JP2004236076A - Receiving device and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply specify jamming waves of multipaths and the same channel or adjacent channels which do harm to a viewing and listening of land-based digital broadcasting. <P>SOLUTION: After a received OFDM (Orthogonal Frequency Division Multiplex) signal is converted to a digital signal in an A/D converter 14, a delay wave profile is generated, and a receiving state decision part 29 specifies multipaths components which cause the viewing and listening obstacle by carrying out FFT (Fast Fourier Transform) processing in an FFT processor 15, extracting a pilot signal, and processing in an IFFT (Inverse Fast Fourier Transform) processor 28. The jamming wave of the same channel and the adjacent channel are extracted from output of a decoding and processing part 16, the jamming wave profile is generated, and the receiving state decision part 29 specifies the jamming wave which causes the viewing and listening obstacle. The delayed wave profile and the jamming wave profile are displayed on a monitor 25 together with decision result of the receiving state decision part, and the content of the viewing and listening obstacle is noticed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a terrestrial digital broadcast receiving apparatus, and more particularly to a receiving apparatus capable of easily installing an antenna by monitoring a receiving state.
[0002]
[Prior art]
Terrestrial digital broadcasting has been started in some regions since 2003, and digital broadcasting is scheduled to be implemented in all regions in 2010. Digital terrestrial broadcasting is basically performed using the UHF (Ultra High Frequency) band, and new transmission facilities including relay facilities will be installed in some areas. Therefore, in regions where analog broadcasting by VHF (very high frequency) has been received, it is necessary to newly install a UHF antenna in order to receive terrestrial digital broadcasting, and to receive analog broadcasting with UHF. If the position of the transmission equipment is changed even in the area where the transmission equipment is located, it is necessary to change the direction of the antenna in accordance with the transmission equipment.
[0003]
At present, in a receiver for receiving BS (Broadcasting Satellite) broadcast or CS (Communications Satellite) broadcast in which digital broadcasting is implemented, various measures are taken to easily install an antenna. No. 1 proposes to determine the level of a received radio wave from an AGC (Automatic Gain Control) voltage level of a tuner and to display the level. Therefore, it has been proposed to install an antenna so that the error rate is minimized. Patent Document 3 discloses a ratio (C / N: Carrier / C / N: Carrier / Noise) and display this to receive Proposals have been made to notify the state of a communication signal.
[0004]
Even in terrestrial digital broadcasting, it is possible to use those technologies, but since it is a terrestrial wave, it is expected that multiple radio waves will interfere due to reflection and diffraction on the transmission path, etc. The conventional proposal cannot detect such a situation, and cannot realize a reception state in which multipath is reliably avoided. Until 2010, it is considered that there will be areas where analog broadcasting and digital broadcasting are presently mixed, and in such an environment, it may be affected by adjacent channel interference, co-channel interference, etc. However, there is also a problem that it is not possible to clearly recognize the specifics of those disturbances, and it is not possible to take clear measures because the cause is unknown. appear.
[0005]
As described above, in the conventional receiving apparatus, the receiving state is determined from the level of the received signal, the error rate of the received digital signal, the C / N of the received signal, and the like, and the antenna is installed. There is a problem that a reception failure due to a factor peculiar to terrestrial digital broadcasting cannot be clearly recognized, and the installation work of the antenna cannot be performed simply in a short time.
[0006]
[Patent Document 1]
JP-A-7-46020 (pages [0023] to [0032], FIGS. 1 to 3)
[Patent Document 2]
JP-A-10-13131 (pages 3 [0011] to [0013], FIGS. 1 to 3)
[Patent Document 3]
JP-A-9-37178 (page 6, [0055] to [0061], FIG. 4)
[0007]
[Problems to be solved by the invention]
As described above, the conventional receiving apparatus cannot specifically identify a reception failure peculiar to terrestrial digital broadcasting, and it has been difficult to set the direction of the receiving antenna simply and accurately.
The present invention has been made in view of the above points, and has been configured to reliably determine and display multipath, adjacent channel interference, and co-channel interference, thereby providing a terrestrial digital broadcast. An object of the present invention is to provide a receiving device capable of easily and reliably performing an antenna installation operation.
[0008]
[Means for Solving the Problems]
A receiving apparatus according to the present invention includes: a receiving unit that receives an OFDM broadcast signal; a delay unit that extracts a pilot signal included in the OFDM signal received by the receiving unit and performs an inverse Fourier transform process on the pilot signal to generate a delayed wave profile. And a display unit that displays the delayed wave profile generated by the delayed wave profile generating unit.
[0009]
According to the present invention, since a delayed wave profile is generated by processing a pilot signal, a multipath signal can be specified and displayed.
A receiving apparatus according to the present invention includes: a receiving unit that selectively receives one channel of an OFDM broadcast signal having a plurality of channels so as to be switchable; a pilot signal included in the OFDM signal received by the receiving unit; A delayed wave profile generating means for generating a delayed wave profile by performing a Fourier transform process; a demodulating means for demodulating the received OFDM signal to output a demodulated signal; An interference wave profile generating means for detecting an interference wave of a channel or both channels to generate an interference wave profile; a delay wave profile generated by the delay wave profile generation means; and a delay wave profile generated by the interference wave profile generation means. From the interference wave profile, the delayed wave and the interference wave Or a reception state determining means for determining become, characterized by comprising a display means for displaying the determination result of the reception state determining means.
[0010]
ADVANTAGE OF THE INVENTION According to this invention, since the factor which becomes a viewing-and-listening obstacle in digital terrestrial broadcasting can be detected and displayed concretely, the installation work of an antenna can be performed reliably in a short time.
The receiving method of the present invention comprises the steps of: receiving an OFDM broadcast signal; stitching for extracting a pilot signal included in the received OFDM signal; and performing an inverse Fourier transform on the extracted pilot signal to form a delayed wave profile. Generating, and displaying the generated delay wave profile.
[0011]
According to the present invention, since a delayed wave profile is generated by processing a pilot signal, a multipath signal can be specified and displayed.
According to the receiving method of the present invention, one channel of an OFDM broadcast signal having a plurality of channels is selectively received in a switchable manner, and a pilot signal included in the received OFDM signal is extracted and inverse Fourier transformed. Generating a delayed wave profile, demodulating the received OFDM signal and outputting a demodulated signal, and interfering with the broadcast signal on the same channel or adjacent channel or both channels from the demodulated signal. Detecting an interference wave profile by detecting the delay wave and the generated interference wave profile, and determining whether the delayed wave and the interference wave cause viewing impairment from the generated delay wave profile and the generated interference wave profile. And a step of displaying.
[0012]
ADVANTAGE OF THE INVENTION According to this invention, since the factor which becomes a viewing-and-listening obstacle in digital terrestrial broadcasting can be detected and displayed concretely, the installation work of an antenna can be performed reliably in a short time.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit block diagram of a receiving device 10 of the present invention.
In FIG. 1, a terrestrial digital broadcast received by an antenna 11 is supplied to a tuner 12, where the tuner 12 selects a channel and converts a selected broadcast signal into a baseband signal. The baseband signal output from the tuner 12 is supplied to an OFDM (Orthogonal Frequency Division Multiplexing) demodulator 13. The OFDM demodulation unit 13 includes an A / D (Analog / Digital) conversion unit 14 that converts a baseband signal into a digital signal, an FFT (Fast Fourier Transform) processing unit 15 that performs a fast Fourier transform on the signal converted into a digital signal, and an FFT. It has a demodulation processing unit 16 for OFDM demodulating the converted signal, a Viterbi decoding unit 17 for Viterbi decoding of the OFDM demodulated signal, and an RS (Reed Solomon) decoding unit 18 for Reed-Solomon decoding of the Viterbi-decoded signal.
[0014]
Further, the OFDM demodulation unit 13 includes an AGC detection unit 19 that detects an AGC control signal for controlling the output level of the tuner 12 to be constant, and an interference wave detection unit that detects an interference wave from the output of the demodulation processing unit 16. 20 includes a transmission parameter detecting unit 21 that detects a transmission parameter defined by an integrated services digital broadcasting-terrestrial (ISDB-T) from an output of the demodulation processing unit 16 from the output of the demodulation processing unit 16.
[0015]
The output of the RS decoding unit 18 of the OFDM demodulation unit 13 is a TS (Transport Stream) signal, which is MPEG-decoded by an MPEG (Moving Picture Experts Group) decoder 22, processed by a video signal processing unit 23, and processed by an OSD (On Screen Display). ) Is supplied to the synthesizing unit 24. When viewing a normal broadcast program, the output of the video signal processing unit 23 is converted to an analog signal by the OSD synthesizing unit 24, and is supplied to the monitor unit 25 as it is for display.
[0016]
The output of the FFT processing unit 15 is supplied to a pilot signal extraction unit 26, in which a pilot signal included in the OFDM signal is extracted, and the extracted pilot signal is subjected to arithmetic processing in a pilot signal operation unit 27. The signal is processed by an IFFT (Inverse First Fourier Transform) processing unit 28 that performs a conversion process, and is supplied to a reception state determination unit 29 as a delayed wave profile. The delay wave profile is a signal representing a multipath situation.
[0017]
The output of the AGC detection unit 19 of the OFDM demodulation unit 13, the output of the interference wave detection unit 20, the output of the transmission parameter detection unit 21, and the output of the Viterbi decoding unit 17 are further supplied to the reception state determination unit 29. . The output of the AGC detector 19 is a signal for controlling the output of the tuner 12 to a constant level, and can be used as an indication of the reception level of the broadcast signal supplied to the tuner 12. The output of the interference wave detection unit 20 indicates an interference wave profile, the output of the transmission parameter detection unit 21 indicates the transmission parameter of ISDB-T, and the error of the digital signal from the output of the Viterbi decoding unit 17 A BER (Bit Error Rate) representing the rate is obtained.
[0018]
The reception state determination unit 29 determines the reception state of the broadcast signal received by the antenna 11 from each of the input signals, and simultaneously determines an interference wave profile, a delay wave profile, a transmission parameter, a reception level, and a BER, respectively, or a predetermined value. Is supplied to the OSD synthesizing unit 24, converted into an analog signal, and displayed on the monitor unit 25. The memory 30 is connected to the reception state determination unit 29, and stores therein an interference wave profile, a delay wave profile, a transmission parameter, a reception level, a BER, and a determination result of the reception state based on them.
[0019]
The principle of obtaining a delayed wave profile will be described. When a multipath exists in the transmission path, the pilot signal extracted by the pilot signal extraction unit 26 is subjected to an inverse fast Fourier transform process by an IFFT processing unit 28, thereby obtaining a signal indicating the state of the multipath as shown in FIG. Can be obtained. That is, the multipath is detected by converting the pilot signal converted into the frequency domain by the processing by the FFT processing unit 15 into the time domain again by the processing by the IFFT processing unit 28. In FIG. 2, T is a signal obtained by delaying the original signal S, and is multipath. The detected information is stored in the memory 30 as data.
[0020]
Further, the principle of obtaining an interference wave profile will be described. For example, when an analog broadcast exists in a certain channel, as shown in FIG. 3, a luminance signal carrier frequency component Yc 1.25 MHz component, a chrominance signal carrier frequency component Cc 3.58 MHz, and an audio signal carrier component Sc4 in a channel band of 6 MHz. A 0.5 MHz component spectrum is present, which is detected by the interfering wave detection unit 20 so that analog broadcasting is performed on the same channel as digital broadcasting, and analog broadcasting is performed on adjacent channels. Can be determined. Furthermore, the levels of these signal components are compared with a preset threshold value, and a broadcast wave having a component equal to or higher than the threshold value can be specified as an interference wave that hinders viewing.
[0021]
Further, the fact that digital broadcasting is being carried out on each channel can also be detected by the interference wave detection unit 20. Channels before and after the channel to be viewed are selected by a tuner, and the interference spectrum detection unit 20 selects a frequency spectrum. Is detected, it is possible to determine whether or not the channel is a channel on which digital broadcasting is being performed. In other words, in a channel on which digital broadcasting is performed, a spectrum of a substantially uniform level is obtained over the entire 6 MHz, whereby it is possible to specify a channel on which digital broadcasting is being performed. Also in this case, by comparing the spectrum level with the threshold value, when the spectrum level exceeds the threshold value, it is possible to identify the interference wave as an obstacle to viewing.
[0022]
FIG. 4 shows an example of the delay wave profile. FIG. 4 shows a state in which two delayed signals T1 and T2 are present with respect to the original signal S, and a dotted line L shows a threshold value for specifying an interference wave. In FIG. 4, T2 exceeding L is specified as a multipath that hinders viewing. Note that GI in FIG. 4 indicates a guard interval (Guard Interval) time.
[0023]
FIG. 5 shows an example of an interference wave profile. FIG. 5 shows the situation of channels N−1 and N + 1 before and after centering on the currently selected channel N. In the channel N-1, the luminance signal carrier component Yc, the chrominance signal carrier component Cc, and the audio carrier component Sc are detected, and it can be seen that analog broadcasting is being performed. A dotted line L indicates a threshold level that becomes an interference wave, and does not become an interference wave that hinders viewing because the N-1 channel does not exceed L.
[0024]
In channel N, since each carrier component of the analog broadcast is detected, analog broadcast is carried out on the same channel, and carrier component Yc of the luminance signal exceeds threshold L, so that analog broadcast on the same channel is viewed. It will be a disturbance wave that will interfere with
[0025]
For channel N + 1, it is determined that digital broadcasting is being performed. However, since it does not exceed the threshold value L, there is no interference.
The interference wave detection processing will be described with reference to the flowchart in FIG. The process is started in step 6a, N-1ch (channel) is selected in step 6b, and it is determined in step 6c whether a digital signal is detected. If a digital signal is detected, the power (signal level) of the digital signal component is detected in step 6d. Data indicating the detected power is stored in the memory 30 in step 6e.
[0026]
If no digital signal is detected in step 6c, it is determined whether an analog signal is detected in step 6f. If an analog signal is detected, the power of the analog signal component (step 6d) is detected in step 6d. (Signal level) is detected, and data indicating the detected power is stored in the memory 30. If neither a digital signal nor an analog signal is detected in steps 6c and 6f, the state is also stored in the memory 30 in step 6e.
[0027]
Thus, the detection of the interference wave of the channel N-1 is completed, and then the detection processing of the interference wave is performed for the channel N + 1.
At step 6g, channel selection of N + 1ch (channel) is performed, and at step 6h, it is determined whether or not a digital signal is detected. If a digital signal is detected, the power (signal level) of the digital signal component is detected in step 6i. Data indicating the detected power is stored in the memory 30 in step 6j.
[0028]
If no digital signal is detected in step 6h, it is determined whether or not an analog signal is detected in step 6k. If an analog signal is detected, the power of the analog signal component (step 6i) is detected in step 6i. (Signal level) is detected, and data indicating the detected power is stored in the memory 30. If neither a digital signal nor an analog signal is detected in steps 6h and 6k, the state is also stored in the memory 30 in step 6j.
[0029]
As described above, the memory 30 stores, in addition to the interference wave profile data, the delay wave profile, the transmission parameter, the reception level, and the BER, and these are read out simultaneously or selectively and sent to the OSD synthesis unit 24. The data is supplied, processed, and displayed on the monitor unit 25.
[0030]
FIG. 7 shows a state in which the delay wave profile, the interference wave profile, the reception level, the BER, and the transmission parameter are displayed on the same screen. In FIG. 7, a reception frequency (channel) 71 is displayed on the upper left of the screen 70, and a reception level 72 and a BER 73 are shown below the reception frequency (channel) 71. Further, below the BER 73, a delayed wave profile 74 is shown. A transmission parameter 75 is displayed at the upper right of the screen 70, an interference wave profile 76 is displayed below the transmission parameter 75, and a message 77 is displayed at the lower center of the screen 70.
[0031]
In the example of FIG. 7, it is shown that there is a multipath exceeding the threshold L in the delay wave profile, and that there is no other factor that hinders viewing when receiving digital broadcast of channel N. . In this case, T2 that exceeds the threshold value L of the delay wave profile is displayed in a distinctive color such as red, for example, and at the same time, the message column 77 indicates that the reception state has been affected by multipath. do it.
[0032]
FIG. 8 shows a specific display example of the transmission parameter 75 displayed in FIG. The entire specification is displayed on an upper portion 81 of the screen 80, and detailed specifications for each of the layers A, B, and C are shown in lower portions 82, 83, and 84, respectively.
As described above, the reception state of the channel selected by the tuner 12 is determined based on the data including the interference wave profile and the delay wave profile, and is displayed. Since the specific cause of the failure can be confirmed, the antenna adjustment can be performed simply and surely.
[0033]
By the way, the installation work of the antenna is usually performed once when the receiver is newly purchased, and thereafter there is no need to adjust the position unless there is a special case such as wind damage due to a typhoon. It is generally performed by a specialized service technician such as an electric appliance store. Therefore, the screen showing the determination result of the reception state shown in FIG. 7 is only required to be displayed for the service technician at the time of the installation work of the antenna, and is too important for the general user because the expertise is too strong. Hard to say.
[0034]
For a general user, for example, as shown in FIG. 9, the display of only the antenna level (reception level) 91 and the message 92 is sufficient, and the display of FIG. 9 is usually selected. The display may be switched to the display shown in FIG. 7 by performing a special operation.
[0035]
Alternatively, the reception state may be detected and stored in the memory 30 for each channel, read out, and displayed on the screen at a time as shown in FIG.
As described above, the delay signal profile is generated by performing the IFFT processing on the pilot signal used in the OFDM method, the interference wave profile is generated from the output of the demodulation processing unit 16, and these are displayed on the monitor unit 25. With this configuration, it is possible to specifically notify a cause of reception obstruction when receiving terrestrial digital broadcasting, so that in the antenna installation work, it is possible to simply and surely know the optimal antenna orientation. And the task can be easily performed.
[0036]
【The invention's effect】
As described above, the receiving apparatus of the present invention generates a delay profile that can specify a multipath from a pilot signal used in the OFDM scheme, and further generates an interference wave profile that can specify an interference wave from the output of the demodulation processing unit. Then, the relationship between the profile and the threshold value is displayed on the monitor unit, and the cause of the obstruction of the viewing is displayed as a message, so that the installation work of the antenna can be performed accurately in a short time. It becomes something.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a receiving device according to the present invention.
FIG. 2 is a waveform chart for explaining the operation of the device shown in FIG.
FIG. 3 is a characteristic diagram of a television signal by analog broadcasting.
FIG. 4 is a characteristic diagram for explaining an operation of a main part of the device shown in FIG. 1;
FIG. 5 is a characteristic diagram for explaining the operation of another main part of the device shown in FIG. 1;
FIG. 6 is a flowchart for explaining the operation of the main part of the apparatus shown in FIG. 1;
FIG. 7 is a view for explaining the operation of the device shown in FIG. 1;
FIG. 8 is a view for explaining the operation of the device shown in FIG. 1;
FIG. 9 is a view for explaining the operation of the device shown in FIG. 1;
FIG. 10 is a view for explaining another operation of the apparatus shown in FIG. 1;
[Explanation of symbols]
Reference Signs List 10 receiving apparatus 11 antenna 12 tuner 13 OFDM demodulation unit 14 A / D conversion unit 15 FFT processing unit 16 demodulation processing unit 17 Viterbi decoding unit 18 RS decoding unit 19 AGC detection unit 20 interference Wave detector 21 Transmission parameter detector 22 MPEG decoder 23 Video signal processor 24 OSD synthesizer 25 Monitor 26 Pilot signal extractor 27 Pilot signal calculator 28 IFFT processor 29 Reception state determination Part 30: memory

Claims (9)

Receiving means for receiving an OFDM broadcast signal;
Delay wave profile generation means for extracting a pilot signal included in the OFDM signal received by the reception means and performing an inverse Fourier transform on the pilot signal to generate a delay wave profile;
Display means for displaying the delayed wave profile generated by the delayed wave profile generating means,
A receiving device comprising: Receiving means for switchably selecting and receiving one channel of an OFDM broadcast signal having a plurality of channels;
Delay wave profile generation means for extracting a pilot signal included in the OFDM signal received by the reception means and performing an inverse Fourier transform on the pilot signal to generate a delay wave profile;
Demodulation means for demodulating the received OFDM signal and outputting a demodulated signal;
From the demodulated signal, interference wave profile generation means for generating an interference wave profile by detecting an interference wave of the same channel or adjacent channel or both channels of the broadcast signal,
Reception state determining means for determining whether the delayed wave and the interfering wave cause viewing disturbance from the delayed wave profile generated by the delayed wave profile generating means and the interfering wave profile generated by the interfering wave profile generating means,
Display means for displaying a determination result of the reception state determination means,
A receiving device comprising: In addition to the determination result of the reception state determination unit, one or both of the profiles generated by the delayed wave profile generation unit and the interference wave profile generation unit are displayed on the display unit. The receiving device according to claim 2, wherein The delay wave profile generated by the delay wave profile generating means includes means for determining whether or not viewing impairment is caused, and the delay wave determined to cause viewing impairment is displayed so as to be visually distinguishable. The receiving device according to claim 1, wherein: 3. The receiving apparatus according to claim 2, wherein the reception state determination means displays a delayed wave or an interfering wave determined to cause viewing impairment so as to be visually distinguishable. Further, the apparatus further includes a detection unit for detecting a reception level of an OFDM broadcast signal supplied to the reception unit, an error rate of a digital signal demodulated by the demodulation unit, and a transmission parameter, and at least one of the detected information is transmitted to the reception state. The receiving device according to claim 2, wherein the display unit displays the determination result at the same time as the determination result. A memory unit for storing, for each channel, information indicating a reception state of the plurality of channels received by the reception unit, which is supplied to the reception state determination unit; and information indicating the reception state of the plurality of channels stored in the memory. 7. The receiving device according to claim 2, wherein the display means is simultaneously displayed on the display means. Receiving an OFDM broadcast signal;
A stitch for extracting a pilot signal included in the received OFDM signal;
Generating a delayed wave profile by performing an inverse Fourier transform process on the extracted pilot signal,
Displaying the generated delayed wave profile;
A receiving method, comprising: Selectively receiving one of the channels of the OFDM broadcast signal having a plurality of channels in a switchable manner;
Extracting a pilot signal included in the received OFDM signal and performing an inverse Fourier transform on the pilot signal to generate a delayed wave profile;
Demodulating the received OFDM signal and outputting a demodulated signal;
From the demodulated signal, detecting an interference wave of the same channel or adjacent channel or both channels of the broadcast signal to generate an interference wave profile,
From the generated delay wave profile and the generated interference wave profile, a step of determining whether the delay wave and the interference wave cause viewing impairment,
Displaying the determination result;
A receiving method, comprising:

Images