KR950009212B1 - Channel display method in vs tunning receiver - Google Patents

Abstract

The method is for displaying a real channel under VS(voltage synthetic)tuning circumstances. The method comprises the steps of; (A)selecting bands when current mode is preset mode; (B)varying PWM data value and a tuning voltage when a search mode is selected; and (C)locking PWM data when a sync. data detected from a video signal, comparing the lock data and data stored on a ROM, and displaying the corresponding channel.

Description

How to display actual channel when receiving VS tuning

1 is a circuit diagram of the present invention.

2 is a flow diagram of a circuit according to the invention.

* Explanation of symbols for main parts of the drawings

10: key matrix 20: micom

30: tuner 40: demodulator

50: video signal processor 60: sync detector

70: tuning voltage generator 80: digitron

The present invention relates to a video cassette recorder (hereinafter referred to as VTR) or TV (Voltage Synthetic (hereinafter referred to as VS)) tuning reception, in particular a real channel number ( The present invention relates to a method of displaying number.

In general, with the introduction of the electronic tuner, the miniaturization of the general home receiver as well as the reception method is very simple. In particular, frequency synthesized tuner using PLL (Phase Locked Loop) (Frequency Synthesis: FS) tuner enables fast and accurate reception as well as the display of received broadcasting station channels, enabling consumers to have a very convenient life. . However, MFT and AFT (Auto Find Tuning) should be added additionally in fine tuning due to cost increase and external factors caused by PLL introduction. In addition, there was a problem in that the size (Size) is larger than the VS method and the data memory capacity of each broadcasting method is increased.

Accordingly, an object of the present invention is to provide a method of displaying a reception actual channel by comparing and comparing reference data and pulse width modulation comparison data while using a conventional VS tuning method of a tuner.

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

1 is a circuit diagram of the present invention, which includes a key matrix 10 having various keys, a ROM 21 storing channel data while recognizing a key input from the key matrix 10, and a sink detector 60 to be described later. A microcomputer 20 including a PWM 22 for applying a PWM signal to lock the PWM change and a comparison unit 23 for comparing the PWM final data locked by the sync signal with reference data stored in each channel; A tuner 30 for generating an intermediate frequency by mixing an RF signal induced by the antenna terminal ANT and a local oscillation frequency generated in an internal local oscillator, and a demodulator 40 for demodulating the output signal of the tuner 30. And a video signal processor 50 for processing the video signal demodulated by the demodulator 40, a sync detector 60 for detecting the sync of the output signal of the video signal processor 50, and the microcomputer 20. Before tuning according to changes in PWM 22 in the The digital voltage to find the actual data corresponding to the final data compared by the tuning voltage generator 70 for generating the voltage (VT) and the comparison unit 23 in the microcomputer 20 to display the actual channel Consists of Tron 80.

2 is a flowchart of a circuit according to the present invention, in which a first step of selecting a band when the current mode is a preset mode and a PWM data value when the search is performed by checking whether a search is performed in the preset mode after performing the first step. And a second process of changing a tuning voltage value, and if there is a sync signal from the video signal after performing the second process, PWM data is locked, and a third process of comparing the final lock data with the ROM memory data and displaying the corresponding channel. Is done.

The present invention will be described in detail with reference to FIGS. 1 and 2 based on the above-described configuration. First, when tuning VS tuning is received, the tuning voltage (VT), which changes the frequency of the local oscillator according to the change of Pulse Width Modulation (PWM), varies continuously from 0 to 33V. It continuously receives and demodulates each RF (Radio Frequency) signal induced by the antenna terminal ANT of the tuner 10 while being continuously changed, and displays the demodulated signal on the screen. However, in order to prevent the reception screen from passing by, it can detect the sync signal in the video signal, lock the PWM change, and maintain the final value to see the screen. In the case of FS tuning, the data for each channel is set and the tuning voltage (VT) is made according to the data. Therefore, the tuning voltage (VT) for each channel is changed to Step instead of the tuning voltage (VT). This makes it easy to display the received channel. However, in the case of VS tuning, since the tuning voltage (VT) changes analogously, the received real channel display standard is ambiguous and thus the channel display cannot be performed. Therefore, the tuning voltage (VT) of all channels of the tuner is checked, and then the PWM data of each channel is stored in the ROM memory as reference data. Of course, there is a difference in the tuning voltage (VT) between manufacturers, and even a slight difference even in the same manufacturer tuner, this problem is solved by putting ± error when setting the reference data. For example, in case of PAL B / G 21 channel, fp = 471.25MHZ, but if the error is ± 0.3MHZ, it will be 471.55-469.95 (MHZ) interval and 21 will display the actual channel. Here, 0.3 MHZ is an exemplary value, and in the case of the fill, an error can be set marginally according to the bandwidth of VHF is 7MHZ and VHF is 8MHZ.

The configuration for actual channel display of the VS tuning reception is shown in FIG. 1 and will be described below. First, a preset key is selected in the key matrix 10 to switch to the preset mode. If the band select switch of the preset mode is selected as the desired band (BAND), the ROM (21) and PWM (22) data in the microcomputer 20 storing the channel data are output as the data of the corresponding band (BAND). Get ready to let

Here, when the channel search key is operated, a series of prepared data are output one after the other. According to the PWM 22 continuously changed in this way, the tuning voltage VT generated by the tuning voltage generator 70 applied to the local oscillator stage inside the tuner 30 varies from 0 to 33V. According to the voltage, the local oscillation frequency is also continuously oscillated and mixed with the RF signal induced at the antenna terminal ANT of the tuner 30, so that the secondary frequency intermediate frequency signal (hereinafter referred to as IF) is a demodulator (40). Is applied. At this time, there is a point where the IF is made precisely, and the sink is detected at the sink detector 60. The detected sync signal becomes a reference control signal of the change of the PWM 22 in the microcomputer 20 to stop the change of the PWM 22. If there is no control signal of PWM (22) change, it will just pass the received screen. In this way, when the reception is completed, the PWM final data locked by the sync signal by the comparison unit 23 in the microcomputer 20 is compared with the reference data in which each channel is memorized in order to indicate what broadcast channel the reception screen is. Thus, the final data is found and the actual channel data corresponding to the data is sent to the Digitron (80) to complete the operation by displaying the actual channel. The operation is described below with reference to the flowchart shown in FIG. First, in step 1A, the microcomputer 20 determines whether the current mode is the preset mode. If the preset mode is not the preset mode, the microcomputer 20 terminates the process.

In step (2A), the band is selected in the preset mode, and in step (3A), it is determined whether or not the search is performed in the preset mode.

In the step (4A), the PWM data value is increased and changed at the same time as the start of the search, so in step (5A), the tuning voltage is increased analogously as the PWM data changes. After the tuning voltage is changed, in step 6A, it is determined whether there is a sync signal detected from the video, and if there is no sync signal, the process ends. If there is a sync signal, step 7A is performed. In step (7A), the PWM data is locked, and in step (8A), the PWM (22) final lock data and the ROM (21) memory reference data are compared. Display to exit.

As described above, the actual receiving channel can be displayed while using the existing VS tuning method as it is, and thus, there is an advantage of reducing cost and convenient tuning.

Claims (1)

In the method of displaying a real channel when receiving a tuning of a video cassette recorder, the first process of selecting a band when the current mode is the preset mode, and the PWM data when the search is performed by checking whether the search is performed in the preset mode after performing the first process. Value and tuning voltage, and if there is a sync signal from the video signal after performing the second process, the PWM data is locked, and the final lock data is compared with the ROM memory data to display the corresponding channel. Real channel display method when receiving the VS tuning, characterized in that consisting of three steps.

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