JP2003230060A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CATV broadcast receiver capable of receiving a plurality of digital system broadcast signals in addition to analog system broadcast signals and reducing a time required for presetting a channel including presetting of a signal form and a transmission mode. <P>SOLUTION: In the case of setting a preset channel of the receiver, a control section presearches whether a particular channel employs each transmission mode of the analog signal form or a particular transmission mode of the digital signal form and stores the result of searching (S2); the particular channel employing the analog signal form where the center frequency depends on the transmission mode or employing the digital signal form where the center frequency indicates a particular transmission mode or no particular transmission mode, and the control section utilizes information of the signal type and the transmission mode to detect a signal of a transmission mode of channels other than the particular channel when the signal type and the type of the transmission mode of the particular channel are already known by presearching (S6). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cable television (CATV) broadcasting and NTSC (National Televis).
Ion System Committee) analog signal, VS
B (Vestigial Side Band) method and QAM (Quadrature
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving device that receives a digital television signal according to the Amplitude Modulation method, and particularly to a receiving device that presets a receiving channel corresponding to three types (STD, IRC, HRC broadcasting modes) used in cable television broadcasting. It is a thing.

[0002]

2. Description of the Related Art In the current receiving apparatus for receiving analog television broadcasting signals in the NTSC system of the United States, a process of presetting a channel of a terrestrial broadcast or a CATV broadcast and a process of selecting a channel after presetting are performed by
It is disclosed in Japanese Patent No. 2685744 (US Pat. No. 4819069), and it is known from the disclosure that channel presetting and channel selection can be performed efficiently.

In the above-mentioned patent, the receiving circuit is configured to set the receiving channels based on the regular arrangement in the frequency band of each receiving channel and the pass band frequency determined by the exclusive selection characteristic including the adjacent voice signal trap. It divides each pass band, detects at which position the video signal is located, and stores the information of the receiving channel in which the signal is located and the position information in the frequency band. Then, at the time of tuning, the stored information of the receiving channel in which the signal is stored and the position information in the frequency band are read and utilized.

FIG. 19 is a block diagram showing a schematic structure of a conventional receiver for receiving an analog television broadcast signal. The receiving device 1 of FIG. 19 includes an antenna 11 to which a radio broadcast signal such as a terrestrial wave is input, a CATV signal input unit 12 to which a CATV broadcast signal is input, and an input NT.
An analog signal tuner circuit 2 for selecting a target channel signal from an SC analog television broadcast signal
1 and an analog signal PLL (Phase Phase) that supplies a signal of a local frequency for channel selection to the analog signal tuner circuit 21.
Locked Loop circuit 22, an analog signal intermediate frequency circuit 23 having, for example, a filter for extracting only a signal in a required intermediate frequency band, an audio signal trap for an adjacent channel, and an analog signal demodulation for demodulating an analog intermediate frequency signal A circuit 24, an analog signal signal processing circuit 25 for performing a selection process, a synthesis process, an emphasis process, etc. on the demodulated analog video signal or audio signal to output a video signal or audio signal, and a microcomputer. Controls from the above channel selection to the output of video signals and audio signals, detects the presence or position of each channel in the frequency band of the analog signal and stores it as information, and conversely the channel is specified. If the analog signal PLL circuit 22 and the analog signal demodulation circuit 24 A control unit 51 for controlling a memory circuit 53 for storing various data and programs for the presence and location information and control for each channel, a video signal control circuit 6 which performs control for displaying a video signal as an image
1 and a video output section 6 such as a CRT or a liquid crystal display panel
2, an audio signal amplification circuit 71 that amplifies an audio signal to a level that can be heard by a viewer, and an audio output unit 72 such as a speaker.

As for the operation of the receiving apparatus 1, at the time of presetting the channel, the control circuit 51 determines, for example, every 6 MHz of the receiving channel based on the pass band determined by the "exclusive selection characteristic including the adjacent voice signal trap". While the local frequency of the analog signal PLL circuit 22 is changed so that the band can be received, it is confirmed whether or not a signal is detected by the analog signal demodulation circuit 24. When the demodulated signal is obtained, the control circuit 51 determines that there is a position and signal in the frequency band of the reception channel.
Store in 3.

When an arbitrary channel is designated by the user of the receiving apparatus 1 or the like, the control circuit 51
Reads the information about the channel from the storage circuit 53 and outputs the analog signal PLL circuit 22 for channel selection.
To the analog signal demodulation circuit 24 for demodulation.

In this way, the receiving apparatus 1 performs the channel preset processing and the channel selection processing of the channel designated by the user after the channel preset.
It can be implemented quickly.

[0008]

In recent years, in addition to analog television broadcasting by the NTSC system, broadcasting of digital television signals by the VSB modulation system and digital television signals by the QAM modulation system has started in the United States. In the terrestrial broadcasting by radio, analog broadcasting by NTSC system and digital broadcasting by VSB modulation system are used. In CATV broadcasting, N broadcasting is used.
An analog broadcast by the TSC system, a digital broadcast by the VSB modulation system, and a digital broadcast by the QAM modulation system are used. Further, in digital broadcasting by the QAM modulation system, two systems of 64QAM and 256QAM are further used.

Also, in CATV broadcasting, three types of transmission modes (standard, IRC: Incremental) are used in order to suppress interference when a television signal is transmitted by a cable.
Related Carriers, HRC: Harmonic Related Carriers
s) is set, and the transmission mode of each channel of CATV broadcasting is set to any one of the above-mentioned three types of transmission modes.

In the receiving device 1 described above, for example, NTS
Only analog broadcasting according to the C system can sequentially detect three types of transmission modes and preset channels, but effective detection and preset methods have not been considered for digital television signal receiving devices. It was Therefore, for example, when a digital television signal receiving device function is added to the receiving device 1 described above, the signal format of each digital signal (VSB, 64Q
(AM, 256QAM), it is necessary to individually set a receiving device and perform signal detection and channel presetting for each transmission mode.

That is, in the conventional CATV broadcast receiver, for example, when a function for receiving a digital television signal is added to the analog television broadcast receiver, the presence or absence of a signal for each channel is detected. However, there is a problem in that the time required for the detection and the presetting of the channel including the signal format and the transmission mode becomes extremely long as compared with the case where only the analog signal is used.

The present invention has been made to solve the above-mentioned problems, and is a CATV capable of receiving a plurality of digital broadcasting signals in addition to an analog broadcasting signal.
An object of the present invention is to reduce the time required for detecting the presence or absence of a signal for each channel and presetting a channel including a signal format and a transmission mode in a broadcast receiving device.

[0013]

In order to achieve the above-mentioned object, a receiving apparatus according to the present invention described in claim 1 demodulates a received analog television broadcast signal and outputs it as a video signal and an audio signal. And an analog signal receiving unit that demodulates and decodes the received digital television broadcast signal and outputs it as a video signal and an audio signal, and an analog signal demodulating process and a digital signal demodulating and decoding process. A control circuit for controlling, a storage circuit that stores at least programs used for demodulation processing of analog signals and demodulation and decoding processing of digital signals, various control information, and at least an area for storing intermediate information during processing and preset channels; A cable television broadcast receiving device comprising:
At the time of setting the preset channel of the receiving device, the control unit controls the center frequency of the carrier in the analog signal format depending on the transmission mode individually, and in the digital signal format, the center frequency of the carrier in the specific transmission mode different from other transmission modes. Pre-search for detecting whether each of the analog signal format transmission modes and the digital signal format specific transmission mode are associated with a specific channel that may or may not be the specific transmission mode When the signal type and the transmission mode type of the specific channel are known by the pre-search, the information of the signal type and the transmission mode of the specific channel is used to store the channels other than the specific channel. A feature is that the signal type and the transmission mode are detected.

Further, according to the present invention of claim 2, in the receiving device according to claim 1, when the signal type and the transmission mode type of the specific channel are not known by the pre-search, the control unit presets the current channel. It is characterized in that the signal type and the transmission mode signal of a channel other than the specific channel are detected by using the information of the signal type and the transmission mode type of the band immediately before the set frequency band.

The present invention according to claim 3 is the receiving apparatus according to claim 2, wherein the signal type and the transmission mode of a channel other than the specific channel are utilized by utilizing the information of the signal type and the transmission mode type of the immediately preceding band. If the signal of is detected, the control unit, when detecting the signal type of the subsequent channel and the signal of the transmission mode, the detection result of the signal type of the channel and the signal of the transmission mode, It is characterized in that it is used together with the information of the transmission mode type.

Further, the present invention of claim 4 is based on claims 1 to 3.
In the receiving device described in any one of 1 to 3, the control unit performs the signal detection of the signal type and the transmission mode of each channel for each band in which the frequency band used by each channel is continuous.

According to the present invention of claim 5, in the receiving device according to claim 1, when the signal type and the transmission mode type of the specific channel are known by the pre-search, the signal type of the specific channel by the pre-search. If the signal of the transmission mode of a channel other than the specific channel cannot be detected using the information of the transmission mode type and the transmission mode type, the control unit does not use the information of the signal type and the transmission mode type of the specific channel by the pre-search. The signal type and the transmission mode of a channel other than the specific channel are detected again.

Further, the present invention of claim 6 is based on claims 1 to 5.
In the receiving device according to any one of the items 1 to 5, a code of at least 4 bits is used as the information of the signal type and the transmission mode for each channel of the cable television broadcast,
Two bits are used for the signal type, and the other two bits are used for the transmission mode type and the presence / absence of a signal.

The present invention according to claim 7 is the receiving apparatus according to claim 6, wherein, when connected to the antenna input, the signal of the antenna input is at least 2 bits, and the signal of the cable television broadcast. It is characterized in that it is distinguished from a signal of cable television broadcasting by using a code having a code number different from that of the signal.

The present invention according to claim 8 is the receiver according to claim 6 or 7, wherein the digital signal receiving section has an analog signal suppressing circuit, and when the preset channel is set, the analog signal format is changed. In a channel in which both of the digital signal formats are detected, the control unit uses the code to perform on / off control of the analog signal suppression circuit.

[0021] According to a ninth aspect of the present invention, in the receiving device according to the eighth aspect, the control section uses a code to perform digital processing in the digital signal receiving section based on the information obtained by the analog signal receiving section. It is characterized in that the signal demodulation and decoding processing is performed, or the analog signal demodulation processing in the analog signal receiving section is performed based on the information obtained in the digital signal receiving section.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. Embodiment 1. 1 is a block diagram showing a schematic configuration of a receiving apparatus that receives an analog broadcast signal and a plurality of digital broadcast signals according to a first embodiment of the present invention.
Incidentally, in FIG. 1, parts having the same functions as those of the conventional receiving device shown in FIG. 19 are assigned the same reference numerals and overlapping description will be omitted.

In addition to the conventional configuration shown in FIG. 19, the receiving apparatus 2 of FIG. 1 selects a signal of a target channel from the inputted VSB system and QAM system (64QAM, 256QAM) digital television broadcast signals. A digital signal tuner circuit 31 for servicing, a digital signal PLL circuit 32 for supplying a signal of a local frequency for tuning to the digital signal tuner circuit 31, and, for example, a digital signal having a filter for extracting only a signal in a required intermediate frequency band The signal intermediate frequency circuit 33, the digital signal demodulation circuit 34 for demodulating the digital intermediate frequency signal, and the decoding of the demodulated digital video signal and audio signal, and further, for example, selection and combination It has a digital signal decoding circuit 35 which carries out various kinds of signal processing and outputs.

Further, the control section 51 detects the presence / absence and the position of each channel in the frequency band of the digital signal in addition to the control of the analog circuits such as the conventional analog signal PLL circuit 22 and the analog signal demodulation circuit 24, and outputs the information. And the control of digital circuits such as the digital signal PLL circuit 32 and the digital signal demodulation circuit 34.

The memory circuit 52 not only stores the presence / absence of a signal for each channel of the conventional analog broadcasting, the position information and various data for control, programs, etc., but also the presence / absence of a signal for each channel of digital broadcasting of plural systems. Stores position information and various data and programs for control.

In the digital signal demodulation circuit 34,
In the same channel, an analog signal suppressing circuit 41 is provided which can suppress the analog signal and detect the digital signal satisfactorily when an analog signal and a digital signal are detected.

FIG. 2 is a diagram showing an example of contents stored in the storage circuit 52 of FIG. 1 as each storage unit. The preset program storage unit 101 stores an operation program for presetting a channel in the receiving device 2.
The operation content will be described later using a flowchart. The program stored in the input mode determination program storage unit 102 is, for example, an arbitrary channel, one of the signal formats is selected, and the analog signal PLL circuit 22 or the digital signal PLL circuit 32 is controlled to control the center of the carrier wave. Frequency is STD mode, IRC mode,
When the signal is detected by either the analog signal demodulation circuit 24 or the digital signal demodulation circuit 34 in any of the HRC modes, the input mode of the detected signal is the current set mode. It is a program determined by the control circuit 51.

NTSC signal discrimination program storage unit 111
The program stored in is, for example, a program that the control unit 51 determines that the output signal of the analog signal demodulation circuit 24 is an NTSC signal from the center frequency of the carrier wave and the signal form. The center frequency of the carrier will be described later with reference to FIG. The program stored in the VSB signal discrimination program storage unit 112 is a program that the control unit 51 discriminates that the output signal of the digital signal demodulation circuit 34 is a VSB signal from the frequency and signal form of the carrier wave. Similarly, the program stored in the 64QAM signal determination program storage unit 113 is a program for the control unit 51 to determine that the output signal of the digital signal demodulation circuit 34 is a 64QAM signal.
In the program stored in the AM signal discrimination program storage unit 114, the output signal of the digital signal demodulation circuit 34 is 25
This is a program for the control unit 51 to determine that it is a 6QAM signal.

As a method of discriminating the NTSC signal, for example, an automatic frequency control (AFT: Automatic Fine Tu) output from the analog signal demodulation circuit 24 is used.
ringing) signal and a horizontal changing pulse synchronized with the horizontal synchronizing signal output from the analog signal signal processing circuit 25.

The antenna input code storage unit 121 includes the presence / absence of a signal and the signal format (NTSCorVSBorNTSC &) of the radio broadcast signal input from the antenna 11.
A code for determining VSB) is stored. The antenna input will be described later with reference to FIG.

The cable input code storage unit 122 stores the CA
Regarding the cable broadcast signal input from the TV signal input unit 12, the presence or absence of the signal and the signal format (NTSCorVSB
or64QAMor256QAMorNTSC & VS
A code for discriminating between B) and the transmission mode (STDorIRCorHRC) is stored. The cable input will be described later with reference to FIG.

The antenna input channel preset table storage unit 131 stores one code individually selected from the antenna input code storage unit 121 for each channel of the radio broadcast signal input from the antenna 11.

The cable input channel preset table storage unit 132 stores one code individually selected from the cable input code storage unit 122 for each channel of the cable broadcast signal input from the CATV signal input unit 12.

Code type determination code temporary storage unit 141
Is used, for example, to temporarily store the temporarily determined code during the channel presetting work, or to temporarily store the code for each channel before storing it collectively in the nonvolatile storage unit. It is a storage unit.

The process repetition number storage unit 151 is a storage unit used to store the number of repetitions when a similar process is repeated with some conditions changed.

Previous band reception mode temporary storage unit 161
Is when the frequency bands of multiple channels are continuous,
A storage unit used when the continuous frequency band is set as one band and the reception mode for one band is discriminated and the information of the reception mode is stored for use in discrimination of the reception mode of the next band. Is.

FIG. 3 shows a carrier signal system (modulation system),
It is a figure which shows the center frequency of the carrier wave of a specific channel and other channels. It should be noted that the specific channel is a CAT in the case of an analog signal (NTSC system).
This is a channel in which the center frequency of the carrier wave is different for each V transmission mode. As can be seen from FIG. 3, in the analog signal (NTSC) channel 5 and channel 6, ST
If the center frequency of the D-mode carrier is Fc0, then I
In RC mode, Fc0 + 2MHz (approx.)
Therefore, in HRC mode, Fc0 + 0.75MHz
(Approx.). On the other hand, in other channels, the center frequencies of the carrier waves in the STD mode and the IRC mode are the same, and only the center frequency of the carrier waves in the HRC mode is Fc0-1.25 MHz (approx.).
Is different from As described above, the 5th channel and the 6th channel are specific channels because the setting of the center frequency of the carrier is different from the other channels.

The center frequency Fc0 of the carrier wave of the analog signal (NTSC) is a value obtained by adding 1.25 MHz to the frequency of the lower edge (LCE) of each channel, and is obtained from the equation Fc0 = LCE + 1.25 MHz. be able to.

On the other hand, VSB which is a digital signal
Fc1 which is the center frequency of the carrier wave of the signal is 0.31 MHz at the frequency of the lower edge (LCE) of each channel.
Is a value obtained by adding Fc1 = LCE + 0.31 MHz
Can be obtained from the formula. Further, Fc2, which is the center frequency of the carrier wave of the QAM signal which is a digital signal, has a frequency of 3.0M at the lower edge (LCE) frequency of each channel.
It is a value obtained by adding Hz, and Fc2 = LCE + 3.0MH
It can be obtained from the formula of z.

In the case of the digital signal, there is no difference between the specific channel and the other channels. In the STD mode and the IRC mode of the VSB signal, the center frequency of the carrier wave is Fc1, and only the HRC mode is Fc1-1. Two
It becomes 5 MHz. Similarly, in the STD mode and the IRC mode of the QAM signal, the center frequency of the carrier wave is Fc2.
Therefore, only the HRC mode is Fc2-1.25 MHz.

These are the EIA-542 standard and EIA-
It is a value defined by the 542-A standard. Also,
The frequency bandwidth allocated to each channel is 6 MH
z, and since the channels are arranged adjacent to each other, the signal format and the transmission mode do not change between the adjacent channels or the adjacent transmission bands.

Therefore, the current analog television signal based on the NTSC system and the digital television signal based on the modulation system such as VSB or QAM are the same CATV.
Even if the signal is transmitted in the same channel, the signal format and transmission mode are the same between adjacent channels and adjacent bands, and if the signal format and transmission mode of some channels can be detected, other adjacent channels and adjacent channels can be detected. The same can be expected for the signal format and transmission mode of the band to be used.

The band described in the present embodiment is a group of channels to be transmitted, which are sequentially divided into frequency bands from a low frequency. Also, CATV
In broadcasting, there is a possibility that digital TV broadcasting by the VSB modulation method of terrestrial waves may be directly sent to a cable as a CATV signal.

FIG. 4A shows an example of contents stored in the antenna input code storage unit 121 of FIG. 2, and FIG. 4B shows FIG.
It is a figure which shows an example of the storage content of the cable input code memory | storage part 122 of this. In the case of antenna input, only the STD mode of the NTSC signal is input as the analog signal, and only the STD mode of the VSB signal is input as the digital signal. Therefore, only 2 bits are required as a code. For example, as shown in FIG. 4A, “00”, which is a code indicating no signal, and ST of the VSB signal,
"01", which is a code indicating that D mode is input
And “11”, which is a code indicating that the STD mode of the NTSC signal is input, and “11”, which is a code indicating that both the STD mode of the VSB signal and the STD mode of the NTSC signal are input. Good.

On the other hand, in the case of cable input,
In addition to analog (NTSC) signals and digital VSB signals by signal type (modulation type), 64QAM signals and 2
Since 56QAM is increased and it is necessary to consider not only the STD mode but also the IRC mode and the HRC mode for each signal type, 4 bits are required as a code.

For example, as shown in FIG. 4B, for analog NTSC signals, a code "0000" indicating no signal and a code "0001" indicating that the HRC mode is input. And "0010" which is a code indicating that STD mode is input, and IRC
A code indicating that a mode is input, "001
1 ”. In this case, the upper two digits "00" is NT
It indicates that it is an SC signal, and the lower two digits indicate a transmission mode of "01" in the HRC mode, "10" in the STD mode, and "11" in the IRC mode.

With respect to the digital VSB signal, the code indicating no signal may be the same as that of the NTSC signal, so "000".
"0101" which is a code indicating that the HRC mode is input by commonly using "0", STD mode and I
"01" which is a code indicating that RC mode is input
10 "and N in addition to STD mode or IRC mode
The code indicating that the STD mode of the TSC is input is “0011”. In this case, “01” in the upper 2 digits indicates that it is a VSB signal, and in the lower 2 digits,
HRC mode "01", STD mode and IRC mode "10", STD or IRC mode plus N
The transmission mode "11" of the STD mode of TSC is shown.

For the digital 64QAM signal, the code indicating no signal may be the same as the NTSC signal, so "0".
000 ”is commonly used, and a code indicating that the HRC mode is input is“ 1001 ”and a code indicating that the STD mode and the IRC mode is input is“ 1010 ”. Also, NTSC signal is 64QAM
The code is not set because it cannot be input at the same time as the signal. In this case, the upper two digits “10” indicates that it is a 64QAM signal, and the lower two digits indicate HRC.
The transmission mode "01" in the mode and the transmission mode "10" in the STD mode and the IRC mode are shown.

For the digital 256QAM signal,
As with the 64QAM signal, the code indicating no signal is NTS.
Since it can be the same as the C signal, "0000" is commonly used and H
"11" which is a code indicating that RC mode is input
01 ”and“ 1110 ”which is a code indicating that the STD mode and the IRC mode are input. Also,
Since the NTSC signal cannot be input at the same time as the 256QAM signal, the code is not set. In this case, the upper two digits “11” indicates that the signal is a 256QAM signal, and the lower two digits indicate “01” in the HRC mode and ST.
The transmission mode "10" of the D mode and the IRC mode is shown.

FIG. 5A shows an example of the stored contents of the antenna input channel preset table storage unit 131 of FIG. 2, and FIG. 5B shows an example of the stored contents of the cable input channel preset table storage unit 132 of FIG. FIG. As shown in FIG. 5A, for each channel of the antenna input, one code (2 bits) selected from FIG. 4A is stored correspondingly. Figure 5 (a)
In the preset table of, for example, 1 of the antenna input
There are no signals on the channels, and two channels are NTSC (S
TD) signal is input.

Further, as shown in FIG. 5B, for each channel of cable input, one code (4 bits) selected from FIG. 4B is stored correspondingly.
In the preset table of FIG. 5B, for example, 1 channel of the cable input has no signal, and 2 and 6 channels are input with NTSC (STD) signal,
It also shows that there is no signal on channel 7.

FIG. 6 is a flowchart showing the operation of the receiving apparatus of this embodiment shown in FIG. Receiver 2
First determines whether the received signal is an antenna input signal or a cable input signal (S).
1). The following operation is performed, for example, by the storage circuit 5 of FIG.
2, preset program storage unit 101, input mode determination program storage unit 102, NTSC signal determination program storage unit 111, VSB signal determination program storage unit 1
12, 64 QAM signal discrimination program storage unit 113, 2
The control circuit 51 determines the program stored in the 56QAM signal determination program storage unit 114, and the analog P
It is implemented by controlling the LL circuit 22, the digital PLL circuit 32, the analog signal demodulation circuit 24, the digital signal demodulation circuit 34, the analog signal signal processing circuit 25, the digital signal decoding circuit 35, and the like.

For determining whether the input signal is from the antenna or the cable, for example,
It may be determined whether the signal is from the antenna or the cable from the channel designation input by the user of the receiver. Further, when a received signal in the STD mode of the NTSC signal or the STD mode of the VSB signal is detected, it is possible to determine whether it is an antenna input or a cable input by detecting the noise level, for example. Generally, the noise level of terrestrial waves is not so high as thermal noise, whereas in CATV, the noise level is often higher than the thermal noise level.

In addition, for example, when a plurality of channels are adjacent to each other, it is impossible for some of the signals to have different center frequencies of the carrier waves from overlapping the same frequency. By the STD mode of NTSC signal or ST of VSB signal
When there are many D modes, the probability of being an antenna input increases.

If it is not a cable input (S1: NO), a channel preset process for antenna input is executed (S10). The antenna input preset processing will be described later with reference to the flowchart of FIG. 7.

When the cable input is selected (S1: YES), the receiving apparatus 2 pre-searches only the specific channel (5 or 6 channels) of the cable input to detect the signal type and the transmission mode of the specific channel. (S2). This pre-search will be described later with reference to the flowcharts of FIGS.

Next, the receiving device 2 confirms whether or not the signal type and transmission mode of the specific channel have become known by the processing of step S2 (S3). When the signal type and transmission mode of the specific channel are known (S3: YE
In S), the lowest frequency band is detected (S4).

As a band of CATV broadcasting, for example,
In the United States, the VHF band is divided into 5 bands, from the lowest band to the highest band, LOW BAND, MIDDL
EBAND, HIGH BAND, SUPER BAN
D and HYPER BAND are set in this order (UH
(Excluding F band). Channels located at the lowest frequency edge of LOW BAND are 2 channels, and channels located at the highest frequency edge are 6 channels. Similarly, the channel located at the edge of the lowest frequency of MIDDLE BAND is 95 channel, and the channel located at the edge of the highest frequency is 22 channel. The channels located at the edge of the lowest frequency of HIGH BAND are 7 channels, and the channels located at the edge of the highest frequency are 13 channels. Furthermore, the number of channels located at the lowest frequency edge of SUPER BAND is 23, and the number of channels located at the highest frequency edge is 3.
There are 6 channels. The channels located at the edge of the lowest frequency of HYPER BAND are 37 channels, and the channels located at the edge of the highest frequency are 158 channels.

In the case of the above-mentioned US example, the receiving device 2
Indicates that the lowest frequency band is LOW BA in step S4.
Analog signal PL so that it can detect ND and preset channels from the lowest frequency 2 channels of LOW BAND to the highest frequency channel 6
Band setting is performed for the L circuit 22 or the digital signal PLL circuit 32 (S5). Then, using the known signal type and transmission mode of the specific channel, the channel preset processing of the remaining channels (2 to 6 channels) is performed (S).
6). The preset processing of other channels using the known information of this specific channel will be described with reference to FIGS.
It will be described later with reference to the flowchart of FIG.

Further, as to the meaning of utilizing the known signal type and transmission mode of a specific channel, as described above, when a plurality of channels are adjacent to each other, the center frequency of the carrier wave is different. This is because the signal type and transmission mode of a specific channel are highly applicable to other channels in the same band. As a result, it is possible to speed up the process of determining the signal type and transmission mode of each channel for presetting the channel.

Then, for example, the above-mentioned HYPE
It is confirmed whether or not the presetting of the channel of S6 is performed with the band setting of the highest frequency such as R BAND (S7). When the band setting is the highest frequency (S7:
YES), the preset result of each channel is stored in the antenna input channel preset table storage unit 13 of FIG.
1 or the cable input channel is stored in the preset table storage unit 132 and then the preset process is terminated, and if the band setting is not the highest frequency band (S
In 7: NO), the next highest frequency band is detected (S8). In the case of the above example, the current status is MIDD.
If it is LE BAND, HIGH BAND is detected. Then, the process of step S5 is performed again.

When the signal type and transmission mode of the specific channel cannot be detected (S3: NO), the determination of the immediately preceding band reception mode is started (S30). The determination of the immediately preceding band reception mode is made by, for example, the LOW BAND described above.
In the band setting of the lowest frequency like this, only the statistical processing (accumulation calculation or average calculation) of the transmission mode of each channel is carried out, and it is not used for presetting the channel, but in the band above MIDDLE BAND , The result of statistically processing the transmission mode of each channel of the previous band is used to preset the channel.

Specifically, for example, a working register (M ″) used for determining the immediately preceding band reception mode is provided, and the value of M ″ is changed according to the detection result of the transmission mode of each channel in the band. . From the detection result of the transmission mode of each channel, the transmission mode is STD mode or I
In the RC mode, 1 is added to the value of M ″, and when the transmission mode is the HRC mode, 1 is subtracted from the value of M ″.

Also in this case, as described above, when a plurality of channels are adjacent to each other, it is impossible that the center frequencies of the carrier waves have different signal formats. Therefore, in the same band, the transmission mode of one channel is different. This is because it has a high probability of being applicable to other channels. By using the statistical result of this band, it is possible to speed up the process of determining the transmission mode of each channel when presetting the channels of other bands.

Then, the lowest frequency band is detected in the same manner as in step S4 (S31), the band is set in the same manner as in step S5 (S32), and the channel preset processing when the signal type and the transmission mode of the specific channel are unknown. Implement (S33). The process of presetting another channel without using the information of the specific channel will be described later with reference to the flowchart of FIG.

After that, as in step S7, it is confirmed whether or not the presetting of the channel in S33 has been performed with the highest frequency band setting (S34). If the highest frequency band setting has been performed (S34: YES), If the preset result of each channel is stored in the antenna input channel preset table storage unit 131 or the cable input channel preset table storage unit 132 shown in FIG. In S34: NO, the next highest frequency band is detected (S35), and the process of step S32 is performed again.

FIG. 7 is a flowchart showing the antenna input preset process of step S10 of FIG. As an antenna input, for example, in the case of the above VHF band in the United States, LOW BAND of each of the above bands is used.
And HIGH BAND only, the signal type is only NTSC signal and VSB signal, and the transmission mode is only STD mode.

Therefore, the channels located at the edge of the lowest frequency are the two channels of LOW BAND,
The channel located at the edge of the highest frequency is 13 channels of HIGH BAND in the case of the VHF band example. In the UHF band, the number of channels located at the edge of the highest frequency is 69.

First, for example, LOW BAND is set to the lowest channel frequency such as channel 2 (S1
1), the center frequency of the carrier wave is set to the STD mode (Fc0 in FIG. 3) (S12).

The control circuit 51 uses the NTSC of the memory circuit 52.
The program read from the signal discrimination program storage unit 111 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 (S13). When the NTSC signal is detected (S13: YES), the control circuit 51 stores the NTSC (STD) code "10" in the signal type determination code temporary storage unit 141 (S2).
2).

When the NTSC signal is not detected (S1
3: NO), the control circuit 51 sets the VS of the storage circuit 52 to VS.
The program read from the B signal determination program storage unit 112 confirms whether or not the VSB signal is detected by the digital signal demodulation circuit 34 (S14).

When the VSB signal is detected (S14: Y
ES), the control circuit 51 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 by the same processing as step S13 (S19). If the NTSC signal is not detected (S19: NO), VSB (S
The code "01" of TD) is stored in the signal type determination code temporary storage unit 141 (S22). When the NTSC signal is detected (S19: YES), the NTSC (ST
The code “11” of D) & VSB (STD) is stored in the signal type discrimination code temporary storage unit 141 (S20).

When the VSB signal is not detected (S14:
If NO, the control circuit 51 confirms again whether the NTSC signal is detected by the analog signal demodulation circuit 24 by the same processing as step S13 (S15). NTSC
When the signal is not detected (S15: NO), the no-signal code “00” is set as the signal type determination code temporary storage unit 1
It is stored in 41 (S16). If the NTSC signal is detected (S15: YES), the code is not stored and the process proceeds to the next step S17.

It is confirmed whether or not it is the highest frequency channel setting in the band (S17), and when it is the highest frequency channel setting (S17: YES), the preset result of each channel is input to the antenna input of FIG. Stored in the channel preset table storage unit 131 or the cable input channel preset table storage unit 132 (S1
8) and then the preset process of the antenna input is ended, and if the channel setting of the highest frequency is not made (S17:
If the answer is NO, the next highest channel frequency is set (S23), and the process of step S12 is performed again.

FIG. 8 is a flow chart showing the process of pre-searching only the specific channel of the cable input in step S2 of FIG. In the present embodiment, the specific channel is a channel such as channels 5 and 6 shown in FIG. 3, in which the center frequency of the carrier wave is different for each transmission mode in the analog NTSC signal.

First, the lowest 5 among the specific channels 5 and 6
The frequency of the channel (Fc0 in FIG. 3) is set (S41), the signal format is set to NTSC, and the transmission mode is set to IRC mode (S42). The signal type determination code temporary storage unit 141 is set to the initial state and no signal is sent. (S43).

The control circuit 51 uses the NTSC of the memory circuit 52.
The program read from the signal discrimination program storage unit 111 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 (S44). When the NTSC signal is detected (S44: YES), the control circuit 51 stores the NTSC (IRC) code “0011” in the signal type determination code temporary storage unit 141 (S5).
8).

When the NTSC signal is not detected by the setting of NTSC (IRC) (S44: NO), the control circuit 5
1, the signal format remains NTSC and only the transmission mode is H
Change to RC mode and set (S45), and then restart NTS
The program read from the C signal determination program storage unit 111 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 (S46). NTSC
When a signal is detected (S46: YES), the control circuit 51 stores the NTSC (HRC) code "0001" in the signal type determination code temporary storage unit 141 (S).
57).

When the NTSC signal is not detected by the setting of NTSC (HRC) (S46: NO), the control circuit 5
1 indicates that the transmission mode is STD mode and the signal format is N.
The setting is made differently from TSC, VSB, 64QAM and 256QAM (S47), and NTSC signal discrimination program storage unit 111 and VSB signal discrimination program storage unit 112, 6 are set.
4QAM signal discrimination program storage unit 113, 256QA
Whether the analog signal demodulation circuit 24 detects the NTSC signal or the digital signal demodulation circuit 34 detects any of the VSB signal, the 64QAM signal, and the 256QAM signal by the program read from the M signal determination program storage unit 114. Confirm (S48). When any of the signals is detected (S47: YES), the control circuit 51 uses the signal format and the transmission mode is STD mode or STD & IRC mode code “0010”, “0”.
Any one of “110”, “1010”, and “1110” is stored in the signal type determination code temporary storage unit 141 (S
56). The processes of steps S47, S48 and S56 will be described later with reference to the flowchart of FIG.

If no signal is detected in the setting of changing to each signal format in the STD mode (S47: NO), the control circuit 51 sets the signal format to VSB and sets the transmission mode to the HRC mode. (S49), based on the program read from the VSB signal discrimination program storage unit 112, it is confirmed whether or not the VSB signal is detected by the digital signal demodulation circuit 34 (S50). When the VSB signal is detected (S50: YES), the control circuit 51 sets the signal type (VSB) and transmission mode (HRC) code “0101” to the signal type determination code temporary storage unit 141.
(S55).

When the VSB signal is not detected in the setting of VSB (HRC) (S50: NO), the control circuit 51
Sets the signal format to 64QAM and 256QAM,
Set the transmission mode to the HRC mode (S51),
64QAM signal discrimination program storage units 113 and 25
According to the program read from the 6QAM signal discrimination program storage unit 114, the digital signal demodulation circuit 34 generates 64
It is confirmed whether the QAM or 256QAM signal is detected (S52). 64QAM signal or 256QAM
When the signal is detected (S52: YES), the control circuit 51 causes the 64QAM (HR) in the case of the 64QAM signal.
The code “1001” of C), the code “1101” of 256QAM (HRC) in the case of a 256QAM signal,
The signal type discrimination code is stored in the temporary storage unit 141 (S
54).

64QAM (HRC) and 256QAM
If the signal is not detected in the setting of (S52: NO), the control circuit 51 confirms whether or not the above process is performed in the channel setting (6 channels) of the highest frequency in the specific channel (S53), If it is the highest frequency channel setting (S53: YES), the process proceeds to step S61 of FIG. 6, and if it is not the highest frequency channel setting (S53: NO), the next highest frequency channel is set. (S59), the process of step S42 is performed again.

FIG. 9 is a flow chart showing the final judgment procedure when the above-mentioned processing is executed by setting the highest frequency channel in the specific channels in step S53 of FIG. 8 (S53: YES). The control circuit 51 reads the code of the specific channel (channels 5 and 6) from the signal type determination code temporary storage unit 141 (S61),
From the code, it is confirmed whether or not all the specific channels have no signal (S62). When all the specific channels have no signal (S62: YES), the control circuit 51
Determines that the signal type of the specific channel is unknown (S69), and ends the pre-search process of the specific channel.

When all the specific channels are not signalless (S62: NO), the control circuit 51 determines from the code whether at least one of the specific channels is signalless and at least one is signaled. Confirm (S6
3). When there are no signal and a signal-present channel in the specific channel (S63: YES), the control circuit 51 stores the code of the signal-present (other than no signal) in the cable input channel preset table storage unit 132 ( S6
8) Then, the pre-search process for the specific channel ends.

When at least one of the codes of the specific channel has a signal (S63: NO), the control circuit 5
1 is below the code of the specific channel from that code 2
It is confirmed whether the digits are the same for codes other than no signal (S64). When the last two digits of each channel have the same code (S64: YES), the control circuit 51 determines
The code having the same digit is stored in the cable input channel preset table storage unit 132 (S68), and the pre-search process for the specific channel is completed.

If the last two digits of the code of the specific channel are not the same (S64: NO), the control circuit 51 determines that the code is VSB and the transmission mode is (STD &
It is confirmed whether or not the IRC) is included (S6).
5). When the code includes VSB (STD & IRC) (S65: YES), the control circuit 51 determines that the VSB
The code (STD) is stored in the cable input channel preset table storage unit 132 (S67), and the pre-search process for the specific channel is completed. This processing is not necessary in the case of wireless terrestrial broadcasting because it is only the STD mode, but in the case of CATV, a digital terrestrial broadcasting signal and an analog terrestrial broadcasting signal coexist in the same channel. In some cases, this is necessary processing.

The code of the specific channel is VSB (STD
& IRC) is not included (S65: NO), the control circuit 51 determines that the signal type of the specific channel is out of regulation (S66), and ends the pre-search process of the specific channel.

FIG. 10 shows steps S47 and S48 of FIG.
9 is a flowchart showing the processing in S56 and S56 in more detail. When neither the NTSC system IRC mode signal nor the NTSC system HRC mode signal is detected from the specific channel, the control circuit 51 sets the signal format to N.
The transmission mode is set to the STD mode while still in TSC (S71).

The control circuit 51 uses the NTSC of the memory circuit 52.
The program read from the signal discrimination program storage unit 111 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 (S72). When the NTSC signal is detected (S72: YES), the control circuit 51 stores the NTSC (STD) code “0010” in the signal type determination code temporary storage unit 141 (S8).
4) If the NTSC signal described below is not detected (S72: NO), the flow merges and the process proceeds to step S73.

When the NTSC signal is not detected in the setting of NTSC (STD) (S72: NO), the control circuit 5
1 indicates whether the VSB signal is detected by the digital signal demodulation circuit 34 by the program read from the VSB signal determination program storage unit 112 by setting the signal format as VSB and changing the transmission mode to the STD or IRC mode (S73). It is confirmed whether or not (S74).

When the VSB signal is detected (S74: Y
ES), the control circuit 51 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 as in step S72 (S81). When the NTSC signal is detected (S81: YES), NTSC (STD) &
The code “0111” of VSB (STD & IRC) is stored in the signal type discrimination code temporary storage unit 141 (S8
3) Go to S53. When the NTSC signal is not detected (S81: NO), the VSB (STD & IRC) code "0110" is added to the signal type determination code temporary storage unit 1
It stores in 41 (S82), and proceeds to step S53 in FIG.

When the VSB signal is not detected (S74:
If NO, the control circuit 51 sets the signal format to 64QAM and sets the transmission mode to (STD & IRC) (S7).
5), the digital signal demodulation circuit 3 according to the program read from the 64QAM signal discrimination program storage unit 113.
It is confirmed whether or not the 64QAM signal is detected in 4 (S
76). When the 64QAM signal is detected (S76: Y
In the ES, the code “1010” of 64QAM (STD & IRC) is stored in the signal type determination code temporary storage unit 141.
(S80), and the process proceeds to step S53 in FIG.

When the 64QAM signal is not detected (S7
6: NO), the control circuit 51 sets the signal format to 256Q.
As the AM, the transmission mode is set to (STD & IRC) (S77), 256QAM signal discrimination program storage unit 1
Based on the program read from 14, it is confirmed whether or not the 256QAM signal is detected by the digital signal demodulation circuit 34 (S78). When the 256QAM signal is detected (S78: YES), the 256QAM (STD & IR
The code "1110" of C) is stored in the signal type determination code temporary storage unit 141 (S79), and the process proceeds to S53. Two
When the 56QAM signal is not detected (S78: NO), the control circuit 51 determines that there is no signal and proceeds to step S49 in FIG.

As described above, the pre-search of the cable input specific channel shown in step S2 of FIG. 6 is performed. Next, the channel preset process using the known signal type of the specific channel in step S6 of FIG. 6 will be described in more detail.

FIG. 11 is a flow chart showing in more detail the channel preset process using the known signal type of the specific channel in step S6 of FIG. First, the frequency of the lowest channel in the band set in step S5 of FIG. 6 is set (S91), and the signal type determination code temporary storage unit 141 is set to no signal as an initial state (S92).

Further, the process repeat count temporary storage unit 151 indicating the repeat count of some processes is set to the initial value (S93). Specifically, for example, a working register (M ′) indicating the number of times of processing is provided, initially set to a value indicating the first time, and when some processing is reprocessed at the same channel frequency, M ′ is set. The value of is changed to the value of the second time to be distinguished, and the processing route (processing content) can be changed at the first time and the second time.

The control circuit 51 reads the code of the specific channel from the cable input channel preset table storage unit 132 (S94), and confirms whether the transmission mode indicated by the code is the HRC mode (S9).
5). When the code indicates the HRC mode (S95: YE
In S), the control circuit 51 proceeds to step S99,
The center frequency of the carrier wave is set to the HRC mode of each signal format. If the code does not indicate HRC mode (S95:
In NO, the control circuit 51 sets the center frequency of the carrier wave to the STD mode or the STD & IRC mode of each signal format (S96), and the NTSC signal determination program storage unit 111 and the VSB signal determination program storage units 112 and 64.
QAM signal discrimination program storage unit 113, 256QAM
According to the program read from the signal determination program storage unit 114, whether the analog signal demodulation circuit 24 detects the NTSC signal or the digital signal demodulation circuit 34 outputs V
It is confirmed whether or not any of the SB signal, the 64QAM signal, and the 256QAM signal is detected (S97). When any of the signals is detected (S97: YES), the control circuit 51 selects a code suitable for the signal format and the transmission mode from FIG. 4B and selects the signal type determination code temporary storage unit 141. (S104). This step S9
The processing of S6, S97 and S104 will be described later with reference to the flowchart of FIG.

When no signal is detected in step S97 (S97: NO), for example, it is confirmed by the value of the working register (M ') whether or not the processing is the value indicating the second time (S98). ). If the process is the second time (S98: YES), the flow proceeds to step S102 to check whether the set channel is the highest channel in the band.

When the process is not the second time but the first time (S9
8: NO), the control circuit 51 sets the center frequency of the carrier wave to the HRC mode of each signal format (S99), and NT.
Whether the NTSC signal is detected by the analog signal demodulation circuit 24 by the program read from the SC signal determination program storage unit 111, the VSB signal determination program storage unit 112, the 64QAM signal determination program storage unit 113, the 256QAM signal determination program storage unit 114, or It is confirmed whether or not the VSB signal, the 64QAM signal, or the 256QAM signal is detected by the digital signal demodulation circuit 34 (S100). When any of the signals is detected (S100: YES), the control circuit 51 selects a code that matches the signal format and the transmission mode from FIG. 4B and selects the signal type determination code temporary storage unit 141. (S105). The processes of steps S99, S100 and S105 will be described later with reference to the flowchart of FIG.

If no signal is detected in step S100 (S100: NO), it is confirmed whether or not the process is a value indicating the first time (S101). If the process is the second time that is not the first time (S101: NO), it is confirmed whether or not the set channel is the highest channel in the band (S102). When the process is the first time (S
101: YES), the process repeat count temporary storage unit 1
51 is set to the second value (S106), the code of the specific channel is not used, and step S9 is performed again.
The processing from 6 to S98 is performed.

If the set channel is not the highest channel in the band (S102: NO), the channel of the current band is set to the next highest channel frequency except the specific channel (S107). , Again returns to step S94. When the set channel is the highest channel in the band (S102: YES)
First, the preset result of each channel is stored in the cable input channel preset table storage unit 132 of FIG. 2 (S103), and then the process proceeds to step S7.

FIG. 12 shows steps S96 and S9 of FIG.
7 is a flowchart showing the processes of S7 and S104 in more detail. The control circuit 51 sets the center frequency of the carrier wave to
Whether the NTSC signal is detected by the analog signal demodulation circuit 24 by the program read from the NTSC signal discrimination program storage unit 111 of the storage circuit 52, which is set when the signal format is NTSC and the transmission mode is the STD mode (S111). Is confirmed (S112). When the NTSC signal is detected (S112: YES), the control circuit 5
1 stores the NTSC (STD) code "0010" in the signal type discrimination code temporary storage unit 141 (S12).
5) If the NTSC signal described below is not detected (S112: NO), the flow merges and the process proceeds to step S113.

When the NTSC signal is not detected in the setting of NTSC (STD) (S112: NO), the control circuit 51 sets the signal format to VSB and changes the transmission mode to STD or IRC mode and sets it (S113). , VS
The program read from the B signal determination program storage unit 112 confirms whether or not the VSB signal is detected by the digital signal demodulation circuit 34 (S114).

When the VSB signal is detected (S114:
If YES, the control circuit 51 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 as in step S112 (S122). If the NTSC signal is detected (S122: YES), the NTSC (S
Code "011" for TD) & VSB (STD & IRC)
1 ”is stored in the signal type determination code temporary storage unit 141 (S124), and the process proceeds to S102 in FIG. When the NTSC signal is not detected (S122: NO), VSB
The code "0110" of (STD & IRC) is stored in the signal type discrimination code temporary storage unit 141 (S123),
It proceeds to S102 in FIG.

When the VSB signal is not detected (S11
4: NO), the control circuit 51 sets the signal format to 64QA.
As M, the transmission mode is set to (STD & IRC) (S115), and the 64QAM signal discrimination program storage unit 1
Based on the program read from 13, it is confirmed whether or not the 64QAM signal is detected by the digital signal demodulation circuit 34 (S116). When the 64QAM signal is detected (S116: YES), the 64QAM (STD & IR
The code “1010” of C) is stored in the signal type determination code temporary storage unit 141 (S121), and S10 of FIG.
Go to 2.

When the 64QAM signal is not detected (S1
16: NO), the control circuit 51 sets the signal format to 256.
As the QAM, the transmission mode is set to (STD & IRC) (S117), and it is confirmed whether the 256QAM signal is detected by the digital signal demodulation circuit 34 by the program read from the 256QAM signal discrimination program storage unit 114 (S118). When the 256QAM signal is detected (S118: YES), the 256QAM (ST
The D & IRC) code "1110" is stored in the signal type determination code temporary storage unit 141 (S119), and FIG.
To S102. When the 256QAM signal is not detected (S118: NO), the control circuit 51 determines that there is no signal and proceeds to step S98 in FIG.

FIG. 13 shows steps S99 and S1 of FIG.
It is a flowchart which shows the process of 00 and S105 in more detail. The control circuit 51 sets the center frequency of the carrier wave when the signal format is NTSC and the transmission mode is HRC mode (S131), and the analog signal demodulation is performed by the program read from the NTSC signal determination program storage unit 111 of the storage circuit 52. It is confirmed whether or not the NTSC signal is detected by the circuit 24 (S132). When the NTSC signal is detected (S132: YES), the control circuit 51 stores the NTSC (HRC) code “0001” in the signal type determination code temporary storage unit 141 (S1).
43), the process proceeds to S102 of FIG.

When the NTSC signal is not detected by the setting of NTSC (HRC) (S132: NO), the control circuit 51 sets the signal format to VSB and changes the transmission mode to the HRC mode (S133), and the VSB. The program read from the signal determination program storage unit 112 confirms whether or not the VSB signal is detected by the digital signal demodulation circuit 34 (S134).

When the VSB signal is detected (S134:
If YES, the control circuit 51 sets the VSB (HRC) code “0101” to the signal type determination code temporary storage unit 1.
It stores in 41 (S142), and proceeds to S102 of FIG.

When the VSB signal is not detected (S13
4: NO), the control circuit 51 sets the signal format to 64QA.
As M, the transmission mode is set to (HRC) (S13
5), the digital signal demodulation circuit 3 according to the program read from the 64QAM signal discrimination program storage unit 113.
It is confirmed whether or not the 64QAM signal is detected in 4 (S
136). When a 64QAM signal is detected (S13
6: YES), the 64QAM (HRC) code "1"
"001" is stored in the signal type determination code temporary storage unit 141 (S141), and the process proceeds to S102 in FIG.

When the 64QAM signal is not detected (S1
36: NO), the control circuit 51 sets the signal format to 256.
As QAM, set the transmission mode to (HRC) (S1
37) 256QAM signal discrimination program storage unit 114
Based on the program read from, it is confirmed whether or not the 256QAM signal is detected by the digital signal demodulation circuit 34 (S138). If the 256QAM signal is detected (S138: YES), the 256QAM (HRC) code "1101" is stored in the signal type determination code temporary storage unit 141 (S139), and the process proceeds to S102 in FIG. When the 256QAM signal is not detected (S138:
11), the control circuit 51 determines that there is no signal and
To step S101.

As described above, the channel preset process using the known signal type of the specific channel shown in step S6 of FIG. 6 is executed. Next, step S in FIG.
The channel preset processing when the signal type of the specific channel 33 is unknown will be described in more detail.

FIG. 14 is a flowchart showing in more detail the channel preset processing when the signal type of the specific channel in step S33 of FIG. 6 is unknown. First,
The frequency of the lowest channel in the band set in step S32 of FIG. 6 is set (S151), and the signal type determination code temporary storage unit 141 is set to no signal as an initial state (S152). Further, the process repeat count temporary storage unit 151 indicating the repeat count of some processes is set to the initial value (S153).

Next, the control circuit 51 confirms whether or not the currently set channel is the lowest channel in the band (S154). When it is the lowest channel (S154: YES), the control circuit 51 proceeds to step S156 to set the center frequency of the carrier wave to the STD mode or STD & IRC mode of each signal format. If it is not the lowest channel (S154: NO), the control circuit 51 stores the previous band reception in the storage circuit 52 of FIG. 2 in which the result of the determination process of the previous band reception mode started in step S30 of FIG. 6 is stored. By referring to the value of the mode temporary storage unit 161, it is confirmed whether or not the value is less than 0 (S155). Last band reception mode temporary storage unit 16
If the value of 1 is less than 0 (S155: YES),
In step S159, the center frequency of the carrier wave is set to the HRC mode of each signal format.

When the value of the immediately preceding band reception mode temporary storage section 161 is not less than 0 (S155: NO), the control circuit 51 sets the center frequency of the carrier wave to the STD mode or STD & IRC mode of each signal format (S15).
6), NTSC signal discrimination program storage unit 111, VS
By the program read from the B signal discrimination program storage unit 112, the 64QAM signal discrimination program storage unit 113, and the 256QAM signal discrimination program storage unit 114,
Whether the NTSC signal is detected by the analog signal demodulation circuit 24 or the VSB signal by the digital signal demodulation circuit 34, 6
It is confirmed whether or not either the 4QAM signal or the 256QAM signal is detected (S157). When any signal is detected (S157: YES), the control circuit 51
The code that matches the signal format and transmission mode is shown in FIG.
Select from (b) and select signal type identification code temporary storage unit 1
It stores in 41 (S164). This step S156,
Details of the processing of S157 and S164 are described in S96, S97 and S1 using the flowchart of FIG.
The process of 04 and the step number are the same, but the detailed description will be omitted. In this case, after the process of step S164, 1 is added to the value stored in the signal type determination code temporary storage unit 141 (S16).
5).

If no signal is detected in step S157 (S157: NO), it is confirmed by the value stored in the process repeat count temporary storage section 151 whether the process indicates the second time. (S158). Processing is 2
If it is the first time (S158: YES), step S
In step 162, it is confirmed whether the set channel is the highest channel in the band.

When the process is not the second time but the first time (S1
58: NO), the control circuit 51 sets the center frequency of the carrier wave to the HRC mode of each signal format (S159),
Whether the NTSC signal is detected by the analog signal demodulation circuit 24 by the program read from the NTSC signal discrimination program storage unit 111, VSB signal discrimination program storage unit 112, 64QAM signal discrimination program storage unit 113, 256QAM signal discrimination program storage unit 114, or Digital signal demodulation circuit 34 VSB signal, 64QA
It is confirmed whether or not either the M signal or the 256QAM signal is detected (S160). When any of the signals is detected (S160: YES), the control circuit 51 selects a code suitable for the signal format and the transmission mode from FIG. 4B and selects the signal type determination code temporary storage unit 141. (S166). The details of the processing of steps S159, S160 and S166 are the same as the processing of S99, S100 and S105 described with reference to the flowchart of FIG. In this case, step S1
After the process of 66, the signal type determination code temporary storage unit 1
1 is subtracted from the value stored in 41 (S167).

If no signal is detected in step S160 (S160: NO), it is confirmed whether or not the value is a value indicating the first time of processing (S161). If the process is the second time that is not the first time (S161: NO), it is confirmed whether the set channel is the highest channel in the band (S162). When the process is the first time (S
161: YES), the process repeat count temporary storage unit 1
51 is set to the value of the second time (S168), the value of the previous band reception mode temporary storage unit 161 is not used, and the processes of steps S156 to S158 are performed again.

If the set channel is not the highest channel in the band (S162: NO), the channel of the current band is set to the next highest channel frequency except the specific channel (S169). , And again returns to step S154. When the set channel is the highest channel in the band (S162: YE
In S), the preset result of each channel is stored in the cable input channel preset table storage unit 132 of FIG. 2 (S163), and then the process proceeds to step S34 of FIG.

As described above, the channel preset process when the signal type of the specific channel shown in step S33 of FIG. 6 is unknown is carried out. Next, an operation when the channel preset processing is executed by the receiver with preset channels will be described with reference to a flowchart.

FIG. 15 is a flow chart showing the channel selection operation after channel preset of the receiving apparatus of the present embodiment shown in FIG. When the user of the receiving device 2 inputs a channel designation (S201), the control circuit 51
For example, it is determined whether the input content of the channel is the input signal from the antenna or the input signal from the cable as shown in step S1 of FIG. 6, and the preset code is read out and shown in FIG. The channel selection process is started using the EIA-542-A standard. Further, when a channel without a preset code or an irregular channel that is not set so as to be able to receive is designated, it is regarded as unreceivable and the channel selection processing is not executed with the current channel. In the channel selection process, first, it is confirmed whether the designated channel is 14 channels or more, or whether the designated content is a digital channel by using preset code content or the like (S2).
02). If it is not a digital channel (S202: N
Channel selection processing of analog (NTSC) channel is carried out in O). The analog (NTSC) channel selection processing will be described later with reference to FIG.

Next, the control circuit 51 confirms whether or not the preset code for the designated channel is a code for a signal (S203). If the preset code is a code with no signal (S203: NO), a digital channel tuning process when there is no code is performed (S210). Note that the digital channel tuning process when there is no code will be described later with reference to FIG.

The control circuit 51 confirms whether the transmission mode indicated by the code of the designated channel is the HRC mode (S204). When the content of the code is the HRC mode (S204: YES), it is further confirmed whether or not the signal type indicated by the code is 256QAM (S211). If the code indicates 256QAM (21
1: YES), the center frequency of the carrier is 256 QAM
Set to (HRC) mode (S213), 256QAM
A reception process in the (HRC) mode is performed (S219).

If the code does not indicate 256QAM (2
11: NO), the control circuit 51 confirms whether or not the signal type indicated by the code is 64QAM (S21).
2). When the code indicates 64QAM (212: YE
In S), the center frequency of the carrier wave is 64QAM (HRC).
The mode is set (S214), and the 64QAM (HRC) mode reception process is performed (S220).

When the code does not indicate 64QAM (212: NO), the center frequency of the carrier is VSB.
(HRC) mode is set (S215), VSB (HR
A reception process in the C) mode is executed (S221).

Even when the content of the code is not the HRC mode (S204: NO), the control circuit 51 further confirms whether or not the signal type indicated by the code is 256QAM (S205). When the code indicates 256QAM (205: YES), the center frequency of the carrier wave is set to 256.
Set to QAM (STD & IRC) mode (S21
6) A reception process in 256QAM (STD & IRC) mode is executed (S222).

If the code does not indicate 256QAM (2
In 05: NO, the control circuit 51 confirms whether or not the signal type indicated by the code is 64QAM (S20).
6). When the code indicates 64QAM (206: YE
In S), the center frequency of the carrier wave is 64QAM (STD &
Set to IRC mode (S217), 64QAM (S
A reception process in the TD & IRC mode is executed (S223).

When the code does not indicate 64QAM (206: NO), the control circuit 51 confirms whether the NTSC signal is received (S207). For example, the center frequency of the carrier wave can be set to the NTSC (STD) mode, and it can be confirmed whether or not the NTSC signal can be received. When no NTSC signal is received (2
07: NO), the center frequency of the carrier is V
Set to SB (STD & IRC) mode (S218),
Performs VSB (STD & IRC) mode reception processing (S
224).

When the NTSC signal is received (20
7: YES), the analog signal suppression circuit 41 in the digital signal demodulation circuit 34 is turned on to improve the reception sensitivity of the digital signal, and then the NTSC signal is not received (207: NO). It joins the process of step S218.

FIG. 16 is a flowchart showing the analog (NTSC) channel selection processing shown in S209 of FIG. First, the control unit 51 refers to the cable input channel preset table shown in FIG. 5B and confirms whether or not there is a cable input code (S).
230). If there is a cable input code (S23
In 0: YES), it is further confirmed whether or not the transmission mode indicated by the code is the HRC mode (S232). When the code indicates the HRC mode (232: YES), it is further confirmed whether or not the designated channel is the specific channel (S236). When the designated channel is the specific channel (S236: YES), the center frequency of the carrier is set to the HRC mode of the specific channel (S242), and the receiving process of the specific channel of the NTSC (HRC) mode is performed (S248). It

If the designated channel is not the specific channel (S236: NO), the center frequency of the carrier wave is set to the HRC mode other than the specific channel (S243).
Reception processing is performed for channels other than the specific channel in the NTSC (HRC) mode (S249).

If the code does not indicate HRC mode (2
In 32: NO), it is further confirmed whether or not the code indicates the IRC mode (S233). When the code indicates the IRC mode (233: YES), it is further confirmed whether or not the designated channel is the specific channel (S237). When the designated channel is the specific channel (S237: YES), the center frequency of the carrier wave is set to the IRC mode of the specific channel (S24).
4), the receiving process of the specific channel in the NTSC (IRC) mode is executed (S250).

If the code does not indicate IRC mode (2
33: NO) and the designated channel is not the specific channel (S237: NO), the center frequency of the carrier is set to the IRC mode other than the specific channel (S:
245), reception processing is performed for a specific channel in the NTSC (IRC) mode (S251).

When there is no cable input code (S23
In 0: NO, it is further confirmed whether or not the designated channel is the specific channel (S231). When the designated channel is a specific channel (S231:
If YES, the center frequency of the carrier wave is set to the IRC mode of the specific channel (S234), and it is confirmed whether the NTSC signal can be received (whether there is the NTSC signal) (S).
238). When there is an NTSC signal (S238: YE
In S), reception processing of a specific channel in IRC mode is performed (S250).

When there is no NTSC signal (S238: N
In (O), the center frequency of the carrier is the HR of the specific channel.
The C mode is set (S239), and it is confirmed whether the NTSC signal can be received (whether there is the NTSC signal) (S24).
6). If there is an NTSC signal (S246: YES), reception processing of the specific channel in the HRC mode is performed (S248). When there is no NTSC signal (S24
At 6: NO, the tuning process using the preset information is completed.

When the designated channel is not the specific channel (S231: NO), the center frequency of the carrier wave is set to the STD & IRC mode other than the specific channel (S2).
35), it is confirmed whether the NTSC signal can be received (whether there is an NTSC signal) (S240). If there is an NTSC signal (S240: YES), reception processing is performed on a channel other than the specific channel in the STD & IRC mode (S251).
To be done.

When there is no NTSC signal (S240: N
In (O), the center frequency of the carrier wave is set to the HRC mode other than the specific channel (S241), and it is confirmed whether the NTSC signal can be received (whether the NTSC signal is present) (S).
247). When there is an NTSC signal (S247: YE
In S), reception processing is performed on a channel other than the specific channel in the HRC mode (S249). If there is no NTSC signal (S247: NO), the tuning process using the preset information is ended.

FIG. 17 is a flow chart showing a digital channel tuning process when there is no code shown in S210 of FIG. The control unit 51 sets the center frequency of the carrier wave to the STD & IRC mode when the signal format is VSB (S261), and confirms whether the VSB signal can be received (VSB signal is present) (S262). When there is a VSB signal (S262: YES), VSB (STD
&& IRC) mode reception processing is performed (S275),
The process ends.

When there is no VSB signal (S262: NO)
The signal format of the center frequency of the carrier is NTSC and ST
The D & IRC mode is set (S263), and it is confirmed whether the NTSC signal can be received (whether there is an NTSC signal) (S264). When there is an NTSC signal (S26
At 4: YES, the analog (NTSC) signal suppression circuit 41 is turned on as needed (S276), and the process ends.

When there is no NTSC signal (S264: N
O), the signal format of the center frequency of the carrier is 64QAM
Is set to STD & IRC mode (S265), 64
Whether QAM signals can be received (whether there are 64 QAM signals)
Whether or not it is confirmed (S266). When there is a 64QAM signal (S266: YES), 64QAM (STD &
Reception processing in the IRC) mode is performed (S277), and the processing ends.

When there is no 64QAM signal (S266: N
O) shows that the signal format of the center frequency of the carrier is 256QA.
Set to STD & IRC mode with M (S267), 2
It is confirmed (S268) whether or not the 56QAM signal can be received (there is the 256QAM signal). When there is a 256QAM signal (S268: YES), 256QAM
Reception processing in the (STD & IRC) mode is performed (S2
78) and the process ends.

When there is no 256QAM signal (S268:
In NO, the signal format of the center frequency of the carrier wave is set to VSB in the HRC mode (S269), and it is confirmed whether the VSB signal can be received (the VSB signal is present) or not (S27).
0) is done. When there is a VSB signal (S270: YE
In S), the VSB (HRC) mode reception process is performed (S279), and the process ends.

When there is no VSB signal (S270: NO)
The signal format of the center frequency of the carrier is 64QAM and H
The RC mode is set (S271), and it is confirmed whether or not the 64QAM signal can be received (there is the 64QAM signal) (S272). When there is a 64QAM signal (S2
In 72: YES, the reception process in the 64QAM (HRC) mode is performed (S280), and the process ends.

When there is no 64QAM signal (S272: N
O) shows that the signal format of the center frequency of the carrier is 256QA.
HRC mode is set by M (S273), 256QA
It is confirmed whether the M signal can be received (whether there is a 256QAM signal) (S274). When there is a 256QAM signal (S274: YES), 256QAM (HR
The reception process in the C) mode is performed (S281), and the process ends.

In the above embodiment, the cumulative processing is used as the statistical processing in the immediately preceding band reception mode temporary storage section, but the average value processing may be used, for example.

The circuits described in the above embodiments are examples of simplified circuits and may have other configurations. For digital signals, the signal format is VS.
The signal format is not limited to B, 64QAM, and 256QAM, and only one of them may be used.

In addition, the analog (NTSC) signal suppressing circuit 41 uses the VSB modulation method because the current analog television signal of the NTSC method and the digital signal of the VSB modulation method may be broadcast in the same channel. It is used to improve signal reception performance. Thus, it applies to bands and channels where analog television and digital signals may overlap.

In the analog signal tuner circuit 21, the analog signal intermediate frequency circuit 23, the digital signal tuner circuit 31, or the digital signal intermediate frequency circuit 33, various filters for selecting a target frequency are provided. Therefore, signals other than the intended signal can be excluded and the intended signal can be selected.

The code used for the antenna input channel preset table is set to 2 bits, and the code used for the cable input channel preset table is set to 4 bits. These are within the range in which the signal format and transmission mode can be discriminated. You may increase or decrease with. For example, when there is one type of digital modulation system, the code used for the channel preset table for cable input may be reduced to less than 4 bits, and conversely, when there are more than three types of digital modulation systems. It may be increased more than 4 bits.

As described above, in the present embodiment, when the preset channel of the receiving device is set, the center frequency of the carrier in the analog signal format is different depending on the transmission mode, and the center frequency of the carrier is different in the digital signal format for other transmission. Which of each of the analog signal format transmission modes, for a specific channel that may or may not be a specific transmission mode different from the mode,
In addition, a pre-search for detecting whether the digital signal format is a specific transmission mode is performed and stored, and if the signal type and the transmission mode type of the specific channel are known by the pre-search, the specific channel is determined. Since the signal of the transmission mode of the channel other than the specific channel is detected by using the information of the signal type and the transmission mode of the above, the receiving apparatus of the CATV broadcast capable of receiving the broadcasting signals of the analog system and the plurality of digital systems. In the above, it is possible to shorten the time required to detect the presence or absence of a signal for each channel and preset the channel including the signal format and the transmission mode.

Embodiment 2. FIG. 18 is a block diagram showing a schematic configuration of a receiving device that receives an analog broadcast signal and a plurality of digital broadcast signals according to the second embodiment of the present invention. The receiver of FIG. 18 is different from the receiver of the first embodiment shown in FIG. 1 in that an analog signal tuner circuit and a digital signal tuner circuit are integrated to form an analog signal / digital signal tuner circuit 81. The point is that the PLL circuit is integrated with the analog signal / digital signal PLL circuit 82 in relation to this point. Other configurations are similar to those of the first embodiment. The operation is also the same as in the first embodiment.

In this embodiment, since the tuner circuit and the PLL circuit for analog and digital signals are integrated, the configuration can be shared except for the parts such as filters that need to be individually installed, and the cost can be reduced. And can be miniaturized.

Further, in each of the above-described embodiments, the reception operation including the ON / OFF control of the analog signal suppression circuit 41 in the digital signal demodulation circuit 34 is performed based on the code including the information of the signal format and the transmission mode. Since this is possible, the signal format and transmission mode are specified by the code, and it becomes possible to mutually use the information obtained by the analog signal receiving circuit and the information obtained by the digital signal receiving circuit.

For example, an NTSC analog signal and N
In the case where a TSC digital signal is received at the same time, it is not possible to obtain, from the analog signal itself, information on the processing content to be performed on the received signal by the analog signal demodulation circuit 24 or the analog signal signal processing circuit 25. However, the information of the same channel or the adjacent channel obtained from the digital signal decoding circuit 35 can be substituted. On the contrary, even when the information of the processing contents performed on the received signal by the digital signal demodulation circuit 34 or the digital signal decoding circuit 35 cannot be obtained from the digital signal itself, the analog signal demodulation circuit 24 or the analog signal signal processing. The information of the same channel or the adjacent channel obtained from the circuit 25 can be substituted.

Therefore, in each of the above-mentioned embodiments, the information obtained from the received signal of the digital signal can be utilized for demodulation or signal processing of the analog signal, and conversely, it can be obtained from the received signal of the analog signal. Since the obtained information can be used for demodulation, decoding, signal processing, etc. of the digital signal, it is possible to improve the receiving performance of the receiving device under adverse conditions.

[0156]

Since the present invention is constructed as described above, it has the following effects.

According to the present invention of claim 1, a CATV capable of receiving broadcast signals of an analog system and a plurality of digital systems.
In the broadcast receiving device, a pre-search of a specific channel was performed, and the result of the pre-search was used for detecting the presence or absence of a signal for each other channel, and for presetting a channel including a signal format and a transmission mode. It is possible to shorten the time required for presetting channels other than the specific channel.

According to the second aspect of the present invention, since the signal format and transmission mode of the band immediately before the preset band are used, the signal type and transmission mode type of the specific channel by the pre-search are not known. Even in this case, the time required for presetting channels other than the specific channel can be shortened.

According to the present invention of claim 3, the obtained signal format and transmission mode for each channel are determined by the signal format and transmission mode of the band immediately before the preset band and the signal format and transmission mode of the subsequent channels. Since it is used together with the band signal format and the transmission mode in the detection of, the time required for channel presetting can be further shortened.

According to the fourth aspect of the present invention, the signal format and transmission mode of the immediately preceding band for each band in which the frequency band is continuous for each channel, and the pre-search result of the specific channel are used as the signal format for other channels. Since it is used for presetting a channel including the transmission mode and the transmission mode, the time required for presetting the channel can be shortened even when the signal format or the transmission mode is different for each band.

According to the present invention of claim 5, the signal type and transmission mode of another channel can be detected without using the result of the pre-search of the specific channel, so that the case where the channel cannot be preset is reduced. be able to.

According to the present invention of claim 6, the signal format and transmission mode of each channel can be discriminated using a code having a small number of bits, so that the processing time required for channel presetting and channel calling can be shortened. be able to.

According to the present invention of claim 7, since the number of bits of the code for antenna input and the number of bits of the cable for cable input are made different, it is possible to prevent the number of bits of the code from being increased more than necessary. The processing time required for channel presets and channel recalls can be reduced.

According to the present invention of claim 8, the code used for presetting the channel turns on the analog signal suppressing circuit when receiving the digital signal. Therefore, the analog signal and the digital signal are supplied to the same channel. Even if there is, it can automatically receive the digital signal in good condition.

According to the present invention of claim 9, the code is used to perform demodulation and decoding processing of the digital signal in the digital signal receiving section based on the information obtained in the analog signal receiving section, or Since the analog signal demodulation processing in the analog signal receiving unit can be performed based on the information obtained in the receiving unit, the receiving performance of the receiving device under adverse conditions can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a receiving device that receives an analog broadcast signal and a plurality of digital broadcast signals according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of contents stored in a storage circuit of FIG. 1 as each storage unit.

FIG. 3 is a diagram showing a signal system (modulation system) of carrier waves and center frequencies of carrier waves of a specific channel and other channels.

FIG. 4A is the antenna input code storage unit 1 of FIG.
21 is a diagram showing an example of stored contents of FIG. 21, and (b) is a diagram showing an example of stored contents of the cable input code storage unit of FIG. 2.

5A shows an example of contents stored in an antenna input channel preset table storage unit shown in FIG. 2, and FIG.
FIG. 3 is a diagram showing an example of stored contents of a cable input channel preset table storage unit of FIG. 2.

FIG. 6 is a flowchart showing an operation of the receiving apparatus of the present embodiment shown in FIG.

FIG. 7 is a flowchart showing an antenna input preset process of step S10 of FIG.

8 is a flowchart showing a process of pre-searching only a specific channel of a cable input in step S2 of FIG.

FIG. 9 is a flowchart showing a final determination procedure when the above-described processing is performed by setting the highest frequency channel among the specific channels in step S53 of FIG. 8 (S53: YES).

10 shows steps S47, S48 and S5 of FIG.
6 is a flowchart showing the process of No. 6 in more detail.

FIG. 11 is a flowchart showing in more detail the channel preset process using the known signal type of a specific channel in step S6 of FIG.

FIG. 12 shows steps S96, S97 and S of FIG.
10 is a flowchart showing the processing of 104 in further detail.

FIG. 13 is a flowchart showing the processes of steps S99, S100, and S105 of FIG. 11 in more detail.

FIG. 14 is a flowchart showing in more detail the channel preset processing when the signal type of a specific channel in step S33 of FIG. 6 is unknown.

FIG. 15 is a flowchart showing a channel selection operation after channel preset of the receiving apparatus of the present embodiment shown in FIG.

FIG. 16 is an analog diagram (NT shown in S209 of FIG.
It is a flowchart which shows the channel selection process of (SC) channel.

FIG. 17 is a flowchart showing a digital channel tuning process when there is no code shown in S210 of FIG.

FIG. 18 is a block diagram showing a schematic configuration of a receiving apparatus that receives an analog broadcast signal and a plurality of digital broadcast signals according to a second embodiment of the present invention.

FIG. 19 is a block diagram showing a schematic configuration of a conventional receiving device that receives an analog television broadcast signal.

[Explanation of symbols]

1, 2, 3 receiver, 11 antennas, 12 C
ATV signal input section, 21 analog signal tuner circuit,
22 analog signal PLL circuit, 23 analog signal intermediate frequency circuit, 24 analog signal demodulation circuit, 2
5 analog signal / signal processing circuit, 31 digital signal tuner circuit, 32 digital signal PLL circuit, 3
3 digital signal intermediate frequency circuit, 34 digital signal demodulation circuit, 35 digital signal decoding circuit, 41
Analog signal suppression circuit, 51 control circuit, 52, 5
3 memory circuit, 61 video signal control circuit, 62 video output section, 71 audio signal amplification circuit, 72 audio output section 81 analog signal / digital signal tuner circuit,
82 analog signal / digital signal PLL circuit, 1
01 preset program storage unit, 102 input mode determination program storage unit, 111 NTSC signal determination program storage unit, 112 VSB signal determination program storage unit, 113 64QAM signal determination program storage unit, 114 256QAM signal determination program storage unit, 121 antenna input code Storage unit, 122
Cable input code storage unit, 131 Antenna input channel preset table storage unit, 132 Cable input channel preset table storage unit, 14
1 signal type discrimination code temporary storage unit, 151 processing repetition number temporary storage unit, 161 immediately preceding band reception mode temporary storage unit

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 19, 2002 (2002.4.1)
9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0072

[Correction method] Change

[Correction content]

When the VSB signal is detected (S14: Y
ES), the control circuit 51 confirms whether or not the NTSC signal is detected by the analog signal demodulation circuit 24 by the same processing as step S13 (S19). If the NTSC signal is not detected (S19: NO), VSB (S
The code "01" of TD) is stored in the signal type determination code temporary storage unit 141 (S21) . When the NTSC signal is detected (S19: YES), the NTSC (ST
The code “11” of D) & VSB (STD) is stored in the signal type discrimination code temporary storage unit 141 (S20).

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

Claims (9)

[Claims] 1. An analog signal receiving section for demodulating a received analog television broadcast signal and outputting it as a video signal and an audio signal, and a received digital television broadcast signal for demodulating and decoding to obtain a video signal and A digital signal receiving unit for outputting as a voice signal, a control circuit for controlling analog signal demodulation processing and digital signal demodulation and decoding processing, programs used for analog signal demodulation processing and digital signal demodulation and decoding processing, and various types. A receiving device for cable television broadcasting, comprising: a storage circuit having at least control information stored therein; intermediate information during processing; and a storage circuit having at least an area for storing a preset channel. In the analog signal format, the center frequency of the carrier is Each of the analog signal format transmissions for a specific channel that may or may not be a specific transmission mode in which the center frequency of the carrier differs from other transmission modes in the digital signal format A pre-search for detecting which of the modes and the specific transmission mode of the digital signal format is performed and stored, and the signal type and the transmission mode type of the specific channel are known by the pre-search. In some cases, the signal type and the transmission mode of the channel other than the specific channel are detected by using the information of the signal type and the transmission mode of the specific channel. 2. When the signal type and the transmission mode type of the specific channel are not known by the pre-search, the control unit controls the signal type and the transmission mode of the band immediately before the frequency band in which the current channel is preset. The receiving apparatus according to claim 1, wherein the type information is used to detect a signal type and a transmission mode signal of a channel other than a specific channel. 3. When a signal of a channel other than a specific channel and a signal of a transmission mode can be detected by using the information of the signal type of the immediately preceding band and the transmission mode type, the control unit is When detecting the signal type and the signal of the transmission mode, the detection result of the signal type of the channel and the signal of the transmission mode is used together with the information of the signal type and the transmission mode type of the immediately preceding band. Item 2. The receiving device according to item 2. 4. The control unit performs signal detection of the signal type and transmission mode of each channel for each band in which the frequency band used by each channel is continuous. The receiving device according to any one of claims. 5. When a signal type and a transmission mode type of a specific channel are known by the pre-search, channels other than the specific channel are utilized by using the information of the signal type and the transmission mode type of the specific channel by the pre-search. When the signal of the transmission mode is not detected, the control unit does not use the information of the signal type and the transmission mode type of the specific channel by the pre-search, and again determines the signal type and the transmission mode of the channel other than the specific channel. The receiving device according to claim 1, wherein the receiving device detects. 6. As information of the signal type and transmission mode for each channel of cable television broadcasting, at least a 4-bit code is used, 2 bits are used for the signal type, and the other 2 bits are used for the transmission mode type. The receiving device according to claim 1, wherein the receiving device is used for the presence or absence of a signal. 7. When connected to an antenna input, the signal of the antenna input is a signal of the cable television broadcast using at least 2 bits and a code having a code number different from that of the signal of the cable television broadcast. The receiver according to claim 6, wherein the receiver is distinguished from the receiver. 8. The digital signal receiving section has an analog signal suppressing circuit, and in a channel in which both an analog signal format and a digital signal format are detected when the preset channel is set, the control section is 8. The receiving apparatus according to claim 6, wherein the code is used to perform on / off control of the analog signal suppression circuit. 9. The control unit uses the code,
The demodulation and decoding processing of the digital signal in the digital signal receiving section is performed based on the information obtained in the analog signal receiving section, or the analog signal receiving section is performed based on the information obtained in the digital signal receiving section. 9. The receiving device according to claim 8, wherein the demodulation processing of the analog signal in 1 is performed.