Abstract:
The present disclosure provides a receiving device including, a receiver configured to receive a signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, a demodulator configured to demodulate a received signal, an estimator configured to estimate a signal-to-noise ratio relating to the propagation path, obtained from a data signal included in the demodulated received signal, and a corrector configured to correct an estimated signal-to-noise ratio in accordance with a transmission parameter obtained from the received signal.

Description:
BACKGROUND 
     The present disclosure relates to receiving devices and methods, demodulating devices and methods, and programs, and particularly to receiving device and method, demodulating device and method, and program that enable enhancement in the accuracy of estimation of the SNR (Signal-to-Noise Ratio) relating to a propagation path. 
     As shown in  FIG. 1 , a digital terrestrial broadcast signal transmitted from a transmitting device  2  of a broadcast station or the like is received by a receiving device  1  via a propagation path  3 . In the digital terrestrial broadcasting and so forth, e.g. OFDM (Orthogonal Frequency Division Multiplexing) is employed as the digital modulation system for data (signal). 
     The propagation path  3  gives the influence of noise and so forth to the signal transmitted from the transmitting device  2 . In general, the influence given to the signal by the propagation path  3  is represented by the SNR. 
     In the receiving device  1 , the path SNR of the propagation path  3 , obtained from the signal transmitted from the transmitting device  2  via the propagation path  3 , is estimated. Hereinafter, the estimated path SNR will be referred to as the estimated SNR. 
       FIG. 2  is a diagram showing the relationship between the ideal path SNR and the estimated SNR. 
     In  FIG. 2 , the estimated SNR represented by the axis along the vertical direction in the diagram is indicated by the dashed line, and the path SNR represented by the axis along the horizontal direction in the diagram is indicated by the solid line. As shown in  FIG. 2 , as the relationship between the estimated SNR (dashed line) and the path SNR (solid line), the value of the estimated SNR is closer to the value of the path SNR when the value of the SNR is larger. In contrast, the value of the estimated SNR is divergent from the value of the path SNR at a higher degree when the value of the SNR is lower. 
     The reason for the occurrence of such divergence will be described with reference to  FIGS. 3A and 3B . 
     In the case of obtaining the estimated SNR from an unknown data signal included in a signal transmitted via the propagation path  3 , generally the result of a hard decision for the constellation of the data signal is utilized. Specifically, when the path SNR is not low, the transmission point corresponds with the estimated transmission point in the constellation in the IQ plane as shown in pattern A of  FIG. 3A , so that the ideal estimated SNR is obtained. In this case, the correct estimated SNR is obtained based on S and N indicated by the solid lines. 
     In contrast, as shown in pattern B of  FIG. 3B , when the path SNR is low, the result of a hard decision is mistaken for an adjacent symbol and the transmission point does not correspond with the estimated transmission point. As a result, an erroneous estimated SNR is obtained. In this case, although the correct estimated SNR is obtained based on S and N indicated by the dashed lines, actually the erroneous estimated SNR is obtained by S′ and N′ indicated by the solid lines. 
     As a method for calculating the SNR, there has been disclosed an OFDM demodulating device that calculates the SNR based on a complex correlation signal obtained by complex correlation calculation of a baseband signal (refer to e.g. Japanese Patent Laid-open No. 2007-208748). 
     SUMMARY 
     As described above, the following problem exists in the case of obtaining the estimated SNR from an unknown data signal. Specifically, in general, when the value of the SNR is low, the transmission point does not correspond with the estimated transmission point and thus an erroneous SNR is obtained, so that the value of the estimated SNR is divergent from the value of the path SNR. 
     This estimated SNR is not only provided to the respective sections in the receiving device to be used for predetermined processing but also used when information relating to the path SNR is notified to the user for example. Therefore, there has been a demand to obtain the estimated SNR with high accuracy. 
     There is a need for a technique to enable enhancement in the accuracy of estimation of the SNR relating to a propagation path. 
     According to an embodiment of the present disclosure, there is provided a receiving device including a receiver configured to receive a signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, a demodulator configured to demodulate a received signal, an estimator configured to estimate an SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, and a corrector configured to correct an estimated SNR in accordance with a transmission parameter obtained from the received signal. 
     According to another embodiment of the present disclosure, there is provided a receiving method of a receiving device. The method includes receiving a signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, demodulating the received signal, estimating an SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, and correcting an estimated SNR in accordance with a transmission parameter obtained from the received signal. 
     According to another embodiment of the present disclosure, there is provided a program for causing a computer to function as a device including a receiver configured to receive a signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, a demodulator configured to demodulate a received signal, an estimator configured to estimate an SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, and a corrector configured to correct an estimated SNR in accordance with a transmission parameter obtained from the received signal. 
     In the receiving device and method and the program according to the above-described embodiments of the present disclosure, a signal that is transmitted via the propagation path and is modulated by a predetermined system prescribed by a predetermined standard is received and the received signal is demodulated. Furthermore, the SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, is estimated, and the estimated SNR is corrected in accordance with the transmission parameter obtained from the received signal. 
     According to another embodiment of the present disclosure, there is provided a demodulating device including a demodulator configured to demodulate a received signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, an estimator configured to estimate an SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, and a corrector configured to correct an estimated SNR in accordance with a transmission parameter obtained from the received signal. 
     According to another embodiment of the present disclosure, there is provided a demodulating method of a demodulating device. The method includes demodulating a received signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, estimating an SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, and correcting an estimated SNR in accordance with a transmission parameter obtained from the received signal. 
     According to another embodiment of the present disclosure, there is provided a program for causing a computer to function as a device including a demodulator configured to demodulate a received signal that is transmitted via a propagation path and is modulated by a predetermined system prescribed by a predetermined standard, an estimator configured to estimate an SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, and a corrector configured to correct an estimated SNR in accordance with a transmission parameter obtained from the received signal. 
     In the demodulating device and method and the program according to the above-described embodiments of the present disclosure, a received signal that is transmitted via the propagation path and is modulated by a predetermined system prescribed by a predetermined standard is demodulated. Furthermore, the SNR relating to the propagation path, obtained from a data signal included in the demodulated received signal, is estimated, and the estimated SNR is corrected in accordance with the transmission parameter obtained from the received signal. 
     The embodiments of the present disclosure can enhance the accuracy of estimation of the SNR relating to a propagation path. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing the outline of a path SNR; 
         FIG. 2  is a diagram showing the relationship between the path SNR and an estimated SNR; 
         FIGS. 3A and 3B  are diagrams showing a result of a hard decision for the constellation of a data signal; 
         FIG. 4  is a diagram showing the configuration of a receiving device according to one embodiment of the present disclosure; 
         FIG. 5  is a diagram showing the detailed configurations of a controller and a demodulating section; 
         FIG. 6  is a flowchart showing estimated-SNR-related processing; 
         FIG. 7  is a flowchart showing estimated SNR correction processing; 
         FIGS. 8A and 8B  are diagrams showing details of estimated SNR correction; 
         FIG. 9  is a diagram showing the relationship between the path SNR and a corrected SNR; and 
         FIG. 10  is a diagram showing a configuration example of hardware of a computer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present disclosure will be described below with reference to the drawings. 
     [Configuration of Receiving Device] 
       FIG. 4  is a diagram showing the configuration of a receiving device according to one embodiment of the present disclosure. 
     A receiving device  1  of  FIG. 4  is equivalent to the receiving device  1  in  FIG. 1  and is e.g. a receiving device compliant with a predetermined standard of digital terrestrial broadcasting. The receiving device  1  includes an antenna  11 , a tuner  12 , a demodulating section  13 , an error correction section  14 , a decoder  15 , and an output section  16 . Furthermore, the receiving device  1  includes a controller  10  that controls the operation of the respective sections in the receiving device  1 . 
     The antenna  11  receives an RF (Radio Frequency) signal transmitted from the transmitting device  2  of a broadcast station or the like via the propagation path  3  and supplies it to the tuner  12 . 
     The tuner  12  performs frequency conversion of the RF signal received by the antenna  11 . An IF (Intermediate Frequency) signal obtained by performing the frequency conversion for the RF signal is supplied to the demodulating section  13 . 
     The demodulating section  13  performs A/D conversion for the signal supplied from the tuner  12  and then executes predetermined demodulation processing such as synchronization processing and equalization processing, to supply data obtained as the result to the error correction section  14 . 
     Furthermore, the demodulating section  13  estimates the SNR relating to the propagation path  3 , obtained from a data signal included in the demodulated received signal. Moreover, the demodulating section  13  acquires a transmission parameter obtained from the received signal. The demodulating section  13  supplies the estimated SNR and the transmission parameter to the controller  10 . 
     The transmission parameter is inserted in e.g. system information (SI) of a body part that configures a frame of a predetermined standard together with a header part. 
     The estimated SNR and the transmission parameter are supplied from the demodulating section  13  to the controller  10 . The controller  10  corrects the estimated SNR in accordance with the transmission parameter. Hereinafter, the corrected estimated SNR will be referred to as the corrected SNR. The controller  10  supplies the corrected SNR obtained by correcting the estimated SNR to the respective sections in the receiving device  1  that execute predetermined processing with use of the corrected SNR. 
     The detailed configurations of the controller  10  and the demodulating section  13  will be described later. 
     The error correction section  14  executes predetermined error correction processing for data supplied from the demodulating section  13  and supplies encoded data obtained as the result to the decoder  15 . 
     In the transmitting device  2  ( FIG. 1 ), for example data of image and audio as a show is subjected to MPEG (Moving Picture Experts Group) encoding and a transmission signal configured by packets including the MPEG-encoded data is transmitted. Furthermore, in the transmitting device  2 , the data is encoded to a code such as an RS (Reed-Solomon) code as a countermeasure against an error occurring on the propagation path  3 . Therefore, the error correction section  14  executes processing of decoding the code and so forth as the error correction processing. 
     The decoder  15  performs e.g. MPEG decoding of the encoded data supplied from the error correction section  14  and supplies data of image and audio obtained as the result to the output section  16 . 
     The output section  16  is configured with display device, speaker, etc. The display device displays an image in association with the image data supplied from the decoder  15  and the speaker outputs audio in association with the audio data. 
     The receiving device  1  is configured in the above-described manner. 
     [Detailed Configurations of Controller and Demodulating Section] 
     With reference to  FIG. 5 , the detailed configurations of the controller  10  and the demodulating section  13  as part of the respective sections configuring the receiving device  1  of  FIG. 4  will be described below. 
     As shown in  FIG. 5 , the demodulating section  13  includes an SNR estimator  42  and a transmission parameter acquirer  43  in addition to a demodulator  41  that executes demodulation processing. 
     The SNR estimator  42  estimates the SNR obtained from a data signal included in the received signal demodulated by the demodulating section  13  and supplies the estimated SNR to the controller  10 . 
     As the method for estimating the SNR, the result of a hard decision for the constellation of the data signal is used as described above with  FIGS. 3A and 3B , and thereby the estimated SNR is obtained. Therefore, as described above, when the path SNR is not low, the transmission point corresponds with the estimated transmission point and the ideal estimated SNR is obtained. In contrast, when the path SNR is low, the transmission point does not correspond with the estimated transmission point and an erroneous estimated SNR is obtained. 
     The transmission parameter acquirer  43  extracts the signal corresponding to the system information from the signal obtained by executing equalization processing for the signal supplied from the tuner  12  and decodes the extracted signal to thereby obtain information on the transmission parameter. The transmission parameter acquirer  43  supplies the acquired transmission parameter to the controller  10 . 
     As the transmission parameter, e.g. a constellation is acquired. The constellation is an entity obtained by defining the arrangement of signal points indicating the combination of the phase and/or amplitude of the in-phase channel (I channel) and the quadrature channel (Q channel) in a digital quadrature modulation system such as PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation). Normally the constellation is represented by the IQ plane. Accordingly, e.g. a constellation of 4QAM, 4QAM-NR, 16QAM, 32QAM, or 64QAM is acquired as the transmission parameter. 
     The transmission parameter may be other than the constellation. For example, another parameter obtained by the demodulation processing by the demodulating section  13 , such as the pseudo noise (PN) code length, may be acquired. 
     The controller  10  includes an estimated SNR correcting unit  21  and a correction parameter storing unit  22 . 
     The correction parameter storing unit  22  stores correction parameters used for correction of the estimated SNR in such a manner that each of the correction parameters is associated with a respective one of the transmission parameters. This transmission parameter is e.g. the constellation or the PN code length as described above and the correction parameter is stored in the correction parameter storing unit  22  in association with the constellation or another parameter. 
     The estimated SNR correcting unit  21  includes a corrected SNR calculator  31  and a correction parameter acquirer  32 . 
     In the estimated SNR correcting unit  21 , the estimated SNR from the SNR estimator  42  is supplied to the corrected SNR calculator  31  and the transmission parameter from the transmission parameter acquirer  43  is supplied to the correction parameter acquirer  32 . 
     The correction parameter acquirer  32  acquires the correction parameter, which is stored in the correction parameter storing unit  22  in association with the transmission parameter on each transmission parameter basis, corresponding to the transmission parameter supplied from the transmission parameter acquirer  43  and supplies the correction parameter to the corrected SNR calculator  31 . 
     The corrected SNR calculator  31  applies the correction parameter supplied from the correction parameter acquirer  32  to a predetermined arithmetic expression and performs calculation with use of this arithmetic expression to thereby calculate the corrected SNR from the estimated SNR. The corrected SNR calculator  31  supplies the corrected SNR obtained by the calculation to the respective sections in the receiving device  1  that execute predetermined processing with use of the corrected SNR. 
     The controller  10  and the demodulating section  13  are configured in the above-described manner. 
     [Estimated-SNR-Related Processing] 
     With reference to a flowchart of  FIG. 6 , estimated-SNR-related processing executed in the receiving device  1  with use of the estimated SNR will be described below. 
     When a digital terrestrial broadcast signal is transmitted from the transmitting device  2  via the propagation path  3 , the signal is received by the tuner  12  via the antenna  11  in the receiving device  1  (step S 11 ). The tuner  12  performs frequency conversion of the received signal and supplies the resulting signal to the demodulating section  13 . 
     In the demodulating section  13 , the SNR estimator  42  estimates the SNR from the result of a hard decision for the constellation of a data signal included in the received signal demodulated by the demodulator  41  (step S 12 ). Furthermore, the transmission parameter acquirer  43  extracts the signal corresponding to the system information from the signal obtained by executing equalization processing for the received signal and decodes the extracted signal to thereby acquire a transmission parameter (step S 13 ). 
     In a step S 14 , the estimated SNR correcting unit  21  executes estimated SNR correction processing for correcting the estimated SNR obtained by the SNR estimator  42  in accordance with the transmission parameter acquired by the transmission parameter acquirer  43 . 
     With reference to a flowchart of  FIG. 7 , details of the estimated SNR correction processing executed by the estimated SNR correcting unit  21  will be described below. 
     In the estimated SNR correcting unit  21 , the corrected SNR calculator  31  acquires the estimated SNR from the SNR estimator  42  and the correction parameter acquirer  32  acquires the transmission parameter from the transmission parameter acquirer  43  (step S 31 ). 
     In a step S 32 , the correction parameter acquirer  32  acquires, from the correction parameter storing unit  22 , the correction parameter corresponding to the transmission parameter from the transmission parameter acquirer  43 . 
     The corrected SNR calculator  31  compares the value of the subject estimated SNR of the acquired estimated SNR with the correction upper limit (to be described later) included in the correction parameter acquired by the correction parameter acquirer  32  (step S 33 ), and determines whether or not the value of the subject estimated SNR is equal to or lower than the correction upper limit (step S 34 ). 
     If it is determined in the step S 34  that the value of the subject estimated SNR is equal to or lower than the correction upper limit, the processing proceeds to a step S 35 . In the step S 35 , the corrected SNR calculator  31  performs calculation with use of a predetermined arithmetic expression to which the correction parameter (the amount of slope correction and the amount of intercept correction to be described later) acquired by the correction parameter acquirer  32 , to thereby calculate the corrected SNR about the value of the subject estimated SNR. 
     Thereafter, the processing returns to the step S 33 . If the value of the next subject estimated SNR is equal to or lower than the correction upper limit (“Yes” of the step S 34 ), the corrected SNR calculator  31  performs calculation with use of the predetermined arithmetic expression to which the correction parameter is applied, to calculate the corrected SNR about the value of the subject estimated SNR. That is, through the repetition of the steps S 33  to S 35 , the corrected SNR based on the correction parameter is calculated about the values of the estimated SNR equal to or lower than the correction upper limit. 
     If it is determined in the step S 34  that the value of the subject estimated SNR surpasses the correction upper limit, the processing proceeds to a step S 36 . In the step S 36 , the corrected SNR calculator  31  outputs, as the corrected SNR, the calculated corrected SNR (corrected SNR calculated in the step S 35 ) for the value of the estimated SNR in the range equal to or lower than the correction upper limit, and the estimated SNR obtained by the SNR estimator  42  as it is for the value of the estimated SNR in the range beyond the correction upper limit. 
     With reference to  FIGS. 8A ,  8 B and  FIG. 9 , a specific example of the estimated SNR correction processing executed by the estimated SNR correcting unit  21  will be described below. 
       FIGS. 8A and 8B  are graphs made by representing, on a logarithmic axis, the values of the estimated SNR before and after the estimated SNR correction processing executed by the estimated SNR correcting unit  21 . In  FIG. 8A  on the left side of the diagram, the relationship between the path SNR and the estimated SNR (estimated SNR before the correction processing) is shown. In  FIG. 8B  on the right side of the diagram, the relationship between the path SNR and the corrected SNR (estimated SNR after the correction processing) is shown. 
     As shown in  FIG. 8A , as the relationship between the estimated SNR indicated by the dashed line and the path SNR (ideal SNR) indicated by the solid line, the estimated SNR is divergent from the path SNR when the value of the SNR is low as described above. 
     Here, pay attention to the value of the estimated SNR. The estimated SNR is divergent from the path SNR only when the value of the SNR is low. So, the range of the divergence is defined by the correction upper limit and the estimated SNR in the range equal to or lower than the correction upper limit is considered as a linear equation having a slope and an intercept. If such slope and intercept that the above-described divergence is eliminated are given as the amounts of correction about this linear equation, the estimated SNR indicated by the dashed line, i.e. the corrected SNR, substantially overlaps with the path SNR indicated by the solid line as shown in  FIG. 8B . 
     If the intercept and slope of the estimated SNR are so corrected that the corrected SNR has a proportional relationship with the path SNR in this manner, the accuracy of the estimated SNR can be enhanced. 
     Specifically, by correcting the estimated SNR e.g. by the following correcting methods 1 and 2, the corrected SNR and the path SNR can be made to have a proportional relationship. 
     [Correcting Method 1] 
     As correcting method 1, there is a method in which the intercept and slope of the estimated SNR on the logarithmic axis are changed to correct the decibel value of the estimated SNR so that the path SNR and the corrected SNR may be proportional to each other. In this case, the corrected SNR is obtained by the following arithmetic expression (1). 
     
       
         
           
             
               
                 
                   
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                     ′ 
                   
                   = 
                   
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                             ax 
                             + 
                             n 
                           
                         
                         
                           
                             ( 
                             
                               x 
                               ≤ 
                               m 
                             
                             ) 
                           
                         
                       
                       
                         
                           x 
                         
                         
                           
                             ( 
                             
                               x 
                               &gt; 
                               m 
                             
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
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         x′ [dB]: corrected SNR 
         x [dB]: estimated SNR 
         a: the amount of slope correction 
         n: the amount of intercept correction 
         m [dB]: correction upper limit (correction upper limit SNR) 
       
    
     As described above, in correcting method 1, three parameters of the amount a of slope correction, the amount n of intercept correction, and the correction upper limit m are given as the correction parameter associated with the transmission parameter such as the constellation or the PN code length. The corrected SNR(x′) is obtained by performing calculation of multiplying the estimated SNR(x) having a decibel value equal to or lower than the correction upper limit m by the amount a of slope correction and then adding the amount n of intercept correction to the value obtained by the multiplication. The corrected SNR(x′) obtained in this manner has a proportional relationship with the path SNR. As for the value of the estimated SNR(x) in the range beyond the correction upper limit m, this value of the estimated SNR(x) is used as it is because the value of the estimated SNR(x) is not divergent from the value of the path SNR. 
     [Correcting Method 2] 
     As correcting method 2, there is a method in which the intercept and slope of the estimated SNR on the logarithmic axis are changed to correct the true value of the estimated SNR so that the path SNR and the corrected SNR may be proportional to each other. In this case, the corrected SNR is obtained by the following arithmetic expression (2). 
     
       
         
           
             
               
                 
                   
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                     ′ 
                   
                   = 
                   
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                             NX 
                             A 
                           
                         
                         
                           
                             ( 
                             
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                               M 
                             
                             ) 
                           
                         
                       
                       
                         
                           X 
                         
                         
                           
                             ( 
                             
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                               M 
                             
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                   ) 
                 
               
             
           
         
       
         
         X′: corrected SNR 
         X: estimated SNR 
         A: the amount of slope correction 
         N: the amount of intercept correction 
         M: correction upper limit (correction upper limit SNR) 
       
    
     As described above, in correcting method 2, three parameters of the amount A of slope correction, the amount N of intercept correction, and the correction upper limit M are given as the correction parameter associated with the transmission parameter such as the constellation or the PN code length. The corrected SNR(X′) is obtained by performing calculation of raising the estimated SNR(X) having a true value equal to or lower than the correction upper limit M to the power of the amount A of slope correction and then multiplying the value obtained by the raising by the amount N of intercept correction. The corrected SNR(X′) obtained in this manner has a proportional relationship with the path SNR. As for the value of the estimated SNR(X) in the range beyond the correction upper limit M, this value of the estimated SNR(X) is used as it is because the value of the estimated SNR(X) is not divergent from the value of the path SNR. 
     Correcting methods 1 and 2 are one example of the method for correcting the SNR so that the corrected SNR and the path SNR may be proportional to each other, and another correcting method may be used. As for comparison between correcting method 1 and correcting method 2, employing correcting method 1 allows a smaller circuit scale because correcting method 1, in which calculation of multiplication and addition is performed, permits a smaller amount of calculation. 
     In both correcting methods 1 and 2, the range of the SNR for which correction is performed is defined by the correction upper limit. Due to this feature, the correction processing is executed only for the low-value range of the SNR, in which the phenomenon that the value of the estimated SNR is divergent from the value of the path SNR occurs, and the correction is not performed for the range in which the correction is unnecessary. Thus, the amount of calculation of the correction processing can be decreased and the processing time can be shortened. 
       FIG. 9  is a diagram showing the relationship among the path SNR, the estimated SNR, and the corrected SNR. 
     In  FIG. 9 , the estimated SNR (cross mark in the diagram) and the corrected SNR (circle-mark in the diagram) represented by the axis along the vertical direction in the diagram are indicated by the dashed lines, and the path SNR represented by the axis along the horizontal direction in the diagram is indicated by the solid line. As described above, the value of the estimated SNR is divergent from the value of the path SNR at a higher degree when the value of the SNR is lower. However, as is apparent also from  FIG. 9 , in the case of the corrected SNR obtained by correcting the estimated SNR, the gap between the values of the SNR is absent even when the value of the SNR is low, and the corrected SNR is close to the ideal path SNR. 
     In the above-described manner, if the SNR is estimated from the result of a hard decision for the constellation of a data signal, the correction parameter (the amount of slope correction, the amount of intercept correction, correction upper limit) associated with the transmission parameter such as a constellation is acquired in the estimated SNR correcting unit  21 . Furthermore, in the estimated SNR correcting unit  21 , calculation with the predetermined arithmetic expression (arithmetic expression (1), (2)) to which the amount of slope correction and the amount of intercept correction are applied is performed only for the values of the estimated SNR in the range equal to or lower than the correction upper limit and the corrected SNR arising from approximation of the value of the estimated SNR to the value of the path SNR is calculated. 
     Referring back to the flowchart of  FIG. 7 , the corrected SNR is output by the corrected SNR calculator  31  to the demodulating section  13  and another subsequent-stage processing unit (not shown) that executes predetermined processing with use of the corrected SNR (step S 36 ). Upon the end of the step S 36 , the processing returns to the flowchart of  FIG. 6  and processing of a step S 15  is executed. 
     In the step S 15 , the demodulating section  13  and the subsequent-stage processing unit (not shown) execute predetermined processing with use of the corrected SNR, so that the estimated-SNR-related processing of  FIG. 6  is ended. For example, the subsequent-stage processing unit (not shown) supplies the corrected SNR to the output section  16  and makes the corrected SNR be displayed on a display. 
     As described above, the estimated SNR with high accuracy can be acquired by executing the estimated SNR correction processing for the estimated SNR by the corrected SNR calculator  31 . Thus, for example if the result of estimation of the SNR is used inside the receiving device  1 , the estimated-SNR-related processing with use of the estimated SNR having higher accuracy can be executed. Furthermore, the high-accuracy result of estimation of the SNR can be presented to the user who uses the receiving device  1 . 
     In the above description of the present embodiment, the estimated SNR correcting unit  21  to execute processing of correcting the estimated SNR and the correction parameter storing unit  22  are part of the controller  10 . However, the estimated SNR correcting unit  21  and the correction parameter storing unit  22  may be considered as part of the demodulating section  13 . That is, it is also possible that the demodulating section  13  of the above-described present embodiment is configured as a demodulating device (demodulating LSI (Large Scale Integration)) obtained by adding the estimated SNR correcting unit  21  to execute processing of correcting the estimated SNR and the correction parameter storing unit  22  to the demodulating section  13 . This demodulating device may include the error correction section  14 , an A/D converter (not shown), and so forth. 
     As the standard of the digital terrestrial broadcasting of the present embodiment, e.g. a standard such as the DTMB (Digital Terrestrial Multimedia Broadcast) is employed. 
     [Description of Computer to which Embodiment of the Present Disclosure is Applied] 
     The above-described series of processing can be executed by hardware and also by software. In the case of executing the series of processing by software, a program configuring the software is installed from a program recording medium into a computer incorporated into dedicated hardware or e.g. a general-purpose personal computer capable of executing various kinds of functions through installation of various kinds of programs. 
       FIG. 10  is a diagram showing a configuration example of a computer that executes the above-described series of processing by a program. 
     In this computer  100 , a CPU (central processing unit)  101 , a ROM (read only memory)  102 , and a RAM (random access memory)  103  are connected to each other by a bus  104 . 
     An input/output interface  105  is connected to the bus  104 . The following units are connected to the input/output interface  105 : an input unit  106  composed of a keyboard, a mouse, a microphone, etc; an output unit  107  composed of a display, a speaker, etc; a storing unit  108  composed of a hard disc, a non-volatile memory, etc; a communication unit  109  composed of a network interface, etc; and a drive  110  that drives removable media  111  such as a magnetic disc, an optical disc, a magneto-optical disc, or a semiconductor memory. 
     In the computer  100  having the above-described configuration, for example the CPU  101  loads a program stored in the storing unit  108  into the RAM  103  via the input/output interface  105  and the bus  104  and runs the program, and thereby the above-described series of processing is executed. 
     Steps that describe the program run by the computer encompass processing that is not necessarily executed in a time-series manner but executed in parallel or individually as well as processing executed in a time-series manner along the described order. 
     Embodiments of the present disclosure are not limited to the above-described embodiment and various changes may be made without departing from the gist of the present disclosure. 
     The present disclosure contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2010-238638 filed in the Japan Patent Office on Oct. 25, 2010, the entire content of which is hereby incorporated by reference.