JP2008167192A - Diversity receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity receiver capable of obtaining an excellent diversity effect regardless of traveling speed. <P>SOLUTION: The diversity receiver (100) includes: a plurality of branches (10, 20) for outputting a plurality of reception signals; a fading frequency detecting part (6) for detecting a fading frequency; frequency selection fading detecting parts (16, 26) for detecting the frequency selection fading of each branch; a plurality of weighting parts (17, 27) for weighting the reception signals to be outputted from the respective branches; and a synthesizing part (30) for synthesizing the plurality of reception signals weighted by the weighting part. The weighting parts are controlled based on the detection result of the fading frequency detecting part and the detection results of the frequency selection fading detecting parts. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a diversity receiver in the field of mobile communication, and more particularly to a diversity receiver in digital broadcast reception.

  In mobile communication, radio waves are reflected and scattered by surrounding buildings and terrain, and radio waves that have passed through a plurality of propagation paths arrive and interfere with each other, resulting in fading. In order to reduce the influence of such fading, there is a diversity reception method as a method of combining two or more received waves to improve transmission quality.

  Also, a diversity receiver that detects the envelope levels of the signals received by the two branches, weights the received signals of each branch according to the envelope level, and synthesizes the weighted signals Is known (see, for example, Patent Document 1).

  FIG. 1 is a diagram schematically illustrating a conventional diversity receiver.

  In the receiver shown in FIG. 1, the first antenna 1, the first antenna amplifier 11, the first tuner unit 12, the first A / D converter 13, the first branch 10 having the first FFT unit 14, and the second antenna 2. And a second branch 20 having a second antenna amplifier 21, a second tuner unit 22, a second A / D converter 23, and a second FFT unit 24, and receiving signals from the first and second branches 10 and 20. In the synthesis unit 30, synthesis is performed.

  FIG. 2 is a diagram for explaining a basic operation in the conventional receiver shown in FIG.

  2A shows the received signal level for each frequency of the first branch 10, FIG. 2B shows the received signal level for each frequency of the second branch 20, and FIG. 2C shows the first and second levels. A signal obtained by combining the received signals of the two branches 10 and 20 with a maximum ratio for each frequency is shown.

  In the first and second branches 10 and 20, when the AGC circuit works, the output signal is individually adjusted so that the signal level becomes a predetermined level. For example, even when the reception state of the first branch 10 is not good (that is, when the initial output signal is generally at a low level as shown by the waveform 40 in FIG. 2A), the AGC circuit works. Therefore, it is amplified to a signal level like the waveform 41 in FIG. However, since the signal whose reception state was originally not good includes noise, it is amplified together with the noise by the AGC circuit. Therefore, the output signals of the first and second branches 10 and 20 have the same signal level, but have different C / N ratios, and synthesis is performed with the same weighting between branches having different C / N ratios. Then, there was a problem that the diver effect deteriorated.

  Such degradation of the diver effect due to the operation of the AGC circuit is likely to occur when the vehicle is stopped or traveling at a low speed with a low fading frequency.

  Even when there is a sensitivity difference between the first and second branches 10 and 20, the output signals of the first and second branches 10 and 20 have the same signal level due to the operation of the AGC circuit. As a result, the diver effect is deteriorated.

JP-A-8-79146 (FIG. 1)

  Therefore, an object of the present invention is to provide a diversity receiver that can solve the above-described problems.

  Another object of the present invention is to provide a diversity receiver capable of obtaining a good diver effect regardless of the traveling speed.

  Another object of the present invention is to provide a diversity receiver capable of receiving digital data satisfactorily regardless of the traveling speed.

  A diversity receiver according to the present invention includes a plurality of branches that output a plurality of received signals, a fading frequency detection unit for detecting a fading frequency, and a frequency selection fading detection unit for detecting frequency selective fading of each branch And a plurality of weighting units for weighting received signals output from each branch, and a combining unit for combining a plurality of received signals weighted by the weighting unit, Control is based on the detection result of the fading frequency detection unit and the detection result of the frequency selective fading detection unit.

  In addition, the diversity receiver according to the present invention includes a plurality of branches that output a plurality of received signals, a fading frequency detector for detecting a fading frequency, and a frequency for detecting frequency selective fading of at least one branch. A selection fading detection unit, a weighting unit for weighting an output signal from at least one branch, and a combining unit for combining a reception signal weighted by the weighting unit and a reception signal output from another branch And the weighting unit is controlled based on the detection result of the fading frequency detection unit and the detection result of the frequency selective fading detection unit.

  According to the diversity receiver according to the present invention, it is possible to prevent the diver effect from being lowered by the AGC circuit following when the fading frequency is small.

  In addition, according to the diversity receiver according to the present invention, weighting of a plurality of branches can be set in accordance with fading frequency and frequency selective fading, so that it is related to the traveling speed of the vehicle on which the diversity receiver is mounted. Therefore, it became possible to receive good digital data.

  Hereinafter, a diversity receiver 100 according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an overview of a diversity receiver 100 according to the present invention.

  A diversity receiver 100 includes a first antenna amplifier 11, a first tuner unit 12, a first A / D converter 13, a first FFT (Fast Fourier Transform) unit 14, a first AGC (Auto Gain Control) circuit 15, and a first equalization. A second branch including a first branch 10 having a section 18, a second antenna amplifier 21, a second tuner section 22, a second A / D converter 23, a second FFT section 24, a second AGC circuit 25, and a second equalization section 28. 20. First detection unit 16 for detecting a first scattered pilot signal from a signal output from the first FFT unit, and a first weighting unit 17 for weighting a signal output from the first equalization unit 18. The second detector 26 detects the second scattered pilot signal from the signal output from the second FFT unit 24, and weights the signal output from the second equalizer 28. A synthesizing unit 30, a demodulating unit 40, a demultiplexing unit 50, an audio decoding unit 60, and an audio processing unit that synthesize the signals weighted by the double weighting unit 27, the first weighting unit 17, and the second weighting unit 27, respectively. 61, a video decoding unit 70, a video processing unit 71, a control unit 80, a memory 81, an I / O 82, and the like.

  The diversity receiver 100 includes a first antenna 1, a second antenna 2, an audio output unit 3 including a plurality of in-vehicle speakers, an operation unit such as a touch panel and buttons, and a display unit 4 including an in-vehicle liquid crystal display, Position information (GPS data) of the vehicle on which diversity receiver 100 is mounted, navigation unit 5 that outputs at least traveling direction information indicating the traveling direction of the vehicle, and vehicle speed detection that detects the vehicle speed of the vehicle on which diversity receiver 100 is mounted. Connected to part 6 and the like. The diversity receiver 100 includes one or more of the first and second antennas 1 and 2, the audio output unit 3, the display unit 4, the navigation device 5, and the vehicle speed detection unit 6 described above, and You may comprise so that it may be contained in any one or more. In addition, as the 1st antenna 1 and the 2nd antenna 2, all types, for example, the film type antenna etc. which are used for a vehicle, can be utilized.

  Furthermore, the diversity receiver 100 includes power ON / OFF, channel selection instructions, and the like by operation inputs from various input devices (buttons, touch panel, etc.) provided on the display unit 4 and / or a remote controller (not shown). It was configured to be controlled by.

  For example, signals received by the first antenna 1 attached to the front side of the vehicle and the second antenna 2 attached to the rear side of the vehicle are amplified by the first antenna amplifier 11 and the second antenna amplifier 21, respectively. The signals are tuned by the first tuner unit 12 and the second tuner unit 22 and input to the first FFT unit 14 and the second FFT unit 24. In the first FFT unit 14 and the second FFT unit 24, for example, the start position of the symbol in each received signal is detected, the Fourier transform is performed on a symbol basis, and the first equalization unit 18 and the second equalization unit 28 are informed. Output. The Fourier-transformed signals input to the first equalization unit 18 and the second equalization unit 28 are corrected according to the respective transmission path characteristics, and the first weighting unit 17 and the second weighting unit 27, respectively. Is input. Then, the first weighting unit 17 and the second weighting unit 27 perform predetermined weighting as will be described later, and are synthesized by the synthesis unit 30 and input to the demodulation unit 40.

  Here, the first branch 10 has a first AGC circuit 15 and outputs a first S level signal for feedback control of the first tuner unit 12 so that the received signal has a desired reception level. Similarly, the second branch 20 also has a second AGC circuit 25 and outputs a second S level signal for feedback control of the second tuner unit 22 so that the received signal has a desired reception level. The controller 80 is configured to be able to acquire the first and second S level signals as signals indicating the reception status of the first branch and the second branch, respectively.

  The first detection unit 16 detects the first scattered pilot signal from the signal output from the first FFT unit 14 and outputs the first scattered pilot signal to the control unit 80. Similarly, the second detection unit 26 detects the second catered pilot signal from the signal output from the second FFT unit 24 and outputs it to the control unit 80. In the control unit 80, the degree of frequency selective fading of the signals received in the first and second branches is estimated from the depth and number of deps of the first and second scattered pilot signals. The estimation of the degree of frequency selective fading will be described later.

  The combining unit 30 includes a signal from the first FFT unit 14 that has been given a predetermined weight by the first weighting unit 17, and a signal from the second FFT unit 24 that has been given a predetermined weight by the second weighting unit 27. Can be output with the maximum ratio synthesis.

  The demodulator 40 performs a deinterleave process, an error correction process, and the like on the combined signal input from the combiner 30 and outputs a TS packet signal. The demultiplexing unit 50 separates the TS packet signal from the demodulating unit 40 and outputs the TS packet signal related to audio to the audio decoder unit 60 and the TS packet signal related to video to the video decoder unit 70.

  The audio decoder unit 60 decodes the received TS packet signal, generates audio digital data, and outputs the audio digital data to the audio processing unit 61. The audio processing unit 61 converts the received audio digital data into analog data, adjusts the volume, adjusts the timing of the video data, and the like, and outputs the result to the audio output unit 3.

  The video decoder unit 70 decodes the received TS packet signal, generates video digital data, and outputs the video digital data to the video processing unit 71. The video processing unit 71 changes the image size of the received video digital data so as to fit the screen size of the display unit 130 (for example, 800 × 640 pixels), or synthesizes graphic data for video broadcasting and video data. Processing is performed and output to the display unit 4.

  The control unit 80 includes a CPU, a RAM, a ROM, and the like, operates according to a program installed in advance, and controls each element of the connected diversity receiver 100. The control unit 80 also includes first and second S level signals from the first and second AGC circuits 15 and 25, first and second scattered pilot signals from the first and second detection units 16 and 26, and navigation. The first and second weighting units 17 and 27 are used based on a control flow to be described later by using part or all of the vehicle position information and traveling direction information from the device 5 and the vehicle speed information from the vehicle speed detection unit 6. To set each weighting.

  FIG. 4 is a diagram for explaining a method of estimating the degree of frequency selective fading from the scattered pilot signal.

  FIG. 4 shows a scattered pilot signal detected every 12 KHz in the frequency band (5.6 MHz) of one selected channel (CH) in digital television broadcasting. The scattered pilot signal is a signal that can be used as a reference signal indicating the reception state. If the reception state is good, the signal level (No) at the time of transmission is detected at the time of reception, but the reception state As the signal level deteriorates, the detection level at the time of reception decreases. Also, a scattered pilot signal that is lower than the signal level (No) at the time of transmission is called a dip. Therefore, the degree of frequency selective fading of the received signal is estimated by setting a threshold value (Ns) (for example, −3 dB) and counting the number of deps (three places shown as 42 in FIG. 4) lower than that. It is possible.

  For example, when the number of deps is 30% or more of the whole, the degree of frequency selective fading is (large), and when the number of deps is less than 30% of the whole and 15% or more, the degree of frequency selective fading is (medium). When the number of dips is less than 15% of the total, the degree of frequency selective fading can be determined as (small). It should be noted that the maximum value of the depth of the dip is obtained (shown as 43 in FIG. 4), and the degree of frequency selective fading may be determined based on the maximum value.

  FIG. 5 is a diagram for explaining an example of a control flow of the diversity receiver 100.

  The control flow shown in FIG. 5 is executed by controlling each element of the diversity receiver 100 according to a program in which the control unit 80 is installed in advance.

  First, the control unit 80 acquires the AGC control amount of each branch using the first and second S level signals from the first and second AGC circuits 15 and 25 (S1).

  Next, the gain of the first branch 10 including the first antenna 1 and the cable from the first antenna 1 to the first antenna amplifier 11, and the gain from the second antenna 2 and the second antenna 2 to the first antenna amplifier 21. The gain of the second branch 20 including the cable is acquired (S2). Since these gains can be obtained by performing measurement or the like before the installation of the first and second antennas 1 and 2, etc., it is assumed that they are stored in the memory 81 or the like in advance. Therefore, the control unit 80 accesses the memory 81 and acquires the gains (sensitivity information) of the first and second branches.

  Next, the control unit 80 acquires the first and second scattered pilot signals from the first and second detection units 16 and 26, and for example, the first and second branches 10 by the method described with reference to FIG. And 20 respectively, the degree of frequency selective fading is estimated (S3).

  Next, the control unit 80 acquires the speed of the vehicle based on the vehicle speed signal from the vehicle speed detection unit 6 (S4).

  Next, the control unit 80 corrects the AGC control amount of each branch using the gain of the branch acquired in Step 2 (S5). For example, when the gain of the first branch 10 is G1 and the AGC control amount is S1, the gain of the second branch 20 is G2, and the AGC control amount is S2, the correction value of the AGC control amount of the first branch 10 is S1. × G2 / (G1 + G2), and the correction value of the AGC control amount of the second branch 20 is S2 × G1 / (G1 + G2).

  Next, the control unit 80 determines whether the correction value of each AGC control amount acquired in step 5 is large, medium, or small based on a predetermined criterion (S6). The weight is set to rank 2 (S7), the weight is set to rank 6 if medium (S8), and the weight is set to rank 8 if large (S9).

  FIG. 6 shows an example of the weight rank table.

  As shown in FIG. 6, a weighted rank of 1 to 8 is set, the lowest is rank 1, and in that case, the signal is set to be 1/8, and the maximum is rank 8, in which case the signal is It is set to be fully synthesized. In addition, it is assumed that the weighting rank shown in FIG. In addition, the weighting rank shown in FIG. 6 is an example, Comprising: It is not limited to this.

  Next, based on the vehicle speed acquired in step 4, the control unit 80 is in a stopped state, operating at a low speed (for example, less than 30 km / h), or operating at a high speed (for example, 30 km / h or more). (S10), if the speed is high, the weighting rank is not changed (S11), if the speed is low, the weighting rank is lowered by one (S12), and if the speed is stopped, the weighting is weighted. The rank is lowered by 2 (S13).

  Next, the control unit 80 determines whether the degree of frequency selection fading acquired in step 3 is large, medium, or small (S14). If the degree is small, the weighting rank is not changed ( S15) If the medium is medium, the weighted rank is lowered by 1 (S16), and if large, the weighted rank is lowered by 2 (S17).

  Next, the control unit 80 performs weighting in the first and second weighting units 17 and 27 based on the weighting rank as a result of performing the setting and changing based on the determinations in steps 6, 10, and 14. Setting is performed (S18), and a series of procedures is terminated.

  For example, when it is determined in step 6 that the correction value of the AGC control amount is small for the first branch 10, the weighting rank 8 is first set in step 9, and then the vehicle is traveling at a low speed in step 10. If it is determined that there is, the weighting rank is lowered by 1 from 8 in step 12 and is reset to 7; if it is determined in step 14 that the frequency selection fading is medium, the weighting rank is determined in step 16. It will be lowered by one rank from 7 and reset to 6. Therefore, in such a case, the control unit 80 sets the first weighting unit 17 to rank 6 (that is, a weighting factor of 6/8).

  In the above control flow, first, the weight rank is determined according to the correction value of the AGC control amount (see S6 to S9). That is, the correction value of the AGC control amount indicates the reception sensitivity state in consideration of the original gain difference of each branch. Therefore, when the correction value of the AGC control amount is large, it is considered that the reception sensitivity state is bad. Therefore, the weighting rank is set to be low (the signal level at the time of synthesis is reduced to reduce the influence). Yes. Conversely, when the correction value of the AGC control amount is small, the reception sensitivity state is considered good, so the weighting rank is set high (increasing the signal level during synthesis to increase the influence). is doing.

  Secondly, the weighting rank is determined according to the vehicle speed (see S10 to S13). That is, when the vehicle is traveling at high speed, the fading frequency is high and AGC control cannot follow, so that the AGC correction as described in the related art does not cause a problem that the diver effect is deteriorated. Therefore, it is set so that the weighting rank is not changed during traveling at high speed. On the contrary, when the vehicle is stopped, the fading frequency is the lowest and AGC control follows. Therefore, the AGC correction as described in the related art works, which causes a problem that the diver effect is deteriorated. Therefore, when the vehicle is stopped, the weighting rank is set to be lowered (the signal level at the time of synthesis is lowered to reduce the influence). Thus, in this control flow, the degree of the fading frequency is estimated based on the vehicle speed by utilizing the fact that the vehicle speed is proportional to the fading frequency.

  Third, a weighted rank is determined according to frequency selection fading (S14 to S17). That is, when the degree of frequency selective fading that can be predicted from the scattered pilot signal is large, there is a high possibility that a frequency region with poor reception sensitivity exists in the received signal. The signal level is lowered to reduce the influence). On the other hand, when the degree of frequency selective fading is small, there is a high possibility that the reception sensitivity is good in the entire frequency band of the received signal, so that the weighting rank is not changed.

  In the above control flow, the weighting rank is determined from the above-described three elements, and control is performed so that optimum weighting is performed.

  In the example described above, control is performed so that weighting is set for each of the first and second branches 10 and 20. However, the smaller correction value of the AGC control amount is fixed to the weighting rank 8, and the other Only the weighted rank may be obtained according to the flow of FIG.

  FIG. 7 is a diagram for explaining another example of the control flow of the diversity receiver 100.

  The control flow shown in FIG. 7 is executed by controlling each element of the diversity receiver 100 according to a program in which the control unit 80 is installed in advance. In the control flow of FIG. 7, the weighting rank (see FIG. 6) and frequency selection fading estimation method are the same as those described in the control flow shown in FIG.

  First, the control unit 80 acquires the gain of the first antenna 1 and the gain of the second antenna 2 (S21). Since these gains can be acquired in advance, it is assumed that they are stored in advance in the memory 81 or the like. Therefore, the control unit 80 accesses the memory 81 and acquires the gains (sensitivity information) of the first and second antennas.

  Next, the control unit 80 acquires the first and second scattered pilot signals from the first and second detection units 16 and 26, and performs frequency selective fading on the first and second branches 10 and 20, respectively. Is estimated (S22).

  Next, the control unit 80 determines whether the gain of each antenna acquired in step 21 is large, medium, or small based on a predetermined criterion (S23). The weight is set to rank 2 (S24), the weight is set to rank 6 if medium (S25), and the weight is set to rank 8 if large (S26).

  Next, the control unit 80 determines whether the degree of frequency selection fading acquired in step 22 is large, medium, or small (S27). If the degree is small, the weighting rank is not changed ( S28) If the medium level, the weighting rank is lowered by 1 (S29), and if it is large, the weighting rank is lowered by 2 (S30).

  Next, the control unit 80 sets the weighting in the first and second weighting units 17 and 27 based on the weighting rank as a result of performing the setting and changing based on the determinations in steps 23 and 27. (S31), and the series of procedures is terminated.

  For example, when it is determined in step 23 that the antenna gain is large for the first branch 10, the weighting rank 8 is first set in step 26, and then frequency selection fading is determined to be medium in step 27. In step 29, the weighting rank is lowered by 1 from 8 and is reset to 7. Therefore, in such a case, the control unit 80 sets the first weighting unit to rank 7 (that is, a weighting factor of 7/8).

  In the above control flow, first, the weighting rank is determined according to the antenna gain (see S23 to S26). That is, when the original antenna gain is high (sensitivity is high), the weighting rank is set high (the signal level at the time of synthesis is increased to increase the influence). Conversely, when the original antenna gain is low (sensitivity is low), the weighting rank is set low (the signal level at the time of combining is lowered to reduce the influence).

  Second, a weighted rank is determined according to frequency selection fading (S27 to S30). That is, when the degree of frequency selective fading that can be predicted from the scattered pilot signal is large, there is a high possibility that a frequency region with poor reception sensitivity exists in the received signal. The signal level is lowered to reduce the influence). On the other hand, when the degree of frequency selective fading is small, there is a high possibility that the reception sensitivity is good in the entire frequency band of the received signal, so that the weighting rank is not changed.

  In the control flow described above, the weighting rank is simply determined from the two elements described above, and control is performed so that good weighting is performed.

  In the example described above, control is performed so that weighting is set for each of the first and second branches 10 and 20. However, the smaller correction value of the AGC control amount is fixed to the weighting rank 8, and the other Only the weighted rank may be obtained according to the flow of FIG.

  In the example shown in FIGS. 5 and 7, the degree of fading frequency is predicted based on the three-stage vehicle speed, and the weighting coefficient is obtained from the weighting rank table. However, since the vehicle speed and the fading frequency are in a proportional relationship, the weighting coefficient corresponding to the fading frequency may be obtained directly from the vehicle speed by calculation.

  In the example shown in FIG. 5, the gain for each branch is stored in the memory 81 in advance. However, since the difference in sensitivity between branches differs for each selected channel (CH), the sensitivity difference between branches for each selected channel is stored in advance in the memory 81 as a table, and the steps of FIG. 2, control may be performed so that the sensitivity difference between branches is acquired from the memory 81. Such a sensitivity difference table 1 is shown in FIG.

  Further, the sensitivity difference between the branches may be acquired from the relationship between the traveling direction of the vehicle and the position of the broadcasting station of the selected channel. FIG. 9A shows such a sensitivity difference table 2, and FIG. 9B shows the positional relationship between the traveling direction of the vehicle and the broadcasting station of the selected channel. For example, when the channel 22 is selected and the broadcasting station of the channel 22 is located in the area B with respect to the current traveling direction of the vehicle, the control unit 80 acquires the sensitivity difference B2. The vehicle position information and the traveling direction information are obtained from the navigation unit 5 and the broadcast station position information of each channel can be stored in advance in the memory 81 or the like. It is possible to determine in which area the broadcasting station of the selected channel is located with respect to the traveling direction. Note that in FIG. 9B, the broadcast station positions are determined by distinguishing the four areas, but the number and positions of the areas are not limited thereto.

It is a block diagram which shows the conventional diversity receiver. It is a figure for demonstrating a frequency division diver. It is a block diagram which shows the outline | summary of the diversity receiver concerning this invention. It is a figure for demonstrating a scattered pilot signal. It is a figure which shows an example of the control flow in the diversity receiver which concerns on this invention. It is a figure which shows an example of a weighting rank table. It is a figure which shows the other example of the control flow in the diversity receiver which concerns on this invention. It is a figure which shows the sensitivity difference table. (A) shows the sensitivity difference table 2, and (b) shows the positional relationship between the traveling direction of the vehicle and the selected broadcast station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st antenna 2 2nd antenna 5 Navigation part 6 Vehicle speed detection part 10 1st branch 15 1st AGC circuit 16 1st detection part 17 1st weighting part 20 2nd branch 25 2nd AGC circuit 26 2nd detection part 27 2nd Overlapping unit 30 Combining unit 80 Control unit 81 Memory 100 Diversity receiver

Claims (5)

A plurality of branches that output a plurality of received signals;
A fading frequency detector for detecting a fading frequency;
A frequency selective fading detector for detecting frequency selective fading of each branch;
A plurality of weighting units for weighting received signals output from the branches;
A combining unit that combines a plurality of reception signals weighted by the weighting unit,
The diversity receiver is controlled based on a detection result of the fading frequency detection unit and a detection result of the frequency selective fading detection unit.   2. The diversity receiver according to claim 1, wherein the weighting unit weights received signals output from the plurality of branches based on sensitivity information of the plurality of branches.   3. The diversity receiver according to claim 1, wherein the fading frequency detection unit detects a fading frequency based on a vehicle speed of a vehicle on which the diversity receiver is mounted.   The diversity receiver according to claim 1, wherein the frequency selective fading detection unit detects frequency selective fading based on a scattered pilot signal. A plurality of branches that output a plurality of received signals;
A fading frequency detector for detecting a fading frequency;
A frequency selective fading detector for detecting frequency selective fading of at least one branch;
A weighting unit for weighting an output signal from at least one branch;
A reception unit weighted by the weighting unit, and a combining unit that combines reception signals output from other branches,
The diversity receiver is controlled based on a detection result of the fading frequency detection unit and a detection result of the frequency selective fading detection unit.

Images