JP2008199133A - Ofdm signal receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the influence caused by a static spurious component generated on a substrate. <P>SOLUTION: The OFDM signal receiver 1 is provided with: a first tuner 11 and a second tuner 21 for receiving an OFDM signal of a selected frequency band; a first FFT circuit 12 and a second FFT circuit 22 for performing FFT processing of respective output signals from the first tuner 11 and the second tuner 21; a diversity combination part 101 for performing diversity combination by using output signals from the first FFT circuit 12 and the second FFT circuit 22; and a first recording part 52 for recording a carrier which is not used for the diversity combination in respective frequency bands. The diversity combination part 101 deletes a carrier corresponding to a selected frequency band from a plurality of carriers included in the output signal from the first FFT circuit 12 or the second FFT circuit 22 to perform diversity combination. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an OFDM signal receiver that receives an OFDM signal.

  In recent years, in OFDM receivers that receive OFDM (Orthogonal Frequency Division Multiplexing) signals such as digital TV broadcast signals, chips such as multiple CPUs and memories are adjacent to each other on the same substrate. The frequency component of the clock becomes a spurious (interference wave) and is mixed as noise in the received OFDM signal.

  In particular, spurious components are often mixed in a high-frequency circuit unit such as an RF (Radio Frequency) tuner in an OFDM signal receiver.

On the other hand, there is known an OFDM signal receiver configured to remove and demodulate such spurious (interfering wave) components after they are detected by a PLL circuit (see, for example, JP-A-2001-339320). .
JP 2001-339320 A

  However, the conventional OFDM signal receiver has a problem that it is difficult to remove spurious in an arbitrary frequency channel.

  Therefore, the present invention has been made in view of the above points, and an object thereof is to provide an OFDM signal receiver that can reduce the influence of static spurious components generated on a substrate.

  According to a first aspect of the present invention, there is provided an OFDM signal receiver that receives an OFDM signal including a plurality of carriers, the first tuner and the second tuner that receive an OFDM signal in a selected frequency band, and the first tuner. A first FFT circuit and a second FFT circuit that perform FFT processing on the output signal from the tuner and the output signal from the second tuner, respectively, and the output signal from the first FFT circuit and the output signal from the second FFT circuit are used. A diversity combining unit that performs diversity combining, and a first recording unit that records a carrier that is not used for diversity combining for each frequency band, and the diversity combining unit refers to the first recording unit. From among a plurality of carriers included in the output signal from the first FFT circuit or the output signal from the second FFT circuit By removing the carrier corresponding to the selected frequency band, and the gist to carry out the diversity combining.

  According to this invention, it is possible to remove a specific carrier that adversely affects the reception quality in the OFDM signal receiver and perform diversity combining, and therefore it is possible to improve the reception quality in the OFDM signal receiver.

In the first aspect of the present invention, a measurement unit that measures the quality of an output signal from the diversity combining unit is provided, and the diversity combining unit outputs an output signal from the first FFT circuit or an output from the second FFT circuit. The diversity combining of a plurality of patterns in which a carrier to be removed from a plurality of carriers included in the signal is changed is performed, and the measurement unit measures the quality of a plurality of output signals generated by the diversity combining of the plurality of patterns. , The carrier not used in each of the diversity patterns of the plurality of patterns is associated with the measured quality and recorded in the second recording unit,
The first recording unit may record the carrier corresponding to the best quality among the recorded qualities for each frequency band with reference to the second recording unit.

  In the first feature of the present invention, a Viterbi decoding unit that performs Viterbi decoding processing on an output signal from the diversity combining unit is provided, and the measurement unit outputs, as the quality, an output from the Viterbi decoding unit. The error rate of the signal may be measured.

  In the first feature of the present invention, a Viterbi decoding unit that performs Viterbi decoding processing on the output signal from the diversity combining unit, and a Reed Solomon decoding processing that performs Reed-Solomon decoding processing on the output signal from the Viterbi decoding unit. A Solomon decoding unit, and the measurement unit may measure an error rate of an output signal from the Reed-Solomon decoding unit as the quality.

  According to this invention, before shipping as a product, it is possible to inspect which carrier causes spurious components to cause deterioration in reception quality in the OFDM signal receiver.

  As described above, according to the present invention, it is possible to provide an OFDM signal receiver that reduces the influence of static spurious components generated on a substrate.

(Configuration of OFDM signal receiver according to the first embodiment of the present invention)
The configuration of the OFDM signal receiver 1 according to the first embodiment of the present invention will be described with reference to FIGS.

  The OFDM signal receiver 1 according to the present embodiment is configured to receive an OFDM signal including a plurality of carriers by a plurality of antennas installed spatially apart.

  As shown in FIG. 1, the OFDM signal receiver 1 according to the present embodiment includes a first antenna 10, a second antenna 20, a first tuner 11, a second tuner 21, a first FFT circuit 12, and a first FFT circuit 12. 2 FFT circuit 22, diversity combining circuit 101, Viterbi decoding unit 102, Reed-Solomon decoding unit 103, MPEG decoding unit 104, video / audio separation unit 105, video decoding unit 106, audio decoding unit 107, and playback A table storage unit 52, an inspection table storage unit 53, an input unit 201, a tuner control unit 202, a diversity control unit 203, a measurement unit 204, and an inspection unit 205.

  The input unit 201, the tuner control unit 202, the diversity control unit 203, the measurement unit 204, and the inspection unit 205 may be realized by the microcomputer 2.

  In the present embodiment, the first reception system is configured by the first antenna 10, the first tuner 11, and the first FFT circuit 12, and the second reception is performed by the second antenna 20, the second tuner 21, and the second FFT circuit 22. Assume that the system is configured. The present invention is not limited to the case where the OFDM signal receiver 1 includes two reception systems, but can be applied to the case where the OFDM signal receiver 1 includes three or more reception systems.

  In addition, the OFDM signal receiver 1 according to the present embodiment is either in a normal mode for receiving an OFDM signal or a pre-inspection mode for generating a reproduction table (described later) before shipping as a product. It is configured to work with.

  When the OFDM signal receiver 1 according to the present embodiment operates in the pre-inspection mode, the OFDM signal is received from the carriers included in the OFDM signal received through the first reception system or the second reception system. It is configured to detect a static spurious component (specific carrier) that adversely affects quality (for example, BER, MER, etc.).

  On the other hand, when operating in the normal mode, the OFDM signal receiver 1 according to the present embodiment does not use the specific carrier (spurious component) detected in the pre-inspection mode for diversity combining, so that the OFDM signal by the specific carrier is used. Is configured to reduce the impact on quality.

  First, the function of each unit when the OFDM signal receiver 1 according to the present embodiment operates in the pre-inspection mode will be described.

  The first tuner 11 is connected to the signal generator 3 corresponding to the OFDM transmission method, and the frequency band (channel) selected from the signal generator 3 using the input device 51 by the prior examiner (channel selection). It is configured to receive an OFDM signal.

  The second tuner 21 is connected to the signal generator 3 corresponding to the OFDM transmission method, and the frequency band (channel) selected from the signal generator 3 by using the input device 51 by the prior examiner (channel selection). It is configured to receive an OFDM signal.

  Here, the first tuner 11 and the second tuner are configured to receive the same channel (in the present embodiment, UHF bands 13ch to 62ch).

  Specifically, in order for the prior examiner to select one of the UHF bands 13ch to 62ch for the microcomputer 2 using a PC or the like connected to the OFDM signal receiver 1 as the input device 51. Input the control signal.

  The input unit 201 in the microcomputer 2 is configured to detect the control signal and notify the tuner control unit 202 and the diversity control unit 203 of the detected control signal.

  The tuner control unit 202 controls the first tuner 11 and the second tuner 21 so as to select a signal of a specific channel (for example, 13ch) from the UHF bands 13ch to 62ch according to the notified control signal. Control.

  The first FFT circuit 12 performs FFT (Fast Fourier Transform) processing on the output signal from the first tuner 11, that is, the output signal from the output signal from the first tuner 11 is changed from the time-axis signal to the frequency. It is configured to convert into a shaft signal.

  The second FFT circuit 22 performs an FFT (Fast Fourier Transform) process on the output signal from the second tuner 21, that is, the output signal from the second tuner 21 is changed from the time axis signal to the frequency. It is configured to convert into a shaft signal.

  Here, FIG. 2 shows an example of an output signal from the first FFT circuit 12, and FIG. 3 shows an example of an output signal from the second FFT circuit 22.

  In the example of FIG. 2, the carrier corresponding to the carrier number n1 and the number of carriers w1 (that is, the carrier specified by the carrier number n1) due to the influence of a clock or the like for operating a chip such as a CPU or memory mounted on the same substrate. (1 w1 carriers present before or after) is a spurious component.

  In such a case, if demodulation processing is performed by performing diversity combining processing in a state including such a carrier, a normal reception signal on the frequency of the carrier is crushed by a noise component, and the BER characteristics deteriorate. End up.

  Further, the influence of the spurious component on the output signal from the first FFT circuit 12 and the output signal from the second FFT circuit 22 is not uniform depending on the positional relationship with the signal generator 3, but in the example of FIG. Therefore, spurious components are not generated.

  Note that the purpose of such preliminary inspection is that either the spurious component (specific carrier) of the output signal from the first FFT circuit 12 or the output signal from the second FFT circuit 22 adversely affects the quality of the OFDM signal on the substrate. It is to check whether it is affecting.

  The diversity combining unit 101 is configured to perform diversity combining using the output signal from the first FFT circuit 12 and the output signal from the second FFT circuit 22.

  Further, the diversity combining unit 101 is configured to perform diversity combining of a plurality of patterns by changing carriers to be deleted from among a plurality of carriers included in the output signal from the first FFT circuit 11 or the output signal from the second FFT circuit 12. Has been.

  Specifically, the diversity control means 203 in the microcomputer 2 includes an arbitrary carrier number (n1 or n2 to be described later) from one of the output signal from the first FFT circuit 11 or the output signal from the second FFT circuit 21. Diversity combining section 101 is controlled such that only the carriers with the number of carriers (w1 or w2 described later) are removed and combined with an output signal including all the other carriers.

  As a result, for example, as shown in FIG. 2, the diversity combining unit 101 uses an arbitrary carrier number n1 (1 ≦ n1 ≦ N) (N is different depending on the transmission method. For example, in the case of mode 3 of ISDB-T, N = 5617) The number of carriers including the carrier w1 (1 ≦ w1 ≦ x) (x is an arbitrary number. Here, x = 5 is assumed), and diversity combining is performed. It is configured as follows.

  At this time, diversity combining section 101 is configured to perform diversity combining using all carriers for the output signal from second FFT circuit 22 shown in FIG.

  Similarly, as shown in FIG. 3, diversity combining section 101 has an arbitrary carrier number n2 (1 ≦ n2 ≦ N) (N is different depending on the transmission method. For example, in the case of mode 3 of ISDB-T, N = 5617) The number of carriers including the carrier w2 (1 ≦ w2 ≦ x) (x is an arbitrary number. Here, x = 5 is assumed), and diversity combining is performed. It is configured as follows.

  At this time, the diversity combining unit 101 is configured to perform diversity combining using all carriers for the output signal from the first FFT circuit 12 shown in FIG.

  Note that any method can be used as a method of selecting the carrier having the carrier number w1 including the carrier having the carrier number n1 or the carrier having the carrier number w2 including the carrier having the carrier number n2.

  The Viterbi decoding unit 102 is configured to perform Viterbi decoding processing on the output signal from the diversity combining unit 101. The Reed-Solomon decoding unit 103 is configured to perform a Reed-Solomon decoding process on the output signal from the Viterbi decoding unit 101.

  The measurement unit 204 of the microcomputer 2 is configured to measure the quality of an output signal from the diversity combining unit 101 (for example, an output signal from the Viterbi decoding unit 101 or a signal after error correction processing by the Reed-Solomon decoding unit 103). ing.

  Here, the measurement unit 204 may be configured to measure an error rate such as BER (Bit Error Rate) or MER (Modulation Error Rate) as the quality described above.

  Further, the measurement unit 204 measures the quality of a plurality of output signals generated by the diversity combining of the plurality of patterns, and associates the measured quality with the carrier that is not used in each of the diversity combining of the plurality of patterns. The inspection table recording unit (second recording unit) 53 is configured to record.

  Specifically, the measurement unit 204 selects the quality (for example, BER) measured by the measurement unit 204, the values of n1 and w1 selected by the diversity control unit 203 in this case, and the tuner control unit 202. A test table for associating with the channel number being stored is stored in the test table recording unit 53. Here, FIG. 4 shows an example of the inspection table stored in the inspection table recording unit 53.

  Similarly, the measurement unit 204 is selected by the tuner control unit 202 by the quality (for example, BER) measured by the measurement unit 204, the values of n2 and w2 selected by the diversity control unit 203 in this case, and the tuner control unit 202. The inspection table for associating with the channel number being stored is stored in the inspection table recording unit 53. Here, FIG. 5 shows an example of the inspection table stored in the inspection table recording unit 53.

  The measurement unit 204 is configured to generate the inspection tables shown in FIGS. 4 and 5 for all channels (13 ch to 62 ch) and store them in the inspection table recording unit 53.

  Note that in the end, whether to perform inspection for all channels (that is, whether to generate a table for inspection) or whether to inspect only for a specific channel (that is, whether to generate a table for inspection). It can be arbitrarily set by the pre-inspector.

  The inspection unit 205 of the microcomputer 2 scans all BERs in the inspection table (see FIGS. 4 and 5) recorded in the inspection table recording unit 53 when the inspection table for 13ch is completed. It is configured.

  Then, the inspection unit 205 extracts the parameter value (n1, w1) or (n2, w2) when the BER is the best, and the extracted parameter value together with the channel number is a reproduction table recording unit (first recording unit). 52 is configured to record.

In the example of FIGS. 4 and 5, the parameter value (n1 = 10, w1 = 1) in the case of BER = 2 × 10 ⁻⁶ and the channel number ch = 13 at that time are shown in the reproduction table recording unit 52 To record.

  Here, when the carrier of the carrier number 10 of the output signal from the first FFT circuit 11 shown in FIG. 2 is not used for diversity combining, the BER characteristic is the best, in other words, the output from the first FFT circuit 11. The carrier of the signal carrier number 10 indicates that it is the largest factor resulting from the deterioration of the BER characteristic due to the influence of spurious.

  Therefore, in the normal mode, when receiving a 13ch OFDM signal, BER characteristics can be improved by performing diversity combining without using such a carrier.

  Therefore, the reproduction table inspection unit 205 of the microcomputer 2 specifies the values of n1 = 10 and w1 = 1 and the channel number (13ch) selected in this case from the output signal from the diversity combining unit 101. The parameter value necessary for removing the carrier is recorded in the reproduction table recording unit 52.

  That is, the reproduction table recording unit 52 refers to the inspection table reference unit 53, and does not use the carrier (inspection table) for each frequency band (each channel, for example, UHF band 13 ch to 62 ch) for diversity combining. The reference unit 53 is configured to record a carrier corresponding to the best quality.

  FIG. 6 shows an example of a reproduction table stored in the reproduction table recording unit 52.

  Second, the function of each unit when the OFDM signal receiver 1 according to the present embodiment operates in the normal operation mode will be described.

  The first tuner 11 receives an OFDM signal in a frequency band (channel) selected (tuned) by the user using the input device 51 (for example, a touch panel or a remote controller) 51 via the first antenna 10. It is configured.

  The second tuner 21 is configured to receive an OFDM signal in a frequency band (channel) selected (tuned) by the user via the second antenna 20 using the input device 51.

  Here, when the user instructs to select 13ch using the input device 51, the input unit 201 of the microcomputer 2 selects such a command via the tuner control unit 202. In addition, the first tuner 11 and the second tuner 21 are controlled.

  The first FFT circuit 12 performs FFT (Fast Fourier Transform) processing on the output signal from the first tuner 11, that is, the output signal from the output signal from the first tuner 11 is changed from the time-axis signal to the frequency. It is configured to convert into a shaft signal.

  The second FFT circuit 22 performs an FFT (Fast Fourier Transform) process on the output signal from the second tuner 21, that is, the output signal from the second tuner 21 is changed from the time axis signal to the frequency. It is configured to convert into a shaft signal.

  The diversity combining unit 101 is configured to perform diversity combining using the output signal from the first FFT circuit 12 and the output signal from the second FFT circuit 22.

  Further, the diversity combining unit 101 refers to the reproduction table recording unit (first recording unit) 52, and among the plurality of carriers included in the output signal from the first FFT circuit 12 or the output signal from the second FFT circuit 22. Thus, diversity combining is performed by removing a carrier corresponding to a frequency band (channel) selected (tuned) by the user.

  Here, when the input unit 201 of the microcomputer 2 notifies the diversity control unit 203 of the above-described command, the diversity control unit 203 refers to the reproduction cable recording unit 52 and sets the parameter value corresponding to 13ch (n1 = 10, w1, = 1), that is, a carrier corresponding to a frequency band (channel) selected (tuned) by the user is detected, and the parameter value is notified to the diversity combining unit 101.

  As a result, diversity combining section 101 operates so as not to use a carrier uniquely determined by n1 and w1 for diversity combining.

  For example, in this embodiment, the parameter values of all channels are recorded in the reproduction table recording unit 52, but only the parameter values of a specific channel are recorded in the reproduction table recording unit 52. It may be configured to be.

  In this case, when the diversity control unit 203 refers to the reproduction table recording unit 52, if there is no parameter value of the currently selected channel, the diversity combining unit 101 receives both as usual. A command is given to perform diversity combining using all the carriers included in the signal from the system.

  As described above, when there is a parameter value of the currently selected channel, the diversity control unit 203 does not use the carrier specified by the parameter value for diversity combining with respect to the diversity combining unit 101. To order.

  The Viterbi decoding unit 102 is configured to perform Viterbi decoding processing on the output signal from the diversity combining unit 101. The Reed-Solomon decoding unit 103 is configured to perform a Reed-Solomon decoding process on the output signal from the Viterbi decoding unit 101.

  The MPEG decoding unit 104 is configured to perform MPEG expansion processing on the signal after the error correction processing by the Reed-Solomon decoding unit 103.

  The video / audio separation unit 105 is configured to separate the signal after the MPEG expansion processing by the MPEG decoding unit 104 into a video signal and an audio signal.

  The video decoding unit 106 is configured to perform a decoding process on the video signal output from the video / audio separation unit 105, and the audio decoding unit 107 performs a decoding process on the audio signal output from the video / audio separation unit 105. Configured to do.

  The video decoding unit 106 is configured to output the decoding result to a video output unit (not shown), and the audio decoding unit 107 is configured to output the decoding result to an audio output unit (not shown). Has been.

  Since the inspection table recording unit 53 is necessary only at the time of preliminary inspection, the inspection table recording unit 53 may be configured to be removed when the OFDM signal receiver 1 is shipped.

(Operation of the OFDM signal receiver according to the first embodiment of the present invention)
With reference to FIG.7 and FIG.8, operation | movement of the OFDM signal receiver 1 which concerns on the 1st Embodiment of this invention is demonstrated.

  First, with reference to FIG. 7, the operation in the pre-inspection mode of the OFDM signal receiver 1 according to the present embodiment will be described.

  As shown in FIG. 7, in step S <b> 101, the signal generator 3 connected to the OFDM receiver 1 according to this embodiment inputs an OFDM signal to the first tuner 11 and the second tuner 21.

  In step S102, the tuner control unit 202 controls the first tuner 11 and the second tuner 21 so as to receive 13ch (T = 13ch).

  The diversity control unit 203 sets “n1 = 1” in step S103, and sets “w1 = 1” in step S104.

  In step S105, the diversity combining unit 204 performs diversity combining by excluding only the carrier corresponding to the parameter value (n1, w1) from the output signal from the first FFT circuit 11 according to the instruction from the diversity control unit 203. Do.

  In step S106, the measurement unit 204 measures the BER for the output signal from the diversity combining unit 204 (for example, the output signal from the Viterbi decoding unit 102 or the Reed-Solomon decoding unit 103), and the currently selected channel number The measured BER is recorded together with the parameter values (n1, w1) in the inspection table corresponding to T.

  In step S107, the diversity control unit 203 determines whether or not “w1 = x”. Here, x is an arbitrary integer. If “YES”, the operation proceeds to step S109, and if “NO”, the operation proceeds to step S108.

  In step S108, the diversity control unit 203 increments the value of “w1” by 1, and the operation returns to step S105.

  In step S109, the diversity control unit 203 determines whether or not “n1 = 5617”. If “YES”, the operation proceeds to step S111, and if “NO”, the operation proceeds to step S110.

  In step S110, the diversity control unit 203 increments the value of “n1” by 1, and the operation returns to step S104.

  The diversity control unit 203 sets “n2 = 1” in step S111 and sets “w2 = 1” in step S112.

  In step S113, the diversity combining unit 204 performs diversity combining by excluding only the carrier corresponding to the parameter value (n2, w2) from the output signal from the second FFT circuit 21 according to the instruction from the diversity control unit 203. Do.

  In step S114, the measurement unit 204 measures the BER for the output signal from the diversity combining unit 204 (for example, the output signal from the Viterbi decoding unit 102 or the Reed-Solomon decoding unit 103), and the currently selected channel number The measured BER is recorded in the inspection table corresponding to T together with the parameter values (n2, w2).

  In step S115, the diversity control unit 203 determines whether or not “w2 = x”. Here, x is an arbitrary integer. If “YES”, the operation proceeds to step S117, and if “NO”, the operation proceeds to step S116.

  In step S116, the diversity control unit 203 increases the value of “w2” by 1, and the operation returns to step S113.

  In step S117, the diversity control unit 203 determines whether or not “n2 = 5617”. If “YES”, the operation proceeds to step S119, and if “NO”, the operation proceeds to step S118.

  In step S118, the diversity control unit 203 increments the value of “n2” by 1, and the operation returns to step S112.

  In step S119, the inspection unit 205 selects the parameter value (n1, w1) or (n2, w2) corresponding to the best BER from the inspection table, and the selected parameter value is currently selected. Along with the channel number T being recorded, it is recorded in the reproduction table.

  In step S120, the tuner control unit 202 determines whether or not “T = 62ch”. If “YES”, the operation ends, and if “NO”, the operation proceeds to step S121.

  In step S121, the diversity control unit 203 increments the value of “T” by 1, and the operation returns to step S103.

  Secondly, with reference to FIG. 8, the operation in the normal operation mode of the OFDM signal receiver 1 according to the present embodiment will be described.

  As shown in FIG. 8, in step S201, the first tuner 11 and the second tuner 21 receive OFDM signals via the first antenna 10 and the second antenna 20, respectively.

  When the user selects a desired channel (frequency band) using the input device 51 in step S202, the tuner control unit 202 determines the desired channel according to a command from the user received via the input unit 201. The first tuner 11 and the second tuner 21 are controlled so as to select the channel of the selected channel, and the first tuner 11 and the second tuner 21 select the desired channel (frequency band) from the received OFDM signals. The OFDM signal corresponding to is selected and received.

  In step S <b> 203, the first FFT circuit 12 performs FFT processing on the output signal from the first tuner 11, and the second FFT circuit 22 performs FFT processing on the output signal from the second tuner 21.

  In step S204, the diversity control unit 203 refers to the reproduction table recording unit 52 and selects the parameter value (n1, w1) or (n2, w2) corresponding to the desired channel described above. The specified carrier is notified to diversity combining section 101 as a carrier that is not used for diversity combining.

  In step S <b> 205, the diversity combining unit 101 performs diversity combining by removing the notified carrier from the output signal from the first FFT circuit 12 and the output signal from the second FFT circuit 22.

  In step S <b> 206, the Viterbi decoding unit 102 and the Reed-Solomon decoding unit 103 perform error correction decoding processing on the output signal from the diversity combining unit 101.

  In step S <b> 207, the MPEG decoding unit 104 performs MPEG expansion processing on the output signal from the Reed-Solomon decoding unit 103.

  In step S208, the video / audio separation unit 105 separates the signal after the MPEG expansion processing by the MPEG decoding unit 104 into a video signal and an audio signal.

  In step S209, the video decoding unit 106 performs a decoding process on the video signal output from the video / audio separation unit 105, and the audio decoding unit 107 performs a decoding process on the audio signal output from the video / audio separation unit 105. .

  Then, the video decoding unit 106 outputs the decoding result to the video output unit (not shown), and the audio decoding unit 107 outputs the decoding result to the audio output unit (not shown).

(Operation and effect of the OFDM signal receiver according to the first embodiment of the present invention)
According to the OFDM signal receiver 1 according to the first embodiment of the present invention, it is possible to remove a specific carrier that adversely affects the reception quality in the OFDM signal receiver 1 and perform diversity combining. The reception quality in the machine 1 can be improved.

  According to the OFDM signal receiver 1 according to the first embodiment of the present invention, before shipping as a product, it is inspected as to which carrier causes spurious component deterioration of the reception quality in the OFDM signal receiver 1. Can do.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Accordingly, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

It is a functional block diagram of the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the signal output from the 1st FFT circuit in the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the signal output from the 2nd FFT circuit in the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the table for a test | inspection in the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the table for a test | inspection in the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the table for reproduction | regeneration in the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement in the preliminary | backup test | inspection of the OFDM signal receiver which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement in the normal reception process of the OFDM signal receiver which concerns on the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... OFDM signal receiver 2 ... Microcomputer 3 ... Signal generator 10 ... 1st antenna 20 ... 2nd antenna 11 ... 1st tuner 21 ... 2nd tuner 12 ... 1st FFT circuit 22 ... 2nd FFT circuit 101 ... Diversity combining circuit 102 ... Viterbi decoding unit 103 ... Reed-Solomon decoding unit 104 ... MPEG decoding unit 105 ... Video / audio separation unit 106 ... Video decoding unit 107 ... Audio decoding unit 201 ... Input unit 202 ... Tuner control unit 203 ... Diversity control unit 204 ... Measurement unit 205 ... Inspection unit 51 ... Input device 52 ... Reproduction table storage unit 53 ... Inspection table storage unit

Claims (4)

An OFDM signal receiver for receiving an OFDM signal including a plurality of carriers,
A first tuner and a second tuner for receiving an OFDM signal of a selected frequency band;
A first FFT circuit and a second FFT circuit for performing FFT processing on the output signal from the first tuner and the output signal from the second tuner, respectively;
A diversity combining unit that performs diversity combining using the output signal from the first FFT circuit and the output signal from the second FFT circuit;
A first recording unit that records a carrier that is not used for the diversity combining for each frequency band;
The diversity combining unit refers to the first recording unit, and selects the frequency band selected from the plurality of carriers included in the output signal from the first FFT circuit or the output signal from the second FFT circuit. An OFDM signal receiver that performs diversity combining by removing a corresponding carrier. Comprising a measuring unit for measuring the quality of the output signal from the diversity combining unit;
The diversity combining unit performs the diversity combining of a plurality of patterns in which carriers to be removed from a plurality of carriers included in an output signal from the first FFT circuit or an output signal from the second FFT circuit are changed,
The measuring unit measures the quality of a plurality of output signals generated by the diversity combining of the plurality of patterns, and associates the measured quality with a carrier that is not used in each of the diversity combining of the plurality of patterns. Recorded in the second recording section,
The said 1st recording part records the said carrier corresponding to the best quality among the recorded quality with respect to each frequency band with reference to the said 2nd recording part. An OFDM signal receiver as described. A Viterbi decoding unit that performs Viterbi decoding processing on the output signal from the diversity combining unit;
The OFDM signal receiver according to claim 2, wherein the measurement unit measures an error rate of an output signal from the Viterbi decoding unit as the quality. A Viterbi decoding unit that performs Viterbi decoding processing on an output signal from the diversity combining unit;
A Reed-Solomon decoding unit that performs Reed-Solomon decoding processing on the output signal from the Viterbi decoding unit,
The OFDM signal receiver according to claim 2, wherein the measurement unit measures an error rate of an output signal from the Reed-Solomon decoding unit as the quality.

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