KR930010172B1 - Remote voice control circuit for catv - Google Patents

Abstract

The control circuit controls channel and volume of a television of rotary tuner type utilizing a cable television signal converter. The circuit includes a microcomputer (13) for generating channel and volume control signal (CCS,ACS) according to channel and volume signal transmitted from a remote controller, a mixer (16) for generating audio carrier signal of 4.5 MHz, a filter (23) for generating baseband audio signal by filtering audio carrier signal generated by the mixer (16), a volume (24) for adjusting baseband audio signal level, a RF converter (22) for converting baseband audio signal into audio intermediate frequency signal, and a signal synthesizer (21) for generating IF and channel RF signal by synthesizing picture and audio intermediate frequency signal.

Description

Remote volume control circuit of TV set using cable broadcasting signal converter

1 is a remote volume control circuit diagram of a conventional mechanical tuner television set.

2A, 2B and 1F output frequency characteristic diagram of FIG.

3 is a remote volume control circuit diagram of a mechanical tuner television set according to the present invention.

* Explanation of symbols for main parts of the drawings

A: CATV tuner 3: Remote receiver

4: Remote Transmitter 13: Micom

14: audio trap 15: video trap

16: mixer 17: oscillator

18: band pass filter 19: amplifier

21: signal synthesizer 22: RF modulator

23: detector 24: volume control

The present invention relates to a remote volume control circuit of a television set using a cable broadcasting signal converter that can remotely control the volume as well as the channel of a television set having a mechanical (rotary) tuner using a cable broadcasting signal converter (CATV converter). It is about.

A CATV converter is required to receive cable broadcasting as a general TV set. Unlike most general TV sets, the CATV converter adopts a remote control method for channel selection.

Thus, connecting a CATV converter to a regular TV set with a mechanical tuner will enable the tuning of the receive channel.

A technology for remotely controlling the volume of a TV set by further developing the channel tuning remote control technology in the mechanical tuner TV set has been proposed above. 1 shows a remote volume control circuit of a mechanical tuner TV set using a conventional CATV converter.

As referred to herein, the RF signal of 50-550MHz input to the CATV converter is converted into an intermediate frequency (IF) signal, a two-channel frequency signal or a three-channel frequency signal in the CATV tuner (A) to convert the first converter (a). Is provided. Accordingly, the first converter (a) receives various frequency outputs (IF, 2-channel RF, 3-channel RF) from the CATV tuner A, sets the IF signal having an image intermediate frequency (PIF) of 45.75 MHz, and converts the second converter ( b), the second converter (b) down-converts the PIF and converts the PIF into a base band. At this time, the 41.25 MHz SIF signal component 4.5 MHz away from the PIF (45.75 MHz) is converted to 4.5 MHz.

The composite signal of the video signal (base band: 0-4.5MHz) and the voice carrier (4.5MHz) is filtered through the band pass filter (d) of the image trap function, and only the audio signal is filtered. After FM detection and volume control, the modulator outputs the modulated channel frequency of the TV set from the RF modulator f together with the video baseband signal through the low pass filter c of the voice trapping function.

That is, when the gain (dB) of the PIF (45.75 MHz) and the SIF (41.25 MHz) of the IF output h of the first converter (a) is Ap and As, respectively, as shown in FIG. And if the volume is adjusted in the volume controller (e) as shown in Fig. 2b of the gain (dB) of its voice carrier output (i), it is As', and finally the voice output can be increased.

However, the conventional remote volume control method as described above modulates and demodulates the video signal for volume control, and thus, a high quality TV screen cannot be obtained.

An object of the present invention is to provide a remote volume control circuit of a television set using a cable broadcasting signal converter that can remove the adverse effect on the video signal system in the remote volume control of a mechanical tuner TV set using a CATV converter.

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

3 is a circuit diagram of the present invention, in which a CATV tuner A into which a CATV RF signal of 50-550 MHz is inputted is converted into an IF signal or an RF signal of a selected channel according to the channel control signal (CCS) output of the microcomputer 13. The output frequency signal of the CATV tuner (A) is provided to the signal synthesizer 21 via the image trapper 14, and the output frequency signal of the CATV tuner (A) It is configured to be provided to the mixer 16 to which the oscillation frequency of the oscillator 17 (LO) is applied.

The voice carrier signal (4.5 MHz) generated by the mixer 16 is configured to be provided to the FM detector 23 through the band pass filter 18 and the amplifier 19, and the voice signal detected by the detector 23 The volume is configured to be adjusted by the audio control signal (ACS) output of the microcomputer 13 through the volume controller 24.

The voice control signal (ACS) output of the microcomputer 13 and the aforementioned channel control signal (CCS) are configured to be generated based on the channel signal and the volume signal of the remote receiver (3) by the remote transmitter (4).

On the other hand, the voice signal (base band) output from the detector 23 is converted into an SIF signal by the RF modulator 22, and then synthesized by a signal synthesizer 21 into which a PIF signal is input, and then a synthesized frequency (IF or channel RF). Configure to output as a signal.

That is, when the respective trap frequencies of the audio trap 14 and the image trap 15 are adjusted to the channel frequency, the signal synthesizer 21 outputs the corresponding channel (2 channels, 3 channels, etc.) at the HF frequency.

On the other hand, the CATV tuner (A) is upconverted with the low pass filter (5), which is an input filter, the first mixer (32) and the VCO oscillator (31) and the bandpass filters (6, 35) for RF signal up conversion. The oscillating output of the VCO oscillator 31 is fed back to the microcomputer 13 through the prescaler 11 for the PLL, including a second mixer 34 and an LO oscillator 33 that down convert the RF signal. Configure.

Referring to the operation of the present invention configured as described above is as follows.

The CATV tuner A of the CATV converter outputs an IF signal or an RF signal for each channel according to the channel control signal (CCS) output of the microcomputer 13 according to the keying of the remote transmitter 4.

In order to help the understanding of the present invention, the following description will be based on the IF signal. When a CATV RF broadcast signal of 50-550 MHz is input to the first mixer 32 for up-conversion via the low pass filter 5 of the CATV tuner A, the RF signal is controlled by voltage under the control of the microcomputer 13. Up-converted to 612.75 MHz by the oscillation frequency signal of the oscillator (VCO) 31, this up-converted signal is provided to the second mixer 34 for down-conversion via the band pass filter 6. Since the 567 MHz fixed oscillation frequency signal of the local oscillator (LO) 33 is input to the second mixer 34, a PIF signal of 45.75 MHz (SIF is 41.25 MHz) is output from the second mixer 34.

The IF signal of the CATV tuner A passes through the speech trap 14 and the SIF of 41.25 MHz is removed to be provided to the signal synthesizer 21. The IF signal of the CATV tuner A is provided to the image trapper 15. PIF at 45.75 MHz is removed and provided to mixer 16.

The image intermediate frequency trap IF signal input to the mixer 16 is mixed with the oscillation frequency of the local oscillator (LO) 17 and converted into an audio carrier signal of 4.5 MHz, and then the amplifier 19 of the band pass filter 18. Is provided to the FM detector 23.

Accordingly, the detector 23 obtains a voice signal (base band), and the volume of the voice signal is converted by the volume controller 24.

At this time, the voice controller 24 is controlled by the voice control signal (ACS) output of the microcomputer 13, the voice control signal (ACS) to the keying signal of the remote transmitter (4) received by the remote receiver (3) It is made inside the microcomputer 13 on the basis.

On the other hand, since the voice signal (baseband) of the detector 23 whose size is adjusted by the volume controller 24 is modulated back to SIF (41.25 MHz) while passing through the RF modulator 22, it is provided to the signal synthesizer 21. In the signal synthesizer 21, the image intermediate frequency signal of the CATV tuner A, which has passed through the voice trapper 14, and the audio intermediate frequency signal from the RF modulator 22 are synthesized and output as final IF signals.

In the above, the case where the output of the CATV converter is IF has been described as an example. However, the keying of the remote transmitter 4 detected by the remote receiver 3 is based on the 2 channel or the channel signal of the remote receiver 3, and thus the microcomputer 13 The oscillation frequency of the variable voltage oscillator 31 is changed by the channel control signal (CCS) output of the control unit, so that the up-conversion frequency of the first mixer 32 is changed, so that the output of the CATV tuner A is two or three channels. RF such as

At this time, it is natural that the trap frequencies of the audio trap 14 and the video trap 15 should be set to the audio and video intermediate frequency signals of the corresponding channel.

Therefore, the signal synthesizer 21 outputs an IF or RF of a desired channel (2, 3, 4, ...).

As described above, in the present invention, when remotely controlling a channel and a volume of a TV set of a mechanical (rotary) tuner using a CATV converter, only a voice signal is selectively pulled out without modulation and demodulation of a video signal, and then processed. Since the video signal is not synthesized and outputted, it is possible to prevent the TV picture quality deterioration due to deterioration of characteristics of the video signal.

Claims (1)

The microcomputer 13 which processes the channel signal and the volume signal input by the remote songs and receivers 4 and 3 to generate the channel control signal CCS and the volume control signal ACS, and the channel control of the microcomputer 13. CATV tuner (A) for selectively converting the CATV RF signal according to the signal (CCS) output to selectively output the IF signal and the channel RF signal, and removes the audio intermediate frequency signal included in the output of the CATV tuner (A) An audio trapper 14 for outputting only an image intermediate frequency signal, an image trapper 15 for outputting only an audio intermediate frequency signal by removing an image intermediate frequency signal included in an output of the CAtV tuner A, and the image; The mixer 16 generates a 4.5 MHz voice carrier signal by mixing the voice intermediate frequency signal passed through the trap 15 at the oscillation frequency of the oscillator 17, and performs FM detection on the voice carrier signal of the mixer 16. A detector 23 for generating a baseband audio signal; A volume controller 24 for adjusting the amplitude of the baseband voice signal of the detector 23 according to the voice control signal (ACS) output of the ECOM 13, and a scaled baseband voice signal of the detector 23. A signal synthesizer for synthesizing the intermediate frequency output of the audio modulator 22 and the intermediate frequency output of the voice trapper 14 and the intermediate frequency output of the RF modulator 22 to output an IF or channel RF signal. And a remote volume control circuit of the television set using the cable broadcasting signal converter, characterized by including (21).

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