KR100867712B1 - NTS & VBS tuner - Google Patents

Abstract

The present invention relates to an NTC and VBS tuner.

The present invention connects a second trap filter for removing 5 MHz bits to a first trap filter connected to an image output terminal of a demodulation integrated circuit that demodulates an intermediate frequency input from an NTSC and VSB tuner into an original broadcast signal. By removing the frequency of the adjacent channel (N + 1) by the VSB digital signal received together when receiving the NTSC broadcast, the bit caused by the adjacent channel of the VSB does not occur in the analog broadcast signal to improve the interference caused by the bit.

Tuner, VSB, Adjacent Channel, Bit

Description

TUNER USING AS NTSC AND VSB}

1A is a waveform diagram of a carrier signal of a conventional NTS tuner.

Fig. 1B is a carrier signal waveform diagram of a conventional NTC and GSB tuner.

2 is a circuit diagram of an NTC and VBS tuner according to an embodiment of the present invention.

Figure 3 is a video signal output waveform diagram of the NTC and GSB tuner according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

21; MOPEL integrated circuit 22; Demodulation integrated circuit

221; First trap filter 222; 2nd trap filter

223; buffer

The present invention relates to an NTC and VBS tuner.

In general, the NTS and VBS tuner combines the US analog modulation method NTSC (hereinafter referred to as NTSC) method and the digital modulation method of residual sideband modulation method (hereinafter referred to as VSB) in one module. It means built-in.

In the case of the NTSC dedicated tuner, which is the analog modulation scheme, that is, as shown in FIG. 1A, the two-channel carrier signal has a picture signal (P) = 55.25 MHz and a sound signal (S) = 59.75 MHz, Since the carrier signal has a picture signal P '= 61.25 MHz and a sound signal S' = 65.75 MHz, the interval between adjacent channels is 6 MHz so that there is no trap considering the adjacent channel.

However, in the case of the NTSC and VSB combined tuners, since the broadcasting system transmits a VSB digital signal to an empty channel which is not used in the NTSC television broadcasting VHF and UHF bands, adjacent channels of the NTSC (6MHz) and VSB (5MHz) Interference between (N + 1) occurs.

That is, as shown in Fig. 1B, the three-channel VSB digital signal adjacent to the picture signal P, which is a carrier signal of NTSC two channels, is 55.25 MHz, and the sound signal S is 59.75 MHz. The digital pilot signal = 60.28 MHz, so that the distance between the NTSC picture signal P and the VSB picture signal P 'is 5.03 MHz so that the N + 1 adjacent channel signal of the VSB, the digital signal, is the NTSC analog signal. Existing in the base band of the (B), there is a problem that affects the NTSC signal and appears as a diagonal bit (BEAT) on the NTSC broadcast screen.

The NTC and VBS tuner of the present invention eliminates the VSB adjacent channel signal to the NTSC signal.

The present invention is a MOPEL integrated circuit; An NTS and VBS tuner including a demodulation integrated circuit having a first trap filter for trapping a sound signal band at an image output terminal, wherein the first trap filter includes an adjacent channel (N + 1) bit of a BS ratio. It includes a second trap filter for removing the.

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

FIG. 2 is a circuit diagram of an NTS and VBS tuner according to an embodiment of the present invention, and FIG. 3 is a waveform diagram of an image signal output of an NTS and VBS tuner according to an embodiment of the present invention.

The MLP integrated circuit 21 is composed of a local oscillator, a phase locked loop, a mixer, and the like, which converts and outputs an intermediate frequency of a tuned broadcast signal with respect to a broadcast signal received from an antenna.

The demodulation integrated circuit 22 separates the intermediate frequency signal output from the MLPEL integrated circuit 21 into an original video signal and an audio signal, demodulates the demodulated integrated circuit 22, and outputs the demodulated integrated circuit 22. A first trap filter 221 formed of a ceramic filter trapping 4.5MHz at a terminal VIDEO-OUT; A second trap filter (222) for removing the adjacent channel (N + 1) bits of VBS from the first trap filter (221); The buffer 223 buffers the frequency output to the second trap filter 222.

The second trap filter 222 is configured in series with the capacitor (C1) and the coil (L2) adjusted to a capacitance value for removing the 5MHz bit.

The buffer 223 includes a transistor Q1 and a resistor R2.

The present invention configured as described above converts the demodulation integrated circuit by converting the broadcast signal received from the antenna into an intermediate frequency corresponding to a channel tuned through a local oscillator, a phase locked loop, and a mixer of the MOPEL integrated circuit 21. The demodulation integrated circuit 22 amplifies the intermediate frequency, demodulates the original broadcast signal, and outputs the same through the video output terminal (VIDEO-OUT).

At this time, the video signal output from the video output terminal (VIDEO-OUT) of the demodulation integrated circuit 22 when receiving NTSC broadcast, which is an analog broadcast, is 4.5MHz, which is a sound signal (S) band, by a ceramic filter, which is a first trap filter 221. Outputs the trapped video signal, but the output video signal is affected by the adjacent channel (N + 1) frequency of the VSB digital signal received together with the NTSC broadcast signal. As shown in the drawing, an image signal having a bit level of -30.6 dB is output.

However, since the image signal output from the first trap filter 221 removes a 5 MHz bit by the capacitor C1 and the coil L2, which are the second trap filter 223, the second trap filter 222. ) Is outputted by removing the frequency (bit) of the adjacent channel (N + 1) of the VSB digital signal.

Therefore, since the second trap filter 222 outputs a video signal having a bit level of -53.6dB as shown in the solid line of FIG. 3, the video signal has an improved bit level of -20dB, thereby improving the analog NTSC. When the broadcast is received, the bit of the adjacent channel (N + 1) of the VSB digital signal is not generated.

As described above, the present invention provides a second trap filter for removing 5 MHz bits in a first trap filter connected to an image output terminal of a demodulation integrated circuit that demodulates an intermediate frequency input from an NTSC and VSB tuner into an original broadcast signal. By removing the frequency of the adjacent channel (N + 1) by the VSB digital signal received together when receiving the analog NTSC broadcast, the analog broadcast signal does not generate a bit due to the adjacent channel of the VSB, resulting in interference due to the bit. It will be improved.

Claims (3)

delete An MOPEL integrated circuit; An NTS and VBS tuner including a demodulation integrated circuit having a first trap filter for trapping a sound signal band at an image output terminal, The first trap filter includes a second trap filter for removing adjacent channel (N + 1) bits of VBS, And the adjacent channel (N + 1) bits are 5 MHz bits. An MOPEL integrated circuit; An NTS and VBS tuner including a demodulation integrated circuit having a first trap filter for trapping a sound signal band at an image output terminal, The first trap filter includes a second trap filter for removing adjacent channel (N + 1) bits of VBS, The second trap filter is an NTS and VBS tuner, characterized in that configured by connecting the capacitor and the coil in series.

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