JP2003046883A - Receiver coping with analog/digital broadcast - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver coping with analog/digital broadcast wherein time necessary for station selecting operation is reduced, and possibility that seek station selecting operation is interrupted halfway is very low, when a broadcast signal in which an analog broadcast program and a digital broadcast program are mixed is received on the same transmission line, and the seek station selecting of a desired station of viewing is performed. SOLUTION: A broadcast signal received with an antenna 2 enters a front end 3 and is converted into an IF signal, which is A/D converted with an A/D converter 4 and inputted in a demodulation part 5. A detector 6 connected with an output end of the front end 3 is constituted to include a deciding means for detecting whether a received broadcast signal is an analog broadcast program having an analog modulated wave or a digital broadcast program having a digital modulated wave containing analog modulation components. The seek station selecting is controlled on the basis of decided data of the detector 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog / digital broadcast in which a receiving section can receive a broadcast signal in which at least one analog broadcast program and a plurality of digital broadcast programs are mixedly transmitted on the same transmission path. Regarding the improvement of the corresponding receiver.

[0002]

2. Description of the Related Art Television broadcasting performed by using a wired transmission line formed by a coaxial cable or an optical cable, a wireless transmission line performed by using satellite waves or terrestrial waves, etc.
Until now, analog broadcast programs that AM-modulate an analog video signal and FM-modulate an audio signal and transmit the signal at a predetermined carrier frequency have been mainstream, but in recent years, analog video signals and audio signal signals have been used. The data after digitization and digital compression is QPSK modulated or Q
Digital broadcasting has been started in which digital modulation is performed using a modulation method such as AM modulation and this signal is transmitted using a digital transmission method such as an OFDM method.

This digital broadcasting is made possible by the remarkable progress of semiconductor technology and image and sound signal compression technology, and is within the frequency band of the same transmission line as compared with the conventional analog broadcasting. , It is possible to broadcast a larger number of program programs, and by adopting a digital transmission system such as the OFDM system, there are many advantages such as high-quality broadcasting with little deterioration of transmission signals. .

In such a broadcasting service, its transmission path is various kinds of transmission such as ground wave transmission, satellite wave transmission, cable transmission, etc., the broadcasting satellite itself used is different, or the transmission medium itself is different. Therefore, the tuning means can be uniquely determined by selecting the broadcasting service desired by the viewer, that is, either the analog broadcasting service or the digital broadcasting service.

As an exceptional case among them, there is an example in which NTSC broadcasting in satellite broadcasting and MUSE high-definition broadcasting coexist, but a common technique called analog FM is used as a modulation method, and Since one HDTV broadcast is transmitted per carrier, the time to display video and audio is short, so first assume that the signal transmitted on that physical channel is MUSE broadcast and then synchronize to establish synchronization. It was processed by a continuous operation of confirming and synchronizing with NTSC when the synchronization cannot be obtained.

Further, in the current television broadcasting, it has been started to change all analog broadcasting programs into digital broadcasting programs. However, with regard to the transmission medium which has been conventionally used for analog broadcasting programs, all of them are suddenly converted to digital. Switching is impossible, and for such a transmission medium, a period in which analog broadcast programs and digital broadcast programs coexist occurs although the period is short or long. For this reason, it becomes necessary to process broadcast signals, which are transmitted in a mixture of analog broadcast programs and digital broadcast programs, on the same transmission line.

[0007]

When receiving a broadcast signal in which an analog broadcast program and a digital broadcast program are mixed on the same transmission path, especially when seeking the service of the digital broadcast program, the seek selection of the digital broadcast program is performed. When performing a station, if seek seek is performed in a state in which an analog broadcast program having an analog modulated wave is included, the number of stations will increase, and the operating time until the desired station is selected becomes extremely large. There is a problem in that efficient channel selection cannot be performed because it becomes longer and the time required for data analysis based on a digital transmission method such as the OFDM method also becomes longer.

Further, even if the user desires to listen to only the digital broadcast program by receiving the broadcast signal in which the analog broadcast program and the digital broadcast program are mixed on the same transmission line, the seek channel selection is the analog broadcast program and the digital broadcast. Since the seek channel selection is performed for both programs without distinguishing the programs in advance, there is a high possibility that the seek channel selection operation will be stopped on the way, and improvement thereof is desired.

Therefore, an object of the present invention is to receive a broadcast signal in which at least one analog broadcast program and a plurality of digital broadcast programs are mixed on the same transmission path and desire to listen from the plurality of digital broadcast programs. Provides a "receiver compatible with analog / digital broadcasting" that shortens the time required for channel selection operation when seeking a channel, and is highly unlikely to stop the operation of seek channel To do.

[0010]

In order to solve the above-mentioned problems, an analog / digital broadcasting-compatible receiver according to the present invention has a characteristic structure as described below.

(1) In a receiver compatible with analog / digital broadcasting, a receiving unit can receive a broadcast signal in which at least one analog broadcast program and a plurality of digital broadcast programs are mixedly transmitted on the same transmission path. Determining means for detecting whether the received broadcast signal is an analog broadcast program having an analog modulated wave or a digital broadcast program having a digital modulated wave containing an analog modulated component; and the receiving unit. Channel selecting means for performing seek channel selection on the basis of the frequency of the received digital modulated wave for the plurality of digital broadcast programs, and demodulating means for demodulating at the corresponding frequency when the channel is selected by the channel selecting means. A receiver compatible with analog / digital broadcasting, which comprises:

(2) The discrimination means of (1) above, when the broadcast signal received by the receiving section is AM-modulated, envelopes the intermediate frequency signal obtained by converting the broadcast signal. A receiver compatible with analog / digital broadcasting, which includes control means for detecting and controlling the demodulation means based on the result information.

(3) The determination means of (1) detects the intermediate frequency signal obtained by converting the broadcast signal when the broadcast signal received by the receiving section is FM-modulated. A receiver compatible with analog / digital broadcasting, which is configured to include a control means for converting the AM wave by performing the envelope detection of the AM wave and controlling the demodulation means based on the result information.

(4) A receiver compatible with analog / digital broadcasting, wherein the control means (3) includes means for converting the intermediate frequency signal into an AM wave by performing slope detection.

(5) The demodulation means of (1) is QPSK.
A receiver compatible with analog / digital broadcasting including demodulation means or QAM demodulation means.

(6) The demodulation means of (1) is OFDM
A receiver compatible with analog / digital broadcasting, which is configured to include means for demodulating a broadcast signal transmitted using a digital transmission method such as a transmission method.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. This form is VHF
An example in which the present invention is applied to a receiver that receives a broadcast signal in which band radio waves serve as a transmission path, and at least one analog broadcast program and a plurality of digital broadcast programs are mixedly transmitted on this transmission path. First, the overall circuit configuration of a receiver compatible with analog / digital broadcasting will be described with reference to FIG.

In FIG. 1, a receiver for analog / digital broadcasting is provided with a C for compositely controlling the entire receiver.
PU1 is provided. In the CPU 1, a control line (not shown) is connected to each circuit block, and the broadcast signal received by the antenna 2 is input to the front end 3 to be converted into an IF signal having a predetermined intermediate frequency.

The IF signal obtained at the front end 3 is
The signal is A / D converted by the A / D converter 4, converted into a digital signal, and input to the demodulation unit 5.

The detector 6 connected to the output end of the front end 3 detects that the broadcast signal received by the antenna 2 is
Is it an analog broadcast program with analog modulated waves,
It is configured to include a discriminating means for detecting whether or not the program is a digital broadcast program having a digitally modulated wave containing an analog modulation component.

Here, the spectrum of the IF signal concerned is
When the broadcast signal is an analog broadcast program having an analog modulation wave, there is a characteristic that components a and b are located in the low band and the high band, as shown in FIG. In the case of a digital broadcast program having a digitally modulated wave containing, the components a and b are not included, but the analog carrier component c and the digital modulation components d and e are included between the components a and b.

Therefore, when the broadcast signal is AM-modulated, the IF signal appearing at the output of the front end 3 is envelope-detected, and the resulting information is output from the detector 6 to the CPU 1 to be demodulated from the CPU 1. By a control command to the unit 5, it is possible to execute seek channel selection corresponding to a plurality of digital broadcast programs without performing data analysis based on a digital transmission system such as an OFDM system.

When the broadcast signal is FM-modulated, simple detection such as slope detection is performed to convert it to an AM wave, and the IF signal appearing at the output of the front end 3 is envelope-detected. By outputting the result information from the wave detector 6 to the CPU 1, a seek command corresponding to a plurality of digital broadcast programs can be performed by a control command from the CPU 1 to the demodulator 5 without performing data analysis based on a digital transmission method such as an OFDM method. Can be executed.

In this seek channel selection operation, a signal component in the vicinity of a channel selected in the VHF band is selected by the control of the CPU 1 and, after being retuned, is given to a mixing circuit. A local oscillation signal is applied from the circuit, and the oscillation frequency of the local oscillation signal is high in response to the channel selection signal output from the CPU 1 so that a desired channel signal component is extracted with high selectivity.

This signal is OFDM-demodulated and MPEG-decoded by the demodulator 5 to be a digital video signal and a digital audio signal, and the digital video signal is D
A / A converter 7 converts it into an analog video signal for display on the image monitor 8, and a D / A converter 9 converts a digital audio signal into an analog audio signal for sound emission from the speaker 10. You can

Therefore, when a broadcast signal in which an analog broadcast program and a digital broadcast program are mixed is received on the same transmission path, particularly when seeking a digital broadcast program seek to receive a service of the digital broadcast program. , Seek tuning is not performed including tuning of analog broadcast programs having analog modulated waves, and seek tuning is performed only for digital broadcast programs, so select the desired station. The operating time up to
Since the data analysis based on the digital transmission system such as the FDM system is not performed for the “seek channel selection”, efficient channel selection can be performed.

When a broadcast signal in which an analog broadcast program and a digital broadcast program are mixed is received on the same transmission path and only the digital broadcast program is desired to be listened to, seek seek is performed for the analog broadcast program and the digital broadcast program. Since neither is performed for both, the conventional problem that the seek channel selection operation is stopped midway is eliminated.

Incidentally, the transmission line in the above-mentioned form is V
This is the case when terrestrial radio waves in the HF band are used as transmission lines.
The present invention is not limited to this, and may be formed by a terrestrial radio wave such as UHF band, a radio wave transmission line of satellite radio waves, or a wire transmission line formed of a coaxial cable or an optical cable.

Further, the number of analog broadcast programs and the number of digital broadcast programs mixed in the broadcast signal are completely arbitrary,
It is obvious that the broadcasting signal which is the subject of the present invention includes at least one analog broadcasting program.

Further, each of the analog broadcast program and the digital broadcast program included in the broadcast signal may not only include the video signal and the audio signal at the same time but may include only the video signal or the audio signal. It is needless to say that the audio signal accompanying the above may be any of monaural, stereo, and main / sub.

[0031]

As is apparent from the above description, according to the present invention, a broadcast signal in which at least one analog broadcast program and a plurality of digital broadcast programs are mixed is received on the same transmission path and a plurality of digital broadcasts are received. When seeking a desired station from a program, the time required for the channel selection operation is shortened, and it is highly unlikely that the operation of the seek channel selection will be stopped midway. It is possible to provide a “receiver compatible with digital broadcasting”.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a schematic circuit configuration of a receiver compatible with analog / digital broadcasting according to an embodiment of the present invention.

FIG. 2 is a diagram showing a spectrum of an IF signal output from the front end shown in FIG.

[Explanation of symbols]

1 CPU 2 antenna 3 front end 4 A / D converter 5 Demodulator 6 detector 7,9 D / A converter 8 image monitor 10 speakers

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C025 AA23 BA01 DA01 DA04                 5J103 AA11 AA13 BA03 BA06 BA07                       CA04 CA05 CA07 CA08 CB02                       CB05 DA07 DA30 DA31 GA08                       GA11 HC03                 5K020 AA02 AA03 AA05 BB04 BB05                       BB08 BB09 DD26 DD27 EE05                       JJ01 NN10                 5K061 AA03 AA09 BB07 BB08 BB09                       BB10 BB15 CC21 CC25 JJ06

Claims (6)

[Claims] 1. A receiver compatible with analog / digital broadcasting, wherein a receiving unit can receive a broadcast signal in which at least one analog broadcast program and a plurality of digital broadcast programs are mixedly transmitted on the same transmission path, Discriminating means for detecting whether the received broadcast signal is an analog broadcast program having an analog modulated wave or a digital broadcast program having a digital modulated wave containing an analog modulated component; And a demodulation unit that performs seek channel selection on the basis of the frequency of the digitally modulated wave selected for the plurality of digital broadcast programs; and a demodulation unit that demodulates at the corresponding frequency when the channel is selected by the channel selection unit. A receiver compatible with analog / digital broadcasting, characterized by comprising: 2. The determining means performs envelope detection of an intermediate frequency signal obtained by converting the broadcast signal when the broadcast signal received by the receiving section is AM-modulated,
The receiver for analog / digital broadcasting according to claim 1, characterized in that it is configured to include control means for controlling the demodulation means based on the result information. 3. When the broadcast signal received by the receiving section is FM-modulated, the determining means detects an intermediate frequency signal obtained by converting the broadcast signal into an AM wave. The receiver for analog / digital broadcasting according to claim 1, further comprising a control means for converting the AM wave, performing envelope detection on the AM wave, and controlling the demodulation means based on the result information. . 4. The receiver for analog / digital broadcasting according to claim 3, wherein the control means includes means for converting the intermediate frequency signal into an AM wave by performing slope detection. . 5. The receiver for analog / digital broadcasting according to claim 1, wherein the demodulating means includes a QPSK demodulating means or a QAM demodulating means. 6. The analog / digital broadcasting compatible according to claim 1, wherein the demodulation means includes means for demodulating a broadcast signal transmitted using a digital transmission system such as an OFDM system. Receiver.