JP5563352B2 - Receiving apparatus and receiving method - Google Patents

Description

  The present invention relates to a receiving apparatus and a receiving method, and more particularly, to a receiving apparatus and a receiving method capable of combining a guard interval and an effective symbol that are not affected by multipath and reducing the circuit scale.

  Conventionally, a broadcasting station that transmits a digital television broadcast signal (hereinafter referred to as “broadcast signal”) adds a guard interval to each effective symbol and transmits it in order to improve resistance to multipath of effective symbols including broadcast contents. ing. For example, a broadcasting station adds a guard interval that duplicates the tail part of each effective symbol to the head of each effective symbol, and transmits it.

  By the way, when receiving a broadcast signal in which a guard interval is added to an effective symbol, a receiving apparatus that receives the broadcast signal receives the tail part of the effective symbol in an overlapping manner. Therefore, the receiving apparatus can effectively use the guard interval by combining the received guard interval and the tail part of the effective symbol, and improve the reception characteristics.

  However, when a multipath occurs, the receiving apparatus receives a broadcast signal (hereinafter referred to as a “delayed signal”) having a delay due to the multipath effect together with the broadcast signal. In this case, a part of other adjacent effective symbols may be superimposed on the guard interval.

  Therefore, when a multipath occurs, the receiving apparatus may deteriorate reception characteristics due to the influence of other adjacent effective symbols when the guard interval and the tail portion of the effective symbol are combined.

  Therefore, there is a receiving apparatus that combines the guard interval and the tail part of the effective symbol while considering the influence of multipath. For example, the receiving apparatus described in Patent Document 1 includes a delay profile unit that measures the delay amount of a delay signal with respect to a received broadcast signal, and the influence of multipath is caused when the delay amount of the delay signal is less than a predetermined threshold. Is determined to be low.

  Then, the receiving apparatus described in Patent Literature 1 combines the tail part of the effective symbol and the guard interval only when it is determined that the influence of the multipath is low, so that the guard interval is taken into consideration. Is effectively used to improve reception characteristics.

JP 2006-304152 A

  However, the receiving apparatus described in Patent Document 1 has a problem that the circuit scale increases because it is necessary to provide a delay profile unit. In addition, the receiving apparatus described in Patent Document 1 requires time to receive a plurality of guard intervals and valid symbols in order for the delay profile unit to measure the delay amount of the delay signal.

  For this reason, the receiving apparatus described in Patent Document 1 needs to be provided with a buffer for temporarily storing a plurality of guard intervals and effective symbols received during measurement of the delay amount by the delay profile unit. Therefore, the circuit size of the receiving apparatus described in Patent Document 1 is increased even by such a buffer.

  For these reasons, it is a major issue how to realize a receiving apparatus and a receiving method that can synthesize effective symbols and guard intervals that are not affected by multipath and that can reduce the circuit scale.

  The present invention has been made to solve the above-described problems caused by the prior art, and is capable of synthesizing effective symbols and guard intervals not affected by multipaths, and capable of reducing the circuit scale and An object is to provide a receiving method.

  In order to solve the above-described problems and achieve the object, the present invention receives a broadcast signal having a section of an effective symbol including broadcast contents and a section of a guard interval in which a part of the effective symbol is duplicated. A receiving means for receiving the broadcast signal; and a signal level of the section of the guard interval from a signal level of the section corresponding to the part of the effective symbol in the broadcast signal received by the receiving means. Subtracting means for subtracting, a value based on the subtraction result by the subtracting means is compared with a predetermined threshold value, and the interval of the guard interval in which the value based on the subtraction result is less than or equal to the predetermined threshold value is defined as the one of the effective symbols. Determining means for determining as a section of the guard interval to be combined into a part.

  According to the present invention, the reception device can perform multipath only by subtracting the signal level of the section of the guard interval from the signal level of the section corresponding to a part of the effective symbol in the received broadcast signal and comparing it with a predetermined threshold. Since it is possible to determine the interval of the guard interval that is not affected by the delay time, it is possible to combine the effective symbol and the guard interval that is not affected by the multipath without providing a delay profile section, and to reduce the circuit scale. There is an effect.

FIG. 1 is a diagram showing an outline of a receiving method according to the present invention. FIG. 2 is a block diagram illustrating the receiving apparatus according to the present embodiment. FIG. 3 is a diagram illustrating the configuration of the combining unit of the receiving apparatus according to the present embodiment. FIG. 4 is a diagram illustrating the operation of the combining unit of the receiving apparatus according to the present embodiment. FIG. 5 is a diagram illustrating the operation of the combining unit of the receiving apparatus according to the present embodiment. FIG. 6 is a diagram illustrating the operation of the combining unit of the receiving apparatus according to the present embodiment. FIG. 7 is a diagram illustrating the operation of the combining unit of the receiving apparatus according to the present embodiment.

  Exemplary embodiments of a receiving apparatus and a receiving method according to the present invention will be described below in detail with reference to the accompanying drawings. First, prior to detailed description of the embodiment, an outline of a reception method according to the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an outline of a receiving method according to the present invention.

  In the following, as shown in FIG. 1A, a case where a broadcast signal a including a section of an effective symbol SY including broadcast contents and a section of a guard interval GI that duplicates the tail part of the effective symbol SY is received. explain. As shown in FIG. 2A, it is assumed that the guard interval GI is added to the head of the effective symbol SY.

  The reception method according to the present invention makes it possible to synthesize the effective symbol SY and the guard interval GI of the section not affected by the multipath without performing delay profiling even when multipath occurs. .

  Specifically, in the receiving method according to the present invention, as shown in FIG. 1B, when the broadcast signal a is received, the broadcast signal a is delayed for a predetermined time, and the tail portion of the broadcast signal a before the delay is transmitted. And the interval of the guard interval GI in the delayed broadcast signal a.

  Subsequently, in the reception method according to the present invention, the signal level in the section of the guard interval GI in the delayed broadcast signal a is subtracted from the signal level in the section of the effective symbol SY in the broadcast signal a before delay.

  Here, in the section where there is no influence of multipath, the signal of the tail part of the effective symbol SY before the delay and the signal of the guard interval GI after the delay are the same, although there are some differences due to the influence of the transmission path. It is a signal containing data.

  For this reason, the signal of the tail part of the effective symbol SY before the delay and the signal of the guard interval GI after the delay are signals having substantially the same waveform. For this reason, the subtraction result is a value close to “0”.

  On the other hand, in a section that is affected by multipath, the waveform of the effective symbol SY and the waveform of the guard interval GI are clearly different because the components of other effective symbols SYa are superimposed on the guard interval GI. Therefore, in the section with multipath influence, the subtraction result does not approach “0” as the section without multipath influence.

  For this reason, in the reception method according to the present invention, the value based on the subtraction result is compared with a predetermined threshold, and the interval in which the value based on the subtraction result is equal to or less than the predetermined threshold is determined as the guard interval GI without the influence of multipath. Judged as a section. As a value based on the subtraction result, an absolute value of the subtraction result can be used.

  In the reception method according to the present invention, the interval of the guard interval determined as the interval not affected by the multipath is determined as the interval (synthesis interval) of the guard interval GI to be combined with the effective symbol SY.

  As described above, in the reception method according to the present invention, even when multipath occurs, it is possible to determine a multipath combining section to be combined with the effective symbol SY without performing delay profiling of the broadcast signal a. .

  For example, when a multipath occurs, in the reception method according to the present invention, as shown in FIG. 1C, when a broadcast signal a is received, a broadcast signal in which a delay occurs due to the multipath together with the broadcast signal a. a (hereinafter referred to as “delayed signal b”) may be received.

  In this case, as shown in FIG. 1 (C), the guard interval GI of the received broadcast signal a has a multipath effect in which a section having no multipath effect and components of other effective symbols SYa are superimposed. There is a section. As described above, when the guard interval GI on which the component of the other effective symbol SYa is superimposed and the effective symbol SY are combined, the reception characteristic is deteriorated due to the influence of the other effective symbol SYa.

  Therefore, in the reception method according to the present invention, the section without the multipath influence in the guard interval GI is determined by the above-described method, and the determined section is determined as a combined section of the guard interval GI.

  That is, in the reception method according to the present invention, as shown in FIG. 1D, the received broadcast signal a is delayed for a predetermined time, and the signal level of the guard interval GI after the delay from the signal level of the effective symbol SY before the delay. Is subtracted.

  Here, as shown in FIG. 1D, the subtraction result of the section without multipath influence is closer to “0” than the subtraction result of the section with multipath influence.

  For this reason, in the reception method according to the present invention, the value based on the subtraction result is compared with a predetermined threshold value, and the interval of the guard interval GI in which the value based on the subtraction result is equal to or less than the predetermined threshold value is defined as the combined interval of the guard interval GI. decide.

  Note that the receiving method according to the present invention can compare the value obtained by smoothing the value based on the subtraction result with a predetermined threshold value in consideration of the influence of white noise or the like superimposed on the broadcast signal a. Such smoothing will be described in the examples described later.

  As described above, in the reception method according to the present invention, the signal level of the guard interval GI is subtracted from the signal level of the tail part of the effective symbol SY in the broadcast signal a, and the value based on the subtraction result is compared with a predetermined threshold value.

  In the reception method according to the present invention, the interval of the guard interval GI in which the value based on the subtraction result is equal to or less than a predetermined threshold is determined as the synthesis interval of the guard interval GI to be synthesized with the effective symbol SYa.

  As a result, according to the reception method according to the present invention, it is possible to combine the effective symbol SY and the guard interval GI in the section not affected by the multipath without providing a delay profile unit in the reception apparatus. Therefore, the circuit scale of the receiving device can be reduced.

  Below, the Example about the receiver and the receiving method to which the receiving method demonstrated using FIG. 1 is applied is described in detail. In the following description, as an example of a receiving apparatus, a receiving apparatus that receives a broadcast signal of a digital television broadcast to which an OFDM (Orthogonal Frequency Division Multiplexing) scheme is applied will be described.

  The present invention is not limited to a receiving apparatus that receives a broadcast signal to which the OFDM scheme is applied, but is applied to a receiving apparatus that receives an arbitrary broadcast signal having a valid symbol period and a guard interval period. Can do.

  FIG. 2 is a block diagram illustrating the receiving device 1 according to the present embodiment. In the figure, only components necessary for explaining the characteristics of the receiving device 1 are shown, and descriptions of general components are omitted.

  As illustrated in FIG. 2, the reception device 1 includes a reception unit 2, a synthesis unit 3, an FFT unit 4, and a demodulation unit 5. The receiving apparatus 1 receives a broadcast signal having an effective symbol section including broadcast contents and a guard interval section obtained by duplicating a part of the effective symbol by an antenna, and receives the received broadcast signal to a predetermined output apparatus 6. It is a device that outputs.

  Here, the receiving unit 2 is a processing unit that receives a broadcast signal in a predetermined frequency band from an antenna, and detects and amplifies the received broadcast signal. The receiving unit 2 converts the detected and amplified analog broadcast signal into a digital broadcast signal and outputs the digital broadcast signal to the combining unit 3.

  The synthesizing unit 3 synthesizes the broadcast signal input from the receiving unit 2 by adding the broadcast signal of the effective symbol section and the broadcast signal of the guard interval section, and the combined broadcast signal is the FFT section. 4 is a processing unit that outputs to 4.

  In particular, the synthesizer 3 performs processing for improving broadcast signal reception characteristics by synthesizing a signal in an interval that is not affected by multipath within the interval of the guard interval, that is, an interval in which intersymbol interference does not occur, with an effective symbol. Part. A specific configuration and operation of the combining unit 3 will be described later.

  The FFT unit 4 performs FFT (Fast Fourier Transform) on the broadcast signal input from the synthesis unit 3, thereby converting the broadcast signal in the time domain into a broadcast signal composed of symbols (signal points) in the frequency domain. It is a processing unit that converts and outputs to the demodulation unit 5.

  The demodulation unit 5 is a processing unit that performs OFDM demodulation on the broadcast signal input from the FFT unit 4 and outputs the demodulated broadcast signal to a predetermined output device 6. The output device 6 is, for example, a display device that displays digital television broadcast video or a speaker that outputs digital television broadcast audio.

  Next, the combining unit 3 of the receiving apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating the configuration of the combining unit 3 of the receiving device 1 according to the present embodiment. As illustrated in FIG. 3, the synthesis unit 3 includes a delay unit 31, amplification units 32 and 33, a subtraction unit 34, an addition range determination unit 35, and an addition unit 36.

  The delay unit 31 shown in the figure is a processing unit that delays a broadcast signal input from the receiving unit 2 for a predetermined time. Specifically, the delay unit 31 delays the broadcast signal by a time corresponding to a valid symbol period, and outputs the delayed broadcast signal to the amplification unit 33 and the subtraction unit 34.

  The amplifying unit 32 is a processing unit that amplifies the broadcast signal input from the receiving unit 2 by a factor of 0.5 and outputs it to the adding unit 36 during a period in which a predetermined control signal is input from the adding range determining unit 35. is there.

  Note that the amplification unit 32 outputs the broadcast signal input from the reception unit 2 to the addition unit 36 as it is during a period in which a predetermined control signal is not input from the addition range determination unit 35.

  The amplifying unit 33 is a processing unit that amplifies the broadcast signal input from the delay unit 31 by a factor of 0.5 and outputs the amplified broadcast signal to the adding unit 36.

  The subtraction unit 34 is a processing unit that subtracts the signal level of the broadcast signal input from the delay unit 31 from the signal level of the broadcast signal input from the reception unit 2 and outputs the subtraction result to the addition range determination unit 35. .

  The addition range determination unit 35 is a processing unit that determines a guard interval section (hereinafter referred to as “combination section”) to be combined (added) with an effective symbol based on the subtraction result input from the subtraction section 34.

  The addition range determination unit 35 determines a section in which no inter-symbol interference occurs due to the influence of multipath within the guard interval, and determines such a section as a guard interval synthesis section.

  In addition, the addition range determination unit 35 outputs a predetermined control signal to the addition unit 36 and the amplification unit 32 only during a period corresponding to the determined synthesis interval. Details of the procedure for determining the synthesis section by the addition range determination unit 35 will be described later.

  The adding unit 36 is a processing unit that synthesizes the guard interval and the effective symbol by adding the signal levels of the broadcast signals input from the amplifying unit 32 and the amplifying unit 33.

  The adding unit 36 adds the signal levels of the broadcast signals input from the amplifying unit 32 and the amplifying unit 33 only during the period when the control signal is input from the adding range determining unit 35 and outputs the result to the FFT unit 4.

  On the other hand, the addition unit 36 transmits the broadcast signal input from the amplification unit 32, that is, the broadcast signal not delayed by the delay unit 31, to the FFT unit 4 during a period when the control signal is not input from the addition range determination unit 35. Output.

  Here, the operation of the synthesis unit 3 shown in FIG. 3 will be described with reference to FIGS. 3 and 4 to 7. 4-7 is a figure which shows operation | movement of the synthetic | combination part 3 of the receiver 1 which concerns on a present Example.

  Here, a case where the receiving apparatus 1 receives a broadcast signal including three components of the same broadcast signal whose arrival time has changed due to the influence of multipath will be described. Here, the time required to receive the guard interval is t.

  In the following description, the broadcast signal received by the receiver 1 is the received wave A, the broadcast signal to be received is the desired wave B, the broadcast signal that arrives 1 / 3t after the desired wave B is the delayed wave C, and the desired wave A broadcast signal that arrives 1 / 3t before the wave B is referred to as a preceding wave D.

  As shown in FIG. 4A, when the receiving apparatus 1 receives the desired wave B in which the guard interval GI in which the data sy of the tail part of the effective symbol SY is copied is added to the head of the effective symbol SY, A is received.

  The received wave A includes a delayed wave C whose arrival time is 1 / 3t later than the desired wave B and a preceding wave D component whose arrival time is 1 / 3t earlier than the desired wave B.

  Here, it is assumed that the desired wave B, the delayed wave C, and the preceding wave D are all the same broadcast signal, that is, a broadcast signal including the same guard interval GI and effective symbol SY.

  In such a case, as shown in FIG. 4B, the component of the delayed wave C and the preceding wave D is superimposed on the received wave A. Specifically, in the head portion of the guard interval GI of the received wave A (section corresponding to 1 / 3t), the component 10 (other effective symbol SYa received before the guard interval GI of the delayed wave C ( Hereinafter, “SYa component 10”) is superimposed.

  In addition, in the tail portion of the effective symbol SY of the received wave A (section corresponding to 1 / 3t), the guard interval GIb component 11 (hereinafter referred to as “GIb component”) received after the effective symbol SY of the preceding wave D. 11 ”) is superimposed.

  That is, the section in which the component 10 of SYa in the guard interval GI of the received wave A is superimposed and the section in which the component 11 of the GIb in the effective symbol SY of the received wave A are superimposed are intersymbol interference due to multipath. This is an affected section (hereinafter referred to as “multipath affected section”).

  In such a case, when the receiving apparatus 1 combines the guard interval GI of the received wave A and the effective symbol SY, the reception characteristic of the desired wave B is deteriorated due to the influence of the component 10 of SYa.

  Therefore, in the receiving apparatus 1, the combining unit 3 determines a section in the guard interval GI of the received wave A that is not affected by inter-symbol interference due to multipath (hereinafter referred to as “multipath unaffected section”). Then, the synthesis unit 3 determines the determined multipath unaffected section as a combined section of the guard interval GI.

  In particular, the synthesizer 3 determines the multipath unaffected section of the guard interval GI in the received wave A without performing delay profiling of the delayed wave C and the preceding wave D with respect to the received wave A.

  Specifically, as illustrated in FIG. 3, when the reception wave A is input from the reception unit 2, the synthesis unit 3 inputs the reception wave A to the delay unit 31, the amplification unit 32, and the subtraction unit 34.

  The amplifying unit 32 amplifies the received wave A input from the receiving unit 2 by 0.5 times and outputs the amplified signal to the adding unit 36 during a period in which the control signal is input from the adding range determining unit 35. On the other hand, the amplifying unit 32 outputs the received wave A input from the receiving unit 2 to the adding unit 36 as it is during a period when the control signal is not input from the adding range determining unit 35.

  Further, as shown in FIG. 5, the delay unit 31 generates a delayed reception wave Aa by delaying the reception wave A input from the reception unit 2 by a time T corresponding to the section of the effective symbol SY.

  Then, the delay unit 31 outputs the generated delayed reception wave Aa to the amplification unit 33. The amplifying unit 33 amplifies the delayed received wave Aa input from the delay unit 31 by 0.5 times and outputs the amplified signal to the adder 36.

  In addition, the delay unit 31 outputs the generated delayed reception wave Aa to the subtraction unit 34. As a result, as shown in FIG. 5, the head of the tail data sy in the effective symbol SY of the received wave A and the head of the guard interval GI of the delayed received wave Aa are input to the subtracting unit 34 at the same time. The

  Subsequently, as shown in FIG. 6A, when the received wave A and the delayed received wave Aa are input, the subtracting unit 34 determines the interval of the guard interval GI in the delayed received wave Aa from the signal level of the received wave A. Subtract signal level.

  Then, the subtraction unit 34 outputs the subtraction result to the addition range determination unit 35. At this time, the waveform shown in FIG. 6A is input to the addition range determination unit 35 as a subtraction result. Subsequently, the addition range determination unit 35 determines the synthesis interval of the guard interval GI based on the subtraction result input from the subtraction unit 34.

  Here, as shown in FIG. 6A, the SYa component 10 is superimposed on the head portion of the guard interval GI of the delayed received wave Aa. Further, the GIb component 11 is superimposed on the tail portion of the effective symbol SY of the received wave A.

  For this reason, in the section where the component 10 of SYa is superimposed, the data included in the received wave A and the delayed received wave Aa are not the same. Similarly, the data included in the received wave A and the delayed received wave Aa are not the same even in the interval in which the GIb component 11 is superimposed. Therefore, the waveforms of the received wave A and the delayed received wave Aa in this section are clearly different.

  On the other hand, in a section where neither the component 10 of SYa nor the component 11 of GIb is superimposed, the same data is included in the received wave A and the delayed received wave Aa. Therefore, the waveforms of the received wave A and the delayed received wave Aa in this section are almost the same.

  For this reason, as shown in the waveform of FIG. 6A, a difference occurs in the signal level between the section where the component 10 of SYa and the component 11 of GIb are superimposed and the section where it is not superimposed.

  In the example shown in FIG. 6A, the signal level in the section in which the SYa component 10 and the GIb component 11 are superimposed shows a higher value than the signal level in the non-superimposed section.

  Here, the subtraction result in the section where neither the component 10 of SYa nor the component 11 of GIb is superimposed is closer to “0” because the waveforms of the received wave A and the delayed received wave Aa in this section are closer to “0”. This is because they are almost identical. Note that the waveform shown in FIG. 6A is distorted because Gaussian noise is superimposed on the received wave A and the delayed received wave Aa.

  And the addition range determination part 35 determines a multipath no influence area from the difference of this subtraction result, and determines the determined area as a synthetic | combination area of the guard interval GI.

  However, as described above, the waveform indicating the subtraction result is distorted by the influence of Gaussian noise. When distortion occurs in the waveform indicating the subtraction result, the determination accuracy of the multipath unaffected section by the addition period determination unit 35 is somewhat lowered. For this reason, the addition period determination unit 35 can also determine the multipath unaffected section after smoothing the waveform of the subtraction result.

  For example, the addition range determination unit 35 performs a moving average of the subtraction results obtained by the subtraction unit 34 in each of the divided sections obtained by dividing the guard interval section into a predetermined number (for example, eight equal parts).

  In FIG. 3, the circuit for performing the moving average of the subtraction results is not shown, but any circuit using a known technique can be used as the circuit for performing the moving average. For example, the synthesis unit 3 may be configured to include a delay circuit necessary for performing a moving average of the subtraction results.

  Thereby, the addition range determination part 35 can remove the distortion resulting from Gaussian noise from the waveform which shows a subtraction result, as shown to FIG. 6 (B). Subsequently, the addition range determination unit 35 compares the signal level indicating the subtraction result with a predetermined threshold value.

  And the addition range determination part 35 determines the area where the signal level which shows a subtraction result is below a predetermined threshold value as an area without multipath influence, and determines the determined area as a synthetic | combination area of the guard interval GI.

  That is, the addition range determination unit 35 determines a section in which the waveforms of the received wave A and the delayed received wave Aa are substantially the same in the same section as a multipath unaffected section, and determines such a section as a combined section of the guard interval GI. To do.

  In FIG. 6, the case where the subtraction result of the section on which the component 10 of SYa or the component 11 of GIb is superimposed is higher than the subtraction result of the section not superimposed is described. May be reversed.

  For example, when the signal level of the component 10 of SYa or the component 11 of GIb is extremely higher than the signal level of the desired wave B, the subtraction result in the section where the component 10 of SYa or the component 11 of GIb is superimposed is negative. May take a value.

  In this case, the subtraction result in the section where neither the component 10 of SYa nor the component 11 of GIb is superimposed may be higher than the result of subtraction in the section where it is superimposed.

  However, even in such a case, the received wave A and the delayed received wave Aa are substantially the same in a section where neither the component 10 of SYa nor the component 11 of GIb is superimposed. On the other hand, the signal waveforms of the received wave A and the delayed received wave Aa are clearly different in the section in which the SYa component 10 or the GIb component 11 is superimposed.

  Therefore, the subtraction result in the section in which neither the component 10 of SYa nor the component 11 of GIb is superimposed has a value closer to “0” than the subtraction result in the superimposed section.

  For this reason, the addition range determination unit 35 compares the absolute value of the subtraction result obtained by the subtraction unit 34 with a predetermined threshold value, so that an interval in which neither the component 10 of SYA nor the component 11 of GIb is superimposed is obtained. Can be determined.

  That is, the addition range determination unit 35 can appropriately determine a section in which the absolute value of the subtraction result obtained by the subtraction section 34 is equal to or less than a predetermined threshold as a section having no multipath effect.

  Subsequently, the addition range determination unit 35 outputs a predetermined control signal to the addition unit 36 and the amplification unit 32 only during a period corresponding to the determined synthesis interval of the guard interval GI.

  The amplifying unit 32 amplifies the received wave A input from the receiving unit 2 by a factor of 0.5 and outputs the amplified signal to the adding unit 36 during the period when the control signal is input from the adding range determining unit 35. In addition, the amplification unit 32 outputs the received wave A input from the reception unit 2 to the addition unit 36 as it is during a period when the control signal is not input from the addition range determination unit 35.

  Then, the adder unit 36 receives the guard interval GI of the received wave A input from the amplifying unit 32 and the delayed received wave Aa input from the amplifying unit 33 during the period when the control signal is input from the adding range determining unit 35. Are added (synthesized).

  For example, as shown in FIG. 7A, the adder 36 receives the received wave A and the delay only during the period of time ta to tb when the control signal is input from the addition range determining unit 35 only during the period of time ta to tb. The received wave Aa is combined and output to the FFT unit 4. On the other hand, the adder 36 outputs the received wave A output from the amplifier 32 to the FFT unit 4 as it is during a period other than the times ta to tb.

  As a result, the synthesizer 3 synthesizes the guard interval gi in the interval where there is no intersymbol interference due to multipath, with respect to the data sy of the tail portion of the effective symbol SY of the received wave A, as shown in FIG. The synthesized wave E can be generated.

  For this reason, the receiving apparatus 1 can improve the reception characteristics of the desired wave B by effectively using the guard interval gi in a section where there is no intersymbol interference due to multipath.

  As described above, the receiving apparatus according to the present embodiment receives a broadcast signal having a section of an effective symbol including broadcast contents and a section of a guard interval obtained by duplicating a part of the effective symbol.

  Subsequently, the receiving apparatus according to the present embodiment delays the guard interval in the received broadcast signal by a time corresponding to the effective symbol period. Subsequently, the receiving apparatus according to the present embodiment subtracts the signal level of the guard interval GI from the signal level of the tail part of the effective symbol in the broadcast signal before delay.

  Subsequently, the receiving apparatus according to the present embodiment compares a value based on the signal level subtraction result with a predetermined threshold value. Then, the receiving apparatus according to the present embodiment determines a guard interval section in which a value based on the subtraction result is equal to or less than a predetermined threshold as a guard interval combining section to be combined with an effective symbol.

  Thus, according to the receiving apparatus according to the present embodiment, it is possible to determine the interval of the guard interval without intersymbol interference due to multipath without performing delay profiling of the broadcast signal.

  Therefore, according to the receiving apparatus of the present embodiment, it is possible to synthesize effective symbols and guard intervals in sections that are not affected by multipath without providing a delay profile unit having a relatively large circuit scale.

  Further, in the receiving apparatus according to the present embodiment, when determining the interval of the guard interval without intersymbol interference, it is only necessary to delay the received broadcast signal for a time corresponding to the effective symbol interval.

  For this reason, according to the receiving apparatus according to the present embodiment, it is not necessary to temporarily store and delay a plurality of received effective symbols as in the case of delay profiling of a received broadcast signal. Can be achieved.

  In addition, the receiving apparatus according to the present embodiment smoothes the subtraction result by the subtraction unit, compares the subtraction result with a predetermined threshold value, and guards a section where the absolute value of the subtraction result or the subtraction result is equal to or less than the predetermined threshold value It is determined as a composite interval.

  For this reason, according to the receiving apparatus according to the present embodiment, it is possible to appropriately determine the synthesis interval of the guard interval even when noise such as Gaussian noise is mixed in the received broadcast signal.

DESCRIPTION OF SYMBOLS 1 Reception apparatus 2 Reception part 3 Synthesis | combination part 4 FFT part 5 Demodulation part 6 Output apparatus 31 Delay part 32 Amplification part 33 Amplification part 34 Subtraction part 35 Addition range determination part 36 Addition part

Claims (4)

A receiving device that receives a broadcast signal having a section of effective symbols including broadcast contents and a section of a guard interval in which a part of the effective symbols is duplicated,
Receiving means for receiving the broadcast signal;
Subtracting means for subtracting the signal level of the section of the guard interval from the signal level of the section corresponding to the part of the effective symbol in the broadcast signal received by the receiving means;
The guard that compares the absolute value of the subtraction result by the subtracting means with a predetermined threshold value and combines the interval of the guard interval in which the absolute value of the subtraction result is not more than the predetermined threshold value with the part of the effective symbol. A determining means for determining as an interval section;
A receiving apparatus comprising: a combining unit configured to amplify and combine the guard interval of the section determined by the determining unit and the effective symbol that is a copy source of the guard interval by a factor of 0.5 . Delay means for delaying the broadcast signal received by the receiving means for a time corresponding to a section of the effective symbol;
The subtracting means is
2. The reception according to claim 1, wherein a signal level of the guard interval in the broadcast signal delayed by the delay unit is subtracted from a signal level of the effective symbol in the broadcast signal before the delay by the delay unit. apparatus. The determining means includes
The value obtained by moving and averaging the subtraction results obtained by the subtracting means in each of the divided sections obtained by dividing the guard interval into a predetermined number is compared with the predetermined threshold value. Receiver. A receiving method by a receiving device that receives a broadcast signal having a section of an effective symbol including broadcast content and a section of a guard interval in which a part of the effective symbol is copied,
Receiving the broadcast signal; and
A subtraction step of subtracting the signal level of the section of the guard interval from the signal level of the section corresponding to the part of the effective symbol in the broadcast signal received by the reception step;
The guard that compares the absolute value of the subtraction result obtained by the subtraction step with a predetermined threshold value and combines the guard interval section in which the absolute value of the subtraction result is equal to or less than the predetermined threshold value with the part of the effective symbol. A determination step for determining as an interval section;
And a combining step of amplifying and synthesizing the guard interval in the section determined by the determining step and the effective symbol that is the replication source of the guard interval by a factor of 0.5.

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