Fourier transform timing generation unit 14 is a component that generates an optimal Fourier transform timing (start time position of Fourier transform) based on the output (synthesis delay profile) of the delay profile synthesis unit 11. The generated Fourier transform timing is notified from the Fourier transform timing generation unit 14 to the Fourier transform unit 2. For example, when an arrival wave having an arrival time exceeding the guard interval appears on the delay profile, the Fourier transform timing generation unit 14 changes the Fourier transform timing so as to be within the guard interval. Thereby, reception performance can be improved. The delay profile synthesis unit 11 creates a synthesis delay profile by a method similar to any one of the first to third embodiments.

  In the fifth embodiment, the time direction interpolation unit 6 and the frequency direction interpolation unit 7 each determine an optimum interpolation coefficient based on the output (synthesis delay profile) of the delay profile synthesis unit 11. For example, when an incoming wave that exceeds the band of the interpolation coefficient appears on the delay profile, the coefficient is changed to the interpolation coefficient so as to be within the band.

  The digital broadcast receiving apparatus according to the fifth embodiment includes the above-described Fourier transform timing control by the Fourier transform timing generation unit 14, control of the interpolation coefficient by the time direction interpolation unit 6, and interpolation by the frequency direction interpolation unit 7. Of the control of the insertion coefficient, at least one control is executed, and all the controls may be combined and executed.

As described above, according to the fifth embodiment, the Fourier transform timing generation unit 14 that determines the start timing (start time position) of the Fourier transform from the combined delay profile generated by the delay profile combining unit 11 is provided. The accurate start timing of the Fourier transform can be determined using the accurate delay profile that does not include the error signal generated by the delay profile synthesis unit 11.
In addition, since at least one of the time direction interpolation unit 6 and the frequency direction interpolation unit 7 determines an interpolation coefficient from the combined delay profile generated by the delay profile combining unit 11, the delay profile combining unit 11 generates the interpolation coefficient. An accurate delay profile that does not include the generated error signal can be used to determine the optimal interpolation factor.
By performing control using the error-free delay profile synthesis result in this way, erroneous control is eliminated even at high speeds or in environments with long delays, improving the reception performance of the receiver. It becomes possible to make it.

  In the fifth embodiment, the case where the Fourier transform timing generation unit 14 is added to the configuration of the fourth embodiment has been described. However, the concept of the fifth embodiment can be applied to any one of the first to third embodiments. Is applied, and at least one of the control of the Fourier transform timing by the Fourier transform timing generation unit 14, the control of the interpolation coefficient by the time direction interpolation unit 6, and the control of the interpolation coefficient by the frequency direction interpolation unit 7 is applied. May be configured to execute, or may be configured to execute all controls in combination.

  The digital broadcast receiving apparatus according to the present invention is an environment in which a mobile body on which the digital broadcast receiver is mounted moves at high speed or there is an incoming wave that exceeds the time range in which the incoming wave can be detected with the SP-based delay profile. Since a delay profile that does not include an error can be provided and accurate reception is possible without erroneous control, it is suitable for an on-vehicle digital broadcast receiving apparatus.

Claims (24)

In a digital broadcast receiving apparatus that receives an orthogonal frequency division multiplexed signal,
A Fourier transform unit for Fourier transforming the received orthogonal frequency division multiplexed signal for each transmission unit;
A subcarrier power calculation unit that calculates subcarrier power data from data Fourier-transformed by the Fourier transform unit;
A first inverse Fourier transform unit that generates a first delay profile by performing an inverse Fourier transform on the subcarrier power data calculated by the subcarrier power calculation unit;
A pilot signal extraction unit for extracting a pilot signal from data Fourier-transformed by the Fourier transform unit;
Dividing the pilot signal extracted by the pilot signal extraction unit by a known value to calculate transmission line characteristic data for the pilot signal of each transmission unit; and
A time direction interpolation unit that interpolates transmission path characteristic data for the pilot signal of each transmission unit calculated by the division unit in the time direction;
A second inverse Fourier transform unit that generates a second delay profile by performing inverse Fourier transform on the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit;
The first delay profile generated by the first inverse Fourier transform unit and the second delay profile generated by the second inverse Fourier transform unit match the first wave arrival times. And the arrival time of a value equal to or greater than a predetermined threshold in the first delay profile of the second delay profile offset from the detection time of the arrival wave. A delay profile synthesis unit that leaves a value and replaces a value corresponding to the arrival time of a value less than the threshold with a value not treated as an incoming wave, and outputs the value as a delay profile of the received orthogonal frequency division multiplexing signal A digital broadcast receiver characterized by that.   The delay profile synthesizing unit converts the contents of the detection time range of the incoming wave in the second delay profile before and after the detection time range instead of the second delay profile generated by the second inverse Fourier transform unit. Of the arrival wave of the first delay profile so that the arrival times of the main wave of the third delay profile copied to the first delay profile generated by the first inverse Fourier transform unit coincide with each other. While offsetting the detection time, a value corresponding to the arrival time of a value equal to or greater than a predetermined threshold in the first delay profile offset from the detection time of the incoming wave is left out of the third delay profile, and less than the threshold The value corresponding to the arrival time is replaced with a value that is not treated as an incoming wave, and the received orthogonal frequency division multiplexing signal Digital broadcast receiving apparatus according to claim 1, wherein the output as extension profile.   2. The digital broadcast according to claim 1, further comprising a Fourier transform timing generation unit that determines a start timing of Fourier transform by the Fourier transform unit based on the content of the delay profile generated by the delay profile synthesis unit. Receiver device.   The time direction interpolation unit determines an interpolation coefficient for the time direction interpolation of the transmission path characteristic data based on the content of the delay profile generated by the delay profile synthesis unit. The digital broadcast receiver according to 1. A frequency direction interpolation unit for interpolating the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit in the frequency direction;
The frequency direction interpolation unit determines an interpolation coefficient for frequency direction interpolation of the transmission path characteristic data based on a content of a delay profile generated by the delay profile synthesis unit. The digital broadcast receiver according to 1. In a digital broadcast receiving apparatus that receives an orthogonal frequency division multiplexed signal,
A Fourier transform unit for Fourier transforming the received orthogonal frequency division multiplexed signal for each transmission unit;
A subcarrier power calculation unit that calculates subcarrier power data from data Fourier-transformed by the Fourier transform unit;
A first inverse Fourier transform unit that generates a first delay profile by performing an inverse Fourier transform on the subcarrier power data calculated by the subcarrier power calculation unit;
A pilot signal extraction unit for extracting a pilot signal from data Fourier-transformed by the Fourier transform unit;
Dividing the pilot signal extracted by the pilot signal extraction unit by a known value to calculate transmission line characteristic data for the pilot signal of each transmission unit; and
A time direction interpolation unit that interpolates transmission path characteristic data for the pilot signal of each transmission unit calculated by the division unit in the time direction;
A second inverse Fourier transform unit that generates a second delay profile by performing inverse Fourier transform on the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit;
The first delay profile generated by the first inverse Fourier transform unit and the second delay profile generated by the second inverse Fourier transform unit match the first wave arrival times. And the first delay profile offset from the arrival time detection time and the corresponding arrival time value of the second delay profile, and A digital broadcast receiving apparatus comprising: a delay profile synthesis unit that outputs a delay profile of a received orthogonal frequency division multiplexed signal.   The delay profile synthesizing unit converts the contents of the detection time range of the incoming wave in the second delay profile before and after the detection time range instead of the second delay profile generated by the second inverse Fourier transform unit. Detection of the arrival wave of the first delay profile so that the arrival times of the main wave of the third delay profile copied to the first delay profile and the first delay profile generated by the first inverse Fourier transform unit coincide with each other The received orthogonal frequency division multiplex signal is obtained by multiplying a corresponding arrival time value of the first delay profile offset from the time of arrival and offsetting the detection time of the incoming wave and the third delay profile. 7. The digital broadcast receiving apparatus according to claim 6, wherein the digital broadcast receiving apparatus outputs the delay profile as a delay profile.   7. The digital broadcast according to claim 6, further comprising a Fourier transform timing generation unit that determines a start timing of Fourier transform by the Fourier transform unit based on the content of the delay profile generated by the delay profile synthesis unit. Receiver device.   The time direction interpolation unit determines an interpolation coefficient for the time direction interpolation of the transmission path characteristic data based on the content of the delay profile generated by the delay profile synthesis unit. 6. The digital broadcast receiver according to 6. A frequency direction interpolation unit for interpolating the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit in the frequency direction;
The frequency direction interpolation unit determines an interpolation coefficient for frequency direction interpolation of the transmission path characteristic data based on a content of a delay profile generated by the delay profile synthesis unit. 6. The digital broadcast receiver according to 6. In a digital broadcast receiving apparatus that receives an orthogonal frequency division multiplexed signal,
A Fourier transform unit for Fourier transforming the received orthogonal frequency division multiplexed signal for each transmission unit;
A subcarrier power calculation unit that calculates and outputs subcarrier power data from data Fourier-transformed by the Fourier transform unit;
A pilot signal extraction unit for extracting a pilot signal from data Fourier-transformed by the Fourier transform unit;
Dividing the pilot signal extracted by the pilot signal extraction unit by a known value to calculate transmission line characteristic data for the pilot signal of each transmission unit; and
A time direction interpolation unit for interpolating in the time direction and outputting transmission path characteristic data for pilot signals of each transmission unit calculated by the division unit;
A signal selection unit that switches and selects output data of the subcarrier power calculation unit and the time direction interpolation unit;
An inverse Fourier transform unit that performs inverse Fourier transform on the output data selected by the signal selection unit;
Obtained by inverse Fourier transform of the first delay profile obtained by inverse Fourier transform of the output data of the subcarrier power calculation unit and the output data of the time direction interpolation unit by the inverse Fourier transform unit A memory unit for storing a second delay profile;
The detection time of the arrival wave of the first delay profile is offset so that the arrival time of the main wave of the first delay profile and the second delay profile read from the memory unit match, and the first delay profile Among the two delay profiles, a value corresponding to the arrival time having a value greater than or equal to a predetermined threshold in the first delay profile in which the detection time of the incoming wave is offset is left and corresponds to the arrival time having a value less than the threshold. A digital broadcast receiving apparatus comprising: a delay profile synthesizing unit that outputs a value as a delay profile of the received orthogonal frequency division multiplexed signal by replacing a value with a value that is not treated as an incoming wave.   The delay profile synthesizing unit converts the contents of the detection time range of the incoming wave in the second delay profile before and after the detection time range instead of the second delay profile generated by the second inverse Fourier transform unit. And offsetting the detection time of the arrival wave of the first delay profile so that the arrival times of the main wave of the third delay profile copied to the first delay profile coincide with each other. Among the profiles, a value corresponding to the arrival time having a value greater than or equal to a predetermined threshold in the first delay profile offset from the detection time of the arrival wave is left, and a value corresponding to the arrival time having a value less than the threshold is set as the arrival wave. It is replaced with a value not treated as and is output as a delay profile of the received orthogonal frequency division multiplex signal. Digital broadcast receiving apparatus according to claim 11, wherein that.   12. The digital broadcast according to claim 11, further comprising a Fourier transform timing generation unit that determines a start timing of Fourier transform by the Fourier transform unit based on the content of the delay profile generated by the delay profile synthesis unit. Receiver device.   The time direction interpolation unit determines an interpolation coefficient for the time direction interpolation of the transmission path characteristic data based on the content of the delay profile generated by the delay profile synthesis unit. 11. A digital broadcast receiving apparatus according to 11. A frequency direction interpolation unit for interpolating the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit in the frequency direction;
The frequency direction interpolation unit determines an interpolation coefficient for frequency direction interpolation of the transmission path characteristic data based on a content of a delay profile generated by the delay profile synthesis unit. 11. A digital broadcast receiving apparatus according to 11. In a digital broadcast receiving apparatus that receives an orthogonal frequency division multiplexed signal,
A Fourier transform unit for Fourier transforming the received orthogonal frequency division multiplexed signal for each transmission unit;
A subcarrier power calculation unit that calculates and outputs subcarrier power data from data Fourier-transformed by the Fourier transform unit;
A pilot signal extraction unit for extracting a pilot signal from data Fourier-transformed by the Fourier transform unit;
Dividing the pilot signal extracted by the pilot signal extraction unit by a known value to calculate transmission line characteristic data for the pilot signal of each transmission unit; and
A time direction interpolation unit for interpolating in the time direction and outputting transmission path characteristic data for pilot signals of each transmission unit calculated by the division unit;
A signal selection unit that switches and selects output data of the subcarrier power calculation unit and the time direction interpolation unit;
An inverse Fourier transform unit that performs inverse Fourier transform on the output data selected by the signal selection unit;
Obtained by inverse Fourier transform of the first delay profile obtained by inverse Fourier transform of the output data of the subcarrier power calculation unit and the output data of the time direction interpolation unit by the inverse Fourier transform unit A memory unit for storing a second delay profile;
The arrival time of the arrival wave of the first delay profile is offset so that the arrival time of the main wave of the first delay profile and the second delay profile read from the memory unit match, and the arrival time Delay profile synthesis that multiplies the corresponding arrival time values of the first delay profile offset from the wave detection time and the second delay profile, and outputs the result as a delay profile of the received orthogonal frequency division multiplexed signal And a digital broadcast receiving apparatus.   The delay profile synthesizing unit converts the contents of the detection time range of the incoming wave in the second delay profile before and after the detection time range instead of the second delay profile generated by the second inverse Fourier transform unit. The detection time of the arrival wave of the first delay profile is offset so that the arrival time of the main wave of the third delay profile copied to each of the first delay profile and the first delay profile coincide with each other. The time delay offset first delay profile is multiplied by the corresponding arrival time value of the third delay profile and output as a delay profile of the received orthogonal frequency division multiplexed signal. Item 17. The digital broadcast receiver according to Item 16.   17. The digital broadcast according to claim 16, further comprising a Fourier transform timing generation unit that determines a start timing of Fourier transform by the Fourier transform unit based on the content of the delay profile generated by the delay profile synthesis unit. Receiver device.   The time direction interpolation unit determines an interpolation coefficient for the time direction interpolation of the transmission path characteristic data based on the content of the delay profile generated by the delay profile synthesis unit. 16. The digital broadcast receiver according to 16. A frequency direction interpolation unit for interpolating the transmission line characteristic data interpolated in the time direction by the time direction interpolation unit in the frequency direction;
The frequency direction interpolation unit determines an interpolation coefficient for frequency direction interpolation of the transmission path characteristic data based on a content of a delay profile generated by the delay profile synthesis unit. 16. The digital broadcast receiver according to 16. In a method for creating a delay profile of a received signal by a digital broadcast receiver that receives an orthogonal frequency division multiplexed signal,
Generating a first delay profile by performing inverse Fourier transform on subcarrier power data calculated from data obtained by performing Fourier transform on a received orthogonal frequency division multiplexed signal for each transmission unit;
The transmission path characteristic data for the pilot signal of each transmission unit obtained by dividing the pilot signal extracted from the data obtained by Fourier-transforming the received orthogonal frequency division multiplexing signal for each transmission unit by a known value is stored in the time direction. Inserting and inverse Fourier transforming the transmission path characteristic data interpolated in the time direction to generate a second delay profile;
Offsetting the detection time of the arrival wave of the first delay profile so that the arrival times of the main wave of the first delay profile and the second delay profile match;
Among the second delay profiles, a value corresponding to the arrival time of a value greater than or equal to a predetermined threshold in the first delay profile offset from the detection time of the incoming wave is left, and the arrival time of a value less than the threshold is supported And a step of replacing the value to be treated as a value not treated as an incoming wave and outputting the value as a delay profile of the received orthogonal frequency division multiplexing signal. In a method for creating a delay profile of a received signal by a digital broadcast receiver that receives an orthogonal frequency division multiplexed signal,
Generating a first delay profile by performing inverse Fourier transform on subcarrier power data calculated from data obtained by performing Fourier transform on a received orthogonal frequency division multiplexed signal for each transmission unit;
The transmission path characteristic data for the pilot signal of each transmission unit obtained by dividing the pilot signal extracted from the data obtained by Fourier-transforming the received orthogonal frequency division multiplexing signal for each transmission unit by a known value is stored in the time direction. Inserting and inverse Fourier transforming the transmission path characteristic data interpolated in the time direction to generate a second delay profile;
A third delay profile obtained by copying the contents of the detection time range of the incoming wave in the second delay profile before and after the detection time range, and a first delay profile generated by the first inverse Fourier transform unit Offsetting the arrival time of the first delay profile so that the arrival times of the main waves coincide with each other;
Of the third delay profile, a value corresponding to the arrival time of a value greater than or equal to a predetermined threshold in the first delay profile offset from the detection time of the incoming wave is left, and the arrival time of a value less than the threshold is supported And a step of replacing the value to be treated as a value not treated as an incoming wave and outputting the value as a delay profile of the received orthogonal frequency division multiplexing signal. In a method for creating a delay profile of a received signal by a digital broadcast receiver that receives an orthogonal frequency division multiplexed signal,
Generating a first delay profile by performing inverse Fourier transform on subcarrier power data calculated from data obtained by performing Fourier transform on a received orthogonal frequency division multiplexed signal for each transmission unit;
The transmission path characteristic data for the pilot signal of each transmission unit obtained by dividing the pilot signal extracted from the data obtained by Fourier-transforming the received orthogonal frequency division multiplexing signal for each transmission unit by a known value is stored in the time direction. Inserting and inverse Fourier transforming the transmission path characteristic data interpolated in the time direction to generate a second delay profile;
Offsetting the detection time of the arrival wave of the first delay profile so that the arrival times of the main wave of the first delay profile and the second delay profile match;
Multiplying the corresponding arrival time values of the first delay profile offset from the detection time of the incoming wave and the second delay profile, and outputs the result as the delay profile of the received orthogonal frequency division multiplexing signal A delay profile creating method comprising the steps of: In a method for creating a delay profile of a received signal by a digital broadcast receiver that receives an orthogonal frequency division multiplexed signal,
Generating a first delay profile by performing inverse Fourier transform on subcarrier power data calculated from data obtained by performing Fourier transform on a received orthogonal frequency division multiplexed signal for each transmission unit;
The transmission path characteristic data for the pilot signal of each transmission unit obtained by dividing the pilot signal extracted from the data obtained by Fourier-transforming the received orthogonal frequency division multiplexing signal for each transmission unit by a known value is stored in the time direction. Inserting and inverse Fourier transforming the transmission path characteristic data interpolated in the time direction to generate a second delay profile;
The arrival time of the main wave of the first delay profile matches the third delay profile obtained by copying the contents of the detection time range of the incoming wave in the second delay profile before and after the detection time range, respectively. Offsetting the detection time of the incoming wave of the first delay profile;
Multiplying the corresponding arrival time values of the first delay profile offset from the detection time of the arrival wave and the third delay profile, and outputs the result as the delay profile of the received orthogonal frequency division multiplexing signal A delay profile creating method comprising the steps of:

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