KR100401242B1 - Satellite broadcasting tuner - Google Patents

Abstract

PURPOSE: A satellite broadcasting tuner is provided to select automatically carrier signals within a tuner by using a PLL IC for controlling a band pass filter function to filter the carrier signals received from satellites. CONSTITUTION: A satellite broadcasting tuner includes a plurality of band pass filters(10,20), an input tuner(140), a mixer(150), a first IF amplifier(190), a surface acoustic wave filter(200), a second IF amplifier(210), and a demodulator(220). The band pass filters(10,20) are used for selecting required carrier signals from plural carrier signals and removing unnecessary frequency bands. The input tuner(140) is used for tuning the carrier signals of the band pass filters(10,20) according to a logical signal of a PLL IC. The mixer(150) is used for outputting IF signals by subtracting or adding the carrier signals of the input tuner from or to oscillating frequencies of a local oscillator. The first IF amplifier(190) is used for amplifying the IF signals. The surface acoustic wave filter(200) is used for removing the unnecessary frequency bands from the IF signals. The second IF amplifier(210) is used for amplifying the IF signals of the surface acoustic wave filter. The demodulator(220) is used for detecting the IF signals of the second IF amplifier.

Description

Satellite tuner

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuner for satellite broadcast reception, and in particular, for satellite broadcast reception, which can automatically select one carrier signal from among various types of carrier signals received from multiple satellites by a PLL IC controlled by a microcomputer. It's about a tuner.

In general, as an example of the rapid development of information and communication, the global village has established an information network by using communication satellites for inter-continental transmission. You can easily access through. In response to the advancement of such information, a tuner mounted on a TV receiver also needs a separate device capable of selecting and tuning a carrier signal received from various satellites. Hereinafter, a conventional satellite broadcast tuner will be described.

1 is a block diagram showing the configuration of a conventional satellite broadcasting tuner, and FIG. 2 is a circuit diagram showing the configuration of the input switching unit of FIG.

As shown in FIG. 1, the conventional satellite broadcast receiving tuner includes first and second band pass filters 110 and 120 that pass only frequencies of a predetermined band in carrier signals of various channels received from a plurality of satellites. And an input switching unit 130 for selecting and passing only a carrier signal of one channel among the carrier signals received from the first and second band pass filters 110 and 120, and from the input switching unit 130. An input tuner 140 for tuning the received carrier signal at a constant frequency according to the tuning signal of the PLLIC 170 at a later stage, and a voltage controlled by the carrier signal received from the input tuner 140 and the PLL IC 170. A mixer 150 for outputting an IF signal by subtracting the oscillation frequency received from the local oscillator 160 in frequency, an IF amplifier 190 for amplifying the IF signal output from the mixer 150, and the IF amplifier ( Unnecessary frequency band among IF signals output from 190) A surface acoustic wave filter 200 for removing the inverse signal, an IF amplifier 210 for amplifying the IF signal output from the surface acoustic wave filter 200 to a constant level, and an IF signal output from the IF amplifier 210 Demodulation unit 220 for detecting the.

As shown in FIG. 2, the input switching unit 130 includes first and second varactor diodes Dv1 having cathodes connected in series to the first and second band pass filters 110 and 120, respectively. (Dv2), a first transistor (TR1) connected to the collector terminal of the anode terminal of the first varactor diode (Dv1) and receives a selection voltage from the input selection power source 132 through the base terminal, and the first A base end is connected to the anode end of the first varactor diode Dv1 and the collector end is composed of a second transistor TR2 connected to the anode end of the second varactor diode Dv2.

The first and second transistors TR1 and TR2 are applied with an operating voltage of 5V through the emitter terminal.

In the conventional satellite broadcasting tuner having the above configuration, when the first and second carrier signals are received from the two satellites by the parabolic antenna, the received first and second carrier signals are respectively the first and second band pass filters. After passing through the 110 and 120, unnecessary frequencies are removed and enter the input switching unit 130.

In the input switching unit 130, the switching transistors TR1 and TR2 are turned on / off by a selection voltage applied from the input selection power supply 132, that is, OV or 5V, and at this time, the varactor diodes Dv1 and Dv2. As a result of proper conduction, one carrier signal is selected from the carrier signals of various channels.

The selected carrier signal is tuned to a frequency required by the input tuning unit 140 according to a predetermined tuning signal of the PLL IC 170. The tuned carrier signal enters the mixer 150 and is subtracted in frequency with the oscillation frequency output from the local oscillator 160 voltage controlled by the PLL IC 170 to generate an IF signal, which is an IF amplifier. At 190 it is amplified to a constant level. When the IF signal output from the IF amplifier 190 passes through the surface acoustic wave filter 200, unnecessary signals are removed, and once again amplified by the IF amplifier 210, the attenuated signal is compensated. Thereafter, the IF signal from the IF amplifier 210 is detected through the demodulator 220 to generate and output a baseband signal.

However, an input selection power source 132 for selectively applying a voltage of OV or 5V to turn on / off the switching transistors TR1 and TR2 among the components of the input switching unit 130 is external to the tuner. It is difficult to realize the miniaturization of the tuner, and the operation of the input switching unit 130 for selecting the required carrier signal is not fully automated, which is a limit in improving the performance of the tuner. In terms of Iran, it is an important issue that must be solved. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a filter function of a band pass filter that passes only a required frequency so as to automatically select a required carrier signal among various carrier signals received from a plurality of satellites. The present invention provides a satellite broadcast tuner that can be controlled by a PLL IC.

1 is a block diagram showing the configuration of a conventional tuner for satellite broadcasting reception;

2 is a circuit diagram illustrating a configuration of an input switching unit of FIG. 3.

Figure 3 is a block diagram showing the configuration of a satellite broadcast tuner of the present invention

4 is a block diagram showing a dual band switching method in a satellite broadcast tuner according to another embodiment of the present invention.

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

10, 20, 10a, 20a, 110, 120: band pass filter unit

30, 40: RC filter 50, 60: switch

130: input switching unit 140: input tuning unit

150: mixer 160: local oscillator

170, 170a: PLL IC 180, 180a: Microcomputer

190, 210: IF amplifier 200: Surface acoustic wave filter

220: demodulator C1, C2: capacitor

D1, D2: Diodes Dv1, Dv2: Varactor Diodes

R1, R2: resistors TR1, TR2: transistors

In order to achieve the above object, the tuner for satellite broadcasting reception of the present invention receives input from a PLL IC controlled by a microcomputer so as to remove unnecessary frequency bands by selecting a required carrier signal among a plurality of carrier signals received from a satellite. An input for tuning the first and second band pass filters whose filter operation is controlled by a logic signal and a carrier signal selectively outputted from the first and second band pass filters by a predetermined control signal applied from a PLL IC. A mixer for outputting IF signals by subtracting the tuning signal, the carrier signal input from the input tuning unit and the oscillation frequency output from the local oscillator voltage controlled by the PLL IC, and the IF signal output from the mixer. IF amplifier that amplifies to a certain level, and surface bomb to remove unnecessary frequency bands among IF signals output from the IF amplifier A wave filter, an IF amplifier for amplifying the attenuated IF signal passed through the surface acoustic wave filter, and a demodulator for receiving and detecting the IF signal output from the IF amplifier.

In addition, the tuner for satellite broadcasting reception of the present invention is a dual for selecting one of the bandpass filter of the first and second bandpass filters having different passbands so that the frequency band required by the carrier signal received from the satellite can pass. In the satellite broadcasting reception tuner having a band switching method, each of the first and second switches whose on / off is controlled by a predetermined logic signal input from a PLL IC to an input terminal of the first and second band pass filters, respectively. The PLL IC, coupled to and outputting an appropriate logic signal to the first and second switches, is controlled by a microcomputer.

Accordingly, the tuner for satellite broadcast reception of the present invention allows the function of a bandpass filter to filter carrier signals received from a plurality of satellites to be controlled by the PLL IC so that the selection of any one carrier signal among the plurality of carrier signals is performed by the PLL IC. The program can be implemented in the controlling microcomputer, and the selection of the required carrier signal can be automated inside the tuner, and the miniaturization of the tuner can be realized.

EXAMPLE

Hereinafter, the tuner for satellite broadcast reception of the present invention will be described in detail.

3 is a block diagram showing the configuration of a tuner for satellite broadcasting according to the present invention.

As shown in FIG. 3, the tuner for satellite broadcasting reception of the present invention selects a carrier signal from among first and second carrier signals inputted through input terminals from a plurality of satellites, thereby eliminating unnecessary frequency bands. First and second band pass filters 10 and 20 whose filter operation is controlled by logic signals 0 and 1 input from the IC 170, the first and second band pass filters 10, An input tuning unit 140 for tuning the carrier signal selectively outputted at 20 by a predetermined control signal applied from the PLL IC 170, and a carrier signal and a PLL IC input from the input tuning unit 140; A mixer 150 for outputting an IF signal by subtracting the oscillation frequency output from the local oscillator 160 controlled voltage by 170 and amplifying the IF signal output from the mixer 150 to a predetermined level. IF amplifier 190 and the IF signal output from the IF amplifier 190 A surface acoustic wave filter (200) for removing unnecessary frequency bands, an IF amplifier (210) for amplifying the attenuated IF signal passing through the surface acoustic wave filter (200), and an IF output from the IF amplifier (210). The demodulation unit 220 receives and detects a signal.

In the above configuration, the diodes D1 and D2 having cathodes connected to the first and second band pass filters 10 and 20, the anodes of the diodes D1 and D2, and the PLL IC 170, respectively. RC filters 30 and 40 which are composed of resistors R1, R2, and capacitors C1, C2, which form a parallel circuit, are connected.

The RC filters 30 and 40 remove noise of the high frequency band included in the logic signal of 1 input from the PLL IC 170, and the diodes D1 and D2 are separated from the PLL IC 170. In addition to conduction according to the applied logic signals of 0 and 1, the carrier signal to the PLL IC 170 is interrupted.

The operation and effects of the present invention having such a configuration will be described.

First, when the first and second carrier signals transmitted at 20 GHz from two satellites are received by the parabola antenna, low noise is amplified through the LNB, and then transmitted to each home through a feedhorn. The first and second carrier signals transmitted to each home are applied to the input terminal of the satellite broadcast reception tuner of the present invention through a BS receiver in a frequency state of 1 to 2 GHz by frequency modulation.

The first and second carrier signals applied to the input terminal of the satellite broadcast receiving tuner are input to the first and second band pass filters 10 and 20. Filtering of the first and second band pass filters 10 and 20 is controlled by a logic signal of the PLL IC 170, thereby selecting one of the first and second carrier signals to input the tuning unit. Is output to 140. That is, when the logic signal of 1 of the PLL IC 170 is input to the band pass filter that filters the carrier signal to be selected among the first or second band pass filter 10, 20, the band pass filter is input. The required carrier signal is outputted to the input tuning unit 140 while filtering the carrier signal.

On the other hand, the band pass filter receiving the logic signal of 0 from the PLL IC 170 cannot perform the filtering function. As a result, the carrier signal inputted to the band pass filter to which the logic signal of 0 is applied is removed while unnecessary frequency bands are removed. It is not output to the tuning unit 140. That is, if the carrier signal inputted to the first bandpass filter 10 is selected from the carrier signals inputted to the first and second bandpass filters 10 and 20, the 0 and 1 values of the PLL IC 170 may be adjusted. A logic signal of one of the logic signals is applied to the first band pass filter 10 and a logic signal of zero is applied to the second band pass filter 20 so that only the first band pass filter 10 has a function of filtering. By carrying out, the required carrier signal can be selected. Here, the microcomputer 180 controls the PLL IC 170 so that the logic signal of 1 of the PLL IC 170 can be applied to the desired band pass filter, and the logic signals 0 and 1 of the PLL IC 170. Means OV and 5V, respectively.

The microcomputer 180 has a program imprinted internally so that a desired carrier signal is selected from among a plurality of received carrier signals. The selected carrier signal entering the input tuning unit 140 may be tuned to the PLL IC 170. Tuned to a desired band according to the signal, the tuned carrier signal is output to the mixer 150.

The carrier signal input to the mixer 150 is converted into an IF signal by subtracting and subtracting the oscillation frequency output from the local oscillator 160 voltage controlled by the PLL IC 170 to an IF signal. 190 is amplified to the required level. The IF signal output from the IF amplifier 190 is removed from the unnecessary frequency band in the surface acoustic wave filter 200, the amplified and attenuated level is compensated again while passing through the IF amplifier 210. The IF signal output from the IF amplifier 210 is input to the demodulator 220 and demodulated into a baseband signal.

Meanwhile, FIG. 4 shows that a dual band switching method is controlled by a PLL IC in a satellite broadcasting tuner according to another embodiment of the present invention. In the figure, reference numeral 10a denotes a first band pass filter, 20a denotes a second band pass filter, 50 denotes a first switch, and 60 denotes a second switch.

As shown in Fig. 2, the first and second switches 50 in which on / off is controlled by logic signals of the PLL IC 170a at the input terminals of the first and second band pass filters 10a and 20a. And (60) are connected.

Therefore, when a logic signal of 1 of the PLL IC 170a is applied to a switch connected to a band pass filter capable of passing the required band, the band required by the switch is turned on as the switch is turned on, thereby requiring the band through the switch in the on state. The filter is input to the band pass filter passing through the filter.

That is, when a logic signal of 1 is applied to the second switch 60 in the PLL IC 170a, the carrier signal input as the second switch 60 is turned on is 18 MHz or 36 MHz through the second switch 60. The filter is input to the second band pass filter 20a capable of passing the frequency band.

Then, a logic signal of zero of the PLL IC 170a is applied to the first switch 50 so that the first switch 50 is turned off. Therefore, it is possible to filter by selecting the required carrier signal from the received carrier signals.

The microcomputer 180a controls the PLL IC 170a by a program imprinted on its own so that a logic signal of 1 is applied to the switch connected to the required bandpass filter.

According to the tuner for satellite broadcasting reception of the present invention as described above, the function of the bandpass filter for filtering the carrier signals received from the plurality of satellites is controlled by the PLL IC so that the selection of any one of the carrier signals can be made. Programmed in the microcomputer controlling the PLL IC, the selection of the required carrier signal can be automated inside the tuner, and the miniaturization of the tuner can be realized.

In addition, there is an effect that the band selection is internally realized by the control of the PLL IC in the satellite broadcast reception tuner having the dual band switching method.

Claims (2)

A plurality of band pass filters whose filter operation is controlled in accordance with a logic signal received from a PLL IC controlled by a microcomputer so as to select a required carrier signal among a plurality of carrier signals received from a satellite and to remove unnecessary frequency bands; An input tuning unit for tuning a carrier signal selectively outputted from the first and second band pass filters by a predetermined control signal applied from a PLL IC; A mixer for outputting an IF signal by subtracting the frequency of the carrier signal input from the input tuning unit and the oscillation frequency output from a local oscillator controlled by a PLL IC in frequency; An IF amplifier for amplifying the IF signal output from the mixer to a predetermined level, a surface acoustic wave filter for removing unnecessary frequency bands from the IF signal output from the IF amplifier, And an IF amplifier for amplifying the attenuated IF signal passing through the surface acoustic wave filter and a demodulator for receiving and detecting the IF signal output from the IF amplifier. In the satellite broadcasting reception tuner having a dual band switching method of selecting one of the bandpass filter having a different passband so that the frequency band required by the carrier signal received from the satellite can pass. , First and second switches whose on / off is controlled by a predetermined logic signal input from a PLL IC are connected to input terminals of the first and second band pass filters, respectively. And the PLL IC for outputting a signal is controlled by a microcomputer.