JP2001007780A - Broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically constitute a broadcast receiver for simultaneously receiving plural broadcasting channels. SOLUTION: Two simultaneously received channel signals are converted into two adjacent frequencies by a high frequency signal converting part 10 and a second high frequency signal converting part 20, so that two intermediate frequency signals can be obtained, and each signal is added by a signal adder/ synthesizer 30. Then, the signal is amplified by an intermediate frequency amplifying part 40, and then demodulated by each corresponding signal demodulating part 50 and 60, and each signal is outputted simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcast receiving apparatus, and more particularly to an apparatus for simultaneously receiving a signal broadcast in an analog system and a signal broadcast in a digital system by a sharing circuit.

[0002]

2. Description of the Related Art Conventionally, as an example of a receiving apparatus of a television signal broadcasted in the NTSC system, a configuration like an analog broadcasting receiving apparatus 2 shown in FIG. 14 has been used. According to this device, it is schematically configured to supply a received signal coming from an antenna and output a demodulated signal of video and audio. The configuration of the analog broadcast receiving apparatus 2 will be described with reference to FIG.
3, a frequency selecting unit 80 including a local oscillator 81 (OSC1), and a high-frequency signal filter 11 (RFF
1) High frequency signal amplifier 12 (AGC1), frequency converter 13 (MIX1), and intermediate frequency filter 14
(IFF1), a high-frequency signal conversion unit 10,
Intermediate frequency amplifier 41 (IFAA), second intermediate frequency converter 42 (MIXB), second intermediate frequency filter 43
(IFFB), the second intermediate frequency amplifier 44 (IFA
B), an intermediate frequency amplifying unit 40 including a fixed frequency oscillator 45 (OSC3), a video signal demodulator 53,
It comprises a video signal amplifier 54, an audio signal demodulator 55, an audio multiplexed signal demodulator 56 (sound demodulation), and a digital signal demodulation unit 60 including a first low-pass frequency filter 57 (LPF1). Further, the operation will be described with reference to FIG. First, the viewer selects the frequency selection unit 8
The microprocessor 83 designates a channel number to be received from a not-shown reception channel indicator connected to the microprocessor 83 of 0, and designates a local oscillation frequency corresponding to the reception frequency to the local oscillator 81. The local oscillator 81 oscillates at a designated frequency, and supplies the oscillation output to one input terminal of the frequency converter 13 of the high-frequency signal converter 10. The other input terminal of the frequency converter 13 is supplied with a reception signal coming from an antenna which has been filtered by the high-frequency signal filter 11 and amplified by the high-frequency signal amplifier 12, and each input signal is mixed by the frequency converter 13. Then, an intermediate frequency signal component that is the frequency of the difference is generated, the intermediate frequency signal component is extracted by the intermediate frequency filter 14, and supplied to the intermediate frequency amplifier 41 of the intermediate frequency amplifier 40 to amplify the intermediate frequency signal. The signal amplified here is supplied to one input terminal of the second intermediate frequency converter 42 (MIXB). Second intermediate frequency converter 42
The other input terminal has a fixed frequency oscillator 45 (OSCB) oscillating at a frequency of a difference between the intermediate frequency and the second intermediate frequency.
Is supplied from the second intermediate frequency converter 42 to the second
A signal converted to the intermediate frequency is generated and output.
This output signal is supplied to a second intermediate frequency filter 43 to extract a second intermediate frequency signal component, and to a second intermediate frequency amplifier 44 (IFAB) for amplification. A part of the amplified second intermediate frequency signal is supplied to the audio signal demodulator 55 of the analog signal demodulator 50 to obtain a demodulated output of the audio signal, and the demodulated output of the audio signal is subjected to the audio multiplex modulation. , The signal is demodulated by the sound multiplex signal demodulator 56 to output a bilingual sound or a stereo sound signal, and another one of the intermediate frequency signals amplified by the second intermediate frequency amplifier 44 is output. The section supplies a video signal demodulator 53 to obtain a demodulated output of a video signal, and a part of the video signal demodulated output is supplied to a first low-frequency filter 57 to obtain an average output level of the video signal and obtain a high-frequency signal. It is supplied to an AGC circuit (not shown) of the amplifier 12 and operates so that the gain of the high frequency amplifier 12 is controlled so that the output level of the video signal output from the video signal demodulator 53 becomes constant. Some other video signal demodulated output is supplied to a video signal amplifier 54, and outputs the amplified video signal.

[0003] Recently, preparations for introducing a digital television system have been advanced, and the start of terrestrial digital broadcasting is near. Here, a terrestrial digital television system using OFDM will be described. FIG. 12 shows a frequency spectrum of a general OFDM signal. An OFDM signal is a modulation method for dividing an information signal to be transmitted into hundreds to thousands of digital carriers, transmitting a frequency-division multiplexed signal, and the like.
Are arranged at equal frequency intervals so as to maintain an orthogonal relationship with each other in order to prevent interference between adjacent carriers. The time given by the reciprocal of the frequency interval is a symbol period, and each carrier is modulated for each symbol period by, for example, well-known QPSK, and the information signal is transmitted.

[0004] The television broadcasting system in Japan is considered to shift from the current analog television broadcasting to a new OFDM terrestrial digital television broadcasting. For example, during the transition period of 10 years after the start of broadcasting, both systems use the same program. , So that both broadcast recipients can receive the program respectively.

FIG. 13 shows a configuration of a digital broadcast receiving apparatus 3 for receiving the terrestrial digital broadcast by the OFDM, which will be described. The digital broadcast receiving device 3 in FIG.
A reception signal of a digital broadcast wave coming from an antenna is supplied, and an encoded video and audio signal is converted to an MPEG-2 signal.
This is schematically configured so as to be output as a bit stream signal based on a transport stream defined by the system standard described above, and blocks having the same functions as those described above are given the same numbers. This OF
The digital broadcast receiving apparatus 3 based on the DM system includes a frequency selection unit 80, a high-frequency signal conversion unit 10, an intermediate frequency amplification unit 40
And digital modulation signal filter 61 (IFFD), A / D
It comprises a converter 62, a digital signal processing circuit 63 (DSP), and a digital signal demodulation unit 60 comprising a second low-pass frequency filter 64 (LPF2). The operation will be described.

First, a viewer designates a channel number to be received from the frequency selection unit 80 in the same manner as described above, and is controlled by the microprocessor 83 to control the local oscillator 81 (OSC1) which oscillates at a frequency corresponding to the reception frequency. A local oscillator output signal and a high frequency signal filter 11 (RFF
The received signal coming from the antenna, filtered by 1) and amplified by the high frequency amplifier 12 (AGC1), is converted by the frequency converter 1
3 (MIX1), mixed and generated, the intermediate frequency signal is extracted by the intermediate frequency filter 14 (IFF1) and output to the intermediate frequency amplifier 41 in the intermediate frequency amplifier 40.
(IFAA), and the amplified signal is supplied to one input terminal of the second intermediate frequency converter 42 (MIXB). Here, in order to supply a low-frequency signal to the AD converter 62, frequency conversion for converting the intermediate frequency to a lower second intermediate frequency is performed. Is a fixed frequency oscillator 45 that oscillates at a frequency that is the difference between the intermediate frequency and the second intermediate frequency.
The output signal of (OSCB) is supplied, and a signal converted to the second intermediate frequency by the second intermediate frequency converter 42 (MIXB) is generated and output. This output signal is supplied to a second intermediate frequency filter 43 (IFFB) to extract a second intermediate frequency signal, and a second intermediate frequency amplifier 44 (IFA) extracts the second intermediate frequency signal.
B) and supplies the amplified signal to the digital signal demodulator 60.
The digital signal processing circuit 63 (DSP) obtains a signal converted into a digital signal and supplies it to a digital signal processing circuit 63 (DSP). Here, a signal that is digitally modulated by OFDM or the like is decoded by FFT processing or the like, a part of the decoded signal is supplied to the second low-frequency filter 64, and an average output level signal of the decoded signal is obtained to obtain a high-frequency signal. Amplifier 12
(AGC1) to control the gain of the high-frequency amplifier 12 so that the output level of the decoded signal output from the A / D converter 62 becomes constant. Part of O is not shown
The QAM decoding of each carrier constituting the FDM signal is performed, and a signal output by the above-described transport stream is obtained.
It has a schematic configuration in which video signals, audio signals, data signals, and the like encoded according to the EG-2 system standard are decoded and output.

[0007]

In a receiving environment where analog broadcasting and digital broadcasting are performed simultaneously, it is required that both broadcasting waves be received by a single receiving device as a receiving device. The above-described conventional apparatus is a single-function apparatus for receiving an analog television signal or receiving a digital broadcast signal, and has a configuration of a receiver for simultaneous analog and digital broadcasts that will appear in the future. It is only possible to use these individually or to combine the circuits of both receivers into one housing. Furthermore, the digital broadcasting era in the future is also an era of multi-channel, and the receiving method of the receiving device is not a function of receiving one channel by one unit as in the conventional receiving device of the analog broadcasting era. And simultaneously playing back a plurality of programs, or when a recording device such as a home server becomes widespread, collectively make a reservation recording for a plurality of viewers and play back. A function as a server, such as distribution to each viewer, is required. In order to use the above-mentioned receiving apparatus for the receiving portion of the recording server, it is desirable to support both analog and digital broadcasting systems and to simultaneously receive a plurality of channels with, for example, one or a small number of receiving apparatuses. Naturally, this function can be realized by a plurality of receiving devices. However, the configuration is not economical and unfavorable because the price is increased, including an increase in mounting area and power consumption.

In the present invention, therefore, the configuration of a receiver for simultaneous analog and digital broadcasting that will appear in the future is to share signals of both broadcasting systems freely by sharing some functional blocks. It aims to provide a low-cost configuration for receiving these signals in an integrated manner and supplying a plurality of demodulated output signals to a recording server and the like. In order to optimize the above, it is configured to eliminate the adverse effect of sacrificing the other characteristic.

[0009]

The present invention comprises the following means to solve the above-mentioned problems. That is,

In a broadcast receiving apparatus for receiving a digitally modulated broadcast wave, a first local oscillator for outputting a signal having a first oscillation frequency corresponding to a first receive channel that can be selectively specified, and Frequency selecting means having a second local oscillator for outputting a signal of a second oscillation frequency in correspondence with a second reception channel which can be designated in a specific manner; and corresponding to the first reception channel coming from an antenna. Signal and the signal of the first local oscillator
A first high-frequency signal converting means for converting the signal into an intermediate frequency, a signal corresponding to the second reception channel coming from an antenna, and a signal from the second local oscillator are supplied to the second Second high-frequency signal conversion means for converting the signal into an intermediate frequency, signal addition and synthesis means for generating a signal obtained by adding and synthesizing the first intermediate frequency signal and the second intermediate frequency signal, and the signal obtained by addition and synthesis From the intermediate frequency amplification means for amplifying
First signal demodulation means for selectively extracting and demodulating a signal corresponding to the first reception channel from a filter provided, and a signal corresponding to the second reception channel from the provided filter based on the amplified combined signal. And a second signal demodulating means for selectively extracting a signal to be demodulated and demodulating the signal, and configured to simultaneously output a plurality of demodulated output signals corresponding to broadcast waves of a plurality of channels.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a broadcast receiving apparatus according to the present invention will be described below with reference to preferred embodiments. FIG.
Is a schematic configuration of the broadcast receiving apparatus 1 according to the embodiment. According to this device, an analog broadcast signal and a digital broadcast signal coming from an antenna are received, and an analog broadcast video and audio signal is output, including a digitally broadcasted video and audio signal. It operates roughly so as to obtain a bit stream signal based on a transport stream defined by the MPEG-2 system standard or the like. Referring to the configuration of FIG. 2, a part of the received signal coming from the antenna and one of the signals supplied from the frequency selection unit 80 are supplied to the high-frequency signal conversion unit 10 to convert the first frequency-converted signal. At the same time, another part of the received signal coming from the antenna and another one of the signals supplied from the frequency selection unit 80 are supplied to the second high-frequency signal conversion unit 20 to be converted into the second frequency-converted signal. But its first
And the second frequency-converted signal,
The intermediate frequency amplifying section 40
And amplifies the intermediate frequency signal, and one of the amplified intermediate frequency signals is supplied to an analog signal demodulation unit 50 to obtain an output of a video signal and an audio signal that have received an analog broadcast wave. The other half of the intermediate frequency signal obtained by the frequency amplification is supplied to the digital signal demodulation unit 60 so as to obtain a bit stream signal of the transport stream.

Next, the configuration and operation of each unit shown in FIG. 1 will be described in detail. First, the frequency selector 80 includes a local oscillator 81 (OSC1), a second local oscillator 82 (OSC2),
And a microprocessor 83. The microprocessor 83 obtains analog broadcast reception channel information or digital broadcast reception channel information from channel selection means such as a remote controller (not shown), and obtains a local oscillator 81 (OSC1) and a 2 local oscillator 82
(OSC2), the oscillation frequency is designated, and the PLL built in the local oscillator 81 and the second local oscillator 82
Oscillation circuit such as oscillates at a designated frequency, and the oscillation output of local oscillator 81 is supplied to one input terminal of frequency converter 13 (MIX1) in high-frequency signal conversion unit 10,
The oscillation output of the second local oscillator 82 is supplied to another input terminal of the second frequency converter 23 (MIX2) in the high-frequency signal converter 20. Next, the high-frequency signal converter 10 includes a high-frequency signal filter 11 (RFF1), a high-frequency amplifier 12 (AGC1), and a frequency converter 13 (MI
X1) and an intermediate frequency filter 14 (IFF1), and converts the signal of the analog broadcast reception frequency specified by the microprocessor 83 of the frequency selection unit 80 from the supplied high frequency signal to the high frequency signal filter 11
And the video demodulator 5 of the analog signal demodulation unit 50
3 is obtained through automatic gain control amplification by the high-frequency amplifier 12 based on the received signal level information of the analog signal obtained through the first low-frequency filter 57, and the input signal of one of the frequency converters 13 is obtained. While supplying a signal to the terminal, the other input terminal of the frequency converter 13 is supplied with an oscillation output signal of a local oscillator 81 oscillated by a signal from the microprocessor 83 of the frequency selection unit 80,
It operates to obtain the signal component converted to the intermediate frequency, and extract and output the signal component converted to the intermediate frequency by the intermediate frequency filter.

On the other hand, the second high-frequency signal converter 20 includes a second high-frequency signal filter 21 (RFF2), a second high-frequency amplifier 22 (AGC2), and a second frequency converter 22 (MIX).
2), and the second intermediate frequency filter 24 (IFF2)
The digital signal processing circuit 63 of the digital signal demodulation unit 60 selects a signal selected according to the reception frequency of the digital broadcast specified by the frequency selection unit 80.
The second intermediate frequency signal obtained by automatically controlling the level information of the digital reception signal obtained by the above with the signal obtained through the second low frequency filter 64 is output in the same manner as the high frequency signal converter 10. Next, the intermediate frequency amplifying unit 40
Are an intermediate frequency amplifier 41 (IFAA), a second intermediate frequency converter 42 (MIXB), a second intermediate frequency filter 43
(IFFB), the second intermediate frequency amplifier 44 (IFAB),
And a fixed frequency oscillator 45 (OSCB), amplifies the signal supplied to the intermediate frequency amplifier and supplies it to one input terminal of the second intermediate frequency converter 42, and the other input terminal has the intermediate frequency The sum with the second intermediate frequency,
Alternatively, an output signal of a fixed frequency oscillator 45 oscillating at a difference frequency is supplied to generate a signal converted to a second intermediate frequency, and a signal component of the second intermediate frequency is extracted by a second intermediate frequency filter 43. The signal amplified by the intermediate frequency amplifier 44 is output.

Here, the analog demodulation unit 50 includes an analog modulation signal filter 52 (IFFC), a video signal demodulator 5
3, a video signal amplifier 54, an audio signal demodulator 55, an audio multiplexed signal demodulator 56 (sound demodulation), and a first low-frequency filter 57 (LPF1), and the analog modulation signal filter 52 is supplied. 2 Select and extract a frequency band including an analog modulation signal from the intermediate frequency signal,
The signal is supplied to a video demodulator 53 and an audio demodulator 55. The video signal demodulator 53 demodulates an analog video signal. One of the demodulated signals is amplified by a video amplifier 54 and output as a video signal. The other one obtains a signal corresponding to the signal strength of the analog video signal by the first low-frequency filter 57 and supplies it to the high-frequency signal conversion unit 10 as a signal for automatic gain control. The audio signal accompanying the signal is demodulated, and when the demodulated signal is an audio multiplex signal, the audio multiplex signal demodulator 56 demodulates the signal and outputs a bilingual audio signal or a stereo audio signal. Further, the digital signal demodulation unit 60 includes a digital modulation signal filter 61.
(IFFD), A / D converter 62, digital signal processing circuit 63 (DSP), and second low-frequency filter 64
(LPF2), the digital modulation signal filter 61 selectively extracts a signal in a frequency band including a digital modulation signal frequency component from the supplied second intermediate frequency signal, and supplies the signal to the A / D converter 62. The digitally converted signal output is obtained and supplied to the digital signal processing circuit 63, which is not shown here, for example, orthogonal demodulation, OFD by FFT.
Demodulation of M signal, QAM decoding of majority carrier signal constituting OFDM, deinterleave processing, data error detection,
Correction, etc., and output the transport stream signal specified by the MPEG system standard.
The level information of the digital signal included in the signal supplied to the digital signal processing circuit 63 is supplied to the second low-frequency filter 6.
A signal corresponding to the signal intensity of the digital modulation signal is obtained via the control signal 4 and supplied to the second high-frequency signal converter 20 as a signal for automatic gain control.

As described above, in the present embodiment, the intermediate frequency amplifying unit 40 is commonly used for amplifying an analog television signal and for amplifying a digital television signal. The conversion to the second intermediate frequency having a lower intermediate frequency is performed to make the operation of the circuits of the analog signal demodulation unit 50 and the digital signal demodulation unit 60 easier. Here, those operations will be described in more detail.

FIG. 2 is a schematic diagram showing an example of a frequency arrangement in which analog television broadcasting and digital television broadcasting are performed. In the conventional broadcasting channels Ch1 to Ch3, NTSC analog broadcasting is used. In the broadcasting, Ch4 to Ch6 show digital broadcasting by OFDM, and reception of these signals will be sequentially described. FIG. 3 shows an example in which an analog signal is received from the above-described frequency array. Of the signals supplied from the antenna, the signal of Ch2 is extracted by the high-frequency signal filter 11, but the cutoff characteristics are not sufficient. Ch1 and Ch3 signals are also mixed. However, only the signal of Ch2 is extracted by the intermediate frequency filter 14 due to its sufficient cutoff characteristic, and the output of the second intermediate frequency filter 43 obtains a signal of the same frequency component converted to a lower second intermediate frequency. ing. Figure 4
Shows a similar example when receiving a digital signal. The signal of Ch5 is extracted by the high-frequency signal filter 21, but the cutoff characteristics are not sufficient, and the signals of Ch4 and Ch6 are mixed. In the filter 24 and the second intermediate frequency filter 43, a target signal is obtained.

FIG. 5 illustrates a frequency relationship when an analog signal and a digital signal are simultaneously received from the above-mentioned frequency array according to the embodiment of the present invention. Of the signals supplied from the antenna, the analog signal of Ch2 is input by the high-frequency signal converter 10 and the digital signal of Ch5 is input by the second high-frequency signal converter 20. At this time, the high-frequency signal filter 11 (RFF
1) and the state of the signal in the second high-frequency signal filter 21 (RFF2), as shown in the figure, the signal of the adjacent channel is leaking due to an insufficient cutoff characteristic, but the intermediate frequency filter 14 (IFF1) and the second intermediate In the frequency filter 24 (IFF2), only a signal symmetrical to reception is extracted due to a sufficient cutoff characteristic, and the second intermediate frequency filter 43
At the output, both signals converted to the lower second intermediate frequency are obtained. FIG. 6 shows the state of the digital wave and the analog wave signal in the second intermediate frequency band. Among the two signals, the digital wave is located at the lower frequency and the frequency supplied to the A / D converter is shown. Is considered to be a low value. The second intermediate frequency output signal of the digital and analog signals obtained in this manner is frequency-divided by an analog signal filter 52 and a digital modulation signal filter 61, and is demodulated by each demodulation unit. Get.

The operation of the shared circuit in terms of frequency has been described above. In order for the shared circuit to operate properly, the signal levels need to be appropriate to each other. The level is supplied to the intermediate frequency amplifier 40, and the operation of the automatic gain adjustment at this time will be further described. FIG. 7 is a waveform diagram of a transmitted analog television signal. This signal is an AM modulated wave of negative polarity, and a horizontal synchronization signal having a high amplitude level is transmitted every horizontal synchronization period. Therefore, there are few factors of amplitude fluctuation due to the nature of the analog television signal itself, and when a signal having a non-constant amplitude level comes in, it is considered that there is some fluctuation in the spatial transmission path. Therefore, in order to eliminate these fluctuation factors, it is desirable to operate the AGC circuit with a fast time constant, and the response speed of the first low-frequency filter 57 (LPF1) that determines the response speed of the analog modulation signal AGC circuit is compared with the response speed. Use a fast target. FIG. 8 shows a waveform diagram of a transmitted digital television signal according to the OFDM method. A transmission wave by the OFDM method is configured by combining a large number of carrier signals orthogonal to each other, but has a waveform that appears as a random signal waveform, and sometimes generates a high peak voltage. Therefore, the level fluctuation of the received OFDM signal is rarely directly caused by the fluctuation factor of the spatial transmission path. On the other hand, if an AGC circuit having a fast response speed is used, unnecessary level control is performed. O with low error rate
This is not preferable in terms of demodulating the FDM signal. For this reason, the second which determines the response speed of the AGC circuit for digital modulation
The response speed of the low-frequency filter 64 is relatively slow. FIG. 9 shows a comparative example of the response characteristics of these filters. FIG. 10 shows a comparison example of a change in gain of the AGC circuit obtained by using these filters.

Although the operation of the shared receiver for broadcasting by analog and digital waves has been described above, the technique of the present invention can be applied to a broadcast receiver for receiving a plurality of digital waves simultaneously. FIG. 11 is a schematic configuration diagram of an apparatus for receiving a plurality of digital waves, and blocks having the same functions as those in the above-described example are given the same numbers. The digital multi-channel broadcast receiving apparatus 4 shown in the figure differs from the above-described broadcast receiving apparatus 1 in that an analog signal demodulation unit 50 is replaced by a second digital signal demodulation unit 70. The second digital signal demodulation unit 70 includes a second digital modulation signal filter 71 (IFFE), an A / D converter 62,
It is composed of a digital signal processing circuit 63 and a second low frequency filter 64. The difference between the second digital signal demodulation unit 70 and the above-mentioned digital signal demodulation unit 60 is as follows.
The characteristic of the second digital modulation signal filter is different from that of the digital modulation signal filter 61, and the only characteristic is that the characteristic is similar to that of the analog modulation signal filter 52. Therefore, the digital multi-channel broadcast receiving device 4
Receives different digital broadcast channels by the digital signal demodulation unit 60 and the second digital signal demodulation unit 70. In this case, the channel selection is performed by the high-frequency signal conversion unit 10 and the second
The high-frequency signal conversion unit 20 performs the operation in the same manner as the operation of the broadcast receiving device 1, and receives digital broadcasts of two channels.

The video signals of the two channels output in this way can be switched by a video switch or the like to display the instantaneously switched video, but only has a normal one-channel reception function. In a digital broadcast receiving apparatus that does not have a channel, for example, the synchronization time of the OFDM demodulation circuit, the time for decomposing the time interleave, and the time for restoring the video from the encoded stream are required until the image is displayed. It takes time from the operation of switching the receiving channel to the display of the video. This is one of the problems of the digital broadcasting system, while an analog receiver can switch the channel and output an image instantaneously, while a digital broadcast receiver cannot display the instantly switched image. But also. However,
Since the digital multi-channel broadcast receiver 4 is configured to simultaneously receive two channels, it has a feature that the display output can be instantaneously switched between the two channels. As described above, the configuration of the digital multi-channel broadcast receiver 4 for simultaneously receiving two channels has been described.
It is also possible to configure a simultaneous channel receiving device. In particular, in the case of a digital broadcast receiver, a signal converted to a low frequency is supplied to the A / D converter due to the nature of the A / D converter because the received signal is converted into a digital signal and then demodulated. Is preferred. In the present invention,
Since the frequency conversion to the second intermediate frequency having a lower frequency is simultaneously performed on a plurality of received signals by common hardware, the circuit scale required for conversion can be reduced as a whole device, and the shape and size and power consumption can be reduced. Great economic effect.

As described above, according to the apparatus of this embodiment, a plurality of digital broadcast channels can be simultaneously received.
This has the effect of enabling simultaneous recording of multiple channels. Further, when the viewing channel is switched between channels performing simultaneous reception, there is an effect that the channel can be switched and displayed quickly, for example, the channel can be displayed without waiting time.

[0022]

According to the present invention, since the intermediate frequency amplifier is commonly used and broadcast waves of different channels are received, a broadcast receiving apparatus for simultaneously receiving a plurality of broadcast channels can be economically constructed. There is.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a broadcast receiving device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a relationship between channel arrangements of analog broadcast waves and digital broadcast waves.

FIG. 3 is a diagram illustrating reception of an analog signal according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating reception of a digital signal according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating simultaneous reception of an analog signal and a digital signal according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating an arrangement of signals at a second intermediate frequency according to the embodiment of the present invention.

FIG. 7 is a waveform diagram of an analog television signal broadcast wave.

FIG. 8 is a waveform diagram of a digital television signal broadcast wave.

FIG. 9 is a diagram illustrating response characteristics of the filter according to the embodiment of the present invention.

FIG. 10 is a diagram illustrating a change in gain of the AGC circuit according to the embodiment of the present invention.

FIG. 11 is a schematic block diagram of a digital two-channel broadcast receiving apparatus according to an embodiment of the present invention.

FIG. 12 is a schematic diagram illustrating a digital broadcast signal.

FIG. 13 is a schematic block diagram of a digital broadcast receiving device.

FIG. 14 is a schematic block diagram of a conventional analog broadcast receiving device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 broadcast receiving device 2 analog broadcast receiving device 3 digital broadcast receiving device 4 digital multi-channel broadcast receiving device 10 high-frequency signal converter 11 high-frequency signal filter 12 high-frequency amplifier 13 frequency converter 14 intermediate frequency filter 20 second high-frequency signal converter 21 2 high-frequency signal filter 22 second high-frequency amplifier 23 second frequency converter 24 second intermediate frequency filter 30 signal addition / synthesizer 40 intermediate-frequency amplifier 41 intermediate-frequency amplifier 42 second intermediate-frequency converter 43 second intermediate-frequency filter 44 2 intermediate frequency amplifier 45 fixed frequency oscillator 50 analog signal demodulation unit 52 analog modulation signal filter 53 video signal demodulator 54 video signal amplifier 55 audio signal demodulator 56 audio multiplexed signal demodulator 57 first low band frequency filter 60 digital signal demodulation Reference Signs List 61 digital modulation signal filter 62 A / D converter 63 digital signal processing circuit 64 second low frequency filter 70 second digital signal demodulator 71 second digital modulation signal filter 80 frequency selector 81 local oscillator 82 second local oscillator 83 Microprocessor

Claims (1)

[Claims] 1. A broadcast receiving apparatus for receiving a digitally modulated broadcast wave, comprising: a first local oscillator for outputting a signal having a first oscillation frequency corresponding to a first reception channel that can be selectively designated; Frequency selection means having a second local oscillator for outputting a signal of a second oscillation frequency corresponding to a second reception channel that can be selectively designated; and a first reception channel coming from an antenna. A first high-frequency signal converting means for supplying a corresponding signal and a signal of the first local oscillator to convert the signal into a first intermediate frequency, and corresponding to the second receiving channel coming from an antenna. High-frequency signal conversion means for supplying a signal to be converted and a signal from the second local oscillator to convert the signal into a second intermediate frequency, and the first intermediate frequency signal and the second intermediate frequency Signal adding / combining means for generating a signal obtained by adding and combining signals; intermediate frequency amplifying means for amplifying the added / combined signal; and a filter provided from the amplified combined signal corresponding to the first reception channel. First signal demodulation means for selectively extracting a signal to be demodulated and demodulating, and a second signal for selectively extracting and demodulating a signal corresponding to the second reception channel from a filter provided from the amplified combined signal. A broadcast receiving apparatus comprising: signal demodulation means, and configured to simultaneously output a plurality of demodulated output signals corresponding to a plurality of channels of broadcast waves.