KR20040003409A - Demodulation chip built-in type digital tuner which is able to receive ground wave and cable broadcasting - Google Patents

Abstract

PURPOSE: A digital tuner employing a demodulation chip capable of receiving ground wave broadcasting signals and cable broadcasting signals is provided to simultaneously receive both the ground wave broadcasting signals and cable broadcasting signals through a single digital tuner, thereby reducing the volume of the digital tuner. CONSTITUTION: A digital tuner employing a demodulation chip includes an RF amplifier(111) for amplifying an input RF signal, an IF amplifier(112) for amplifying an input IF signal, and a tuner demodulator for demodulating the input IF signal to output a broadcasting signal. The tuner demodulator includes a QAM IC(121), an OFDM IC(122), first, second and third switches(123,124,125). The QAM IC demodulates the IF signal inputted from the IF amplifier to output a cable broadcasting signal through a plurality of output ports. The OFDM IC demodulates the IF signal received from the IF amplifier to output a ground wave broadcasting signal through the output ports of the QAM IC. The first switch selectively applies power to the QAM IC and OFDM IC to operate the ICs. The second switch selectively applies an RF AGC signal output from the QAM IC or OFDM IC to the RF amplifier. The third switch selectively supplies an IF AGC signal output from the QAM IC or OFDM IC to the IF amplifier.

Description

DEMODULATION CHIP BUILT-IN TYPE DIGITAL TUNER WHICH IS ABLE TO RECEIVE GROUND WAVE AND CABLE BROADCASTING}

The present invention relates to a digital tuner, and in particular, it is possible to receive terrestrial and cable broadcasts simultaneously in one digital tuner, so that the reception of terrestrial and cable broadcasts can be relatively reduced in volume and manufacturing cost. The present invention relates to a demodulation chip embedded digital tuner.

Currently, the trend of digital tuners is to develop tuners by embedding demodulation ICs for terrestrial, cable, and phase.

In addition, a technology has been developed that uses two or more digital tuners in one set to receive two different broadcasts such as terrestrial and cable broadcasting or cable and satellite broadcasting in one set.

However, when receiving two broadcasts in one set, two or more digital tuners are required, and since the demodulation IC is used separately for each digital tuner, the volume of the set is relatively large and the manufacturing cost is increased. There is this.

Therefore, an object of the present invention is to solve the above problems, and to allow the reception of the terrestrial wave and the cable at the same time in one digital tuner to relatively reduce the volume of the set, and to reduce the manufacturing cost.

1 is a block circuit diagram schematically showing the configuration of a demodulation chip-embedded digital tuner capable of receiving terrestrial and cable broadcasting according to the present invention.

<Description of the symbols for the main parts of the drawings>

110: tuner unit 111: RF amplifier

112: IF amplifier 120: tuner demodulator

121: QAM IC 122: OFDM IC

123 ~ 125: 1st ~ 3switch IC

Features of the present invention for achieving the above object,

A tuner unit including an RF amplifier for amplifying and outputting an RF signal input according to an RF AGC signal input from the outside, an IF amplifier for amplifying and outputting an IF signal according to an IF AGC signal input from the outside, and an input; A tuner demodulator including a demodulation IC for demodulating the IF signal to be output as a broadcast signal,

The tuner demodulation unit,

A QAM IC for demodulating the IF signal input from the IF amplifier and outputting a cable broadcast signal through a plurality of output terminals;

An OFDM IC which demodulates the IF signal input from the IF amplifier and outputs the terrestrial broadcast signal through the joint of the output terminal of the QAM IC;

First switching means connected to a reset terminal of the QAM IC and the OFDM IC and switched according to a control signal input from the outside to selectively apply power to the QAM IC or the OFDM IC to operate the switches;

An RF AGC output terminal of the QAM IC and the OFDM IC and an RF AGC input terminal of the RF amplifier of the tuner unit are connected between the QAM IC and the OFDM IC, and are switched according to a control signal output from the QAM IC or the OFDM IC to be output from the QAM IC or the OFDM IC. Second switching means for selectively applying an AGC signal to the RF amplifier;

IF connected between the IF AGC output terminal of the QAM IC and the OFDM IC and the IF AGC input terminal of the IF amplifier of the tuner unit, the IF is switched according to a control signal output from the QAM IC or the OFDM IC and is output from the QAM IC or the OFDM IC. And third switching means for selectively applying an AGC signal to the IF amplifier.

Here, a line connected to any one contact point of the first switching means and a reset end of the QAM IC, and a line connected to another contact point of the first switching means and a reset end of the OFDM IC,

Ground and grounded resistors are each connected in parallel.

Hereinafter, a configuration of a demodulation chip-embedded digital tuner capable of receiving terrestrial wave and cable broadcasting according to the present invention will be described in detail with reference to FIG. 1.

1 is a block circuit diagram schematically showing the configuration of a demodulation chip embedded digital tuner capable of receiving terrestrial and cable broadcasting according to the present invention.

Referring to FIG. 1, the demodulation chip-embedded digital tuner 100 capable of receiving terrestrial and cable broadcasts according to the present invention includes a tuner unit 110 and a tuner demodulator 120.

The tuner unit 110 includes an RF amplifier 111 and an IF amplifier 112.

The RF amplifier 111 amplifies and outputs the input RF signal according to the RF AGC signal input from the tuner demodulator 120.

The IF amplifier 112 amplifies and outputs the input IF signal according to the IF AGC signal input from the tuner demodulator 120.

The tuner demodulator 120 includes a QAM IC 121, an OFDM IC 122, a first switch IC 123, a second switch IC 124, and a third switch IC 125.

Quadrature Amplitude Modulation (QAM) IC 121 demodulates the IF signal input from IF amplifier 112 and outputs a cable broadcast signal through a plurality of output stages.

Orthogonal Frequency Division Multiplexing (OFDM) IC 122 demodulates the IF signal input from the IF amplifier 112 and outputs the terrestrial broadcast signal through the output terminal of the QAM IC 121 jointly. .

Each of the first switch ICs 123 is connected to the reset terminals of the QAM IC 121 and the OFDM IC 122, and is switched according to a control signal input from a remote controller or an operation panel (not shown), and the QAM IC. The power supply of the voltage supply terminal Vcc is selectively applied to the 121 or the OFDM IC 122 to selectively operate them. Here, a line connected to any one contact point of the first switch IC 123 and the reset end of the QAM IC 121 and the other contact point of the first switch IC 123 and the reset end of the OFDM IC 122 are connected. The line is connected to the ground and the grounded resistors R1 and R2 in parallel.

The second switch IC 124 is connected between the RF AGC output terminal of the QAM IC 121 and the OFDM IC 122 and the RF AGC input terminal of the RF amplifier 111 of the tuner unit 110, and the QAM IC 121 or The RF AGC signal, which is switched according to the control signal output from the OFDM IC 122 and output from the QAM IC 121 or the OFDM IC 122, is selectively applied to the RF amplifier 111.

The third switch IC 125 is connected between the IF AGC output terminal of the QAM IC 121 and the OFDM IC 122 and the IF AGC input terminal of the IF amplifier 112 of the tuner unit 110, and the QAM IC 121 or It is switched according to the control signal output from the OFDM IC 122 and selectively applies the IF AGC signal output from the QAM IC 121 or the OFDM IC 122 to the IF amplifier 112.

Hereinafter, an operation of a demodulation chip-embedded digital tuner capable of receiving terrestrial and cable broadcasting according to the present invention will be described in detail with reference to FIG. 1.

First, when the user wants to receive the terrestrial broadcast and the user switches to the terrestrial broadcast mode through the remote control or the operation panel to generate a control signal corresponding thereto, the first switch IC 123 receiving the signal receives the voltage supply terminal Vcc. The reset terminal of the OFDM IC 122 is connected.

Then, a voltage of a predetermined level or more is applied to the reset terminal of the OFDM IC 122, and the voltage is applied to the reset terminal of the QAM IC 121.

Accordingly, the OFDM IC 122 performs a series of operations to demodulate the terrestrial broadcast, and simultaneously controls the second switch IC 124 and the third switch IC 125 to control the RF amplifier 111 of the tuner unit 110. RF AGC input terminal and the RF AGC output terminal of the OFDM IC 122 and the RF AGC input terminal of the IF amplifier 112 and the IF AGC output terminal of the OFDM IC 122 are respectively connected.

Then, an RF AGC signal and an IF AGC signal are output to the RF amplifier and the IF amplifier so that the terrestrial broadcast signal is tuned in the tuner unit 110.

The OFDM IC 122 outputs a signal such as MPEG T / S through an output terminal shared with the QAM IC 121.

On the contrary, when the user wants to receive the cable broadcast and the user switches to the cable broadcast mode through the remote control or the operation panel to generate the corresponding control signal, the first switch IC 123 receiving the signal receives the voltage supply terminal Vcc. And the reset terminal of the QAM IC 121 are connected.

Then, a voltage of a predetermined level or more is applied to the reset terminal of the QAM IC 121, and the voltage is applied to the reset terminal of the OFDM IC 122.

Accordingly, the QAM IC 121 performs a series of operations to demodulate the cable broadcast, and simultaneously controls the second switch IC 124 and the third switch IC 125 to control the RF amplifier 111 of the tuner unit 110. RF AGC input terminal and QAG IC 121 of the RF AGC input terminal and the RF AGC input terminal of the IF amplifier 112 and IF AGC output terminal of the QAM IC 121 are respectively connected.

Then, the RF amplifier 111 and the IF amplifier 112 output the RF AGC signal and the IF AGC signal so that the cable broadcast signal is tuned in the tuner unit 110.

The QAM IC 121 outputs a signal such as MPEG T / S through an output terminal used in common with the OFDM IC 122.

Accordingly, the volume of the digital tuner can be relatively reduced by embedding a QAM IC and an OFDM IC to receive terrestrial broadcasting and cable broadcasting in one tuner, and using one analog tuner unit and an output terminal jointly.

As described above, according to the demodulation chip-type digital tuner capable of receiving terrestrial and cable broadcasts according to the present invention, the digital tuner can simultaneously receive terrestrial waves and cables, thereby relatively reducing the volume of the set and reducing the manufacturing cost. Can be saved.

Claims (2)

A tuner unit including an RF amplifier for amplifying and outputting an RF signal input according to an RF AGC signal input from the outside, an IF amplifier for amplifying and outputting an IF signal according to an IF AGC signal input from the outside, and an input; A tuner demodulator including a demodulation IC for demodulating the IF signal to be output as a broadcast signal, The tuner demodulation unit, A QAM IC for demodulating the IF signal input from the IF amplifier and outputting a cable broadcast signal through a plurality of output terminals; An OFDM IC which demodulates the IF signal input from the IF amplifier and outputs the terrestrial broadcast signal through the joint of the output terminal of the QAM IC; First switching means connected to a reset terminal of the QAM IC and the OFDM IC and switched according to a control signal input from the outside to selectively apply power to the QAM IC or the OFDM IC to operate the switches; An RF AGC output terminal of the QAM IC and the OFDM IC and an RF AGC input terminal of the RF amplifier of the tuner unit are connected between the QAM IC and the OFDM IC, and are switched according to a control signal output from the QAM IC or the OFDM IC to be output from the QAM IC or the OFDM IC. Second switching means for selectively applying an AGC signal to the RF amplifier; IF connected between the IF AGC output terminal of the QAM IC and the OFDM IC and the IF AGC input terminal of the IF amplifier of the tuner unit, the IF is switched according to a control signal output from the QAM IC or the OFDM IC and is output from the QAM IC or the OFDM IC. And a third switching means for selectively applying an AGC signal to the IF amplifier. The method of claim 1, A line connected to one contact point of the first switching means and a reset end of the QAM IC, and a line connected to another contact point of the first switching means and a reset end of the OFDM IC, A digital tuner built-in demodulation chip capable of receiving terrestrial and cable broadcasts, wherein ground and grounded resistors are connected in parallel.