JPH10335985A - Channel-selecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a channel-selecting device which can select a channel at high speed and can receive videos with high accuracy. SOLUTION: A PLL(phase-locked loop) data-generating means 2 generates PLL data which is tuned with the signal of a selected channel by adding FOD (fine offset data) to a reference frequency. A tuner means 3 acquires signals based on the PLL data. A correction-commanding means 4 discriminates the amount of correction required for the PLL data and outputs a data correcting command. A fine data-holding means 5 holds the FOD, when channel selection ends as an FD(fine data) which corresponds to the selected channel. An input switching means 7 inputs the FD corresponding to the selected channel to the PLL data-generating means 2 as the FOD, when the FD is held by means of the holding means 5. A fine data correcting means 8 holds a fixed width of frequency band containing the FD at the center as a fine window, and when correction is required on the FOD beyond the fine window, uses the frequency corresponding to the edge of the fine window as a new FD.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel selecting device, and more particularly to a channel selecting device for selecting a signal of a selected channel.

[0002]

2. Description of the Related Art Generally, in a video projector such as a television for receiving signals in the UHF band and the VHF band, an RF (Radio Frequency) signal of a channel to be received is converted into a U / V signal.
(UHF / VHF) Take out with a tuner.

A specific operation of the U / V tuner is as follows.
Receiving an RF signal received by a U / V antenna, selecting only a signal of a selected channel, amplifying the signal, and converting it to an intermediate frequency signal.

[0004] In order to obtain the best received image, efficient and stable conversion is required when the amplified RF signal is converted to an intermediate frequency. For that purpose, it is necessary that the local oscillation frequency generated by the internal local oscillation circuit is stable. In other words, the local transmission frequency wave is such that the video intermediate frequency of the carrier obtained on the output side of the tuner is 58.
It must always be correctly tuned to 75 MHz.

[0005] However, the local oscillation frequency changes depending on the ambient temperature and aging. Therefore, usually, in the channel selection device, AFT (Automatic Fine Tunig automatic frequency adjustment) processing is performed in order to prevent a change in the local transmission frequency and maintain the correct frequency.

In the frequency synthesizer system, which is one of the methods for controlling channel selection, in performing AFT processing, an AFT signal output from a tuner is detected, and an RF signal is obtained by shifting the frequency according to the state. ing. Also,
When the RF signal can be obtained, after a certain period of time, the tuning data at that time is recorded in the memory as data optimal for the selected channel (hereinafter, referred to as fine data). Then, the tuning speed when the same channel is selected next time is increased.

[0007]

However, it is necessary to acquire fine data only in the AF output from the tuner.
Since the T signal is stable, in a conventional channel selection device that acquires fine data after a certain period of time for all channels uniformly, it is not always the case that optimal data is recorded. There was a problem.

The present invention has been made in view of such a point, and improves the accuracy of fine data by recording, as fine data, tuning data when an AFT signal is stable for a selected channel. It is an object of the present invention to provide a channel selecting device.

[0009]

In order to solve the above-mentioned problems, according to the present invention, in a channel selecting apparatus for selecting a signal of a selected channel, reference frequency holding means for holding a reference frequency corresponding to each channel. And PLL data generating means for adding fine offset data to a reference frequency corresponding to the selected channel to generate PLL (Phase Locked Loop) data synchronized with the signal of the selected channel, based on the PLL data. A tuner means for acquiring a signal by using the PLL data, and judging whether or not correction is required for the fine offset data based on the signal acquired based on the PLL data. Correction command means for outputting a data correction command to the data generation means,
At the end of tuning, fine data holding means for holding the fine offset data as fine data corresponding to the selected channel, and fine data corresponding to the selected channel are held in the fine data holding means. In this case, there is provided an input switching means for inputting the fine data as the fine offset data to the PLL data generating means, and a fine window holding means for holding a fixed frequency band centered on the fine data as a fine window. When the correction command means determines that the fine offset data needs to be corrected beyond the fine window, the frequency corresponding to the edge of the fine window is used as new fine data as the fine data. Channel selection device is provided which is characterized by having a fine data correction means for inputting the lifting means.

In the case of selecting a signal of a selected channel in the channel selection device having such a configuration, the reference frequency holding means holds a reference frequency corresponding to each channel. The PLL data generating means adds the fine offset data to the reference frequency corresponding to the selected channel, and generates PLL data synchronized with the signal of the selected channel. The tuner obtains a signal based on the PLL data. The command correction means determines from the signal acquired based on the PLL data how much correction is necessary or not necessary for the fine offset data. If correction is necessary, the data correction command is sent to the PLL data generation means. Is output. Fine data holding means
At the end of tuning, the fine offset data is held as fine data corresponding to the selected channel.
The input switching means inputs the fine data to the PLL data generating means as fine offset data when the fine data corresponding to the selected channel is stored in the fine data holding means. The fine data correction means has fine window holding means for holding a fixed frequency band centered on the fine data as a fine window, and the correction command means determines that fine offset data needs to be corrected beyond the fine window. In this case, the frequency corresponding to the edge of the fine window is input to the fine data holding means as new fine data.

When a signal of the channel selected in this way is selected, fine offset data for generating appropriate PLL data is held as fine data, and a fine window having a fixed width centered on the fine data is held. Can be held corresponding to each channel, and when the fine offset data needs to be corrected beyond the fine window, the frequency corresponding to the edge of the fine window can be held as new fine data. Therefore, it is possible to increase the tuning speed of the selected channel and to improve the accuracy of the received video to be selected.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the principle configuration of the channel selection device of the present invention.

The channel selection apparatus of the present invention comprises a reference frequency holding means 1, a PLL (Phase Locked Loop) data generating means 2, a tuner means 3, a correction command means 4,
Fine data holding means 5, reference offset holding means 6, input switching means 7, fine data correction means 8
And selects a signal of a selected channel.

The reference frequency holding means 1 is constituted by a ROM, and holds a preset reference frequency corresponding to each channel. The PLL data generation means 2 is a CPU
And the like, and holds the fine offset data 2a in an internal RAM. When a channel is selected as a channel to be tuned, a reference frequency corresponding to the selected channel is obtained from the reference frequency holding means 1 and fine offset data is added thereto to synchronize with a signal of the selected channel. (Phase Locked Loop) Generates data. It should be noted that a PLL is supplied from a correction command unit 4 described later.
When a correction command for data is input, the fine offset data 2a held in the internal memory is corrected. Also, the correction value at this time is notified to the fine data correction means 8.

The tuner means 3 comprises a U / V (UHF / VHF) tuner or the like, and acquires a signal based on the input PLL data. The correction command unit 4 is constituted by a CPU or the like, and determines from the signal obtained by the tuner unit 3 how much correction is necessary or not necessary for the PLL data generated by the PLL data generation unit 2. When the PLL data needs to be corrected, a data correction command is output to the PLL data generating means 2.

The fine data holding means 5 comprises a non-volatile memory (NVM: Non Volatile Memory), and holds the fine offset data at that time as fine data corresponding to the previously selected channel at the end of channel selection.

The reference offset holding means 6 is constituted by a ROM and holds preset reference offset data. The input switching means 7 comprises a CPU or the like,
Have M. When a channel is selected, if fine data corresponding to the channel is held in the fine data holding means 5, the fine data is acquired,
The data is input to the PLL data generating means 2 as fine offset data. If the fine data corresponding to the selected channel is not held in the fine data holding means 5, the reference offset data is obtained from the reference offset holding means 6, and is input to the PLL generating means 2 as the fine offset data. .

The fine data correction means 8 is constituted by a CPU or the like, and holds a fixed frequency band centered on the fine data as a fine window in an internal RAM. When the correction value of the correction to the fine offset data in the PLL data generation means 2 exceeds the fine window, the frequency corresponding to the edge of the fine window is input to the fine data holding means 5 as new fine data.

When a signal of a selected channel is tuned by such a channel tuning device, fine offset data for generating appropriate PLL data is held as fine data, and then the fine data is focused. A fine window having a constant width can be held for each channel. When the fine offset data needs to be corrected beyond the fine window, the frequency corresponding to the edge of the fine window can be held as new fine data, so that the tuning speed of the tuning channel can be increased. And the accuracy of the received video to be tuned can be improved.

Next, an embodiment of the channel selection device of the present invention will be described. FIG. 2 is a functional block diagram when the channel selection device of the present invention is applied to a television receiver.

The television receiver 10 has an external video, U / V
Input signal from either antenna or BS antenna,
CRT (Cathod Ray Tube) 21 according to user's instructions
And output to the speaker 22.

The television receiver 10 captures television signals in the UHF band and the VHF band using a U / V antenna, and converts the captured signals into a video signal (V) and an audio signal (R,
L) and a U / V tuner 11 that demodulates the satellite broadcast television signal with a BS antenna and demodulates the captured signal into a video signal (V) and an audio signal (R, L).
And an S tuner 12.

An instruction from a user is received by an operation key 13a or a remote controller 13b provided on the television receiver 10, and is input to a CPU 14 for controlling the operation of the television receiver 10.

The television receiver 10 also has a memory 15 used by the CPU 14 for operation control, a selected input signal, and a video signal (V), an audio signal (R), and an audio signal (L). AV (Audio Visual) switch 16 to be separated
Are provided.

It should be noted that the CPU 14 has a function of the P shown in FIG.
Processing corresponding to the LL data generation means 2, the correction command means 4, the input switching means 7, and the fine data correction means 8 is performed. The ROM inside the CPU 14 stores reference frequency and reference offset data, and the CPU 14 corresponds to the reference frequency holding unit 1 and the reference offset holding unit 6 shown in FIG. The memory 15 corresponds to the fine data holding means 5 shown in FIG. And U /
The V tuner 11 corresponds to the tuner means 3 shown in FIG.

The television receiver 10 further controls the picture and brightness of the video signal separated by the AV switch 16, converts the video signal into RGB (Red, Green, Blue) signals, and outputs the RGB signals to the CRT 21. Video processor 17 that performs
And an audio processor 18 for adjusting the volume, balance and sound quality of the separated audio signal, and an amplifier 19 for amplifying the adjusted audio signal and outputting it to the speaker 22.

The AFT output terminal of the U / V tuner 11 is connected to the A / D input terminal of the CPU 14.
Further, the CPU 14 is connected to each component in the television receiver 10 via an IIC (Inter IC) bus in order to output a control signal. The control signal to the U / V tuner 11 includes PLL data.

Next, the television receiver 10 having such a configuration will be described.
In the following, a flow of processing of the CPU 14 when selecting a television signal in the UHF band or the VHF band will be described. FIG.
FIG. 5 is a state transition diagram illustrating processing of the CPU 14 when a television signal is received by the television receiver 10 to which the channel selection device of the present invention is applied. Hereinafter, the M shown in FIG.
The description will be given along the ODE number.

When receiving a channel selection from the operation keys 13a or the remote controller 13b, the CPU 14
Move to E0. [MODE0] The CPU 14 outputs fine data (FINE DATA) corresponding to the selected channel.
) Is searched in the memory 15. If fine data can be retrieved in the memory 15, the process proceeds to MODE10.
Also, if fine data could not be searched, MODE
Proceed to 1. If an MFT (Manual Fine Tuning manual frequency adjustment) signal is input from the operation keys 13a or the remote controller 13b, the process proceeds to MODE9.

[MODE1] The CPU 14 obtains a reference frequency corresponding to the selected channel, adds offset data set in advance for MODE1 to the obtained reference frequency, generates PLL data, and outputs the PLL data. / V
Output to the tuner 11. Then, the current AFT signal is detected from the voltage value of the AFT output input from the U / V tuner 11 at that time. The AFT signal includes DOWN and UP, and a state in which neither is detected is called a dead zone. When the AFT signal is detected, the process proceeds to MODE6. If neither DOWN nor UP is detected as a result of the detection for 50 ms, the process proceeds to MODE2. The offset data normally set for MODE1 is +
0.15625 MHz.

[MODE2] The CPU 14 sets the MODE1
Then, the offset data set in advance for MODE2 is added to the reference frequency acquired in step (1) to generate PLL data to be output to the U / V tuner 11, and the AFT signal is detected.
When the AFT signal is detected, the process proceeds to MODE6. If neither DOWN nor UP is detected as a result of the detection for 40 ms, the process proceeds to MODE3. Normal MO
The offset data set for DE2 is -1.65.
225 MHz.

[MODE3] The CPU 14 sets the MODE1
The offset data set in advance for MODE3 is added to the reference frequency acquired in step (1) to generate PLL data to be output to the U / V tuner 11, and an AFT signal is detected.
When the AFT signal is detected, the process proceeds to MODE6. If neither DOWN nor UP is detected as a result of the detection for 40 ms, the process proceeds to MODE4. Normal MO
The offset data set for DE3 is -1.15.
625 MHz.

[MODE4] The CPU 14 sets the MODE1
Then, offset data set in advance for MODE4 is added to the reference frequency acquired in step (1) to generate PLL data to be output to the U / V tuner 11, and an AFT signal is detected.
When the AFT signal is detected, the process proceeds to MODE6. If neither DOWN nor UP is detected as a result of the detection for 40 ms, the process proceeds to MODE5. Normal MO
The offset data set for DE4 is +1.65.
225 MHz.

[MODE5] The CPU 14 sets the MODE1
Then, offset data set in advance for MODE5 is added to the reference frequency acquired in step (1) to generate PLL data to be output to the U / V tuner 11, and an AFT signal is detected.
When the AFT signal is detected, the process proceeds to MODE6. If the processing loop of MODE1 to MODE5 has already been completed twice, the process proceeds to MODE8. In addition, 30
If neither DOWN nor UP is detected as a result of detecting ms, the process proceeds to MODE1 again. Normal MODE
The offset data set for 5 is +1.1562
5 MHz.

[MODE6] The CPU 14 detects the detected A
A test is performed to determine whether an AFT signal on the opposite side of the FT signal is detected. That is, the detected AFT signal is “DO
In the case of "WN", the frequency of the PLL data is reduced until the AFT signal "UP" is detected, and when the AFT signal "UP" is detected, the process proceeds to MODE7. Also,
PLL when the detected AFT signal is “UP”
The frequency of the data is increased until the AFT signal “DOWN” is detected, and the process proceeds to MODE 7 when the AFT signal “DOWN” is detected. If the AFT signal on the opposite side is not detected as a result of the test for 20 ms,
Proceed to MODE1 again.

[MODE7] The CPU 14 tests the PLL data. In this PLL data test, first, it is checked whether or not there is a dead zone between two AFT signals. If no dead zone is detected within 30 ms, the process proceeds to MODE1 again. Next, the number of H-SYNC-PULSE (the number of H synchronization signals, hereinafter referred to as the number of HSPs) when the PLL data is in the dead zone is counted. During 30 ms, including the dead zone detection, the number of HSP
If the reference value held in the internal memory No. 4 is not satisfied, the process proceeds to MODE1. If the number of HSPs is within a certain reference range, the tuning data (PLL data) at this time
Is recorded in the memory 15. This data recording will be described later in detail.

[MODE8] The CPU 14 executes NARRO
W AFT processing is performed. This processing is performed every 30 ms with AF
This is a process for detecting the T signal and correcting the PLL data to a more appropriate value.
This is effective until an instruction to select another channel or turn off the power is received from 3b.

[MODE9] The CPU 14 operates the operation key 1
Manual frequency adjustment by the remote controller 3a or the remote controller 13b is accepted. If an instruction to perform the AFT process is received, the process proceeds to MODE1.

[MODE10] The CPU 14 tests whether the searched fine data is appropriate. That is, first, the frequency of the searched fine data is lowered. As a result, if the AFT signal is “DOWN”, the searched fine data is not appropriate. Therefore, the process proceeds to MODE1. When the frequency of the searched fine data is reduced, if the AFT signal “UP” is detected, or if nothing is detected (dead zone), the process proceeds to MODE11.

[MODE11] Next, the CPU 14 raises the frequency of the searched fine data. As a result, when the AFT signal is “UP”, the searched fine data is not appropriate. Therefore, the process proceeds to MODE1. If the frequency of the searched fine data is increased and the AFT signal “DOWN” is detected or nothing is detected (dead band), MOD
Proceed to E12.

[MODE12] The CPU 14
Similarly, if the test result is OK (the dead zone is present and the number of HSPs when the PLL data is in the dead zone is within a certain reference range), the tuning data (PLL Data) in memory 1
Record in 5.

Next, data recorded in the memory 15 in MODE 7 and MODE 12 will be described. FIG.
FIG. 4 is a diagram illustrating a relationship between fine data held in a memory 15 and a fine window.

The frequency f0 in MODE7 and MODE12
Is tested, and if the result is OK, the frequency f0 is recorded in the memory 15 as fine data corresponding to the selected channel. At this time, the frequency f0 is stored in the internal memory of the CPU 14 as a fine window of the selected channel.
, A frequency band w0 having a constant width is generated and recorded.

As described above, NA performed in MODE8
The RROW AFT process is a process of detecting an AFT signal even during signal reception and correcting PLL data to a more appropriate value. Therefore, the fine data f0 is temporarily stored in the memory 1
Even after recording at 5, the PLL data is successively corrected to a more appropriate frequency.

Therefore, in the present invention, when the fine offset data for generating the PLL data is corrected beyond the fine window w0 recorded in the memory 15, the corrected fine offset data is recorded as fine data.

That is, in order to correct the PLL data,
When the fine offset data is corrected to the frequency f3 beyond the fine window w0 in the NARROW AFT process, the frequency f2 corresponding to the edge of the fine window w0 is recorded in the memory 15 as new fine data. At the same time, a frequency band w2 centered on the fine data f2 is generated as a new fine window and recorded in the memory 15.

As described above, according to the present invention, after the tuning data is once recorded in the memory as fine data, if more appropriate tuning data is detected,
This is recorded again as fine data corresponding to the selected channel.

Therefore, when the same channel is next selected, the PLL data input to the U / V tuner 11
The result of the previous NARROW AFT process can be used, the tuning speed can be increased, and the accuracy of the selected received video can be improved.

In the present invention, if the corrected fine offset data is located at a short distance from the fine data previously recorded in the memory, the recording is not updated. That is,
For example, in FIG. 4, when the correction of the fine offset data is corrected to a frequency f1 or the like that does not exceed the fine window w0, this error is regarded as an allowable range.

Therefore, by appropriately setting the width of the fine window, it is possible to balance power consumption and fine data accuracy. As described above, in the channel selection apparatus of the present invention, when selecting a signal of a selected channel, when appropriate PLL data is detected, fine offset data which is data for generating the PLL data is held as fine data. . Then, when the fine offset data for generating appropriate PLL data is corrected outside the preset allowable range, the value previously set as the end of the allowable range is set as new fine data. Therefore, the result of the AFT processing can be maximally utilized in the next and subsequent channel selection, and the channel selection speed of the selected channel can be increased, and the accuracy of the received video to be selected can be improved. It becomes possible.

[0051]

As described above, in the channel selection apparatus of the present invention, the tuning data when the AFT signal is stabilized is recorded as fine data for the selected channel. Can be used in the next and subsequent channel selections to maximize the accuracy of fine data, increase the selection speed of the selected channel, and improve the accuracy of the received video. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle configuration of a channel selection device of the present invention.

FIG. 2 is a functional block diagram when the channel selection device of the present invention is applied to a television receiver.

FIG. 3 is a state transition diagram illustrating processing of a CPU when a television signal to which the channel selection device of the present invention is applied receives a television signal.

FIG. 4 is a diagram illustrating a relationship between fine data and a fine window held in a memory.

[Explanation of symbols]

1 Reference frequency holding means 2, PLL data generation means 2a Fine offset data 3, Tuner means 4, Correction command means 5, Fine data holding means 6, Reference offset holding Means 7 Input switching means 8 Fine data correction means 8a Fine window holding means

Claims (2)

[Claims] 1. A channel tuning apparatus for tuning a signal of a selected channel, comprising: a reference frequency holding unit for holding a reference frequency corresponding to each channel; and a fine offset to a reference frequency corresponding to the selected channel. PLL data generating means for adding data and generating PLL data synchronized with the signal of the selected channel; tuner means for obtaining a signal based on the PLL data; and a signal obtained based on the PLL data. How much correction is required for the fine offset data,
Or if it is not necessary, and if correction is necessary, a correction command means for outputting a data correction command to the PLL data generation means; and at the end of channel selection, the fine offset data corresponds to the selected channel. Fine data holding means for holding as fine data, and when fine data corresponding to the selected channel is held in the fine data holding means,
An input switching unit for inputting the fine data as the fine offset data to the PLL data generating unit; and a fine window holding unit for holding a fixed width frequency band centered on the fine data as a fine window, When the command means determines that the fine offset data needs to be corrected beyond the fine window, the fine data to be inputted to the fine data holding means as a new fine data with the frequency corresponding to the edge of the fine window. A channel selection device, comprising: correction means. 2. The apparatus according to claim 1, further comprising: reference offset data holding means for holding a plurality of reference offset data, wherein said input switching means does not hold fine data corresponding to said selected channel in said fine data holding means. 2. The channel selection apparatus according to claim 1, wherein in said case, said reference offset data is input to said PLL data generating means as said fine offset data.