KR0157520B1 - Channel selection method using aft - Google Patents

Abstract

The present invention relates to a channel tuning method using an AFT, wherein an AFT signal from an image intermediate frequency, which outputs H in a region lower than a received signal frequency and outputs L in a high frequency region, changes from H to L. The microprocessor recognizes the status of the channel, and when the channel selection is completed by receiving a specific channel, it compares with the data value of the previously stored channel and judges the same channel if it is within a certain step range and jumps a certain frequency. By performing the search again afterwards, it prevents skipping during channel tuning and prevents the phenomenon of auto-tuning continuously after tuning a specific channel.

Description

Channel Tuning Method Using AFT

1 is a flowchart showing a conventional channel tuning process.

2 is a block diagram of the present invention.

3 is a flowchart showing the operation of the present invention.

* Explanation of symbols for main parts of the drawings

11: high frequency conversion unit 12: tuner

13 video intermediate frequency unit 14 video signal processing unit

15: microprocessor

The present invention relates to a channel tuning method using AFT. In particular, in a product employing a V / S tuning method, channel skipping due to a malfunction of synchronization detection during channel tuning or a particular channel cannot be tuned continuously. The present invention relates to a channel tuning method using an AFT to improve fast and accurate channel tuning.

In general, it is well known that AFT (Auto Fine Tunning) is the best award screen while un-tuning is performed by changing a channel input from a TV, VCR or the like that receives a television broadcast signal.

Recently, when the user selects the automatic channel selection mode, the user finds a channel with broadcasting while up or down the channel and performs untuning in the corresponding channel.

That is, conventionally, as shown in FIG. 1, when the user selects the automatic channel selection mode by the method of automatic channel tuning (step 1), the channel with broadcasting is searched up one by one (step 2). .

Check if the synchronization signal (Sync) is detected in the current channel (step 3). If there is a synchronization signal (Sync), perform auto-tuning (AFT) (step 4), and then check whether the synchronization signal is detected again. (Step 5), if detected, the corresponding channel is stored (step 6), then the predetermined frequency is jumped together with the case where the synchronization signal is not detected in steps 3 and 5 (step 7), and then the search of step 2 is performed. Was performed.

However, according to the conventional automatic channel tuning method as described above, the video signal level is lowered at the moment of moving from the noise area to the signal area under the signal condition of the strong electric field, that is, at the moment of receiving the video signal, As a result, the synchronization signal of the video signal becomes smaller than the recognition level of the normal synchronization signal in the synchronization signal detection process, thereby causing a malfunction of the synchronization signal detection, thereby preventing the normal channel from being received.

In addition, if a ripple occurs in the automatic gain control detection stage due to the detection response characteristic of the automatic gain control (AGC) in the non-signal state, the portion of the video signal becomes large at this moment and the video signal becomes smaller accordingly. As a result, the synchronization signal detection unit does not recognize the video signal and has a disadvantage of jumping to recognize the next channel.

Accordingly, an object of the present invention is to provide a channel tuning method using an AFT that uses an AFT detection port and enables fast and accurate channel tuning when a signal is input regardless of an electric field.

In order to achieve the above object, the present invention provides a state in which an AFT signal is changed from H to L from an image intermediate frequency that outputs H in a region lower than a reception signal frequency in an AFT range and outputs L in a high frequency region. When a channel is completed by receiving a specific channel, the microprocessor recognizes it and compares it with the data value of the previously memorized channel. The search is performed to prevent skipping during channel tuning, and to prevent the auto-tuning operation from being repeated after tuning a specific channel.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

A high frequency converter 11 for amplifying and detecting the frequency of the television broadcast signal received through the antenna 10 into a separate frequency, and amplifying a high frequency signal from the high frequency converter 11, A tuner 12 which performs channel connection conversion while mixing with a local oscillation signal of a, and a high frequency signal from the tuner 12 with an oscillation signal from a local oscillator to mix an intermediate frequency signal corresponding to the difference between both. The video intermediate frequency unit 13 for outputting, the video signal processing unit 14 for processing the intermediate frequency signal and outputting it as a video signal, and the video signal processing unit 14 are synchronized with the synchronization detection signal (Sync.Det. While outputting the tuning voltage (VT) to the tuner (12) while receiving the input to the On Screen Display (OSD: On Screen Display) (16) clock (CLK), data signal (Date) and strobe signal (Strobe) Output W is configured by the microprocessor 15 to be mixed with the video signal.

The video intermediate frequency unit 13 inputs the auto-tuning signal AFT to the microprocessor 15 while inputting the auto gain control signal AGC to the tuner 12.

In the channel tuning method using the AFT of the present invention configured as described above, when the user turns on the power (step 20), and then selects a mode of the automatic channel new station (step 21), the microprocessor 15 recognizes the antenna 10. In step 22, a tuning mode VT is output to the tuner 12 receiving the high frequency signal of the television broadcast signal through the high frequency conversion unit 11 so as to perform the tuning of the low channel.

While performing the search mode, the video intermediate frequency unit 13 inputs the auto-tuning signal AFT to the microprocessor 15 (step 23), and the microprocessor 15 sets the auto-tuning signal AFT to L. After checking whether or not it is input (step 24), if it is input to L, the pulse width modulation data (PWM) is output to the tuner 12 so that tuning is performed in the tuner 12 according to the tuning voltage VT (step 25). Then, it is checked whether the synchronization detection signal Sync. Det. Is input through the video signal processor 14 (step 26).

If the synchronous detection signal Sync. Det. Is L, the tuning voltage VT is increased by a predetermined value so that the current channel step becomes the next channel step (step 27), and L is continuously input until the next channel step. In step 28, the controller returns to step 22 to continue searching if it is correct, and if the synchronization detection signal Sync. Det. Is H, the channel untuning function is performed again (step 29).

As a result of the channel non-tuning performed again, it is checked whether the synchronization detection signal Sync. Det. Is H (step 30), if L, jumps to the next channel (step 31), and naturalizes to step 22, while H If the tuning is completed, the tuning is completed (step 32), and then it is checked whether the data of the previously memorized channel is the same (step 33).

If the comparison result is different, the current channel is memorized (step 34), and after step 31, the channel is returned to step 22 to tune to the next channel.

Therefore, according to the channel tuning method using the AFT of the present invention, the microprocessor detects a state in which the auto-tuned signal is converted from H to L and prevents it from being skipped during channel tuning, and the channel data previously stored after the channel search is performed. Compared to the value, if it is within a certain step, it is determined to be the same channel to prevent the phenomenon that only the AFT operation is continued on a specific channel.

Claims (1)

Performing auto-tuning while checking whether the auto-tuning signal (AFT) is input to L while searching channels by the user's selection, and sync. Det. To L after auto-tuning. When inputting, the current channel step becomes the next channel step while checking whether the sync detection signal (Sync. Det.) Is input to L, and the synchronization detection signal (Sync. Det.) Is input to H and tuning After this is completed, the channel tuning method using the AFT, characterized in that the current channel is performed by the steps of confirming whether or not the previously stored channel.