JP2001028575A - Digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically configure a digital broadcast receiver that can simultaneously receive a plurality of broadcast channels. SOLUTION: A high-frequency conversion section 10 and a 2nd high-frequency conversion section 20 simultaneously receiving two channel signals convert them into two intermediate frequency signals with two frequencies which are close to each other, a signal summing and combining unit 30 sums and combines respective signals, an intermediate frequency amplifier section 40 amplifies the sum signal, and an A/D converter 61 converts the amplified signal into a digital signal. Then digital filters 62, 64 separate signals corresponding to the two channels and signal demodulators 63, 65 demodulate the respective signals, corresponding to the two channels and output them simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast receiving apparatus, and more particularly, to an apparatus having a common circuit and receiving multi-channel digital broadcast waves simultaneously.

[0002]

2. Description of the Related Art Conventionally, analog television broadcasting according to the NTSC system has been performed, but recently preparations have been made to introduce a digital television system, and terrestrial digital broadcasting experiments using OFDM have been conducted. Examination for the main broadcast is also steadily proceeding. Here, a terrestrial digital television system using OFDM will be described. FIG. 13 shows a frequency spectrum of a general OFDM signal. An OFDM signal is a modulation method in which an information signal to be transmitted is divided and frequency-multiplexed into several hundred to several thousand carriers for transmission. The carriers constituting the OFDM are orthogonal to each other in order to prevent interference between adjacent carriers. Are arranged at equal frequency intervals so as to maintain The time given by the reciprocal of this frequency interval is the symbol period,
Each carrier is modulated for each symbol period by, for example, a well-known digital modulation method such as multi-level QAM or QPSK, and an information signal is transmitted. Hierarchical modulation shown in FIG. For example, QAM
Multi-level modulation is selected, and broadcast for mobile reception and broadcast for fixed reception of high-definition video are performed.Digital broadcasting is designed to broadcast many programs, including those. It has been done.

FIG. 12 shows an OFD made in this manner.
An example of a digital broadcast wave receiving apparatus for receiving digital terrestrial broadcasting by M is shown and described. The digital broadcast wave receiving device 5 shown in FIG. 1 supplies a received digital broadcast wave signal received from an antenna, and converts a video and audio coded signal into
It is designed to be output as a bit stream signal based on a transport stream defined by the MPEG-2 system standard. The configuration of this device will be described. The digital broadcast wave receiving device 5 includes a microprocessor 8
3, a third frequency selector 80C including a local oscillator 81 (OSC1), and a high-frequency signal filter 11
(RFF1), high-frequency signal amplifier 12 (RFA1), frequency converter 13 (MIX1), and intermediate-frequency filter 14 (IFF1)
0, an intermediate frequency amplifier 41 (IFAA), an intermediate frequency converter 42 (MIXB), a second intermediate frequency filter 43
(IFFB), the second intermediate frequency amplifier 44 (IFA
B) and an intermediate frequency amplifying section 40 composed of a fixed frequency oscillator 45 (OSCB), and an A / D converter 72 (AD
C1) and a third digital signal processing circuit 73 (DSP
3) The second and third digital signal demodulation unit 70 composed of
Composed of B and

Next, the operation will be described. First, the viewer instructs a receiving channel number from a receiving channel indicator (not shown) connected to the microprocessor 83 of the third frequency selecting unit 80C, and the microprocessor 83 instructs the local oscillator 81 to output a local signal corresponding to the receiving frequency. Specify the oscillation frequency. The local oscillator 81 oscillates at a designated frequency and outputs the oscillation output to the high-frequency signal converter 10.
To one input terminal of the frequency converter 13 of FIG. The other input terminal of the frequency converter 13 is supplied with a received 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 these signals are multiplied and mixed by the frequency converter 13. Then, an intermediate frequency signal component having a 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 amplified signal is supplied to one input terminal of the intermediate frequency converter 42. The other input terminal of the intermediate frequency converter 42 is supplied with the signal of the fixed frequency oscillator 45 oscillating at the frequency of the difference between the intermediate frequency and the second intermediate frequency, and is converted by the intermediate frequency converter 42 into the second intermediate frequency. The generated signal is generated and output. This output signal is supplied to a second intermediate frequency filter 43, where the second intermediate frequency signal component is extracted. The extracted signal is amplified by a second intermediate frequency amplifier 44, and the second A
/ D converter 72.

[0005] In the second A / D converter 72, the supplied analog signal is converted into a digital signal and supplied to a third digital signal processing circuit 73. Here, decoding of a signal digitally modulated by OFDM or the like by FFT processing or the like, QAM decoding of each carrier constituting the OFDM signal, and the like are performed, and a signal based on the above-described transport stream is output. For example, a video signal, an audio signal, a data signal, and the like encoded according to the MPEG-2 system standard are decoded and output.

FIG. 14 shows an example of an operating frequency of the digital broadcast wave receiving apparatus 5 described above. In this example, UHF
Digital broadcasting of channels 1-4 is made in the band,
These signals are passed by the high-frequency signal filter 11, and the passed signals are converted to an intermediate frequency by the frequency converter 13, and the signal of the channel 1 to be received by the intermediate frequency filter 14 is indicated as IF-1. And converted by the intermediate frequency converter 42 to a second intermediate frequency, which is a low frequency signal indicated as IF-2, and the converted signal is amplified and supplied to the second A / D converter 72. It has become. Since the second A / D converter 72 performs digital conversion of an analog signal supplied at a low frequency, a commonly available A / D conversion element is used.

[0007]

[Problems to be solved by the invention] By the way, the digital broadcasting era in the future is also the era of multi-channel,
The receiving method of the receiving device is not a function of receiving one channel by one unit like the receiving device in the analog broadcasting era so far, but a plurality of channels are simultaneously received and a plurality of programs are simultaneously reproduced, and In order to realize a server function, a centralized recording device such as a home server collectively performs scheduled recording for a plurality of viewers and distributes the playback to each viewer. Become. Here, the digital broadcast receiving device used for the receiving portion of the recording server is required to have a function of simultaneously receiving a plurality of channels. Although it is possible to realize this function by using a plurality of receivers, the configuration is not economical and unfavorable because the price increases, including an increase in mounting area and power consumption.

Therefore, the present invention aims at simultaneously transmitting signals of a plurality of channels by, for example, one or a small number of receivers, and by sharing some of the functional blocks of the receiver circuit, a plurality of channels are received. , And a configuration for supplying a plurality of demodulated output signals to a recording server or the like can be provided at a low cost.

[0009]

The present invention comprises the following 1) to 3) for solving the above-mentioned problems. That is,

1) 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 reception channel that can be selectively specified; And optionally selectable second
Frequency selecting means having a second local oscillator for outputting a signal of a second oscillation frequency corresponding to the receiving channel of
A first high-frequency signal conversion means for receiving a signal corresponding to the first reception channel coming from an antenna and a signal of the first local oscillator and converting the signal into a first intermediate frequency; A second high-frequency signal conversion means for receiving a signal corresponding to the second reception channel coming from an antenna and a signal of the second local oscillator and converting the signal into a second intermediate frequency; Signal addition / combining means for generating a signal obtained by adding and combining a first intermediate frequency signal and the second intermediate frequency signal; intermediate frequency amplifying means for amplifying the added / combined signal; and the amplified combined signal To a digital signal, a signal corresponding to the first reception channel is selectively extracted and demodulated by a digital filter provided therein, and the converted digital signal A second signal demodulation means for selectively extracting and demodulating a signal corresponding to the second reception channel by a digital filter provided, and simultaneously outputting a plurality of demodulated output signals corresponding to broadcast waves of a plurality of channels. A digital broadcast receiving device characterized by being configured to output.

2) In a broadcast receiving apparatus for receiving a digitally modulated broadcast wave, high-frequency signal filter means for supplying a signal coming from an antenna and passing signals corresponding to a plurality of reception channels, and the high-frequency signal filter means High-frequency amplification means for amplifying the signal supplied from the
A for converting the high-frequency amplified signal into a digital signal
D conversion means, first digital variable filter means supplied with the AD-converted signal, and passing a signal in a frequency band corresponding to a first reception channel which can be selectively designated, and the first digital variable filter means First digital signal processing means for supplying a signal passed by the variable filter means and obtaining a demodulated signal; and a frequency corresponding to a second reception channel which is supplied with the AD-converted signal and which can be selectively designated. A second digital variable filter means for passing a signal of the band, and a second digital signal processing means for supplying a signal passed by the second digital variable filter means and obtaining a demodulated signal; A digital broadcast receiving apparatus configured to simultaneously output a plurality of demodulated output signals corresponding to the broadcast waves.

[0012] 3) The high frequency amplifying means for amplifying the signal supplied from the high frequency signal filtering means includes a means for converting the high frequency signal into an intermediate frequency and amplifying it, and a plurality of demodulated outputs corresponding to a plurality of channels of broadcast waves. The digital broadcast receiving apparatus according to the above 2), wherein the digital broadcast receiving apparatus is configured to simultaneously output signals.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the digital broadcast receiving apparatus according to the present invention will be described below with reference to preferred embodiments. FIG. 1 is a schematic configuration of a digital broadcast receiving apparatus 1 according to the embodiment. According to this device, a digital broadcast signal of a plurality of channels coming from an antenna is received,
The operation is performed so as to obtain a bit stream signal based on a plurality of transport streams defined by the MPEG-2 system standard and the like, including video and audio signals broadcast in a digital system corresponding to the respective channels. The configuration shown in FIG. 1 will be described. A part of the received signal coming from the antenna and one of the signals supplied from the frequency selector 80 are shown.
One is supplied to the high-frequency signal conversion unit 10 to obtain the first frequency-converted signal, and the other part of the reception signal coming from the antenna and the other one of the signals supplied from the frequency selection unit 80 Is supplied to the second high-frequency signal conversion unit 20 to obtain a second frequency-converted signal. The first and second frequency-converted signals are added and synthesized by the signal addition / synthesizer 30. The added synthesized signal is output to the intermediate frequency amplifier 4
0, and amplifies the intermediate frequency signal. The amplified intermediate frequency signal is supplied to the digital signal demodulation unit 60,
It is schematically configured to obtain a plurality of bitstream signals of the above-described transport stream.

Next, the configuration and operation of each unit shown in FIG. 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, for example, two digital broadcast reception channels by channel selection means such as a remote controller (not shown) and obtains a local oscillator 81 (OSC1) and a second local oscillator 82 (OSC2). ) Designates an oscillation frequency, and the local oscillator 81 and the second local oscillator 8
An oscillation circuit such as a PLL built in the oscillator 2 oscillates at a designated frequency, and an oscillation output of the local oscillator 81 is a frequency converter 13 (MIX1) in the high-frequency signal converter 10.
Of the second local oscillator 8
2 is supplied to the other input terminal of the second frequency converter 23 (MIX2) in the second high-frequency signal converter 20. Next, the high-frequency signal converter 10 includes a high-frequency signal filter 11 (RFF1) and a high-frequency amplifier 12 (RFA).
1) a frequency converter 13 (MIX1), and an intermediate frequency filter 14 (IFF1). The first digital broadcast reception frequency specified by the microprocessor 83 of the frequency selection unit 80 among the supplied high-frequency signals. A signal is selected by the high-frequency signal filter 11 and a digital signal processing circuit 6 of the digital signal demodulation unit 60 described later
3 (DSP1), based on the received signal level information of the OFDM signal, obtains an output signal that has been subjected to automatic gain control amplification by the high-frequency amplifier 12, supplies the signal to one input terminal of the frequency converter 13, and performs frequency conversion. Table 13
The other input terminal is supplied with an oscillation output signal of a local oscillator 81 which oscillates according to a signal from the microprocessor 83 of the frequency selection unit 80 to obtain a signal component converted to an intermediate frequency. The signal component of the frequency is extracted, and the output signal is supplied to the signal addition / synthesizer.

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 (RFA2), and a second frequency converter 23 (MI
X2), and the second intermediate frequency filter 24 (IFF
2), a signal of the second digital broadcast reception frequency specified by the microprocessor 83 of the frequency selection unit 80 is selected by the second high-frequency signal filter 21 (RFF2), and the digital signal demodulation unit 60 is described later. OFDM obtained from signal processing circuit 65 (DSP2)
High frequency amplifier 22 based on received signal level information
To obtain an output signal that has been amplified by automatic gain control and supply a signal to one input terminal of the frequency converter 23,
The other input terminal of the frequency converter 23 has a frequency selector 8
A signal from the second local oscillator 82, which oscillates in accordance with the second digital broadcast reception frequency in accordance with a signal from the microprocessor 83 of 0, supplies an intermediate frequency signal supplied from the high frequency signal converter 10. In addition to obtaining a signal component converted to an intermediate frequency positioned adjacent to the component in frequency, a signal component of the intermediate frequency is extracted by the second intermediate frequency filter 24, and the output signal is converted to another input signal of the signal adder / combiner 30. The signal is supplied to the terminal, added and synthesized together with the signal supplied from the high-frequency signal converter 10, and the added and synthesized signal is supplied to the intermediate frequency amplifier 40.

The intermediate frequency amplifier 40 includes an intermediate frequency amplifier 4
1 (IFAA), intermediate frequency converter 42 (MIXB),
A second intermediate frequency filter 43 (IFFB), a second intermediate frequency amplifier 44 (IFAB), and a fixed frequency oscillator 45 (OSCB) are provided. The signal is supplied to one input terminal, and the other input terminal of the intermediate frequency converter 42 is provided with the sum of the intermediate frequency and 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 supplied to the digital signal demodulation unit 60.

The digital signal demodulation unit 60 includes an A / D converter 6
1 (ADC), digital bandpass filter 62 (DB
F1), the aforementioned digital signal processing circuit 63 (DSP
1), the second digital bandpass filter 64 (DBF
2) and the aforementioned second digital signal processing circuit 65 (D
SP2), the analog signal supplied from the intermediate frequency amplifier 40 is converted into a digital signal by the A / D converter 61, and the converted digital signal is converted into a digital bandpass filter 62 (DBF1) and a second digital signal. A signal in a frequency band corresponding to the signal supplied from the high-frequency signal conversion unit 10 that is supplied to the band-pass filter 64 (DBF2) and is adjacent to the intermediate frequency band;
Each of the signals in the frequency band corresponding to the signal supplied from the second high-frequency signal conversion unit 20 is obtained, and the signal obtained corresponding to the signal supplied from the high-frequency signal conversion unit 10 is transmitted to the digital signal processing circuit 63. The signal obtained corresponding to the signal supplied from the second high-frequency signal conversion unit 20 is supplied to the second digital signal processing circuit 65. In the digital signal processing circuit 63 and the second digital signal processing circuit 65, for example, O
It performs demodulation of an FDM signal, QAM decoding of a majority carrier signal constituting OFDM, deinterleaving processing, data error detection and correction, etc., and outputs a transport stream signal defined by the MPEG system standard, and OFDM supplied The signal level information is supplied to the corresponding high-frequency signal converters 10 and 20, and the high-frequency amplifier 12 and the second high-frequency amplifier 22 perform automatic gain control amplification as described above.

As described above, in the present embodiment, the intermediate frequency amplifying unit 40 amplifies the digital television signals for two channels, and furthermore, the intermediate frequency amplifying unit 40
Converts the intermediate frequency to a lower second intermediate frequency, and converts the A / D converter 61 of the digital signal demodulation unit 60, the respective digital bandpass filters 62 and 64, and the respective digital signal processing circuits 63 and 65, etc. The circuit operation speed is reduced to facilitate the circuit operation.

Here, these operations will be described in more detail. FIG. 2 is a schematic diagram showing a stream output of two channel signals reproduced by the digital broadcast receiving apparatus according to the embodiment of the present invention. The above-described digital broadcast receiving apparatus 1 has a function of simultaneously receiving signals of two channels. When simultaneously receiving channels 1 and 3, a bit stream of S 1 to S 3 broadcasted on channel 1 is transmitted. S7 broadcast on channel 3
This indicates that the bit stream of S9 can be output simultaneously.

FIG. 3 is a diagram for explaining the relationship between frequencies according to the embodiment of the present invention.
Shows the frequency relationship when broadcast waves of channels 1 and 3 are received at the same time. In the figure, the above-described high-frequency signal filter 11 (RFF1) is, for example, UH
A signal obtained by selectively extracting a signal of the frequency of channel 1 broadcasted in the F broadcast band and converting it to an intermediate frequency is obtained from the intermediate frequency filter 14, and the second high frequency signal filter 21 (RFF2) is For example, UH
A signal selectively extracted and centered on the signal of the frequency of channel 3 broadcasted in the F broadcast band and converted to an intermediate frequency is obtained from the second intermediate frequency filter 24, and obtained from these intermediate frequency filters 14 and 24. The frequency arrangement of the signals is adjacent as shown in the figure, and these signals are added and synthesized by the signal synthesis adder 30 described above.
Also in the above-mentioned second intermediate frequency filter 43 (IFFB) in the above-mentioned intermediate frequency amplifying section 40, adjacent frequency allocation is performed as shown in FIG.

FIG. 4 is a diagram showing the arrangement of signals at the second intermediate frequency according to the embodiment of the present invention with the frequency axis enlarged, and as shown in FIG. , The local oscillator 81 and the second local oscillator 82 have an oscillating frequency of one of the frequency bands required for transmitting signals of the respective channels, which is lower than the center value of the intermediate frequency.
This indicates that an intermediate frequency signal centered on a frequency shifted in the opposite direction by a frequency equal to or more than / 2 is generated.

Next, FIG. 5 is a schematic configuration of a digital broadcast receiving apparatus 2 according to a second embodiment of the present invention, which receives digital broadcast signals of a plurality of channels coming from an antenna, MPEG, including video and audio signals broadcast digitally for each channel
-2 A schematic configuration is obtained so as to obtain bit stream signals of a plurality of transport streams specified by a system standard or the like. The operation of the figure will be further described. In the figure, the received signal coming from the antenna is a second high-frequency signal filter 11B (RFF1) of the second high-frequency signal converter 10B, which simultaneously selects many channel signals. , A plurality of reception channel signals are selected and supplied to the high frequency amplifier 12 (RFA1), the selected plurality of reception channel signals are simultaneously amplified, and the amplified signal is input to one input terminal of the frequency converter 13 (MIX1). And a signal of a fixed frequency oscillator 15 (OSC) oscillating at a fixed frequency is supplied to the other input terminal of the frequency converter 13 and is generated as a frequency component of a difference between these input signal frequencies. An intermediate frequency component is obtained, and the obtained intermediate frequency component is converted to an intermediate frequency filter 14 (I
FF1) and the second intermediate frequency amplifying unit 40B
Of the second digital signal demodulation unit 60B.
A / D converter 61 (ADC) converts the supplied analog intermediate frequency signal into a digital signal, and a part of the converted signal is converted to the second frequency signal. The digital variable filter 66 (V) whose pass frequency band is varied by the microprocessor 83 of the selector 80B.
BF1), extracts a signal of a designated frequency band, and extracts the extracted signal into a digital signal processing circuit 63 (DS
P1), the modulated signal is demodulated to obtain a bit stream signal, and the other part of the signal converted by the A / D converter 61 is passed through the microprocessor 83 so that the passing frequency band is varied. Supplied to a second digital variable filter 67 (VBF2), extracts a signal of a designated frequency band, and supplies the extracted signal to a second digital signal processing circuit 65 (DSP2). In order to obtain a bit stream signal.

FIG. 6 is a diagram showing a frequency relationship according to the second embodiment of the present invention, and the operation of the second digital broadcast receiving apparatus 2 will be further described. The signal supplied to the frequency converter 13 of the second high-frequency signal converter 10B of this device is:
The signal supplied from the fixed frequency oscillator 15 and the signal supplied from the antenna are converted by the second high-frequency signal filter 11B into, for example, all frequency bands of the broadcast waves of channels 1 to 4 as indicated by RF in FIG. , And a signal amplified by the high-frequency amplifier 12. At this time,
The intermediate frequency filter 14 is supplied with a signal obtained by converting the signals of channels 1 to 4 into an intermediate frequency from the frequency converter 13 and converts the signal passed as the intermediate frequency component into the intermediate frequency amplifier 41 of the second intermediate frequency amplifier 40B. And amplifies the amplified signal. The amplified signal is converted into a digital signal by the A / D converter 61 of the second digital signal demodulation unit 60B, and the converted signal is converted into a digital variable filter 66 and a second digital variable filter. 67. These digital variable filters 66 and 67 are set to a pass band corresponding to the channel number selected and operated by a channel number selection device (not shown) by the microprocessor 83 of the second frequency selection unit 80B. In the illustrated example, the digital variable filter 66 passes a signal having a frequency corresponding to channel 1 and supplies the passed signal to a digital signal processing circuit 63 to obtain a bit stream signal obtained by demodulating channel 1 and a second digital signal. The variable filter 67 passes a signal having a frequency corresponding to channel 3 and supplies the passed signal to the second digital signal processing circuit 65 to operate in a frequency relationship such that a bit stream signal obtained by demodulating channel 3 is obtained. I do.

The second digital broadcast receiver 2 described here has a single superheterodyne system configuration, and has a simpler configuration of the intermediate frequency processing circuit than the double superheterodyne system shown in the above example. Can be
In addition, since the local oscillator uses a fixed frequency and amplifies the high-frequency signal in a lump, it does not require a PLL or its control circuit system. It has such features that it can be configured.

In the third embodiment shown below, a bit stream signal demodulated and output directly from a received signal is obtained without converting the received signal into an intermediate frequency. FIG. 7 shows a schematic configuration of the third digital broadcast receiving apparatus, and will be described. A third digital broadcast receiving apparatus 3 shown in FIG. 3 supplies a signal input from an antenna to a second high-frequency signal filter 11B (RFF1), and passes a signal in a frequency band that can be received by the apparatus. The passed signal is amplified by the high frequency amplifier 12 (RFA1), and the signal obtained by the amplification is amplified by the A of the second digital signal demodulator 60B.
/ D converter 61 (ADC) to convert it into a digital signal, and convert the converted signal into a digital variable filter 66 (VB
F1) and a second digital variable filter 67 (VB
F2). As described above, the digital variable filter 66 is set to pass the signal of the frequency selected by the microprocessor 83, and the passed signal is supplied to the digital signal processing circuit 63 (DSP1) to demodulate the bit. While generating the stream signal, the second digital variable filter 67 similarly passes the signal corresponding to the second reception channel,
The passed signal is passed through a second digital signal processing circuit 65 (DS
P2) to generate a bit stream signal obtained by demodulating the signal of the second reception channel.

As described above, for example, three types of programs are broadcast on one channel of the bit stream output here. The microprocessor 83 transmits the bit stream on one channel by a program selector (not shown). One of a plurality of selected programs is selected and received, and an information signal of the selected program is output.

FIG. 8 is a diagram for explaining the operation of the third digital broadcast receiving apparatus 3 in terms of frequency, and the operation of the apparatus will be described. The received signal coming from the antenna is
Is supplied to the high frequency filter 11B of
The high-frequency signals of channels 1 to 4 are passed and supplied to high-frequency amplifier 12 for amplification. The amplified signals are supplied to A / D converter 61 to be converted into digital signals, and the signals converted into digital signals are converted into digital signals. Although supplied to the variable filter 66 and the second digital variable filter 67, when a receiving channel selection device (not shown) selects, for example, reception signals of channel 1 and channel 3, these digital variable filters 66, 67 operates to pass the signal of channel 1 and the signal of channel 3 respectively, and the digital signal processing circuit 63 and the second digital signal processing circuit 65 are obtained by demodulating the signals of channel 1 and channel 3, respectively. Operates to output a bit stream signal.

Note that the third digital broadcast receiving apparatus shown here does not perform frequency conversion to an intermediate frequency,
A signal is supplied to the A / D converter 61 at a high frequency. This is a circuit configuration that supposes the future when the technology for increasing the speed of circuit elements, mainly semiconductors, advances and the era when broadcast waves can be directly converted to A / D signals has arrived. Has a feature that the circuit part accompanying the frequency conversion can be omitted, the circuit configuration is simplified, image interference and other distortion generation factors can be reduced, and further, a local oscillator is used. Since it does not have such a feature, it also has such a feature that the leakage power of the local oscillation output is not supplied to the antenna and does not perform an operation of causing unnecessary radiation.

FIG. 9 shows another embodiment of the digital signal processing section. In the figure, a third digital signal demodulation unit 70 is a circuit unit that performs the same function as, for example, the second digital signal demodulation unit 60B of the second digital broadcast receiving device 2 described above. The signals from the sections 40 and 40B and the like are modulated by the modulated signal filter 71.
(IFFD) and the second modulated signal filter 74 (IF
FE), the signal supplied to the modulation signal filter 71 passes a signal having a frequency corresponding to the reception channel selected by the microprocessor 83, and the passed signal is passed through a second A / D converter 72 (ADC1). Is converted to a digital signal, and the converted signal is supplied to a third digital signal processing circuit 73 (DSP3) to obtain a demodulated bit stream signal, and the signal supplied to the modulation signal filter 74 is selected by the microprocessor 83. Pass the signal of the frequency corresponding to the other receiving channel
The passed signal is converted into a digital signal by a third A / D converter 75 (ADC2), and the converted signal is supplied to a fourth digital signal processing circuit 76 (DSP4) to obtain another demodulated bit stream signal. It is configured like this. Although the third digital signal demodulation unit 70 described here has a different circuit configuration, similar to the above-described second digital signal demodulation unit 60B, the third digital signal demodulation unit 70 amplifies different digital broadcasts using a common intermediate frequency amplifier. By performing demodulation processing of each channel signal by using the signal processing circuit of (1), signals of different channels are simultaneously received and an operation is performed to obtain a plurality of demodulated output signals.

Here, using a common intermediate frequency amplifier, the digital broadcast signal and the N broadcast conventionally broadcast
An embodiment in which both analog broadcast waves by TSC are received will be described. FIG. 10 shows a fourth digital broadcast receiving apparatus 4 for simultaneously receiving digital broadcast and analog broadcast.
The configuration will be described. The signal supplied from the antenna is supplied to the high-frequency signal conversion unit 10 and the second high-frequency signal conversion unit 20, and the first and second signals corresponding to the channel-selected first and second reception channels are respectively provided as described above. 2 are obtained, the signals of the respective intermediate frequencies are added and synthesized by a signal adder, supplied to an intermediate frequency amplifying unit 40 and amplified, and the amplified signal is converted to an analog signal demodulating unit. 50 and the third digital signal demodulation unit 70C. The analog signal demodulation unit 50 supplies a part of the signal supplied from the intermediate frequency amplification unit 40 to an analog modulation signal filter 52 (IFFC) to extract a component of the analog signal frequency, and one of the extracted signals is a video signal. The video signal is supplied to a demodulator 53 to be demodulated and amplified by a video amplifier 54 to output a video signal. The other signal supplied from the analog modulation signal filter 52 is supplied to an audio demodulator 55 When the demodulated signal is a bilingual broadcast or a stereo audio signal, the audio multiplex demodulator 56 demodulates the signal, outputs the demodulated signal as an audio signal, and outputs Another part of the signal supplied from the frequency amplifying section 40 is a modulation signal filter 71 (IF
FD), a frequency component of the digital modulation signal is extracted, and the extracted signal is supplied to a second AD converter 72 (ADC).
The digital signal is converted into a digital signal in 1) and supplied to the third digital signal processing circuit 73, where the digital signal is decoded, and the decoded transport stream signal is output.

FIG. 11 shows a fourth digital broadcast receiving apparatus 4.
The relationship between the operating frequencies is shown, and the operation of the device will be described with reference to FIG. In this example, digital broadcasting is performed on channels 1 and 3 and analog broadcasting is performed on channels 2 and 4. However, reception of analog broadcasting on channel 4 and digital broadcasting on channel 1 are selected by a channel selector (not shown). When the local oscillator 81 of the frequency selection unit 80 oscillates at a frequency corresponding to the channel 4 and supplies an output signal thereof to the high-frequency signal conversion unit 10 to generate an intermediate frequency signal corresponding to the channel 4,
The second local oscillator 82 of the frequency selector 80 is the channel 1
And oscillates at a frequency corresponding to the above-mentioned frequency, supplies the output signal to the second high-frequency signal converter 20, and generates an intermediate frequency signal corresponding to the channel 1 and adjacent to the intermediate frequency signal in frequency. The signals of the intermediate frequencies corresponding to the channels 1 and 4 are added and synthesized by the signal addition / synthesizer 30, and then supplied to the intermediate frequency amplifier 40.
The amplified signal is supplied to the analog signal demodulation unit 50 and the third and third digital signal demodulation unit 70C, and outputs a signal obtained by simultaneously receiving both the analog signal and the digital signal as described above. .

The signal obtained in this manner is supplied to a display device or the like (not shown) to display an image. As a method of using the broadcast receiving apparatus, for example, a channel switching operation by a remote controller is frequently performed. It is relatively often used to enjoy a large number of broadcast programs. In the case of a conventional analog terrestrial broadcast receiver, a video is switched in a relatively short time by performing a channel switching operation. However, in the case of digital terrestrial broadcasting, in the case of receiving an OFDM signal broadcast using a large number of carriers, the time required for synchronization required for demodulation to be taken and demodulation to be started, and the temporal interleave processing to be performed. Time for rearranging the data in the original order.
This requires a lot of time, such as the time required to decode a bit stream coded according to the system and obtain a video signal, and the time required to display a video after a channel switching operation is performed is long. These improvements are necessary to make the receiving system convenient for the user. According to the present embodiment, since two-channel video signals can be output simultaneously, those video signals can be displayed as images instantaneously switched by a changeover switch or the like. However, viewers can perform convenient instantaneous channel switching reception.

As described above, according to the apparatus of each embodiment,
Some analog circuits can be shared for reception of multiple digital broadcast channels, such as processing of analog signals such as frequency conversion to the second intermediate frequency and amplification of multiple received signals at the same time using common hardware. I do it. Sharing an analog circuit is different from a digital circuit in which a large-scale integrated circuit or the like can realize large-scale signal processing with a small circuit, and it is relatively difficult to reduce the size and save energy. Therefore, by sharing an analog circuit as in the present embodiment, it is possible to reduce the circuit scale, economically reduce the shape and size of the device, and reduce power consumption.
In that respect, it is preferable, and the effect is large. In addition to enabling simultaneous recording of channels that are receiving simultaneously with the received signals of multiple channels, switching channels that are being simultaneously received and switching between channels are possible, such as displaying without waiting time. Has the effect.

In each of the above embodiments of the digital broadcast receiving apparatus, a configuration for simultaneously receiving two channels has been described. Similarly, three or four channels,
Alternatively, it is possible to configure more simultaneous receiving devices.

[0035]

According to the first aspect of the present invention, the intermediate frequency amplifying section or the high frequency signal amplifying section is simultaneously amplified using a common circuit to receive broadcast waves of different channels. This is advantageous in that a digital broadcast receiving apparatus that outputs signals received from a plurality of broadcast channels at the same time or that switches and outputs the signals instantaneously can be economically configured. According to the second aspect of the present invention, a plurality of channel signals for performing broadcast reception among signals supplied from the antenna are selected by the high-frequency signal filter and are simultaneously amplified by the high-frequency amplifier. There is an effect that a digital broadcast receiving apparatus that demodulates and outputs channel signals simultaneously can be economically configured. Furthermore, according to the third aspect of the present invention, in particular, since high-frequency amplification is performed by converting the intermediate frequency to an intermediate frequency, at the present time, in addition to the effect of the second aspect, a digital broadcast receiving apparatus having high reception sensitivity is economically constructed. There is an effect that can be done.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing a stream output of two channel signals reproduced by the digital broadcast receiving apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a frequency relationship according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating an arrangement of signals at a second intermediate frequency according to the embodiment of the present invention.

FIG. 5 is a schematic block diagram of a digital broadcast receiving apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram for explaining a frequency relationship according to a second embodiment of the present invention.

FIG. 7 is a schematic block diagram of a digital broadcast receiving apparatus according to a third embodiment of the present invention.

FIG. 8 is a diagram for explaining a frequency relationship according to a third embodiment of the present invention.

FIG. 9 is a schematic block diagram of a digital signal demodulation unit according to a fourth embodiment of the present invention.

FIG. 10 is a schematic block diagram of a digital broadcast receiving apparatus according to a fifth embodiment of the present invention.

FIG. 11 is a diagram illustrating a frequency relationship according to a fifth embodiment of the present invention.

FIG. 12 is a digital broadcast wave receiver configured on the assumption of a conventional technique.

FIG. 13 is a schematic diagram showing how stream information is broadcast by OFDM.

FIG. 14 is a diagram showing a frequency relationship according to a digital broadcast wave receiving device configured assuming a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 digital broadcast receiving device 2 second digital broadcast receiving device 3 third digital broadcast receiving device 4 fourth digital broadcast receiving device 5 digital broadcast wave receiving device 10 high-frequency signal converter 10B second high-frequency signal converter 11 high frequency Signal filter 11B Second high frequency signal filter 12 High frequency amplifier 13 Frequency converter 14 Intermediate frequency filter 15 Fixed frequency oscillator 20 Second high frequency signal converter 21 Second high frequency signal filter 22 Second high frequency amplifier 23 Second frequency converter 24th 2 intermediate frequency filter 30 signal addition / combiner 40 intermediate frequency amplifier 40B second intermediate frequency amplifier 41 intermediate frequency amplifier 42 intermediate frequency converter 43 second intermediate frequency filter 44 second 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 multiplex signal demodulator 60 Digital signal demodulation unit 60B Second digital signal demodulation unit 61 A / D converter 62 Digital bandpass filter 63 Digital signal processing Circuit 64 Second digital bandpass filter 65 Second digital signal processing circuit 66 Digital variable filter 67 Second digital variable filter 70 Third digital signal demodulator 70B Second third digital signal demodulator 70C Third third digital signal Demodulation unit 71 Modulation signal filter 72 Second A / D converter 73 Third digital signal processing circuit 74 Second modulation signal filter 75 Third A / D converter 76 Fourth digital signal processing circuit 80 Frequency selection unit 80B Second frequency selection Unit 80C third frequency selection unit 81 local origin Vibrator 82 Second local oscillator 83 Microprocessor

Claims (3)

[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 conversion means for supplying a corresponding signal and a signal of the first local oscillator to convert the signal into a first intermediate frequency; and a second high-frequency signal conversion means for inputting the second reception channel from the antenna. A second high-frequency signal conversion means for supplying a corresponding signal and a signal of the second local oscillator to convert the signal into a second intermediate frequency; and the first intermediate frequency signal and the second intermediate signal. Week And signal adding synthesizing means for generating a synthesis by adding signal and the number signal, the intermediate frequency amplifying means for amplifying the synthesis by adding signal, the amplified summed composite signal into a digital signal,
First signal demodulation means for selectively extracting and demodulating a signal corresponding to the first reception channel by a digital filter provided, and, from the converted digital signal,
Second signal demodulation means for selectively extracting and demodulating a signal corresponding to the second reception channel by a digital filter provided, and simultaneously outputting a plurality of demodulated output signals corresponding to broadcast waves of a plurality of channels. A digital broadcast receiving apparatus characterized by being configured as described above. 2. A broadcast receiving apparatus for receiving a digitally modulated broadcast wave, comprising: high-frequency signal filtering means for supplying a signal coming from an antenna and passing signals corresponding to a plurality of receiving channels; High-frequency amplification means for amplifying the signal supplied from the control unit, and A for converting the high-frequency amplified signal into a digital signal
D conversion means, first digital variable filter means to which the AD-converted signal is supplied and which allows a signal in a frequency band corresponding to a first reception channel which can be selectively specified to pass, and the first digital variable filter means A first digital signal processing unit that receives a signal passed by the variable filter unit and obtains a demodulated signal; a frequency corresponding to a second reception channel that is supplied with the AD-converted signal and that can be selectively specified A second digital variable filter means for passing a signal of the band, and a second digital signal processing means for receiving the signal passed by the second digital variable filter means and obtaining a demodulated signal; A digital broadcast receiving apparatus configured to simultaneously output a plurality of demodulated output signals corresponding to the broadcast waves. 3. A high frequency amplifying means for amplifying a signal supplied from said high frequency signal filtering means includes means for converting a high frequency signal into an intermediate frequency and amplifying the signal, and a plurality of demodulated outputs corresponding to a plurality of channels of broadcast waves. 3. The digital broadcast receiving apparatus according to claim 2, wherein the digital broadcast receiving apparatus is configured to output signals simultaneously.