KR930011595B1 - Multi-broadcasting receiving system having common use image if circuit - Google Patents

Abstract

The PIF circuit which makes a sound detector in common comprises: a SIF trap circuit (2) trapping the frequency in a sector 4.5 MHz apart from the PIF for NTSC signal; a SAW circuit (3) trapping the frequency in sectors respectively 5.5 MHz and 6.5 MHz apart from the PIF for PAL and SECOM; a video detector circuit (4) producing the composite signal to be trapped by a sound trapping circuit (5); a video trapping circuit including ceramic filter; a mixer (7) feeding SIF signal to a sound detector (8) which produces the FM sound signal.

Description

Common Video Intermediate Frequency (PIF) Circuit of Multi-Broadcast Reception System

1 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

1: Pre-amplification part

2: NTSC dedicated voice intermediate frequency (SIF) trap

3: Arm / Sekam voice intermediate frequency (SIF) trap unit 4: Image detection circuit unit

5: audio signal trap unit 6: video signal trap unit

7 mixer unit 8 voice detection circuit unit

71: oscillation unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a picture intermediate frequency (PIF) circuit for processing a tuner output of a TV receiver, and more particularly, to a multi-broadcast reception system capable of receiving all TV broadcast signals of NTSC, arm, and Secam methods. It relates to a common video intermediate frequency circuit.

Recent rapid developments in traffic and telecommunications have resulted in a significant number of population movements and a great deal of information exchange around the world.

General information can be collected mainly through radio media, such as TV sets or VCRs.

However, in the world, when the TV receivers move between countries or regions because the TV broadcasting method is different depending on the region or country, it may not be possible to receive normal TV maintenance in the moved region. have.

In addition, even if many TV viewers want to obtain various information from neighboring countries or regions, they cannot obtain desired information due to different TV broadcasting methods.

The present invention is to design a PIF stage for processing the tuner output of a TV set as a multi-type, that is, a multi-broadcasting reception system, and to switch it appropriately as necessary to effectively convert the TV broadcast signals according to various broadcasting methods in a desired region. An object of the present invention is to provide a common video intermediate frequency circuit of a multi-broadcast reception system capable of receiving a signal.

Hereinafter, the present invention will be described in accordance with the accompanying drawings.

As referred to in FIG. 1, the intermediate frequency (IF) signal output from the tuner stage is configured to be provided to the NTSC dedicated SIF trap unit 2 after the preamplification unit 1 is first amplified and the NTSC dedicated SIF trap. The IF signal passed through the unit 2 is configured to be provided to the image detection circuit unit 4 via the arm-specific SIF trap unit 3 composed of a saw filter.

The NTSC dedicated SIF trap unit 2 is designed to trap around 4.5 MHz from the PIF. The Arm / Sekam SIF trap section 3 is designed as a double trap saw filter that traps around 5.5 MHz from the PIF in the case of the arm system and 6.5 MHz from the PIF in the case of the Secam method. Here, the PIF in each broadcasting scheme is 38.9 MHz.

Meanwhile, the image detection circuit unit 4 detects an input intermediate frequency (IF) signal and outputs a composite video signal. The composite video signal is an audio signal included in the composite video signal by the audio signal trap unit 5. Is removed so that it appears as a pure video output.

In addition, the composite image signal output from the image detection circuit unit 4 is provided to the mixer unit 7 to which the first and second oscillation outputs of the oscillator 71 are applied via the image signal trap unit 6 composed of a ceramic filter. The voice intermediate frequency signal output from the western part 7 is FM-detected by the voice detection circuit unit 8 and output as a voice signal.

Referring to the operation and effects of the present invention configured as described above are as follows.

First, the 38.9 MHz PIF signal output from the tuner stage is ultra-amplified by the pre-weighted section 1 and then passed through the NTSC dedicated SIF trap section 2 and the arm / sekam SIF trap section 3 to the image detection circuit section 4. Delivered.

At this time, NTSC broadcast SIF is located at 34.4MHz, 4.5MHz away from the 38.9MHz PIF, ARM broadcast SIF is located at 33.4MHz, 5.5MHz away from the 38.9MHz PIF, Secam broadcast SIF is 38.9 It is located at 32.4 MHz, 6.5 MHz from the PIF of MHz.

However, since the arm / Sekam SIF trap part 3 is composed of two trap circuits, ie, double saw filters, that trap each SIF separated from 5.5 MHz and 6.5 MHz from the PIF (38.9 MHz), the arm P / S (image / Voice) and the desired gain difference can be obtained from the Secam P / S. However, if the PAL / Sekam SIF trap section 3 passes the IF signal according to the NTSC method, it is 4.5 MHz away from the PIF (38.9 MHz). There is no attenuation in the SIF and the desired gain difference in the NTSC P / S cannot be achieved.

In order to cover this, the NTSC dedicated SIF trap 2 is provided at the front end of the arm / Sekam SIF trap 3, and the NTSC dedicated SIF trap 2 is enabled at the time of NTSC broadcast reception. The image detection circuit unit 4 is provided with NTSC, arm, and Secam PIF signals having a constant gain difference in the P / S.

Accordingly, the image detection circuit unit 4 detects AM intermediate signals (PIF) signals of various broadcasting methods and outputs composite video signals. The composite video signals are trapped according to the P / S difference for each broadcasting method. It is output as a baseband video signal via an audio signal trap section 5 of a circuit (NTSC 4.5MHz, arm: 5.5MHz, Secam: 6.5MHz).

In addition, the composite video signal output from the video detection circuit unit 4 is a voice intermediate frequency signal for each broadcasting method in the video signal trap unit 6 in which the corresponding trap circuit similar to the audio signal trap unit 5 is implemented with a ceramic filter. Only the filtered output is provided to the mixer unit 7.

SIF signals applied to the mixer unit 7 are 4.5 MHz (NTSC), 5.5 MHz (arm), and 6.5 MHz (Secam).

In order to FM detect such a SIF signal as one discreminator, the mixer section 7 requires an oscillation section 71 having a double oscillation output.

The double oscillation output of the oscillator 71 is designed to be 0.5MHz and 1.5MHz so that the mixer 7 outputs a second SIF of 6MHz. Specifically speaking, mixing the oscillating output of 1.5 MHz with NTSC SIF (4.5 MHz) yields a second SIF of 6 MHz (4.5 MHz + 1.5 MHz) and 0.5 MHz with eight SIFs (5.5 MHz). Mixing the oscillation output of the 2nd SIF can be converted to 6MHz (5.5MHz + 0.5MHz). Also, mixing the oscillation output of 0.5MHz with the Secam S1F (6.5MHz) results in 6MHz (6.5MHz-0.5MHz). A second SIF can be obtained.

Therefore, the 6 MHz voice intermediate frequency signal output from the mixer unit 7, that is, the NTSC or the second SIF of the arm or secam broadcasting method, is FM detected by the voice detection circuit unit 8 and output as a baseband voice signal.

Therefore, the present invention can receive TV signals of different broadcasting systems as a single TV set between countries or regions.

In addition, according to the present invention, in the design of a multi-broadcast reception system, a voice detection circuit, which is a voice signal delimiter, is commonly used, thereby reducing the size and cost of a TV set.

Claims (1)

NTSC-only SIF trap 2, in which the trap is enabled when the IF output signal of the tuner stage passing through the preamplifier 1 is NTSC-type, and NTSC-only SIF trap in the preamplifier 1 and disabled state. An arm / sekam SIF trap section 3 in which the arm / sekam trap is selectively enabled when the IF output signal of the tuner stage passing through section 2 is arm / sekam method, and the NTSC dedicated SIF trap section 2 and The P / S of the video detection circuit unit 4 for AM detection of the PIF trapped by the SIF trap by the arm / sekam SIF trap unit 3 and the video detection circuit unit 4 according to the broadcasting method P / S ( P / S difference between the audio signal trap unit 5 for outputting the video baseband by selectively removing the audio signal according to the video / audio) difference, and the output of the composite video signal of the video detection circuit unit 4 for each broadcasting method. And a video signal trap unit 6 for selectively removing the video signal and outputting the video signal to the mixer unit 7 according to the present invention. A mixer unit 7 for selectively mixing the SIF for each broadcasting method of the call trap unit 6 with the double oscillation output of the oscillator 71 to generate a secondary SIF of a constant frequency, and the mixer unit 7 And a voice detection circuit section (8) for FM detection of the second SIF to output a voice base band.

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