KR0141527B1 - Channel detecting device using electronic tunner of frequency synthesize - Google Patents

Abstract

The present invention relates to a channel detection apparatus using an electronic tuner of a frequency synthesis method such as a television receiver. The apparatus of the present invention changes a control signal by changing a tuner for receiving television broadcast signals from a key input unit and an antenna, an intermediate frequency amplifier for outputting AFC voltage, a signal detector for detecting a synchronization signal, an up signal, and a down signal, and a reference frequency. A control unit is stored in the storage unit. Accordingly, the present invention can automatically detect and detect a channel when it is located between channels using a frequency synthesizing electronic tuner and cannot detect a channel of an adjacent country.

Description

Channel detection device using electronic tuner of F / S method

1 is a block diagram of a device for detecting a channel using an electronic tuner of the F / S method of the present invention,

2 is a flowchart illustrating a process of detecting a channel implementing the present invention;

3 is a view showing a waveform of a channel and a waveform of noise, and FIG. 4 is a table of VHF television reception frequencies.

* Explanation of symbols for main parts of the drawings

10: key input unit 20: control unit

30: Tuner 40: Intermediate frequency amplifier

50: signal detector 60: storage unit

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a channel receiver such as a television receiver, and more particularly, to a channel detection apparatus for detecting an intermediate channel located between channels or a channel of an adjacent country using an electronic tuner of frequency synthesis.

Conventional tuners have a mechanical type that mechanically turns a channel knob to switch coils of a high frequency amplification circuit and a local oscillation circuit. However, due to the problem of the large number of contact points and the need to turn the channel knob separately for UHF, an electronic tuner has been developed and used in television receivers. Potentiometer Preset, Voltage Synthesize (V / S), and Frequency Synthesize (F / S) are mainly used for the electronic tuner. The F / S method always memorizes the intermediate frequency and the local oscillation frequency (fosc) of the channel, and searches for the channel frequency band according to the user inputting the channel number. Many countries in the world are divided into several frequency bands. If a user moves to another country or is adjacent to another country where the broadcasting frequency group is different, there is a problem that the previous electronic tuner cannot tune the broadcasting frequency because the intermediate frequency and the local oscillation frequency (fosc) used for the broadcasting channel number are different. . As shown in Table 1 of Figure 4, television receivers in Australia with the VHF television frequency cannot watch television broadcasts in New Zealand as shown in Table 2. This is because the local oscillation frequency (fosc) stored in the previous channel number does not become.

An object of the present invention for solving the above problems is to provide an apparatus for automatically programming to solve the point that the local oscillation frequency is changed according to the channel number in different regions of the frequency group.

An object of the present invention is to tune a channel using a frequency synthesis method, a tuner for outputting an intermediate frequency signal to the signal detector and the intermediate frequency amplifier, and amplifies the intermediate frequency signal from the tuner, An intermediate frequency amplifier for outputting to the signal detector, a signal detector for detecting a horizontal synchronous signal from the intermediate frequency signal from the tuner, and detecting an up signal and a down signal based on the AFC voltage from the intermediate frequency amplifier; A storage unit for storing the local oscillation frequency at the time of detection and a local oscillation frequency selected by the user from among the local oscillation frequencies stored in the storage unit, and for selecting a desired radio wave based on the read local oscillation frequency. By a control unit for outputting a tuning signal.

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

1 shows an apparatus for detecting a channel in an F / S type electronic tuner according to an exemplary embodiment of the present invention. As shown, the control unit 20 supplies a tuner 30 with a tuning signal for changing the local oscillation frequency according to a user's key input. The tuner 30 generates a local oscillation frequency based on a tuning signal, generates an intermediate frequency (IF) signal mixed with a broadcasting frequency input from an antenna, and then outputs the signal to the signal detector 50 and the intermediate frequency amplifier 40. Output The intermediate frequency amplifier 40 amplifies the intermediate frequency signal and outputs the video signal and the audio signal separately. In addition, the intermediate frequency amplifier 40 outputs an AFC (Automatic Frequency Control) signal for supplying a constant local oscillation frequency in the tuner 30 to the signal detector 50. The signal detector 50 receives the intermediate frequency signal and the AFC signal and detects the reference frequency of the channel. The controller 20 outputs the current frequency signal from the signal detector 50 to the storage 60. The storage unit 60 stores the current frequency signal as a local oscillation frequency corresponding to the channel number.

The operation of the first FIG. Device configured as described above will be described in detail with reference to the accompanying drawings.

According to the existing channel number, if a completely different television broadcast is received or cannot be received, the user presets the channel again on the television receiver. Here, the preset refers to a process of resetting the local oscillation frequency for the channel number. First, the user sets the initial local oscillation frequency to 44 MHz and makes a key input to find a channel while raising the frequency (step 101). The control unit 20 generates a tuning signal according to a user's key input and outputs the tuning signal to the tuner 30. The tuner 30 tunes the desired frequency according to the local oscillation frequency generated based on the tuning signal. The tuned frequency is mixed with the local oscillation frequency to generate an intermediate frequency signal and output to the intermediate frequency amplifier 40 and the signal detector 50. The intermediate frequency amplifier 40 receives an intermediate frequency signal from the tuner 30 and outputs an AFC signal, which is a control signal for maintaining the local oscillation frequency of the tuner 30, to the signal detector 50. The signal detector 50 receives the intermediate frequency signal from the tuner 30 and detects the synchronization signal (step 102). If the synchronization signal is not detected, the user adds 1 MHz to the current local oscillation frequency (step 103) and detects the synchronization signal again (step 102). When the signal detection unit 50 detects the synchronization signal, it continuously detects an UP signal (step 104). Here, the up signal is generated due to the characteristics of the channel and is a characteristic of a broadcast frequency in which the AFC input voltage from the intermediate frequency amplifier 40 is 3.5V or more. If the up signal is not detected, the user adds 62.5 KHz to the current local oscillation frequency through the key input unit 10 to detect the synchronization signal again (step 105). When the up signal is detected, the signal detector 50 detects a down signal. The down signal is a characteristic of a broadcast frequency in which the AFC input voltage from the intermediate frequency amplifier 40 is 1.8 V or less. FIG. 3A is a waveform diagram of a channel, and FIG. 3B is a waveform diagram showing a noise and the like. As shown, the sync signal, the up signal, and the down signal are typically not detected together with the noise. If the signal detector 50 does not detect the down signal, the user continues to add 62.5 KHz to the current local oscillation frequency (step 105) to detect the synchronization signal (step 102) and the up signal again (step 104). Repeat until detected. When the signal detection unit 50 detects the down signal, the control unit 20 stores the local oscillation frequency at this time in the storage unit 60 (step 107). The user detects the next channel by adding 3 MHz to the current frequency to detect the next channel (step 108). Normally, the frequency difference between channels is over 3MHz, so add 3MHz to the detected local oscillation frequency. The controller 20 compares whether the frequency added with 3 MHz is greater than the maximum frequency of 999 MHz (step 109). In comparison, if less than the maximum frequency, a step (step 102) for detecting a synchronization signal of the next channel is performed. If the comparison is greater than the maximum frequency, the preset process ends.

As described above, the F / S method can receive broadcasts from neighboring countries using an electronic tuner, can preset channels again when migrating to another country, and conveniently controls the above process automatically. Provides the effect to use.

Claims (2)

An apparatus for tuning channels using a frequency synthesis method, comprising: a tuner for outputting an intermediate frequency signal to a signal detector and an intermediate frequency amplifier; An intermediate frequency amplifier for amplifying the intermediate frequency signal from the tuner and outputting an AFC voltage to the signal detector; A signal detector for detecting a horizontal synchronization signal from the intermediate frequency signal from the tuner and detecting an up signal and a down signal based on the AFC voltage from the intermediate frequency amplifier; A storage unit for storing a local oscillation frequency when the down signal is detected; And a control unit which reads out a local oscillation frequency selected by a user from among local oscillation frequencies stored in the storage unit, and outputs a tuning signal so that the tuner can select a desired radio wave based on the read local oscillation frequency. Channel detection device using / S-type electronic tuner. The channel detection apparatus of claim 1, wherein the channel detection apparatus of the F / S method is automatically controlled.