KR950014727B1 - Automatic gain control device of medium frequency circuit - Google Patents

Abstract

The apparatus is for displaying the status of AGC and AFT of an IF circuit under testing. The apparatus includes an audio signal generator(1) for generating audio signal, an OSD(6) for generating video signal, a modulator(2) for modulating output signals of the audio signal generator(1) and the OSD(6), an IF unit(4) for generating AGC and AFT voltage, a comparator(5) for comparing the AGC and AFT voltage to a reference voltage, a microcomputer(7) for generating character data according to output signal of the comparator(5), and a display(8) for displaying character data generated in the microcomputer(7).

Description

Automatic gain control and automatic fine tuning status display of intermediate frequency circuits

Figure is a block diagram showing a display device according to the present invention.

* Explanation of symbols for main parts of the drawings

1: voice signal generating circuit 2: modulator

3: tuner 4: measured IF circuit

5: Comparator 6: OSD Circuit

7: Micom 8: Monitor.

The present invention relates to automatic gain control (hereinafter referred to as "AGC") and automatic fine tuning (hereinafter referred to as "AFT") status indication of an intermediate frequency (hereinafter referred to as "IF") circuit, in particular AGC And an AGC and AFT status display device of an IF circuit suitable for automatically displaying the AFT status.

Conventionally, there is no process that can be confirmed after the adjustment of the IF circuit under measurement is performed through the instrument. Therefore, even if a defect occurs due to the misalignment of AGC and AFT of the IF circuit under test, there is a problem that can be confirmed only after production of the product.

In order to solve the above problems, an object of the present invention is to provide an AGC and AFT adjustment state display device for automatically displaying AGC and AFT adjustment states in an IF circuit.

In order to achieve the above object, the present invention provides an audio signal generating means for generating an audio signal, an OSD (On Screen Display) means for outputting a video signal, a modulator means for modulating a signal output from the audio signal generating means and the OSD means; Tuning means for tuning the modulated signal output from the modulator means, IF-measured means for outputting AGC and AFT voltages as input to the signal output from the tuning means, and AGC and AFT voltages output from the measured-measurement IF means. Comparison means for comparing with the control unit; and a microcomputer for controlling the tuning means and the OSD means using the signal output from the comparing means to output a character indicating the adjustment state, and adjusting the adjustment state according to the signal output from the OSD means. IF circuit, characterized by comprising a monitor for displaying the characters to display It provides AGC and AFT adjustment status and display device.

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

Figure is a block diagram of an AGC and AFT adjustment state display device according to the present invention.

AGC and AFT adjustment state display device according to the present invention is a voice signal generating circuit (1), modulator (2), tuner (3), IF circuit (4), comparator (5), OSD circuit as shown in the figure. (6) and the microcomputer 7 and the monitor 8, the AGC and AFT of the IF circuit 4 to be measured are first adjusted, and then the state thereof is displayed.

The audio signal generation circuit 1 generates an audio signal and outputs it to the modulator 2, and the OSD circuit 6 generates a blue screen signal, which is a type of video signal, under the control of the microcomputer 7. Output to the modulator (2).

The modulator 2 modulates an audio signal and a video signal output from the voice signal generating circuit 1 and the OSD circuit 6 and outputs the modulated audio signal to the tuner 3.

The tuner 3 tunes the modulated signal output from the modulator 2 according to the control of the microcomputer 7.

When the IF signal tuned by the tuner 3 is input to the IF circuit 4 to be measured, the measured IF circuit 4 outputs AGC and AFT voltages, video signals, and audio signals according to adjustment conditions.

That is, the video signal output from the IF circuit 4 to be measured is applied to the OSD circuit 6, the audio signal is output to the monitor 8, and the AGC and AFT voltages are output to the comparator 5.

The comparator 5 compares the voltages of the input AGC and AFT with a reference value and outputs the result to the microcomputer 7.

The microcomputer 7 controls the OSD circuit 6 to output a character indicating an adjustment state by using the comparison result output from the comparator 5, and the OSD circuit 6 controls the initial AGC and AFT. Controls to output a blue screen signal to indicate the adjustment status.

The OSD circuit 6 uses the signal output from the microcomputer 7 to display the final video signal for representing the character indicating the adjustment state to the monitor 8, that is, "AFT +, 0,-", "AGC +". A video signal indicating "0,-" is output to the monitor (8).

The monitor 8 displays the AGC and AFT adjustment states in the form of "+, 0,-".

In addition, the adjustment state of the AGC and AFT voltage may be displayed according to the signal output from the microcomputer 7 by using the LED.

Adjusting the AGC and AFT causes the OSD circuit 6 to output a blue screen signal to indicate the initial AGC and AFT adjustment status. For this purpose, the microcomputer 7 outputs a blue screen signal to the OSD circuit 6. The control signal for the output is output.

The control signal for the blue screen output from the microcomputer 7 is input to the OSD circuit 6 to become a blue screen signal.

The voice signal generated by the voice signal generation circuit 1 is input to the modulator 2 together with the blue screen signal output from the OSD circuit 6, and then modulated into an audio signal and a video signal, and then the tuner 2 Through the IF circuit 4 to be measured.

The audio and video signals output from the tuner 3 are detected by the AGC and AFT voltages through the IF circuit 4 to be output to the comparator 5. The AGC and AFT voltages output from the IF circuit 4 to be measured are compared with a reference value in the comparator 5 and output to the microcomputer 7.

The signal output from the comparator 5 is input to the microcomputer 7 to control the OSD circuit 10 and the tuner 3 so that the OSD circuit 6 outputs a character indicating an adjustment state. The video signal is output to the OSD circuit 6 through the microcomputer 7.

The video signal indicative of the adjustment state input to the OSD circuit 6 is processed through the OSD circuit 6 and then output to the monitor 8 to output "AFT +, 0,-", "AGC, +, 0, Is displayed as-".

The present invention configured and operated as described above can check the adjustment status immediately after the AGC and AFT adjustments, and thus, there is an effect of eliminating problems incurred by an incorrect adjustment in advance.

Claims (3)

An audio signal generating circuit 1 for generating an audio signal; An OSD circuit 6 for outputting a video signal; A modulator circuit (2) for modulating the signals output from the voice signal generating circuit (1) and the OSD circuit (6); A tuner 3 for tuning the signal output from the modulator circuit 2; An IF circuit 4 for outputting AGC and AFT voltages as a signal output from the tuner 3; A comparator 5 for comparing the AGC and AFT voltages output from the IF circuit 4 to be measured with a reference value; A microcomputer (7) for controlling the tuner (3) and the OSD circuit (6) by using the signal output from the comparator (5) so as to output a character indicating an adjustment state; AGC and AFT adjustment status display device of the IF circuit, characterized in that it comprises a monitor (8) for displaying a character indicating the adjustment status in accordance with the signal output from the OSD circuit (6). 2. The apparatus of claim 1, wherein the OSD circuit (6) outputs a blue screen signal to indicate an initial AGC and AFT adjustment state. The AGC and AFT adjustment state display device of an IF circuit according to claim 1, further comprising an LED indicating an AGC and an AFT adjustment state according to a signal output from the microcomputer (7).