JP3793448B2 - Receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus that receives a transmission signal including an OFDM signal in which one symbol period includes a guard period and an effective symbol period, and particularly has a poor reception environment such as in-vehicle mobile reception or mobile reception. The present invention relates to a diversity reception type receiving apparatus corresponding to the situation.
[0002]
[Prior art]
In digital terrestrial broadcasting in Japan, Europe, etc., an OFDM (Orthogonal Frequency Division Multiplexing) system that is resistant to multipath interference is adopted. According to the OFDM system, since SFN (Single Frequency Network) reception is possible, the frequency can be used effectively. FIG. 6 is a diagram for explaining a symbol configuration example of an OFDM signal. As shown in the figure, one symbol period 501 is generally composed of a guard period 502 and an effective symbol period 503. Further, in the guard period 502, a part after the effective symbol period 503 is cyclically copied. With this configuration, intersymbol interference does not occur for the delayed multipath up to the length of the guard period 501.
[0003]
By the way, as a terrestrial digital broadcast receiver, a portable receiver having a small and portable shape corresponding to mobile reception and an in-vehicle mobile receiver have been proposed. Such a receiver is desired to have a performance capable of stable reception even when the reception environment becomes unstable during movement due to fading, fluctuations in electric field strength, and the like.
[0004]
One effective method for realizing stable reception while moving is diversity reception. As a conventional technique of a digital broadcast receiver using diversity reception, an OFDM signal such as “Digital Broadcast Receiver” described in Japanese Patent Laid-Open No. 2001-86091 and “OFDM Receiver” described in Japanese Patent Laid-Open No. 2001-168833 is used. As shown in the method of synthesizing each selected OFDM signal before demodulation after channel selection (referred to as synthesis processing on the time axis) or “OFDM receiver” described in Japanese Patent Laid-Open No. 2001-168833, There is a method of combining each demodulated modulated wave symbol signal after selecting and demodulating an OFDM signal (referred to as a combining process on the frequency axis).
[0005]
FIG. 7 is a schematic diagram of a conventional diversity receiver of the type that performs a combining process on the time axis.
[0006]
In the figure, reference numerals 601 and 603 are antennas for receiving transmission signals including OFDM signals, reference numerals 602 and 604 are tuners, reference numeral 605 is a synthesis circuit, reference numeral 606 is an OFDM demodulation circuit, reference numeral 607 is a demodulation / decoding circuit, and Reference numeral 608 denotes a data output terminal.
[0007]
An OFDM signal selected by the tuner 602 from transmission signals received by the antenna 601 is input to the synthesis circuit 605. Similarly, an OFDM signal selected by the tuner 604 from among transmission signals received by the antenna 603 is input to the synthesis circuit 605. The synthesizing circuit 605 is a method such as selective synthesis or maximum ratio synthesis of these two OFDM signals (for these methods, see, for example, “Shuichi Okaoka, Written by Wave Summit Course“ Mobile Communications ”, Ohmsha, March, 1999). , JP pp. 198-200, first edition, second printing ”). The OFDM demodulating circuit 606 generally extracts the signal of the effective symbol period 503 shown in FIG. 6 from the combined OFDM signal, and performs FFT (Fast Fourier Transform) on the frequency axis. Convert to a signal. Thereby, a modulated wave symbol signal of each of a plurality of orthogonal frequency signals constituting the OFDM signal is obtained. The demodulation / decoding circuit 607 demodulates each modulated wave symbol signal to obtain symbol data, decodes this to reproduce the data, and outputs the data from the data output terminal 608.
[0008]
FIG. 8 is a schematic diagram of a conventional diversity receiver of the type that performs a combining process on the frequency axis.
[0009]
In the figure, reference numerals 701 and 704 are antennas for receiving transmission signals including OFDM signals, reference numerals 702 and 705 are tuners, reference numerals 703 and 706 are OFDM demodulation circuits, reference numeral 707 is a synthesis circuit, reference numeral 708 is a demodulation / decoding circuit. Reference numeral 709 denotes a data output terminal.
[0010]
An OFDM signal selected by the tuner 702 from among transmission signals received by the antenna 701 is input to the OFDM demodulation circuit 703. The OFDM demodulating circuit 703 generally extracts the signal of the effective symbol period 503 shown in FIG. 6 from the selected OFDM signal, and performs FFT on this to convert it into a signal on the frequency axis. As a result, a modulated wave symbol signal of each of a plurality of orthogonal frequency signals constituting the OFDM signal is obtained and input to the synthesis circuit 707. Similarly, an OFDM signal selected by the tuner 705 from among transmission signals received by the antenna 704 is input to the OFDM demodulation circuit 706. The OFDM demodulation circuit 706 generally extracts the signal of the effective symbol period 503 shown in FIG. 6 from the selected OFDM signal, and performs FFT on this to convert it into a signal on the frequency axis. As a result, a modulated wave symbol signal of each of a plurality of orthogonal frequency signals constituting the OFDM signal is obtained and input to the synthesis circuit 707. The synthesis circuit 707 synthesizes the modulated wave symbol signals of these two systems using a technique such as selective synthesis or maximum ratio synthesis. Demodulation / decoding circuit 708 demodulates each synthesized modulated wave symbol signal to obtain symbol data, decodes this to reproduce the data, and outputs the data from data output terminal 709.
[0011]
[Problems to be solved by the invention]
By the way, in the conventional diversity receiver of the type that performs the combining process on the time axis, as described above, the same number of tuners as the antennas are required. Further, a synthesis circuit for synthesizing the OFDM signals selected by each tuner is required. On the other hand, a conventional diversity receiving apparatus of a type that performs a combining process on the frequency axis requires the same number of tuners and OFDM demodulation circuits as antennas. Also, a synthesis circuit for synthesizing the modulated wave symbol signal demodulated by each OFDM demodulation circuit is required.
[0012]
Thus, the conventional diversity receiver requires the same number of tuners or tuners and OFDM demodulation circuits as antennas. Also, a synthesis circuit for synthesizing the OFDM signal or the modulated wave symbol signal is required. For this reason, there exists a problem that an apparatus structure becomes large scale and cost increases.
[0013]
The present invention has been made in view of the above circumstances, and an object of the present invention is to realize diversity reception of OFDM signals with a relatively simple configuration.
[0014]
[Means for Solving the Problems]
In order to solve the above problem, the receiving apparatus of the present invention receives a transmission signal including an OFDM signal in which one symbol period includes a guard period and an effective symbol period.
[0015]
The receiving apparatus of the present invention is selected by the plurality of antennas that receive the transmission signal, a selection unit that selects one of the transmission signals received by the plurality of antennas, and the selection unit. A tuner that selects the OFDM signal from the transmission signal, and a signal located within an FFT (Fast Fourier Transform) window period are extracted from a symbol period of the OFDM signal that is selected by the tuner, and the extracted signal is subjected to FFT. And an OFDM demodulator that demodulates each modulated wave symbol signal of each of the orthogonal frequency signals constituting the OFDM signal, and a selection controller that controls the selection circuit.
[0016]
  Here, in the symbol period other than the FFT window period, the selection control unit sequentially switches the transmission signals from the plurality of antennas, compares the signal levels, and selects in the FFT window period according to the comparison result. The transmission signal from the antenna to be determined is determined, and the selection unit is controlled to select the transmission signal from the determined antenna.In addition, the tuner performs AGC (automatic gain control so as to keep the signal level of the selected OFDM signal constant. Auto Gain Control ) Has a function. The response time of the automatic gain control is set longer than the switching interval of the transmission signals from the plurality of antennas performed by the selection control unit in a symbol period other than the FFT window period, and the selection The interval is set shorter than the interval from the end of switching of the transmission signals from the plurality of antennas performed in the symbol period other than the FFT window period to the start time of the FFT window period.
[0017]
According to the receiving apparatus of the present invention, transmission signals from the plurality of antennas can be input to the selection unit, and the selection unit can select an antenna transmission signal having the best reception level. For this reason, since the processing means after the selection unit including the tuner and the OFDM demodulation unit can be made into one system, a diversity receiving apparatus for OFDM signals can be realized with a relatively simple configuration.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0019]
First, a first embodiment of the present invention will be described.
[0020]
FIG. 1 is a schematic diagram of a diversity receiver to which the first embodiment of the present invention is applied.
[0021]
In the figure, reference numerals 101a to 101d are antennas for receiving transmission signals including OFDM signals, reference numeral 102 is a selection circuit, reference numeral 103 is a tuner, reference numeral 104 is an ADC circuit (Analog Digital Converter), reference numeral Reference numeral 105 denotes an orthogonal demodulation circuit, reference numeral 106 denotes an FFT circuit, reference numeral 107 denotes a demodulation / decoding circuit, reference numeral 108 denotes a data output terminal, reference numeral 109 denotes an FFT window setting circuit, reference numeral 110 denotes a selection control circuit, and reference numeral 111 denotes an AGC ( Auto Gain Control (automatic gain control) circuit. Here, the orthogonal demodulation circuit 105 and the FFT circuit 106 correspond to an OFDM demodulation circuit. In the present embodiment, a case where four antennas are used will be described. However, the number of antennas may be any number as long as it is two or more.
[0022]
A transmission signal received by each of the antennas 101 a to 101 d is input to the selection circuit 102. The selection circuit 102 selects a transmission signal received by one of the antennas 101a to 101d in accordance with the selection control signal from the selection control circuit 110.
[0023]
The tuner 103 selects a desired OFDM signal designated by the operator or the like from the transmission signal selected by the selection circuit 102. Then, the selected OFDM signal is automatically gain controlled in accordance with the AGC signal from the AGC circuit 111 to be converted into an intermediate frequency OFDM signal and output to the ADC circuit 104.
[0024]
The ADC circuit 104 converts the intermediate frequency OFDM signal output from the tuner 103 into a digital signal and outputs the digital signal to the quadrature demodulation circuit 105. In response, the orthogonal demodulation circuit 105 converts the digitized OFDM signal into a complex baseband OFDM signal.
[0025]
The FFT circuit 106 extracts a signal included in the FFT window period set by the FFT window setting circuit 109 from the complex baseband OFDM signal output from the ADC circuit 104. Then, the extracted signal is subjected to FFT to be converted into a signal on the frequency axis. Thereby, a modulated wave symbol signal of each of a plurality of orthogonal frequency signals constituting the OFDM signal is obtained.
[0026]
The FFT window setting circuit 109 sets an FFT window period for extracting a signal from the symbol period at an optimal position corresponding to the multipath included in the OFDM signal selected by the tuner 103. Then, a first period signal for specifying the FFT window period is generated and output to the FFT circuit 106, and a period between the FFT window period and the FFT window period (symbol period-FFT window period coincides). ) Is generated and output to the selection control circuit 110.
[0027]
As described above, it is possible to construct an SFN in the OFDM scheme. In reception at the SFN, all transmission waves from stations other than the currently receiving station are observed in the same manner as multipath interference. This interference includes not only a path that arrives later than the desired reception wave, but also a path that reaches in advance, as compared with a normal multipath interference. Therefore, when an OFDM signal having the symbol configuration shown in FIG. 6 is used as a desired received wave, if the effective symbol period 503 is extracted as it is, a signal that has undergone intersymbol interference with a symbol 501 positioned before the symbol 501 to be extracted. The reception performance deteriorates. Therefore, the FFT window setting circuit 109 sets the period during which no intersymbol interference occurs to be the FFT window period.
[0028]
FIG. 2 is a diagram for explaining an OFDM signal subjected to multipath interference. Here, reference numeral 801 denotes a desired received wave, reference numeral 802 denotes a multipath that arrives late, and reference numeral 803 denotes a multipath that arrives in advance. As shown in the figure, after the symbol n of the desired received wave 801, the intersymbol interference caused by the preceding symbol n-1 in the multipath 802 that arrives late, and the one that follows the multipath 803 that arrives in advance. It is necessary to extract a signal included in the period 804 having the same length as the effective symbol period, which is not affected by the intersymbol interference caused by the symbol n + 1. This extraction period 804 is called an FFT window period. The FFT window period is adaptively controlled by examining the delay profile and symbol correlation.
[0029]
Regarding the setting of the FFT window period, “Orthogonal Frequency Division Multiplexing Receiver” described in Japanese Patent Publication No. 2963895 (Japanese Patent Laid-Open No. 2000-022657) or Japanese Patent Publication No. 3022854 (Japanese Patent Laid-Open No. 2000-134176). ) Described in “Delay Profile Analysis Device and Symbol Synchronization Method”.
[0030]
Demodulation / decoding circuit 107 demodulates each modulated wave symbol signal output from FFT circuit 106 to obtain symbol data, decodes this to reproduce the data, and outputs the data from data output terminal 108.
[0031]
The AGC circuit 111 measures the average power of the intermediate frequency OFDM signal digitized by the ADC circuit 104. Then, an AGC signal is generated and output so that the measured value becomes a predetermined reference value, and the tuner 103 performs automatic gain control of the selected OFDM signal.
[0032]
The selection control circuit 110 sets the selection processing period during the period specified by the second period signal output from the FFT window setting circuit 109. In this selection processing period, the selection circuit 102 is controlled using the selection control signal, the antennas 101a to 101d to be used are switched in order, and the output signal (complex baseband OFDM signal) of the orthogonal demodulation circuit 105 of each of the antennas 101a to 101d. ) Compare levels. Then, antennas 101a to 101d to be selected are determined according to the comparison result (in this embodiment, antennas 101a to 101d having the highest signal level are determined to be selected), and from the determined antennas 101a to 101d The selection circuit 102 is controlled using the selection control signal so as to select the transmission signal.
[0033]
FIG. 3 is a diagram for explaining the operation of the selection control circuit 110.
[0034]
In the figure, reference numeral 201 denotes a period indicating the level of the complex baseband OFDM signal obtained from the transmission signal of the antenna (here, the antenna 101b) selected at the previous time, that is, the symbol n-1, and reference numeral 206 denotes the current time. That is, this is a period indicating the level of the complex baseband OFDM signal obtained from the transmission signal of the antenna selected here at the symbol n (antenna 101a in this case). Reference numeral 202 denotes a period indicating the level of the complex baseband OFDM signal obtained from the transmission signal of the antenna 101a, reference numeral 203 denotes a period indicating the level of the complex baseband OFDM signal obtained from the transmission signal of the antenna 101b, reference numeral 204 Is a period indicating the level of the complex baseband OFDM signal obtained from the transmission signal of the antenna 101c, and reference numeral 205 is a period indicating the level of the complex baseband OFDM signal obtained from the transmission signal of the antenna 101d. Further, reference numeral 207 denotes a selection processing period, and reference numeral 208 denotes a period specified by the second period signal.
[0035]
Here, in order to simplify the description, the FFT window period is set without considering multipath. That is, the effective symbol period is set to the FFT window period. In this case, the period 208 specified by the second period signal coincides with the guard period.
[0036]
In the period 201, since the AGC function by the tuner 103 and the AGC circuit 111 is working, the average signal level of the complex baseband OFDM signal obtained from the transmission signal of the previously selected antenna indicates a steady level value. .
[0037]
Now, the selection control circuit 110 sets the selection processing period 207 within the period 208 specified by the second period signal received from the FFT window setting circuit 109. In the selection processing period 207, the selection circuit 102 is controlled using the selection control signal, and the antennas 101a to 101d to be used are switched in order. Thereby, in each of the periods 202 to 205, the average signal level of the complex baseband OFDM signal obtained from the transmission signals of the corresponding antennas 101a to 101d is measured.
[0038]
Here, in this embodiment, it is assumed that the response speed (time) of the AGC signal from the AGC circuit 111 is set to a time longer than each of the periods 202 to 205. For this reason, the AGC function of the tuner 103 does not work for the complex baseband OFDM signal output from the orthogonal demodulation circuit 105 in each of the periods 202 to 205. Accordingly, in the complex baseband OFDM signal output from the orthogonal demodulation circuit 105 in each of the periods 202 to 205, the signal level strength of the transmission signal from the corresponding antennas 101a to 101d appears as it is. Therefore, among the periods 202 to 205, the antennas 101a to 101d corresponding to the period indicating the maximum average signal level are the antennas having the highest transmission signal level.
[0039]
In the example shown in FIG. 3, the average signal level in the period 202 is the largest, and therefore the selection control circuit 110 controls the selection circuit 102 using the selection control signal so that the transmission signal from the antenna 101a is selected. . As a result, in the period 206, the antenna 101a is selected as the antenna selected this time.
[0040]
Here, in the present embodiment, the response speed (time) of the AGC signal from the AGC circuit 111 is shorter than the period between the selection process period 207 and the FFT window period (<period 208-selection process period 207). Is set. For this reason, the AGC function of the tuner 103 works until the FFT window period starts, and the average signal level of the complex baseband OFDM signal obtained from the transmission signal of the antenna selected this time settles to a steady level.
[0041]
The first embodiment of the present invention has been described above.
[0042]
According to the present embodiment, with the above configuration, transmission signals from the plurality of antennas 101a to 101d are input to the selection circuit 102, and the selection circuit 102 selects the transmission signals of the antennas 101a to 101d having the best reception level. . For this reason, as shown in FIG. 1, the processing circuit after the selection circuit 102 can be made into one system, so that a diversity receiving apparatus for OFDM signals can be realized with a relatively simple configuration.
[0043]
Next, a second embodiment of the present invention will be described.
[0044]
FIG. 4 is a schematic diagram of a diversity receiver to which the second embodiment of the present invention is applied. Here, components having the same functions as those of the first embodiment shown in FIG.
[0045]
This embodiment is different from the first embodiment shown in FIG. 1 in that a selection control circuit 301 and an AGC circuit 302 are used in place of the selection control circuit 110 and the AGC circuit 111. Others are the same as the first embodiment shown in FIG.
[0046]
The AGC circuit 302 measures the average power of the intermediate frequency OFDM signal digitized by the ADC circuit 104, generates and outputs an AGC signal so that the measured value becomes a predetermined reference value, and outputs to the tuner 103. The automatic gain control of the selected OFDM signal is performed. This is the same as the first embodiment described above, but is different from the AGC circuit 111 of the first embodiment in that the AGC function is stopped while the AGC stop signal is output from the selection control circuit 301.
[0047]
The selection control circuit 301 sets the selection processing period during the period specified by the second period signal output from the FFT window setting circuit 109. In this selection processing period, the selection circuit 102 is controlled using the selection control signal, the antennas 101a to 101d to be used are switched in order, and the output signal (complex baseband OFDM signal) of the orthogonal demodulation circuit 105 of each of the antennas 101a to 101d. ) Compare levels. Then, antennas 101a to 101d to be selected are determined according to the comparison result (in this embodiment, antennas 101a to 101d having the highest signal level are determined to be selected), and from the determined antennas 101a to 101d The selection circuit 102 is controlled using the selection control signal so as to select the transmission signal. This is the same as the selection control circuit 110 of the first embodiment. However, the selection control circuit 301 of the present embodiment further outputs an AGC stop signal for stopping the AGC function to the AGC circuit 302 during the set selection processing period.
[0048]
FIG. 5 is a diagram for explaining the operation of the selection control circuit 301. Here, the same code | symbol is attached | subjected to what shows the period same as each period shown in FIG.
[0049]
In the period 201, since the AGC function by the tuner 103 and the AGC circuit 302 is working, the average signal level of the complex baseband OFDM signal obtained from the transmission signal of the antenna selected last time indicates a steady level value. .
[0050]
Now, the selection control circuit 301 sets the selection processing period 207 within the period 208 specified by the second period signal received from the FFT window setting circuit 109. In the selection processing period 207, the selection circuit 102 is controlled using the selection control signal, and the antennas 101a to 101d to be used are switched in order. Thereby, in each of the periods 202 to 205, the average signal level of the complex baseband OFDM signal obtained from the transmission signals of the corresponding antennas 101a to 101d is measured.
[0051]
Here, in the present embodiment, the AGC stop signal is output from the selection control circuit 301 during the selection processing period 207. As a result, the AGC circuit 302 and the tuner 103 stop the AGC function during the selection processing period 207. Specifically, during the selection processing period 207, the AGC circuit 302 maintains the signal value of the AGC signal immediately before the AGC function is stopped, that is, causes the AGC circuit 302 to maintain the gain immediately before the AGC function is stopped, An AGC signal having a signal value is output. FIG. 4 shows an example of the former.
[0052]
For this reason, the AGC function of the tuner 103 does not work for the complex baseband OFDM signal output from the orthogonal demodulation circuit 105 in each of the periods 202 to 205. Accordingly, in the complex baseband OFDM signal output from the orthogonal demodulation circuit 105 in each of the periods 202 to 205, the signal level strength of the transmission signal from the corresponding antennas 101a to 101d appears as it is. Therefore, among the periods 202 to 205, the antennas 101a to 101d corresponding to the period indicating the maximum average signal level are the antennas having the highest transmission signal level.
[0053]
In the example shown in FIG. 5, the average signal level in the period 202 is the largest, and therefore the selection control circuit 301 controls the selection circuit 102 using the selection control signal so that the transmission signal from the antenna 101a is selected. . As a result, in the period 206, the antenna 101a is selected as the antenna selected this time.
[0054]
Now, when the selection processing period 207 ends, that is, when the period 206 starts, the control control circuit 301 stops outputting the AGC stop signal. As a result, the AGC function by the AGC circuit 302 and the tuner 103 is restarted, and the average signal level of the complex baseband OFDM signal obtained from the transmission signal of the currently selected antenna quickly settles to a steady level value.
[0055]
The second embodiment of the present invention has been described above.
[0056]
According to the present embodiment, in addition to the effect of the first embodiment described above, there is an advantage that the response speed of the AGC operation can be freely set because the response speed of the AGC operation is not limited.
[0057]
In addition, this invention is not limited to said embodiment, Many deformation | transformation are possible within the range of the summary.
[0058]
For example, in each of the above embodiments, the selection control circuits 110 and 301 set the selection processing period 207 within a period other than the FFT window period in the symbol period according to the second period signal output from the FFT window setting circuit 109. It is set. However, when the FFT window period is fixed to the effective symbol period, the guard period may be specified from the FFT window period and the symbol period and set within the guard period.
[0059]
Further, in each of the above embodiments, the present invention is also effective for a configuration that does not require the AGC circuits 111 and 302.
[0060]
【The invention's effect】
As described above, according to the present invention, diversity reception of OFDM signals can be realized with a relatively simple configuration.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a diversity receiver to which a first embodiment of the present invention is applied.
FIG. 2 is a diagram for explaining an OFDM signal subjected to multipath interference;
FIG. 3 is a diagram for explaining an operation of a selection control circuit 110 shown in FIG. 1;
FIG. 4 is a schematic diagram of a diversity receiver to which the second embodiment of the present invention is applied.
5 is a diagram for explaining an operation of a selection control circuit 301 shown in FIG. 4; FIG.
FIG. 6 is a diagram for explaining a symbol configuration example of an OFDM signal.
FIG. 7 is a schematic diagram of a conventional diversity receiver.
FIG. 8 is a schematic diagram of a conventional diversity receiver.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101a-101d ... Antenna 102 ... Selection circuit 103 ... Tuner 104 ... ADC circuit 105 ... Orthogonal demodulation circuit 106 ... FFT circuit 107 ... Demodulation / decoding circuit 108 ... Data output terminal 109 ... FFT window setting circuit 110, 301 ... selection control circuit, 111, 302 ... AGC circuit

Claims (6)

A receiving apparatus that receives a transmission signal including an OFDM (Orthogonal Frequency Division Multiplexing) signal in which one symbol period includes a guard period and an effective symbol period,
A plurality of antennas for receiving the transmission signals;
A selection unit that selects one of the transmission signals received by the plurality of antennas;
A tuner for selecting the OFDM signal from the transmission signal selected by the selection unit;
A signal located within an FFT (Fast Fourier Transform) window period is extracted from the OFDM signal symbol period selected by the tuner, and each of the orthogonal frequency signals constituting the OFDM signal is subjected to FFT on the extracted signal. An OFDM demodulator for demodulating the modulated wave symbol signal of
A selection control unit for controlling the selection circuit,
The selection control unit
In the symbol period other than the FFT window period, the transmission signals from the plurality of antennas are sequentially switched to compare the signal levels, and the transmission signal from the antenna to be selected in the FFT window period is determined according to the comparison result. Determining and controlling the selection unit to select the transmission signal from the determined antenna ;
The tuner is
An AGC ( Auto Gain Control ) function for automatically controlling the gain so as to keep the signal level of the selected OFDM signal constant ;
The response time of the automatic gain control is
The selection control unit is set to be longer than the switching interval of the transmission signals from the plurality of antennas performed in the symbol period other than the FFT window period, and the selection control unit is in the symbol period other than the FFT window period. A receiving apparatus , wherein the interval is set to be shorter than an interval from the end of switching of the transmission signals from the plurality of antennas to the start of the FFT window period . The receiving device according to claim 1,
The selection control unit
A receiving apparatus, wherein the transmission signal from an antenna having the highest signal level is determined as a selection target. The receiving device according to claim 1 or 2 ,
The selection control unit
The receiving apparatus, wherein the selection control unit stops the AGC function of the tuner during a period in which the transmission signals from the plurality of antennas are sequentially switched in a symbol period other than an FFT window period. The receiving device according to claim 3 ,
The tuner is
A receiving apparatus that performs gain control of a signal level of the selected OFDM signal so as to obtain a gain immediately before the AGC function is stopped while the AGC function is stopped. Claim 1, 2, 3 or is a receiving apparatus according 4,
The receiving apparatus further comprising: an FFT window setting unit that sets an FFT window period in the OFDM demodulating unit. Claim 1, 2, 3 or is a receiving apparatus according 4,
The FFT apparatus, wherein the FFT window period coincides with the effective symbol period.

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