KR970007471B1 - Tuner of television - Google Patents

Abstract

The present invention provides a TV tuner which selects a cable broadcasting signal and a satellite broadcasting signal in common, and utilizes an oscillator, thus improving the overall circuit's stability and simplifying the construction. This TV tuner having a cable broadcast processing loop processing signals via a circuit loop with a first amplifier, a first bandpass filter, a tuning circuit (62), etc., and satellite broadcast processing loop processing signals via a circuit loop with a second amplifier (22), a third bandpass filter, etc., includes a signal controller (130); a first local oscillator (54); a first mixer (43); a fourth bandpass filter (34); a third amplifier (23); a second local oscillator (55); a first switching circuit (13); a second mixer (44); an automatic gain control detector (82); an automatic gain control amplifier (92); and a second switch (12).

Description

TV tuners

1 is a block diagram showing a conventional TV tuner.

2 is a block diagram showing a television tuner according to the present invention.

* Explanation of symbols for main parts of the drawings

13: first switching unit 23: amplifier

34: band pass filter 43: first mixer

121: demodulation processing circuit 130: tuning signal control unit

200: cable broadcasting processing loop 300: satellite broadcasting processing loop

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuner for television, and more particularly, to a tuner for television that tunes cable and satellite broadcast signals in common.

Satellite broadcasting is applied to next-generation high-definition television (HDTV) or conventional television, and provides a clearer image to a farther distance using a communication satellite. In addition, cable television (CATV) refers to watching a broadcast program desired by a subscriber by connecting a transmission line between a broadcasting station and the subscriber.

For example, by installing a K-Ball transmission line and a satellite antenna on a television, viewers can watch satellite broadcasting through satellites and broadcast viewing through cable transmission lines.

1 is a block diagram showing a conventional TV tuner, reference numeral 11 denotes a switch (SW) connected to a cable transmission line and a tuner of the present apparatus, and 21-25 amplifies an RF signal and an intermediate frequency. It is a heavy aeration. 31-34 is a band pass filter (BPF) for extracting only a corresponding signal within a predetermined frequency band, and 41-42 are first and second mixers for mixing the applied frequencies, respectively.

51-53 is a local oscillator for supplying a local oscillation frequency to the first and second mixers 41-42, 61 is a power divider, and 71 is a surface acoustic wave filter (or SW). 81 is an automatic gain control detector for detecting the gain of the signal applied from the SAW, 91 is an automatic gain control amplifier for amplifying the gain detected by the automatic gain control detector 8l, and 110 is a switch.

In the conventional television tuner configured as described above, when a mixer and a local oscillator are configured to process a broadcast signal applied from the outside, the use of two or more local oscillators is essential. This complicates the hardware structure of the device.

Accordingly, an object of the present invention is to provide a TV tuner that can tune to a cable broadcast signal and a satellite broadcast preference in common.

The first band pass filter of the present invention provides a cable broadcasting signal input by a switch operation, except for achieving the above object. Signal processing through a cable loop processing loop for signal processing through a circuit loop composed of tuning circuits, and a circuit loop composed of a second amplifier and a third band pad filter for satellite broadcast signals input by the second band pass filter. A television tuner having a satellite broadcasting processing loop for demodulating a broadcast signal selected by a broadcast mode selection control signal and outputting an intermediate frequency, wherein the tuner is operated by a user and is either a cable broadcasting mode or a satellite broadcasting mode. A tuning signal control unit for detecting a signal and outputting a switch control signal and a local oscillation control signal according to the detection result; A first local oscillator operated by a local oscillation control signal of the station signal control unit to provide a local oscillation frequency corresponding to the broadcast mode output from the station signal control unit; A first mixer for mixing and processing a broadcast signal frequency applied through one of the cable broadcast processing loop and the satellite broadcast processing loop and a local oscillation frequency supplied from the first local oscillator; A fourth band pass filter for limiting and outputting the broadcast frequency transmitted from the first mixer to a frequency of a predetermined band; A second local oscillator providing a preset local oscillation frequency; A first switch unit configured to switch whether or not transmission to the second mixer with respect to the oscillation frequency oscillated in the second local oscillator by the broadcast mode control signal of the preset signal control unit; A second mixer for mixing a frequency amplified by the third amplifier and a signal applied by a switch operation of the first switch unit; An SAW filter for amplifying the frequency applied by the second mixer and surface acoustic wave filtering the amplified signal; A demodulation processing circuit for demodulating the signal filtered by the SAW filter; An automatic gain control detector for detecting a gain of a signal output from the SAW filter; An automatic gain control amplifier for amplifying the gain detected by the automatic gain control detector; And a second switch unit configured to switch control so that the gain output from the automatic gain control amplifier can be selectively transmitted from the tuning circuit and the second amplifier.

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

2 is a block diagram showing a television tuner according to an embodiment of the present invention.

2, the television tuner according to the embodiment of the present invention detects any one of the cable broadcasting processing loop 200, the satellite broadcasting processing loop 300, the cable broadcasting mode and the satellite broadcasting mode, and the detection result. The broadcast mode output from the tuning signal control unit 130 is operated by the tuning signal control unit 130 for outputting the switch control signal and the local oscillation control signal and the local oscillation control signal provided from the tuning signal control unit 130 according to the present invention. A local oscillator 54 for providing a local oscillation frequency corresponding to the broadcast signal frequency and the local oscillator supplied from a circuit loop selected from a cable broadcast processing loop 200 and a satellite broadcast processing loop 300; In the first mixer 43 for mixing the local oscillation frequency, the band pass filter 34 for limiting and outputting the broadcast frequency transmitted from the first mixer 43 to a predetermined band frequency, and the band pass filter 34. sign Switching control of transmission to the second mixer 44 with respect to the oscillation frequency oscillated by the second local oscillator 55 by the broadcast mode control signal of the amplifier 23 and the tuning signal control unit 130 that amplify the broadcast frequency. A second mixer 44 and a second mixer (mixing), which mix the first amplifying unit l3, the frequency amplified by the amplifier 23 and the signal applied by the switching operation of the first switching unit 13 SWA filter 72 for amplifying the frequency applied by the signal and filtering the amplified signal with the elastic surface, a demodulation processing circuit 121 for demodulating the signal filtered by the SAW filter 72, and a SAW filter 72. Automatic gain control detector 82 for detecting the gain of the signal filtered by the filter; Automatic gain control amplifier 92 for amplifying the gain detected by the automatic gain control detector 82; output from the automatic gain control amplifier 92 Can be selectively transmitted to the tuning circuit 62 and the amplifier 22. It consists of the second switching unit 12 for controlling the switching lock.

In this case, the cable broadcasting processing loop 200 includes a switch 11 for intermittently switching the broadcasting frequency applied from the cable transmission line, an amplifier 21 for amplifying the provided cable broadcasting signal via the switch 11, And a band pass filter 33 for filtering only frequencies of a predetermined band, and a tuning circuit 62 for tuning the frequencies filtered by the band pass filter 33.

The satellite broadcast processing loop 30 includes a band pass filter 31 for filtering a broadcast frequency applied from a receiver to a predetermined band frequency, an amplifier 22 for amplifying a signal output from the band pass filter 31, and an amplifier. And a band pass filter 32 for filtering the signal amplified at 22 to a predetermined band frequency.

The operation of the embodiment of the present invention configured as described above will be described in detail.

First, when the cable broadcasting mode is selected by the user, the tuning signal control unit 130 transmits a local oscillation control signal to the local oscillator 54 to transmit an oscillation frequency for which the cable broadcasting mode can be selected. To pass on. The first mixer 43 mixes the frequency passed through the cable broadcasting processing loop 200 and the oscillation frequency provided from the local oscillator 54 to transfer the processed intermediate frequency to the band pass filter 34. The band pass filter 34 extracts only a frequency of a predetermined band with respect to the signal input from the first mixer 43 and then provides it to the amplifier 23, and the amplifier 23 amplifies it and transfers it to the second mixer 44. do. On the other hand, the first switching unit 13 is turned off by the switch control signal according to the selection of the cable broadcasting mode. Therefore, the local oscillation frequency transmitted from the second local oscillator 5 is not supplied to the second mixer 44, and only the intermediate frequency amplified by the amplifier 23 is amplified by the amplifier 26 and then the SAW filter 72. Is delivered to. The SW filter 72 transfers the intermediate frequency to the demodulation processing circuit 121. The automatic gain control detector 82 detects the gain of the signal applied from the SAW filter 72 and transfers it to the automatic gain control amplifier 92. In the automatic gain control amplifier 92, the gain provided from the automatic gain control detector 82 is amplified and amplified and provided to the second switch 12, and the second switch 12 adjusts the gain. Transfer to one mixer (43).

On the contrary, when the satellite broadcasting mode is selected by the user, the tuning signal control unit 130 transmits the local oscillation control signal to the local oscillator 54 and transmits the oscillation frequency from which the satellite broadcasting mode can be selected. To pass). The first mixer 43 mixes the frequency passed through the satellite broadcast processing loop 300 and the oscillation frequency provided from the local oscillator 54 to transfer the processed incremental frequency to the band pass filter 34. The band pass filter 34 extracts only a frequency of a predetermined band with respect to the signal input from the first mixer 43 and then supplies the frequency to the amplifier 23. The amplifier 23 amplifies it and transfers it to the second mixer 44. do.

On the other hand, the first switching unit 13 is operated by the silver by the switch control signal according to the selection of the satellite broadcasting mode. Therefore, the local oscillation frequency transmitted from the second local oscillator 55 is supplied to the second combiner 44, mixed with the frequency output from the amplifier 23, transmitted to the amplifier 26, and then amplified, and then the SAW filter ( 72). The SAW filter 72 transfers the intermediate frequency to the demodulation processing circuit 121. The automatic gain control detector 82 detects the gain of the signal applied from the SAW filter 72 and transfers it to the automatic gain control amplifier 92. In the automatic gain control amplifier 92, the gain provided from the automatic gain control detector 82 is amplified and amplified and provided to the second switch 12, and the second switch 12 applies the tuning circuit 62 and the redundancy circuit. It passes to the mixer 43.

In addition, this invention is not limited to the said Example, A deformation | transformation is possible in the range which does not deviate from the technical summary of this application.

As described above, the present invention can improve the stability of the entire circuit and simplify the hardware configuration by using only one oscillator without using two oscillators in the first oscillator.

In addition, the output level of the mixer can be improved by using a band pass filter and a switch without using a power divider.

Claims (3)

A cable broadcast processing loop for processing the cable broadcast signal input by the switching operation through a circuit loop composed of a first amplifier, a first band pass filter, a tuning circuit 62, and the like, and a second band pass filter. And a satellite broadcast processing loop for processing a satellite broadcast signal through a circuit loop composed of a second amplifier 22, a third band pad filter, and the like, and demodulating and processing a broadcast signal selected by a broadcast mode selection control signal. A television tuner that outputs a frequency, the television tuner being operated by a user to detect either a cable broadcasting mode or a satellite broadcasting mode, and to detect the result. A tuning signal control unit l30 for outputting a switching control signal and a local oscillation control signal according to the control signal; A first local oscillator (54) operated by a local oscillation control signal of the tuning signal control unit to provide a local oscillation frequency corresponding to the broadcast mode output from the tuning signal control unit; A first mixer (43) for mixing and processing the broadcast signal frequency applied through any one of the cable broadcast processing loop and the satellite broadcast processing loop and the local oscillation frequency supplied from the local oscillator 34; A fourth band pass filter 34 which limits and outputs the broadcasting frequency transmitted from the remixer 43 to a frequency of a predetermined band; A third amplifier 23 for amplifying the broadcast frequency applied by the fourth band pass filter 34; A second local oscillator 55 supplying a preset oscillation frequency; A first switching unit (13) for switching the transmission of the oscillation frequency transmitted from the second local oscillator (55) to the second mixer (44) by the broadcast mode control signal of the tuning signal control unit (130); A second mixer (44) for mixing a frequency amplified by the third amplifier (23) and a signal applied by the switching operation of the first switching unit (13); An SAW filter (71) for amplifying the frequency applied by the second mixer (44) and surface acoustic wave filtering the amplified signal; A demodulation processing circuit (121) for demodulating the signal filtered by the SAW filter (71); An automatic gain control detector (82) for detecting a gain of a signal output from the SAW filter (71); An automatic gain control amplifier 92 for amplifying the gain detected by the automatic gain control detector 82; And a second switching unit 12 for switching control to selectively transfer the gain output from the automatic gain control amplifier 92 to the tuning circuit 62 and the second amplifier 22. Tuner vision tuner. 2. The cable broadcasting processing loop 200 according to claim 1, wherein the cable broadcasting processing loop 200 interrupts and switches the broadcasting frequency applied from the cable transmission line, and the cable broadcasting applied by the silver / off operation of the switch 11. A first amplifier 21 for amplifying the signal, a first band pass filter 33 for filtering only frequencies of a predetermined band, and a tuning circuit 62 for tuning the frequencies filtered by the first band pass filter 33. Tuner for television, consisting of measurements). The satellite broadcasting processing loop 300 of claim 1, wherein the satellite broadcasting processing loop 300 outputs from the second band pass filter 31 and the second band pass filter 31 for filtering the broadcasting frequency applied from the receiver to a predetermined band frequency. And a third band pass filter (32) for filtering the signal amplified by the second amplifier (22) at a predetermined band frequency.