JPH10276385A - Receiver and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a change in a reception period constant by decreasing the period as small as possible in the case of receiving signals of pluralities of channels periodically. SOLUTION: In the case that pluralities of channels are periodically received at first, wide Automatic Fine Tuning(AFT) control is conducted in the step S2, and when a dead band is detected, presence of a video signal is confirmed in the step S4, channel data (reception frequency) and AFT data (data denoting deviation direction) at that time are stored in a memory in the step S5. In the case of 2nd and succeeding reception, the channel data and the AFT data having been stored in the memory are read in the step S6, and the video signal are received by changing the reception frequency by a change enable minimum unit frequency in the step S7. In this case, detection processing of the dead band is not conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus and method, and more particularly, to a case where signals of a plurality of channels are periodically received, the cycle is made as short as possible, and the variation of the cycle is reduced. The present invention relates to a receiving apparatus and a receiving method which are reduced as much as possible.

[0002]

2. Description of the Related Art Some recent television receivers have a function of reducing images of a plurality of channels and displaying the images as still images sequentially in one multi-screen. In a television receiver having such a function, it is necessary to sequentially and quickly switch and receive signals of a plurality of channels. Such a technique is disclosed, for example, in JP-A-1-218207.

[0003] In the invention disclosed in the publication,
At the time of the first tuning operation, the optimum tuning frequency of the received signal of each television broadcast channel is searched and stored, and at the time of the next and subsequent tuning operations, based on the stored tuning frequency information, I try to tune in. Thereby, it is possible to quickly and accurately select a channel.

[0004]

However, in the technique described in the above publication, the tuning frequency is set to 200 even during the tuning operation after the optimum tuning frequency is stored.
change to higher or lower frequency by kHz,
A tuning process is performed. As a result, it took 200 ms, for example, to complete one tuning. As a result, for example, when signals of four channels are sequentially received, the cycle of one cycle becomes as long as 800 ms, and there is a problem that information is lost more.

Further, when the receiving frequency is changed to a higher or lower frequency by 200 kHz and a desired AFT (Automatic Fine Tuning) signal cannot be obtained, so-called wide AFT control is performed. Therefore, there is a problem that the time until the end of channel selection of each channel is not constant, and the loss of information of each channel becomes uneven.

The present invention has been made in view of such a situation, and when signals of a plurality of channels are periodically received, the cycle is shortened as much as possible so that loss of information is reduced. At the same time, the period is made as constant as possible, thereby suppressing the unevenness of information loss.

[0007]

According to a first aspect of the present invention, there is provided a receiving apparatus for receiving a signal of a predetermined channel;
Detecting means for detecting a shift in the reception frequency by the receiving means; storage means for storing the shift detected by the detecting means;
And a control unit for controlling a reception frequency of the reception unit in accordance with the shift stored in the storage unit.

According to a fifth aspect of the present invention, there is provided a receiving method for receiving a signal of a predetermined channel, a detecting step for detecting a deviation of a receiving frequency in the receiving step,
It is characterized by comprising a storage step of storing the deviation detected in the detection step, and a control step of controlling the reception frequency of the reception step in accordance with the deviation stored in the storage step.

According to a sixth aspect of the present invention, there is provided a receiving device for receiving a signal of a predetermined channel, a storing device for storing a value corresponding to a previous receiving frequency by the receiving device, and the receiving device comprising: When a reception frequency corresponding to the stored value is being received, detection means for detecting that the reception state is within the range of the dead band or outside the range of the dead band, When it is detected that the receiving state of the means is out of the range of the dead zone,
Until the detecting means detects that the receiving state of the receiving means is within the dead zone, the first controlling means for controlling the receiving frequency of the receiving means, and the detecting means sets the receiving state of the receiving means to: A second control unit that controls the reception frequency of the reception unit by a predetermined value regardless of the detection result by the detection unit when the detection unit detects that the reception frequency is out of the range of the dead zone. I do.

[0010] According to a seventh aspect of the present invention, in the receiving method, a receiving step of receiving a signal of a predetermined channel, a storing step of storing a value corresponding to a previous receiving frequency in the receiving step, and a receiving step. When a reception frequency corresponding to the stored value is being received, in a detection step of detecting that the reception state is within the range of the dead band or outside the range of the dead band, When it is detected that the reception state in the step is out of the range of the dead band, the reception frequency in the reception step is detected in the detection step until the reception state in the reception step is detected in the range of the dead band. In the first control step and the detection step, the reception state in the reception step is detected to be out of the range of the dead zone. When, irrespective of the detection result in the detecting step, by the value which is determined in advance, characterized in that it comprises a second control step of controlling the reception frequency on the receiving step.

[0011] The receiving device according to claim 1 and claim 5
In the receiving method described in (1), the deviation of the reception frequency is stored, and the reception frequency is controlled in accordance with the stored deviation.

A receiving device according to claim 6 and a receiving device according to claim 7.
In the reception method described in the above, when the reception state is detected to be outside the dead zone, not only the reception frequency is controlled until it is detected that the reception state is outside the dead band, but also the reception state is controlled. Irrespective of the detection result, the reception frequency is controlled by a predetermined value.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. In order to clarify the correspondence between each means of the invention described in the claims and the following embodiments, each means is described. When the features of the present invention are described by adding the corresponding embodiment (however, an example) in parentheses after the parentheses, the result is as follows. However, of course, this description does not mean that each means is limited to those described.

The receiving device according to the first aspect of the present invention includes a receiving means (for example, the electronic tuning tuner 2 in FIG. 1) for receiving a signal of a predetermined channel, and a detecting means (for example, FIG. 1 AFT signal generation circuit 1
0), storage means (for example, the memory 13 in FIG. 1) for storing the deviation detected by the detection means, and control means (for example, for controlling the reception frequency of the reception means corresponding to the deviation stored in the storage means). And a microcomputer 12) shown in FIG.

According to a sixth aspect of the present invention, there is provided a receiving unit for receiving a signal of a predetermined channel (for example, the receiving unit in FIG. 1), and a storing unit for storing a value corresponding to a previous reception frequency by the receiving unit. (For example, the memory 13 in FIG. 1),
Detecting means for detecting, when the receiving means is receiving a receiving frequency corresponding to the value stored in the storage means, that the receiving state is within the range of the dead zone or outside the range of the dead zone. (E.g., the AFT signal generation circuit 10 in FIG. 1) and the detecting means detect that the receiving state of the receiving means is out of the range of the dead zone. The first control means (for example, step S72 in FIG. 7) for controlling the receiving frequency of the receiving means until the detection state is within the range, and the receiving state of the receiving means is out of the range of the dead zone by the detecting means. When it is detected that there is, regardless of the detection result by the detecting means, the second controlling means (for example, step S78 in FIG. 7) for controlling the receiving frequency of the receiving means by a predetermined value is used. Characterized in that it obtain.

FIG. 1 shows an example of the configuration of a television receiver to which the receiving device of the present invention is applied. The electronic tuning tuner 2 receives the radio wave of a predetermined channel (broadcasting station) via the antenna 1 at the receiving unit 21 and outputs the intermediate frequency signal. This electronic tuning tuner 2 is a VCO (Voltage Controlled Oscillator) 2
2, a frequency divider 23, a phase comparator 24, a low-pass filter (LPF) 25, and a reference signal generator 26, which constitute a PLL (Phase Locked Loop).

That is, the VCO 22 generates a clock having a predetermined frequency and phase corresponding to the control voltage input from the low-pass filter 25, and outputs the clock to the receiving unit 21 and the frequency divider 23. The receiving unit 21 converts a video carrier signal of a predetermined channel received by the antenna 1 into an intermediate frequency signal using a clock input from the VCO 22 and outputs the intermediate frequency signal. The frequency divider 23 divides the frequency of the clock input from the VCO 22 by a predetermined frequency division ratio in response to a command from the microcomputer 12 and outputs the frequency to the phase comparator 24. The phase comparator 24 detects a phase difference between the signal input from the frequency divider 23 and the reference signal generated by the reference signal generator 26, and outputs a signal corresponding to the phase difference to the low-pass filter 25. The low-pass filter 25 smoothes a signal corresponding to the phase difference supplied from the phase comparator 24 and outputs the signal to the VCO 22 as a control voltage.

A SAW (Surface Acoustic Wave) filter (Surface Acoustic Wave Filter) 3 removes unnecessary band components other than the intermediate frequency signal from the signal supplied from the receiving section 21, and forms an AFT (Automatic Fine Fine) with the video detection circuit 4. Tuning)
The signal is supplied to the signal generation circuit 10. The video detection circuit 4
The input intermediate frequency signal is detected, and the video signal is
The signal is output to the / D converter 5 and the synchronization signal detection circuit 11.

The A / D converter 5 performs A / D conversion on the input video signal, supplies it to the memory 6, and stores it. The memory controller 9 appropriately compresses the data supplied to the memory 6 to generate, for example, multi-screen still image data as shown in FIG. FIG. 2 stored in the memory 6
The multi-screen image data shown in FIG. 1 is D / A converted by the D / A converter 7 and then output to the CRT 8 for display.

The AFT signal generation circuit 10 generates an AFT signal from the input intermediate frequency signal and outputs it to the microcomputer 12. The AFT signal is generated by comparing the input intermediate frequency signal with a predetermined reference intermediate frequency signal, and the frequency of the intermediate frequency signal input from the SAW filter 3 is shifted to a higher frequency side than the reference intermediate frequency signal. If it is shifted, it becomes an AFT + signal, and if it is shifted to a lower frequency side, it becomes an AFT- signal. The synchronization signal detection circuit 11 detects a synchronization signal included in the video signal supplied from the video detection circuit 4, and outputs the detection signal to the microcomputer 12.

The microcomputer 12 controls an AF corresponding to the AFT signal input from the AFT signal generation circuit 10.
T data and channel data corresponding to the frequency of the channel currently being received by the receiving unit 21 are stored in the memory 1
3 is stored. When inputting various commands to the microcomputer 12, the input unit 14
Operated by the user. Note that the memory 13 is omitted,
A microcomputer incorporated in the microcomputer 12 may be used.

Next, referring to the flowchart of FIG.
The operation in the case of periodically receiving (selecting) a plurality of channels in the configuration example of FIG. 1 will be described.

When the user operates the input unit 14 and inputs a command for a process of sequentially receiving each channel periodically, the microcomputer 12 firstly executes step S1.
In, it is determined whether or not a predetermined channel (the first channel to be periodically received) is to be received for the first time.
Whether it is the first reception can be determined from whether or not the memory 13 stores the channel data and the AFT data of the channel. If it is determined in step S1 that the reception is the first reception, the process proceeds to step S2, and the microcomputer 12 executes so-called wideband AFT control. Details of the wideband AFT control are shown in the flowcharts of FIGS.

In the flowchart of FIG. 4, first,
In step S21, the microcomputer 12 sets the frequency division ratio of the frequency divider 23 to 1 M
The value is set to a value when a signal of a frequency higher (or lower frequency) by Hz is received. The clock output from the VCO 22 is divided by the frequency divider 23,
4 is input. The phase comparator 24 compares the phase of the clock with the reference signal input from the reference signal generator 26, and outputs a signal corresponding to the phase error. The low-pass filter 25 smoothes the signal corresponding to the phase difference,
It is supplied to the VCO 22 as a control voltage. VCO 22
A clock having a frequency and a phase corresponding to the input control voltage is output. In this way, the frequency and phase of the clock generated by the VCO 22 are set to a frequency higher (or lower) by 1 MHz than when a signal of a normal frequency is received.

Since the receiving section 21 performs a receiving operation using the clock input from the VCO 22, when the receiving section 21 is receiving a video carrier having a regular frequency, the output intermediate frequency signal is output. The frequency becomes 1 MHz higher than the normal frequency. This intermediate frequency signal is
The signal is input to the AFT signal generation circuit 10 via the SAW filter 3. The AFT signal generation circuit 10 generates an AFT + signal when the frequency of the intermediate frequency signal is higher than the normal frequency, and generates an AFT- signal when the frequency is lower.

In step S22, the microcomputer 12 determines whether the AFT + signal is supplied from the AFT signal generation circuit 10. Now
In step S21, the frequency of the clock generated by the VCO 22 is set to a value for receiving a carrier having a frequency higher by 1 MHz than the normal frequency (clock frequency higher by 1 MHz than the normal clock frequency). If the signal 21 is receiving a carrier having a regular frequency, the AFT + signal should be output from the AFT signal generation circuit 10.

Therefore, in step S22, AFT
When it is determined that the + signal is output from the AFT signal generation circuit 10, it is necessary to adjust the frequency of the intermediate frequency signal to a lower frequency. Then, next, step S
Proceeding to 23, the frequency division ratio of the frequency divider 23 is changed to the frequency division ratio when the frequency of the clock generated by the VCO 22 is set to a frequency lower by 200 kHz than the current value. Then, in step S24, the AFT signal generation circuit 1
0 determines whether an AFT- signal is output. A
If it is determined that the FT- signal has not been output, the process returns to step S23, and the clock frequency is further increased by 200 k.
The frequency is changed to a frequency lower by Hz. Then, in step S24 again, it is determined whether or not the AFT-signal has been detected.

As described above, when the clock frequency is successively adjusted to a lower frequency by 200 kHz,
Eventually, the clock frequency in the receiving unit 21 becomes too low than the normal frequency, so the AFT signal generation circuit 10 outputs an AFT- signal at that time.

The microcomputer 12 determines in step S
If it is determined at 24 that the AFT- signal has been detected, the process proceeds to step S25, where the VCO 22 controls the frequency divider 23 so as to generate a clock having a frequency 31.5 kHz higher than the current clock frequency. . This 31.5 kHz is the minimum resolution frequency that can be changed by the VCO 22 (PLL).

Then, the process proceeds to a step S26, wherein it is determined whether or not a dead zone is detected. That is, the microcomputer 12 determines whether the AFT + signal is not input from the AFT signal generation circuit 10 and the AFT- signal is not input. When the deviation of the frequency of the intermediate frequency signal is within a range of ± 50 kHz from the normal frequency, the AFT signal generation circuit 10 outputs neither the AFT + signal nor the AFT- signal. In other words, in this state, the AFT signal generation circuit 10 determines that a carrier having a normal frequency is being received. 31.5kHz
Is less than half the value of the dead band 100 kHz. Accordingly, the clock frequency output from the VCO 22 is set to 31.5 k from the frequency band lower than the dead band.
When the frequency is sequentially set to a higher frequency in Hz, the frequency of the intermediate frequency signal is always set to a value within the frequency band of the dead zone. Therefore, in step S26, when it is determined that the frequency of the intermediate frequency signal has reached the range of the dead zone, it is determined that the correct clock frequency has been set.
The microcomputer 12 ends the broadband AFT control.

On the other hand, in spite of the fact that the frequency division ratio is set to a value of 1 MHz higher than the normal clock frequency,
If it is determined in step S22 that the AFT + signal has not been detected, there is a possibility that the frequency of the carrier is set to a value higher than the normal frequency by 1 MHz and that no broadcast is being performed. is there. Therefore, in this case, the process proceeds to step S27, and the frequency division ratio is changed to a value for setting a clock frequency higher by 2 MHz than the current clock frequency. And
In step S28, it is determined whether an AFT + signal has been detected. If it is determined that the AFT + signal has been detected, the process returns to step S23, where the frequency is corrected to a lower value by 200 kHz in the same manner as described above, and a process of detecting a dead zone is executed.

On the other hand, even if the clock frequency is set to a frequency higher by 2 MHz than the current frequency, the AF
If it is determined in step S28 that the T + signal has not been received, the process proceeds to step S29, and the AFT
After the start of the process, it is determined whether or not a predetermined period of time has elapsed. If the fixed time has not elapsed, the process returns to step S27, and the frequency division ratio is further increased by 2 MHz.
Change to the value when setting only high clock frequency,
In step S28, it is determined whether an AFT + signal has been detected. Then, when the AFT + signal is detected, the processing after step S23 is executed.

If it is determined in step S29 that a certain period of time has elapsed, the frequency of the carrier may be shifted to a lower frequency side than the normal frequency, so that a dead band exists on the lower frequency side. Whether or not to perform is detected in the processing after step S30. That is, in step S30, the frequency division ratio is set to 1 MHz from the normal frequency.
The value is set to a value when a carrier having a frequency lower by z is received (the clock frequency is made lower than the normal clock frequency by 1 MHz). In step S31, AFT
-Determine whether a signal has been detected. If it is determined that the AFT-signal has been detected, the process proceeds to step S32,
The receiving frequency of the carrier is 2 times higher than the frequency currently being received.
The value of the frequency divider 23 is changed so that the value becomes higher by 00 kHz. Then, in step S33, AFT +
It is determined whether or not a signal has been detected. If not, the process returns to step S32, and the value of the reception frequency is changed to a value higher by 200 kHz.

As described above, the reception frequency (clock frequency) of the carrier wave is corrected to a higher value by 200 kHz, and when the AFT + signal is detected, the process proceeds to step S34, and the frequency at that time is reduced by 31. .5kHz
Change the clock frequency to just lower frequency. And
In step S35, it is determined whether or not a dead zone has been detected, and if not detected, the process returns to step S34, and further 31.5 kHz from the current clock frequency.
Change the clock frequency to just lower frequency. And
When it is determined in step S35 that the dead zone has been detected, the AFT processing ends.

Even if the clock frequency is changed to a clock frequency lower by 1 MHz than when a carrier having a regular frequency is received, the AFT
If it is determined in step S31 that no signal has been detected, the frequency of the carrier may be set to a frequency lower than the normal frequency by 1 MHz or more. Therefore, in step S36, the frequency division ratio is changed to a value of the clock frequency lower by 2 MHz than the current clock frequency. Next, proceed to step S37,
It is determined whether or not the AFT-signal has been detected. If it is determined that the AFT-signal has been detected, step S32 is performed.
To execute the subsequent processing.

If it is determined in step S37 that the AFT- signal has not been detected, the process proceeds to step S3.
After the start of the AFT control, it is determined whether or not a fixed time set in advance (this fixed time is longer than the time in step S29) has elapsed. If so, the process returns to step S36, and the subsequent processes are repeatedly executed.

If it is determined in step S38 that a predetermined time has elapsed, the process proceeds to step S39, where it is determined that no broadcast is currently being performed, and the AFT process is terminated.

As described above, when it is determined in step S26 or S35 that a dead zone has been detected, the process proceeds from step S2 to step S3 in FIG. 3, and the microcomputer 12 sets the horizontal synchronization pulse (H
Pulse). That is, when the synchronization signal detection circuit 11 detects the horizontal synchronization signal included in the video signal output from the video detection circuit 4, it generates a detection pulse and outputs it to the microcomputer 12. The microcomputer 12 counts the number of the pulses. Then, in step S4, based on the number of pulses counted in step S3, the video detection circuit 4
It is determined whether the signal currently being output is a video signal.

That is, when the video detection circuit 4 outputs a video signal correctly, since 525 horizontal scanning lines are included in the video signal of one frame, the detection pulse corresponding thereto is detected. Should be done. On the other hand, when the receiving unit 21 happens to receive a noise, an audio signal, or the like, the detected signal includes
No horizontal sync signal is included. Therefore, step S4
, The microcomputer 12 determines whether or not the video detection circuit 4 outputs a video signal based on whether or not the number of input pulses is equal to or greater than a predetermined number set in advance. I do. If it is determined that the signal is not a video signal, the process returns to step S2, and the subsequent processing is repeatedly executed.

If it is determined in step S4 that the video detection circuit 4 is outputting a video signal, the process proceeds to step S4.
Proceeding to 5, the microcomputer 12 causes the memory 13 to store the channel data and the AFT data of the channel currently being received. Here, the channel data is information (for example, the frequency division ratio of the frequency divider 23 in this case) corresponding to the frequency (reception frequency) of the video carrier currently being received by the receiving unit 21, and the AFT data Is data corresponding to the AFT signal output from the AFT signal generation circuit 10 at that time. For example, AF
When the T signal generation circuit 10 outputs the AFT + signal, the AFT data is set to 10, when the AFT- signal is output, the AFT data is set to 01, and when the AFT signal is not output (the dead zone). ), A
The FT data is set to 00. In this case, since the dead zone has been detected, 00 is stored in the memory 13 as the AFT data.

The video signal output from the video detection circuit 4 is also input to an A / D converter 5, A / D converted, supplied to a memory 6 and stored. The memory controller 9 processes the pixel data for one field (or one frame) stored in the memory 6 and reduces the horizontal and vertical lengths of the screen to half the standard length. Perform the following processing. Then, the reduced image is stored in the memory 6.
Is drawn in a predetermined area (an area for recording pixel data of the channel currently being received) in the VRAM area. Then, the pixel data is read from the memory 6, and the D / A
After D / A conversion by the converter 7, the data is output to the CRT 8 and displayed.

The above processing is sequentially performed for each channel to be periodically and repeatedly received. As a result, the CRT 8, for example, as shown in FIG. 2, the multi-screen, four reduced images of channels C ₁ to C _4,
They are displayed simultaneously as still images.

Next, the microcomputer 12 operates in the second mode.
When the second reception process is performed, since the channel data and the AFT data of each channel are already stored in the memory 13, it is determined in step S1 in FIG. 3 that the reception process is not the first reception process. In this case, the process proceeds to step S6, in which the microcomputer 12 reads the channel data and the AFT data stored in the memory 13, and in step S7, according to the read channel data and the AFT data, performs one-step AFT.
Execute control processing. Details of the one-step AFT control are shown in the flowchart of FIG.

In the flowchart of FIG. 6, first, in step S51, the microcomputer 1
No. 2 determines whether the AFT data is 01 or not. That is, it is determined whether or not the AFT-signal has been generated at the time of the previous reception. As described above, at the first reception, the dead zone has been detected, so the AFT data should be 00. Therefore, in this case, a determination of NO is made in step S51, and the process proceeds to step S54.

In step S54, the read A
It is determined whether or not the FT data is 10. That is, it is determined whether or not the AFT + signal has been generated at the time of the previous reception. In this case, the AFT data is
Since it is 00, the determination of NO is made in this case as well, and the process proceeds to step S53.

In step S53, a tuning process corresponding to the channel data is performed. That is, the microcomputer 12 controls the frequency divider 23 in accordance with the channel data read from the memory 13 and causes the receiving unit 21 to receive a channel having a frequency corresponding to the value stored in the memory 13.

Thereafter, the flow advances to step S3 in FIG. 3 to execute an H pulse counting process. That is, the microcomputer 12 monitors the detection pulse output from the synchronization signal detection circuit 11 and counts the number of horizontal synchronization signals.
In step S4, it is determined whether or not the number of detected pulses is larger than the reference value. If the number is smaller than the reference value, it is determined that noise or the like has been received, and the process returns to step S2. Is executed repeatedly,
If the number of detection pulses is within the range of the reference value, it is determined that the video signal has been received, and the process proceeds to step S5, and the channel data indicating the reception frequency being received at that time is stored in the memory 13 again. Let it. At this time, AFT signal generation circuit 10 outputs A
AFT data corresponding to the FT signal is stored in the memory 13.

At the time of the first reception, since the dead zone has been detected in step S26 of FIG. 4 or step S35 of FIG. 5, the AFT data is set to 0.
0, but at the time of the second reception, since the dead zone detection processing has not been performed, for example, the reception unit 21
If the reception frequency is shifted due to a change in the temperature characteristic of the AFT signal, the AFT signal generation circuit 10 generates an AFT + signal or an AFT- signal. Of course, if no deviation has occurred, the AFT signal generation circuit 10 does not generate any signal. In this way,
At the time of the second reception, 01, 10, or 00 is stored as the AFT data in step S5.

In the same manner, the second reception process is executed for other channels, and still images on the multi-screen are sequentially updated.

Then, at the time of the third reception processing,
In step S6 of FIG. 3, the channel data and the AFT data are read, and in step S7, one step A
When performing the FT control, the AFT data is determined to be one of 00, 01, or 10 in step S51 of FIG. The AFT data just read is 01
If it is determined in step S51 that the clock frequency has shifted to the lower frequency side than the frequency of the carrier at the time of the previous reception. Therefore, in this case, the process proceeds to step S52, and the channel data is set to a value larger by 31.5 kHz. Then, the process proceeds to step S53 to execute a process of causing the receiving unit 21 to receive a frequency higher by 31.5 kHz.

On the other hand, in step S51,
If it is determined that the AFT data at the time of the previous reception is not 01, the process proceeds to step S54, where the AFT data is 1
It is determined whether it is 0. If it is determined that the AFT data is 10, the clock frequency has shifted to a frequency higher than the frequency of the carrier at the time of previous reception. The frequency is set to be lower by 31.5 kHz. Then, the process proceeds to step S53, and the frequency lower than the frequency at the previous reception by 31.5 kHz is set to the
Is performed.

On the other hand, if the dead zone has been detected at the time of the previous reception, the AFT data is 00. In this case, a determination of NO is made in step S54. In this case, the process immediately proceeds to step S53, without changing the channel data, that is,
The receiving unit 21 receives the same receiving frequency as the previous receiving frequency.

As described above, the reception frequency is shifted to the higher frequency side or the lower frequency side by 31.5 kHz, or after the reception processing is performed at the same reception frequency as the previous time, at step S3 in FIG. , H pulse counting process is performed, and it is determined in step S4 whether the number is within a reference range. If it is out of the reference range (if the video signal is not received), the process returns to step S2, and the wideband AFT control is performed. Data and AFT data are stored in the memory 13. If the channel data at this time has been changed in step S52 or step S55, the changed value is stored. Also, AFT
Data corresponding to the AFT signal output by the AFT signal generation circuit 10 at that time is stored.

The above processing is sequentially performed for each channel at the third time.

Hereinafter, the same processing is performed when a plurality of channels are sequentially and periodically received. For example, in a case where four channels are sequentially received sequentially, focusing on one channel, the time from receiving that channel until receiving the same channel next time is required to select one channel. Assuming that the time is 100 ms, the time is 400 ms. During such a short time,
Since there is almost no sharp change in the temperature characteristics of the electronic tuning tuner 2, the value that changes from the previous value is 3
Although it is an extremely small value of 1.5 kHz, AFT
Even if a signal is generated in the meantime, the deviation should be small, so that the reception frequency can be sufficiently pulled into the dead zone with only a slight adjustment.

In some cases, a video signal is output while the AFT signal is detected temporarily. In this case, since the deviation from the dead zone is extremely small, the video signal may be disturbed so that the video becomes difficult to see. Is almost none.

If the channel data and the AFT data stored in the memory 13 are destroyed due to, for example, static electricity or the like, noise or the like is received. In this case, as described above, it is determined in step S4 of FIG. 3 that the received signal is not a video signal, and the process returns to step S2.
Since broadband AFT control is performed, it is possible to return to a correct reception state again.

As described above, Step S7 (Step S5)
Since the change width of the reception frequency in (2, S55) is only one step (31.5 kHz), which is the minimum unit that can be changed, it is possible to shorten the tuning time. Further, after changing the reception frequency by one step, the dead band detection process is not executed (as the wideband AFT process is not executed) as long as the video signal is received, so that the tuning time when the reception frequency is shifted is reduced. It is possible to keep substantially constant.

As described above, there is a possibility that the video signal is output in a state where the AFT signal is detected.
The width of the dead zone detected in step S26 of FIG. 5 and step S35 of FIG. 5 may be set from a conventional range of ± 50 kHz to a narrower range, for example, ± 45 kHz. By doing so, the video signal output in the state where the AFT signal is detected is a video signal within the range of the dead zone in the conventional case, and it is possible to obtain a video signal substantially similar to the conventional case. Becomes possible.

Further, for example, when it is assumed that the actual carrier frequency deviates considerably from the normal carrier frequency, as in the case of a CATV system, the reference becomes a reference when performing wideband AFT control in advance. A plurality of set frequencies can be prepared, and a process of pulling each frequency into the dead zone can be performed.

Further, it is possible to detect a synchronization signal other than the horizontal synchronization signal when determining whether or not the signal is drawn into the dead zone.

FIG. 7 shows a second processing example. The processing of steps S71 to S78 is basically the same as that of FIG.
7 is the same as the processing of steps S1 to S7 shown in FIG. 7, but in step S75 of FIG. 7 corresponding to step S5 of FIG. 3, the AFT data is not stored, and only the channel data is stored in the memory 13. It has been made like that. Therefore, in step S76 in FIG. 7 corresponding to step S6 in FIG. 3, only the channel data stored in the memory 13 is read out, and step S7 is performed.
At 7, an AFT detection process is performed.

That is, the microcomputer 12
In step S77, the AFT signal generation circuit 10 receives the input of the AFT signal generated at that time, and in step S77, receives the received AFT signal corresponding to the channel data read in step S76. , Generate AFT data. Then, in step S78, the AF generated in step S77
One-step AFT control is performed according to the T data. Other processes are the same as those in FIG.

In the processing example of FIG. 7, step S
After reading the channel data at 76, step S
Until the one-step AFT control is performed at 78, a waiting time is required to perform the AFT detection processing at step S77.
Although the cycle period is slightly longer, compared to the conventional case,
The period can be much shorter. .

The flowchart of FIG. 3 shows the processing in the case where the channel selection processing is performed periodically. However, in the case where both the periodic channel selection and the random channel selection are performed, the flowchart of FIG. 8 is used. The processing shown in FIG.

That is, in this processing example, in step S81, whether the instruction from the input unit 14 is a periodic channel selection or a random channel selection (ie, whether a predetermined channel is specified) Is selected). The microcomputer 12 determines in step S8
If it is determined in step 1 that the current instruction is a periodic tuning, the process proceeds to step S82. The processing from step S82 to step S88 is similar to the processing from step S1 to step S7 in FIG.

On the other hand, in step S81,
If it is determined that the command is random selection, the process proceeds to step S83, and the subsequent processes are executed.

In FIG. 8, steps S71 to S7 in FIG. 7 are replaced with steps S82 to S88.
8 can also be performed.

The present invention is not limited to the case of receiving terrestrial television broadcasting, but can also be applied to the case of receiving CATV broadcasting, satellite broadcasting, digital satellite broadcasting, and the like.

[0070]

As described above, according to the receiving apparatus according to the first aspect and the receiving method according to the fifth aspect, the deviation of the reception frequency is detected and stored, and thereafter the stored frequency is stored. Since the reception frequency is controlled in response to the shift, the cycle for sequentially receiving signals on multiple channels can be shortened, and variations in tuning time when a shift occurs in the receive frequency are suppressed. It is possible to do.

A receiving device according to claim 6 and a receiving device according to claim 7
According to the receiving method described in the above, when it is detected that the receiving state is out of the range of the dead zone, regardless of the deviation of the receiving frequency, the receiving frequency is controlled by a predetermined value. Therefore, not only can the cycle be shortened and information loss can be suppressed, but also variation in tuning time can be suppressed and unevenness in information loss can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a television receiver to which a receiving device of the present invention has been applied.

FIG. 2 is a diagram showing a display example of a CRT 8 in FIG.

FIG. 3 is a flowchart illustrating a process of the configuration example of FIG. 1;

FIG. 4 is a flowchart illustrating a detailed process of AFT control in step S2 of FIG. 3;

FIG. 5 is a flowchart illustrating a detailed process of AFT control in step S2 of FIG. 3;

FIG. 6 is a flowchart illustrating a detailed process of one-step AFT control of step S7 in FIG. 3;

FIG. 7 is a flowchart illustrating another operation example of the configuration example of FIG. 1;

FIG. 8 is a flowchart illustrating still another operation example of the configuration example of FIG. 1;

[Explanation of symbols]

1 antenna, 2 electronic tuning tuner, 4 video detection circuit, 6 memory, 8 CRT, 9 memory controller, 10 AFT signal generation circuit, 11 synchronization signal detection circuit, 12 microcomputer, 13
Memory, 14 input unit, 21 receiving unit, 22 V
CO, 23 divider, 24 phase comparator, 25
Low-pass filter, 26 reference signal generator

Claims (7)

[Claims] 1. A receiving apparatus for receiving signals of a plurality of channels periodically, a receiving means for receiving a signal of a predetermined channel, a detecting means for detecting a shift of a receiving frequency by the receiving means, and the detecting means A storage unit for storing the shift detected in step (a), and a control unit for controlling a reception frequency of the receiving unit in accordance with the shift stored in the storage unit. 2. The receiving apparatus according to claim 1, wherein the detecting unit detects a direction of the shift of the reception frequency, and the storage unit stores the direction of the shift. 3. The control device according to claim 2, wherein the control unit changes the reception frequency of the reception unit in a range narrower than a range of a dead zone of the detection sensitivity of the detection unit in accordance with the shift stored in the storage unit. The receiving device according to claim 1, wherein 4. The apparatus according to claim 1, wherein the control unit changes the reception frequency of the reception unit by a minimum changeable unit in accordance with the shift stored in the storage unit. Receiving device. 5. A receiving method for receiving signals of a plurality of channels periodically, a receiving step of receiving a signal of a predetermined channel, a detecting step of detecting a reception frequency shift in the receiving step, and the detecting step And a control step of controlling a reception frequency of the receiving step in accordance with the shift stored in the storing step. 6. A receiving apparatus for periodically receiving signals of a plurality of channels, receiving means for receiving a signal of a predetermined channel, and storing means for storing a value corresponding to a previous reception frequency by said receiving means. When the receiving unit is receiving a reception frequency corresponding to the value stored in the storage unit, the reception state may be within a dead band or outside the dead band. Detecting means for detecting, when the detecting means detects that the receiving state of the receiving means is out of the range of the dead zone, the detecting means sets the receiving state of the receiving means to the range of the dead zone. A first control unit that controls a reception frequency of the reception unit until the reception state is detected, and a reception state of the reception unit is set in a range of the dead zone by the detection unit. A second control unit that controls a reception frequency of the reception unit by a predetermined value when the outside is detected, regardless of a detection result by the detection unit. Receiver. 7. A receiving method for receiving signals of a plurality of channels periodically, a receiving step of receiving a signal of a predetermined channel, and a storing step of storing a value corresponding to a previous receiving frequency in the receiving step. In the receiving step, when receiving a reception frequency corresponding to the value stored in the storage step, that the reception state is within the range of the dead band, or outside the range of the dead band. A detecting step of detecting, and in the detecting step, when it is detected that the receiving state in the receiving step is out of the range of the dead zone, in the detecting step, the receiving state in the receiving step is the dead zone. Until it is detected that the reception frequency is within the range, a first frequency for controlling the reception frequency of the reception step is determined.
The control step, and in the detection step, when it is detected that the reception state in the reception step is out of the range of the dead zone, regardless of the detection result in the detection step, a predetermined value A second control step of controlling a reception frequency in the reception step.