JP2008135973A - Television broadcast receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an influence of video noise caused by an operation clock of digital television broadcasting reception processing during receiving analog television broadcasting by the simple control of reception processing by a configuration that can start to display a digital broadcasting receiving screen in a short period of time upon switching from the reception of the analog television broadcasting to the reception of digital television broadcasting. <P>SOLUTION: A sub-microcomputer 3d stops forming an operation clock of a clock generating part 4 of a front end 3a to control the front end 3a in a sleep mode during receiving the analog television broadcasting and prevents the influence of video noise caused by the operation clock of digital television broadcasting reception processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a television broadcast receiving apparatus that receives digital television broadcasts and analog television broadcasts, and more particularly, to reduction of video noise at the time of analog television broadcast reception based on an operation clock of digital television broadcast reception processing.

  In recent years, a transition from analog television broadcast to digital television broadcast has been made. Various television broadcast receivers for receiving digital television broadcast and analog television broadcast have been proposed.

  These television broadcast receiving apparatuses generally receive a digital television broadcast or an analog television broadcast according to a selection of a reception channel by a digital / analog shared tuner unit, and receive the digital television broadcast when the tuner unit outputs. The digital intermediate frequency output of the channel is demodulated into transport stream digital data by the front end unit, and the image compression of the demodulated digital data is expanded by the image decoder unit (MPEG decoder unit) to reproduce the baseband digital video output . When receiving an analog television broadcast, the analog video output of the reception channel demodulated by the tuner unit is converted into digital data by a video decoder unit, and the digital data is converted into a baseband digital video output through the image decoder unit. Reproduce.

  Then, the digital video output of the baseband of the reception channel of the digital television broadcast and the analog television broadcast is processed into an image display output by display processing and displayed on the display device.

  By the way, in this type of television broadcast receiving apparatus, it is known that reception performance deteriorates due to the influence of the receiving circuit side of digital television broadcast when analog television broadcast is received.

  Specifically, the demodulating operation lock of the front end unit is formed by doubling a reference clock of, for example, 25 MHz to 50 MHz. However, depending on the reception channel of the analog television broadcast, the K-th order of the operating clock (K is (Integer including 1) may be in the vicinity of the video carrier frequency of the receiving channel. At this time, the harmonic is superimposed on the analog video output of the demodulated output of the tuner unit as noise, Reception performance is degraded.

  If it is attempted to prevent the deterioration of the reception performance by the shield of the circuit unit or the signal cable, a shield case or a shield plate is required, which increases the size and the cost.

  Therefore, when receiving an analog television broadcast, the entire digital demodulation circuit unit such as the front end unit is stopped by supplying power, or the integrated circuit (IC that forms the front end unit and the back end unit of the subsequent stage, respectively. ) Reset terminal is controlled by a microcomputer (hereinafter referred to as “microcomputer”), the oscillation circuit of the operation clock of each of the front-end unit and the back-end unit is stopped, and a slave microcomputer for controlling the reception processing of digital television broadcasting It is also proposed that the reception processing of the analog television broadcast is controlled by the main microcomputer, and the deterioration of the reception performance is prevented by the operation control of the circuit unit without providing a shield case or a shield plate (for example, Patent Document 1).

Utility Model Registration No. 3119101 (abstract, paragraphs [0007]-[0013], [0034]-[0044], FIG. 1, FIG. 2, FIG. 3, etc.)

  As described in Patent Document 1, when receiving analog television broadcasting, the driving of the entire digital demodulation circuit unit is stopped, or the operation clock oscillation circuits of both the front end unit and the back end unit are stopped, In addition, when the microcomputer for receiving processing control is switched from the slave microcomputer for digital television broadcasting to the main microcomputer, there is a problem that control of receiving processing such as start / stop control of circuit operation and switching control becomes extremely complicated. In addition, when switching from analog to digital for TV broadcasting to receive processing based on channel selection, and switching the microcomputer for receiving processing control from the slave microcomputer for digital TV broadcasting to the main microcomputer, and vice versa, especially from receiving analog TV broadcasting When switching to digital TV broadcast reception, the digital TV broadcast reception process starts from the reset state of the microcomputer, so it takes time for the screen display to start. In some cases, after selecting the digital TV broadcast channel There is a situation where it takes a long time of about 10 seconds until the screen of the channel is displayed, and the user is dissatisfied.

  The present invention has a configuration in which display of a digital TV broadcast reception screen can be started in a short time when switching from reception of analog TV broadcast to reception of digital TV broadcast. An object of the present invention is to prevent the influence of video noise caused by the operation clock of digital TV broadcast reception processing during broadcast reception.

  In order to achieve the above object, a television broadcast receiver of the present invention is a television broadcast receiver that receives digital television broadcast and analog television broadcast, and has a reception channel selection function for digital television broadcast and analog television broadcast. The digital / analog shared tuner unit that receives digital TV broadcast or analog TV broadcast according to the channel selection, and the digital intermediate frequency output of the reception channel output by the tuner unit upon reception of the digital TV broadcast is converted into digital data of the transport stream. A demodulating front-end unit; a video decoder unit for converting analog video output of a reception channel demodulated and output by the tuner unit upon reception of analog television broadcast; to digital data of the transport stream; An image decoder unit that decompresses a compressed image of digital data of log video output and reproduces a baseband digital video output; and a reception processing control unit that controls the operation of each unit. The front end unit oscillates A clock generation unit that doubles the formed reference clock to form an operation clock for demodulating the digital intermediate frequency output, and the reception processing control unit is configured to receive the analog television broadcast when the analog clock is received. The present invention is characterized by comprising noise reduction control means for stopping the formation of an operation clock and controlling the front end unit to a sleep mode.

  The television broadcast receiver of the present invention is the television broadcast receiver according to claim 1, wherein the clock generation unit includes an oscillation circuit unit of the reference clock and a multiplier circuit unit of the reference clock, The noise reduction control means controls at least one of the oscillation circuit unit and the multiplier circuit unit to stop operation when receiving an analog television broadcast (Claim 2).

  The television broadcast receiver according to the present invention is the television broadcast receiver according to claim 1 or 2, wherein the reception processing control unit includes a K-th order (K is 1) of the operation clock when receiving the analog television broadcast. A frequency discriminating means for discriminating whether or not the frequency of the integer) is a frequency in a constant frequency range including the video carrier frequency of the receiving channel; and the noise reduction control means when the K-th order frequency is outside the constant frequency range And a stop restricting means for prohibiting the stop of the formation of the operation clock according to (3).

  According to the first aspect of the present invention, when receiving an analog television broadcast by selecting a reception channel, the reception processing control unit stops the operation clock of the clock generation unit provided in the front end unit and sets the front end unit in the sleep mode. To control.

  At this time, the noise of the analog television broadcast video is the K-order harmonic of the high-frequency operation clock of the clock generation unit provided in the front-end unit of the next stage of the tuner unit. The operation clock of the back-end unit has almost no effect on the video of the analog TV broadcast, and the reception performance of the analog TV broadcast does not deteriorate even if these operation clocks are not stopped.

  Therefore, by stopping the operation clock of the clock generator provided in the front-end unit during reception of analog TV broadcast, noise caused by the operation clock of the reception process of digital TV broadcast on the analog TV broadcast video output of the tuner unit The reception performance of the analog television broadcast is improved by controlling the reception process without superimposing and without using a shield case or a shield plate.

  Then, instead of stopping the driving of the entire front end unit that digitally demodulates the digital TV broadcast when receiving the analog TV broadcast, the operation clock formation of some of the clock generation units is stopped and the front end unit is set to the sleep mode. Control is simple, and the operation of the back-end unit in the subsequent stage is not stopped, so the control is simple.

  Moreover, since the above-mentioned microcomputer for receiving processing control does not switch from the slave microcomputer of the digital TV broadcast to the main microcomputer when receiving the analog TV broadcast, the TV broadcast received by selecting the receiving channel is changed from the analog TV broadcast to the digital TV. Even when switching to broadcasting, digital TV broadcast reception processing can be started immediately without resetting the microcomputer, etc., and the time until the screen display of digital TV broadcasting starts is extremely short, dissatisfying the user. There is nothing.

  Therefore, when switching from reception of analog TV broadcast to reception of digital TV broadcast, the display of the reception screen of digital TV broadcast can be started in a short time. Sometimes, it is possible to prevent the influence of image noise caused by the operation clock of the digital television broadcast reception process.

  According to the second aspect of the present invention, the clock generation unit includes a reference clock oscillation circuit unit and a reference clock multiplying circuit unit, and noise reduction of the reception processing control unit during reception of an analog television broadcast. The effect of claim 1 can be achieved by controlling the practical reception process in which at least one of the oscillation circuit unit and the multiplication circuit unit is controlled to be stopped by the control means.

  According to the invention of claim 3, when receiving an analog television broadcast, if the K-order harmonics of the operation clock of the clock generator do not affect the video carrier frequency of the reception channel as noise, the stop limiting means In order to continue the operation clock generation of the clock generator by the prohibition control, the digital television broadcast reception process is started very quickly when the reception of the analog television broadcast is switched to the reception of the digital television broadcast. An advantage that the display of the reception screen of the digital television broadcast can be started in a short time can be further provided.

  In order to describe the present invention in more detail, an embodiment thereof will be described in detail with reference to FIGS.

  FIG. 1 shows a circuit block of a television broadcast receiving apparatus 1 to which the present invention is applied, FIG. 2 is a flowchart of its reception processing control, FIG. 3 shows an example of a signal waveform of a television broadcast, and FIG. An example of signal characteristics of a television broadcast, FIG. 5B is an example of signal characteristics of an analog television broadcast.

(Constitution)
In the television broadcast receiving apparatus 1 in FIG. 1, reference numeral 2 denotes a digital / analog tuner unit having a reception channel selection function for digital television broadcasts and analog television broadcasts. Receives the selected channel of digital TV broadcast or analog TV broadcast according to the selection of the reception channel from the signal, and receives and demodulates and outputs the digital IF signal that is the digital intermediate frequency output of the selected reception channel when receiving the digital TV broadcast. When receiving an analog television broadcast, an analog composite video signal which is an analog video output of the selected reception channel is received and demodulated and output.

  Reference numeral 3 denotes a reception processing unit subsequent to the tuner unit 2, which includes a digital broadcast signal IC, and includes a front end unit 3a, a video decoder unit 3b, an MPEG decoder unit 3c, and a sub-microcomputer 3d.

  The front end unit 3a is a next-stage circuit unit of the tuner unit 2. The digital IF signal of the tuner unit 2 is input, and the front end unit 3a operates in the same manner as a well-known front end unit, and converts the digital IF signal of digital television broadcasting. Digital demodulation of digital data of a well-known transport stream (TS).

  The video decoder unit 3b is also a next-stage circuit unit of the tuner unit 2. The analog composite video signal of the tuner unit 2 is input, and the video decoder unit 3b operates in the same manner as a known video recorder. Is converted into digital data by A / D conversion.

  The MPEG decoder unit 3c forms the image decoder unit of the present invention and operates in the same manner as a well-known MPEG decoder, and compresses the digital data of the transport stream of the front end unit 3a and the digital data of the analog video output of the video decoder unit 3b. The baseband digital video output is reproduced by decompressing the image and corresponds to the back-end unit.

  Further, the sub-microcomputer 3d forms the reception processing control unit of the present invention, and the operations of the front end unit 3a, the video decoder unit 3b, and the MPEG decoder unit 3c are shown in the reception processing unit 3 as indicated by broken line arrows in the figure. In addition, the operation of the tuner unit 2 is controlled via an IIC (Inter IC Controller) communication bus.

By the way, the front end unit 3a has a clock generation unit 4. The clock generation unit 4 is formed by providing an oscillation circuit unit 4a having a crystal oscillation circuit configuration and a double circuit unit 4b.

  Then, the reference clock generated by the oscillation circuit unit 4a by free-running oscillation is multiplied by a multiple set by the multiplication circuit unit 4b to form an operation clock for demodulating the digital intermediate frequency output.

  On the other hand, the sub-microcomputer 3d is controlled in operation via the communication bus by the main microcomputer 5 that controls the overall operation of the television broadcast receiver 1, and executes various control programs to control the respective units 2, 3a to 3c.

  The sub-microcomputer 3d executes the front-end clock control program in steps S1 to S8 in FIG. 2, and has noise reduction control means, frequency discrimination means, and stop restriction means of the present invention formed by the software processing. .

  The noise reduction control means is basically means for stopping the formation of the operation clock of the clock generation section 4 and controlling the front end section 3a to the sleep mode when receiving the analog television broadcast. This is a practical configuration means for controlling at least one of the oscillation circuit unit 4a and the multiplication circuit unit 4b to stop operation by reset hold or power supply stop when receiving an analog television broadcast.

  The frequency discriminating means determines whether or not the frequency of the harmonic of the operation clock at the K-th order (K is an integer of 1 to a set order) is within a certain frequency range including the video carrier frequency of the reception channel when receiving the analog television broadcast. It is a means for discriminating.

  The stop limiting unit instructs the noise reduction control unit to prohibit control when the K-th order frequency is outside the fixed frequency range, and prohibits the stop of the operation clock formation. When there is no possibility of the operation clock harmonics being superimposed on the broadcast video output, the operation of the clock generator 4 is not stopped.

  Next, reference numeral 6 in FIG. 1 denotes a display output processing unit subsequent to the reception processing unit 3. Based on the display control of the main microcomputer 5, the digital video output of the reception channel output from the MPEG decoder unit 3c is used as a screen display signal. Convert and output. Reference numeral 7 denotes a display device connected to the display output processing unit 6, which is composed of, for example, a liquid crystal display, a plasma display, or a CRT. Display the image on the screen.

  In FIG. 1, the audio circuit block and the like are omitted. For digital television broadcasting, since digital video output is reproduced and output after image data is stored to some extent in an image memory (not shown) of the MPEG decoder 3c, when reception of digital television broadcasting is started by channel switching or the like. , It takes some time before the playback screen is displayed.

  Next, the fixed frequency range determined by the frequency determining means will be described.

  First, the signal frequency characteristics of each channel of digital television broadcasting and analog television broadcasting are as shown in FIG.

  FIG. 3A shows frequency characteristics for one channel of digital television broadcasting in Japan and the United States. In digital television broadcasting, a digital signal band of 5.6 MHz exists in a channel bandwidth of 6 MHz. In the figure, Fc is the center frequency of the channel band, and FW (L) and FW (H) are the lower limit and upper limit frequencies of the channel band.

  FIG. 3B shows frequency characteristics for one channel of NTSC analog television broadcasting in Japan and the United States, and the video area v and the audio area s are included in the 6 MHz channel bandwidth. In the figure, Fc, FW (L), and FW (H) are the center frequency, lower limit, and upper limit frequencies of the channel band, Fp is the video carrier frequency, and Fs is the audio carrier frequency.

  Since the analog video is transmitted by the upper waveband AM modulation method, the video region v is (Fp-1.25 MHz) to (Fp + 4.5 MHz) with respect to the video carrier frequency Fp in the NTSC method. When interference wave noise is mixed (superimposed) in this region v, the noise appears as beat noise in the image displayed on the screen as it is.

  Therefore, when receiving NTSC analog television broadcasting in Japan or the United States, the fixed frequency range has a slight margin so as to cover the video region v, for example, (Fp-2 MHz) to (Fp + 5 MHz). Set to

  Then, the front end unit is shifted to the sleep mode only when receiving the analog log TV broadcast of the channel whose harmonics of the operation clock of the front end unit are in the range of (Fp-2 MHz) to (Fp + 5 MHz). Avoid generating harmonics of the operating clock.

(Operation)
Next, the operation of the television broadcast receiving apparatus 1 will be described with reference to FIGS.

  First, when the power is turned on, the main microcomputer 5 activates the sub-microcomputer 3d and the like, and the tuner unit 2 and the reception processing unit 3 enter a reception standby state by the operation control of the sub-microcomputer 3d.

  When a channel is selected by the user, the following operation is basically performed based on this channel selection.

  When a digital television broadcast channel is selected, the tuner unit 2 outputs the digital IF signal of the reception channel to the front end unit 3a. At this time, in the front end unit 3a, the clock generation unit 4 is operated by the sub-microcomputer 3d, and based on the operation clock formed by multiplying the reference clock of the oscillation circuit unit 4a by the multiplication circuit unit 4b, The digital IF signal is digitally demodulated into transport stream digital data.

  Then, the digital data of the transport stream of the front end unit 3a is subjected to decompression processing of the compressed image of the MPEG decoder unit 3c to form a baseband digital video output, and the display output processing unit 6 based on this digital video output In response to the screen display signal, the digital television broadcast image of the reception channel is displayed on the screen of the display device 7.

  When an analog television broadcast channel is selected, the tuner unit 2 sends the analog composite video signal of the reception channel to the video decoder 3b to convert it into digital data.

  Then, the digital data of the video decoder 3b is subjected to the decompression process of the compressed image of the MPEG decoder unit 3c to form a baseband digital video output. By the screen display signal of the display output processing unit 6 based on this digital video output The video of the analog TV broadcast of the reception channel is displayed on the display device 7.

  By the way, in this embodiment, the respective units 3b and 3c of the reception processing unit 3 excluding the front end unit 3a are driven to be fed and maintained in an operating state even during reception of the analog television broadcast. In addition, the circuit units other than the clock generation unit 4 of the front end unit 3a are also driven to be fed and held in an operating state. Further, the sub-microcomputer 3d always continues to control the reception process.

  Then, when the sub-microcomputer 3d repeatedly executes the front-end clock control program of FIG. 2, the formation of the operation clock of the clock generation unit 4 of the front-end unit 3a is turned on / off.

  That is, the sub-microcomputer 3d determines whether or not a channel preset has been selected in step S1 of FIG.

  And when receiving and selecting each channel of the entire reception range in ascending or descending order by channel preset, the receiving channel is frequently switched from the digital TV broadcasting channel to the analog TV broadcasting channel, and vice versa, When the operation clock generation of the clock generator 4 is turned on / off each time, the control becomes complicated. For this reason, when a channel preset is selected, the operation clock generation of the clock generator 4 is not turned on or off based on the determination in step S1.

  On the other hand, in normal times when channel preset is not performed, the process proceeds from step S1 to step S2 to monitor the occurrence of switching of the reception channel.

  When the reception channel is switched, the process proceeds to step S2 or step S3. In steps S3 and S4, it is determined whether the channel is switched from the digital television broadcast channel to the analog television broadcast channel or vice versa. Specifically, this determination is made by referring to another preset memory (not shown) of digital TV broadcast and analog TV broadcast of the main microcomputer 5 from the sub-microcomputer 3d, and the digital TV written in both preset memories by channel preset. Based on channel information of broadcast and analog TV broadcast, the reception channel is switched from digital to analog before and after channel switching.

  At this time, if the channel is switched from the digital TV broadcast channel to the analog TV broadcast channel, the process proceeds from step S3 to step S6 unconditionally, and the oscillation circuit unit 4a and the multiplier circuit unit 4b are controlled by the noise reduction control means. The front end unit 3a may be controlled to sleep mode by controlling at least one of the operation stop, but in the present embodiment, the process proceeds from step S3 to step S5, and the clock generation unit 4 is shifted by the frequency discrimination means. It is determined whether or not the harmonics of the operation clock are within the fixed frequency range based on the video carrier frequency Fp of the receiving channel.

  Then, if the harmonics of the operation clock of the clock generation unit 4 are in the fixed frequency range, the harmonics of the operation clock may be superimposed as noise on the analog television broadcast image, so steps S5 to S6. As described above, the control of the noise reduction control means controls at least one of the oscillation circuit unit 4a and the multiplication circuit unit 4b to stop the operation, and controls the front end unit 3a to the sleep mode, Avoid generating clock harmonics.

  If the channel is switched from an analog TV broadcast channel to a digital TV broadcast channel, the process proceeds from step S4 to step S7 to determine whether or not the front-end unit 3a is controlled in the sleep mode. If it is controlled, the process proceeds to step S8, the operation stop of the oscillation circuit unit 4a and the multiplication circuit unit 4b is canceled, and the formation of the operation clock of the clock generation unit 4 is restarted, and the sleep mode of the front end unit 3a is changed. To release.

  Therefore, in the case of this embodiment, at the time of receiving an analog television broadcast, the operation clock of the clock generation unit 4 provided in the front end unit 3a is stopped, and the digital television broadcast reception process is performed on the analog television broadcast video output of the tuner unit 2. It is possible to improve the reception performance of analog television broadcasts by preventing the noise caused by the operation clock from being superimposed.

  Then, instead of stopping the driving of the entire front end unit 3a at the time of receiving an analog television broadcast, only the operation clocks of some of the clock generation units 4 are stopped and the front end unit 3a is controlled to the sleep mode. In addition, since the operation clock does not stop in the MPEG decoder unit 3c or the like corresponding to the back end unit in the subsequent stage, the control is simple.

  Moreover, since the reception processing control microcomputer is not switched from the sub-microcomputer 3d to the main microcomputer 5 during reception of the analog TV broadcast, even if the received TV broadcast is switched from the analog TV broadcast to the digital TV broadcast, the sub-microcomputer 3d The digital television broadcast reception process can be started immediately without resetting, and the time until the screen display of the digital television broadcast is started is extremely short, and the user is not dissatisfied.

  Therefore, when switching from reception of analog TV broadcast to reception of digital TV broadcast, the display of the reception screen of digital TV broadcast can be started in a short time. Sometimes, it is possible to prevent the influence of image noise caused by the operation clock of the digital television broadcast reception process.

  In addition, when the analog microcomputer broadcast is received by the frequency discrimination means and the stop restriction means of the sub-microcomputer 3d, the harmonics of the operation clock of the clock generator 4 do not affect the video carrier frequency of the reception channel as noise. Since the operation clock of the clock generation unit 4 is continuously formed so that the front end unit 3a is not shifted to the sleep mode, when switching from the reception of the analog TV broadcast to the reception of the digital TV broadcast, it is extremely quick. It is possible to start the reception process of the digital television broadcast in a shorter time after starting the reception process of the digital television broadcast, and to improve the reception performance of the digital television broadcast.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, the determination criterion of the frequency determination means The fixed frequency range may be set appropriately in consideration of signal frequency characteristics and the like that differ depending on the broadcasting system of analog television broadcasting.

  Of course, the configuration of the reception processing unit 3 and the like may be different from that of the embodiment. In this case, each of the units 3a to 3c in the reception processing unit 3 may be formed of a hardware circuit, or may be formed of a software circuit.

  Furthermore, the present invention can be applied to a television broadcast receiver that receives various types of digital television broadcasts and analog television broadcasts.

  The television broadcast receiving apparatus may have a single receiver configuration, a configuration built in a recording / reproducing device, or the like. In the case of the built-in configuration, the display device 7 in FIG. 1 is omitted.

It is a block diagram of the television broadcast receiver of one Embodiment of this invention. It is a flowchart for operation | movement description of a television broadcast receiving apparatus same as the above. The above shows an example of a signal waveform of a television broadcast. FIG. 10A shows an example of signal characteristics of a digital television broadcast, and FIG.

Explanation of symbols

2 tuner unit 3a front end unit 3b video decoder unit 3c MPEG decoder unit 3d sub-microcomputer 4 clock generation unit 4a oscillation circuit unit 4b double circuit unit

Claims (3)

  Digital / analog having a reception channel selection function for digital TV broadcast and analog TV broadcast and receiving digital TV broadcast or analog TV broadcast according to selection of a reception channel in a TV broadcast receiving apparatus for receiving digital TV broadcast and analog TV broadcast A shared tuner unit, a front end unit that demodulates a digital intermediate frequency output of a reception channel output by the tuner unit upon reception of digital television broadcasts into transport stream digital data, and the tuner unit upon reception of analog television broadcasts. A video decoder for converting the analog video output of the reception channel to be demodulated and output into digital data, and decompressing the digital data of the transport stream and the compressed image of the digital data of the analog video output. An image decoder unit that reproduces a subband digital video output; and a reception processing control unit that controls the operation of each unit. The front end unit doubles the oscillation-generated reference clock to output the digital intermediate frequency output. A clock generation unit configured to generate an operation clock for demodulation, and the reception processing control unit stops forming the operation clock of the clock generation unit during reception of an analog television broadcast, and sets the front end unit in a sleep mode. A television broadcast receiving apparatus comprising noise reduction control means for controlling the apparatus.   2. The television broadcast receiving apparatus according to claim 1, wherein the clock generation unit includes an oscillation circuit unit for the reference clock and a multiplication circuit unit for the reference clock, and the noise reduction control unit is configured for analog television broadcast. A television broadcast receiver characterized in that at least one of the oscillation circuit unit and the multiplier circuit unit is controlled to stop operation during reception.   3. The television broadcast receiver according to claim 1, wherein a frequency of a K-th order (K is an integer including 1) of the operation clock is a video carrier frequency of a reception channel when receiving the analog television broadcast. And a frequency discriminating unit that discriminates whether or not the frequency is within a certain frequency range including, and prohibiting the noise reduction control unit from stopping the formation of the operation clock when the K-th order frequency is outside the certain frequency range. A television broadcast receiving apparatus, further comprising stop restriction means.

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