KR970004658Y1 - Tuner for satellite broadcasting system - Google Patents

Abstract

None.

Description

Satellite tuner

Figure 1 (a) is a block diagram showing the configuration of a tuner for satellite broadcasting in the conventional European system

(b) is a block diagram showing a conventional tuner for receiving satellite broadcasting in the Japanese system.

2 is a block diagram showing the configuration of a tuner for receiving satellite broadcasting of the present invention

3 is a detailed circuit diagram showing a switching circuit of the tuner for satellite broadcasting reception of the present invention

* Explanation of symbols for main parts of the drawings

21: input filter 22: the first amplifier

23: synchronization unit 24: oscillator

25: PLL circuit section 26: mixer

27: second amplifier 28: switching circuit

29: first band pass filter 29 (a): second band pass filter

30: third amplifier 30 (a): fourth amplifier

The present invention relates to a tuner for receiving satellite broadcasting, and in particular, the European and Japanese phase broadcasting is composed of one satellite broadcasting tuner receiver, and a switching circuit is selectively formed between the bandpass filters of each satellite broadcasting. It was designed to receive satellite broadcasting for Japan.

The configuration and operation of a conventional tuner for receiving satellite broadcasting (ST (a) R, NHK) for Europe and Japan will be described with reference to FIG.

First, (a) of FIG. 1 is a tuner circuit for STAR satellite broadcasting for Europe, in which the first IF signal band is 950 MHzk-2050 MHz and the second IF signal is 479.5 MHz, which is amplified by a low nose block (LNB) to convert frequency. An input filter (10) for receiving and filtering respective satellite broadcast reception signals, a first amplifier (2) for amplifying the output satellite broadcast signal, and a tuning unit (3) for tuning the amplified reception signal And an oscillator 4 for oscillating a local oscillation signal, a PLL circuit portion 5 for receiving a oscillation signal of the oscillator 4 and applying a phase locked loop PLL, and an output signal of the tuning unit 3. And a mixer 6 which receives the oscillation signal of the oscillator 4 and converts it into an IF signal by the sum and difference of the two frequencies, a second amplifier 7 which amplifies the signal converted into the IF signal, and the amplified signal. A band pass filter 8 for receiving an IF signal and passing the IF signal, and amplifying the passed IF signal, respectively Claim 3 is composed of amplifier 9.

FIG. 1 (b) shows a tuner circuit of NHK satellite broadcasting in Japan, in which the first IF signal band is 1030MHz-2050MHz and the second IF signal is 402.78MHz, which is amplified by a low nose block (LNB) to convert frequency. An input filter lA for receiving and filtering each of the received satellite broadcast signals, a first amplifier 2 (a) for amplifying the output satellite broadcast signal, and a tuning unit for tuning the amplified received signal. (3 (a)), an oscillator 4A for oscillating a local oscillation signal, a PLL circuit portion 5 (a) for receiving a oscillation signal of the oscillator 4A and applying a phase locked loop PLL; A mixer 6 (a) which receives the output signal of the tuning unit 3 (a) and the oscillation signal of the oscillator 4 (a) and converts it into an IF signal by the sum and difference of the two frequencies, and the IF A second amplifier 7 (a) for amplifying the converted signal, a band pass filter 8 (a) for receiving the amplified IF signal and passing the IF signal, and the passed signal And a third amplifier 9 (a) that amplifies the IF signal, respectively.

Referring to the operation of the conventional tuner for satellite broadcasting configured as described above is as follows.

First, in the case of the STAR satellite tuner ((a) of FIG. 1), the satellite broadcasting telephone collected by the parablade antenna is amplified in the LN (b) and the frequency is converted so that the first signal of the ST (a) R satellite broadcasting signal is received. The IF signal is filtered by the input filter 1 in the band of 950MHz-2050MHz and amplified by the first amplifier 2, respectively.

At this time, the amplified IF received signal is input to the tuning unit 3 and tuned, and the oscillation signal generated by the oscillator 4 is phase-locked by the PLL circuit unit 5 to the tuning unit 3 and the mixer 6. A second amplifier for converting the oscillation signal of the tuned signal oscillator 4 of the tuning unit 3 into the second IF signal based on the sum and difference of the two frequencies by mixing in the mixer 6. Amplify in 7).

In the case of the ST (a) R satellite broadcasting, the amplified second IF signal is amplified by the third amplifier 9 through the band pass filter 8 in the case of ST (a) R satellite broadcasting and is intended for satellite broadcasting for Europe desired by the receiver. Will be received.

In the case of NHK satellite broadcasting ((b) of FIG. 1), the satellite broadcasting telephone collected by the parabolic antenna is amplified in the LN (b) and the frequency is converted so that the first signal of the ST (a) R satellite broadcasting reception signal is converted. The IF signal is filtered by the input filter 1A in a band of 950MHz-2050MHz and amplified by the first amplifier 2 (a), respectively.

At this time, the amplified LF received signal is inputted to the tuning unit 3A and tuned, and the oscillation signal generated by the oscillator 4A is phase-locked by the PLL circuit unit 5A to the tuning unit 3A and the mixer 6A. A second amplifier to convert the tuned signal of the tuning unit 3A and the oscillator signal of the oscillator 4A into a mixer 6A, converting the second IF signal to 479.5 MHz by the sum and difference of the two frequencies. Amplify at 7A.

The amplified IF signal is to amplify the IF signal (402.78 MHz) of the NHK satellite broadcast in the third amplifier 9A through the band pass filter 8A to receive satellite broadcast directed to the receiver.

However, the conventional tuner for receiving satellite broadcasting has two antennas installed in order to receive both STAR satellite and NHK satellite broadcasting. There was a problem that the product price rises.

Therefore, in order to solve such a problem, the present invention includes the NHK satellite broadcasting frequency of Japan included in the broadcasting frequency band of the Chinese star broadcasting, so that each satellite broadcasting is processed with one path from the input filter to the amplifier. By passing through the band pass filter of the appropriate path for each IF processing, it is possible to selectively receive two satellite broadcasts with one tuner, so as to simplify the circuit design and simplify and multiplex the tuner configuration. There is a purpose.

The configuration and operation of the present invention satellite broadcasting tuner for achieving the above object will be described with reference to FIGS. 2 and 3.

First, referring to FIG. 2, the configuration of the present invention includes an input filter 21 for receiving and passing a satellite broadcasting reception signal (IF signal) amplified at an LNB and having a frequency converted thereto, and amplifying the passed IF signal. A first amplifier 22, a tuner 23 for tuning the amplified IF signal, an oscillator 24 for outputting a local oscillation signal, and an oscillator signal for receiving the oscillator signal of the oscillator 24; PLL circuit section 25 for applying a phase locked loop, a mixer 26 for inputting the output of the tuning section 23 and the oscillation signal of the oscillator 24 and converting it into an IF signal, and converting it into the 1F signal. A second amplifier 27 for amplifying the decoded signal, a switching circuit 28 for selecting the amplified IF signal according to a satellite broadcast to be received, and a satellite broadcasting (ST) selected by the switching circuit unit 28. a) a first band pass filter 29 for passing the IF signal of R) and the first band pass filter 29 A third amplifier 30 for amplifying an IF frequency, a second band pass filter 29A for passing an IF signal of a Japanese satellite broadcasting (NHK) selected by the switching circuit section 28, and the second band pass filter And a fourth amplifier 30A for amplifying the IF frequency passed through 29A.

As shown in FIG. 3, the switching circuit unit 28 includes a diode D1 constituting an IF signal transmission path for satellite broadcasting for Europe and a diode D2 constituting an IF signal transmission path for satellite broadcasting for Japan. ) And a transistor Q1 on / off by the input switching signal Lsw to switch the diode D1 on / off, and on / off by the power switching signal Lsw to turn on the diode D2. It consists of a transistor Q2 and a diode D4 for switching on / off.

Reference numeral Rl-R3 denotes a resistor, D3 denotes a diode, and C1-C3 denotes a capacitor.

The present invention configured as described above will be described with respect to the operation of the satellite broadcasting tuner. European (950MHz-2050MHz) and Japanese (1030MHz-2050MHz) frequency signals of the satellite broadcast waves collected by the parabolic antenna are simultaneously amplified in the LNB, and the frequency is converted so that the IF signals of the satellite broadcast signals are input filters (21). Is filtered and amplified in the first amplifier 22.

At this time, the amplified IF received signal is input to the tuning unit 23 and tuned, and the phase oscillation signal generated by the oscillator 24 is fixed by the PLL circuit unit 25 to adjust the tuning unit 23 and the mixer 26. When inputted to the second amplifier 27, the tuned frequency signal of the tuning unit 23 and the originating signal of the oscillator 24 are mixed in the mixer 26 and converted into IF signals based on the sum and difference of the two frequencies. Amplify at.

Then, the switching circuit unit 28 is controlled to appropriately select the IF signal processing path for Europe and Japan of the amplified IF signal.

That is, as shown in FIG. 3, when the input switching signal Lsw input by the user from the outside is high, the transistor Q1 is turned on and the diode D1 is turned off.

In addition, since the diode D4 is turned off and the transistor Q2 is turned off, the power source (b) + is supplied to the diode D2 through the resistor R3 to conduct the diode D2 so that the second amplifier 27 is turned on. The IF signal outputted from the amplifier is outputted to the second band pass filter 29A through the capacitor C3, the diode D2, and the capacitor C2, and is amplified by the fourth amplifier 30A. 402.78 MHz).

In addition, when the diode D4 is turned on when the input switching signal Lsw is low and the transistor Q2 is turned on, the diode D2 is blocked and the transistor Q1 is turned on to conduct the diode D1. The IF signal output from the second amplifier 27 is amplified by the third amplifier 30 while being output to the first band pass filter 29 through the capacitor C3, the diode Dl, and the capacitor C1. The user receives the European IF signal (479.5MHz).

As described above, in the present invention, since NHK satellite broadcasting frequency of Japan is included in the broadcasting frequency band of Chinese star broadcasting, amplification, tuning, and IF conversion are performed in one path from the input filter to the amplifier. By switching the signal path in the switching circuit section with a suitable IF filter path, it is possible to selectively receive two satellite broadcasts with one tuner, thereby simplifying the circuit configuration, multiplexing the tuner, and reducing the unit cost. There is.

Claims (2)

An input filter 21 for receiving a satellite broadcast signal from an LNB at the front end, a first amplifier 22 for amplifying the output of the input filter 21, and a tuning unit 13 for tuning the amplified IF reception signal. Oscillator 24 for outputting a local oscillation signal, a PLL circuit portion 25 for applying a phase-locked loop to the oscillation signal of the oscillator 24, and an output signal and an oscillator 24 of the tuning unit 23. A mixer 26 for receiving an oscillation signal of a second signal and converting the signal into an IF signal, a second amplifier 27 for amplifying the signal converted into the IF signal, and a signal amplified by the second amplifier 27, A switching circuit section 28 for switching and supplying an IF band pass filter 29 or an IF band pass filter 29A for Japan, and a first band for passing an European IF signal switched and input by the switching circuit section 28; A pass filter 29, a third amplifier 30 for amplifying the output of the first band pass filter 29, and the switching A second band pass filter 29 (a) for passing a Japanese IF signal switched and input from the furnace 28, and a fourth amplifier amplifying the output of the second band pass filter 29 (a) ( 30 (a)) tuner for satellite broadcasting. The method of claim 1, wherein the switching circuit 28 comprises: a diode (D1) constituting the IF signal transmission path for satellite broadcasting for Europe, a diode (D2) constituting the IF signal transmission path for satellite broadcasting for Japan, A transistor Q1 that is turned on / off by an input switching signal Lsw to turn on / off the diode D1, and a transistor Q1 that is turned on / off by an input switching signal Lsw to turn the diode D2 on / off A tuner for satellite broadcasting reception comprising a switching transistor (Q2) and a diode (D4).