JPS59171374A - Television broadcast system - Google Patents

Abstract

PURPOSE:To simplify the system and to improve the signal characteristic by converting a television sound signal FM-modulated at a studio into a sound intermediate frequency signal without being demodulated at a transmission station and giving the signal to a television transmitter main circuit. CONSTITUTION:A sound demodulator of a television STL receiver and a sound IF modulator of a television transmitter are omitted, and a sound IF converter 15 comprising a frequency divider 16, a mixer 17 and a local oscillator 18 is provided newly, the sound subcarrier signal demodulated at a television STL receiving main circuit 8 and branched at a branching device 9 is given directly to a sound IF converter 15 to obtain a sound intermediate frequency signal, the signal is converted into a television broadcast wave at the television transmitter main circuit and then amplified, synthesized with a video carrier so as to form a television broadcast radio wave. Thus, the sound demodulator of the television STL receiver and the sound IF modulator of the television transmitter are omitted by having only to add the sound IF converter and the television sound broadcast wave without characteristic deterioration is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a digital broadcasting system.

Figures 1 and 2 show TV S in conventional television broadcasting.
Typical system diagrams of T L equipment and TV transmitters are shown. Figure 1 shows the TV STL transmitter installed in the concert hall, and Figure 2 shows the 7Level STI and receiver installed in the broadcasting station. and television transmitter 117) system diagram is shown.

The human/j) signal received from the audio signal input terminal 2 is a 11'7 voice modulation A3 with a high frequency 6 of the video signal band.
．． ~8M) (The audio subcarrier set in the zF stage is combined with the FML video signal from the Js terminal I) in the synthesizer 4. After that, the STL transmitter main circuit 5C Michael 7 Wave FM L.

It is transmitted by radio waves from the microwave output terminal 6 to the transmitting station. At the transmitting station, the manually modulated microwave is input from the microwave input terminal 7 to the STL receiver. ' and sound %j subcarrier signal 'jK division 12,.

The video signal is sent to A.V. by the video IF modulator 11 of the television transmitter. M
and modulated to a video intermediate frequency of +7.75 MHz.

The audio subcarrier double is the audio signal (1) which is demodulated by the audio demodulator 10 and then FMed by the RF voice IF' modulator 12 of the television transmitter to produce an audio intermediate 1M wave number of 22.25 MHz. Converted to J.

The video and audio intermediate frequency signals are each converted into predetermined television broadcast waves by the television transmitter main circuit 13, amplified and combined, and then broadcast on television. 2. TV audio is twice as old (1) Even though the FM waves are the same in the TV STL device and the TV transmitter, they are modulated and depressed by the TV STL device and then further modulated by the TV transmitter. The system configuration is complicated, and since modulation and demodulation are repeated, signal characteristics are degraded by the modulation and demodulation circuits.

In order to eliminate these drawbacks, the present invention provides F'M
By converting the received TV audio signal into an audio intermediate frequency signal without demodulating it at a transmitting station and connecting it to the main circuit of the TV transmitter, the system is simplified and the signal characteristics are improved.

Embodiments of the present invention are not shown in FIGS. 3 and 4. TV STL
The receiver's audio demodulator and the TV transmitter's audio ITi' modulator are deleted and the divider by 1 frequency 16. Mixer 171 Local oscillator 18
A new audio IF converter 15 is installed, and the TV S
The audio subcarrier signal demodulated by the T L reception main circuit 8 and demultiplexed by the demultiplexer 9 is directly connected to the audio IF converter 15 to obtain an audio intermediate frequency signal, and then transmitted to the TV transmitter main circuit. After converting to TV broadcast waves, they are amplified, combined with video carrier waves, and combined with TV broadcast waves. Here, the frequency divider 10 is used to match the audio frequency deviation of the TV STL device and the audio frequency deviation of the 1-Level transmitter.k)
Generally speaking, the audio frequency deviation of TV STL equipment is +
, 10 kHz or higher -1".

If the frequency deviation is ±25 kHz -C, frequency divider 1 (3) is not needed.
etc. > -W frequency deviation or ±50 kI (If z, the frequency divider 10 can be divided by 16 to match the -fq voice frequency deviation of the TV broadcast wave + 25 kHz. In this case, 6 to 8 The audio subcarrier frequency of the TV STL device set between MHz is also divided by 14: (~4 MT(
It becomes a frequency between z.

Therefore, if the oscillation frequency of the local oscillator 18 is set as the sum of the audio subcarrier frequency of the television STL and the audio intermediate frequency of the television transmitter, which is a frequency between 3 and 4 MTh, or as a constant frequency, the mixer 18 mixes the audio. It is possible to obtain intermediate frequencies.

As explained above, by simply adding a 5L/1 audio IF converter to the present invention, TV STL reception (7
The audio demodulator of i11i and the audio Tl'' modulator of the television transmitter can be deleted, and a television audio broadcast wave without this deterioration in transmission characteristics can be obtained.

[Brief explanation of the drawing]

1 and 2 are typical system diagrams of a conventional TV STL device and a TV broadcaster, FIG. 3 is a system diagram of a TV STL receiver and a TV transmitter according to an embodiment of the present invention, and FIG. The figure is a detailed system diagram of the audio IF converter shown in Figure 3. 8: STL reception main circuit, 9: Brancher, 11"Video I
F modulator, 13: TV transmission main circuit, 15: Audio IF converter, 16-frequency divider, 17: mixer, 18: local oscillator.

Claims (1)

[Claims] In a television broadcasting system that uses a TV STL system for transmitting television signals from a concert group installed at a television broadcasting station to a television broadcasting station, a video broadcast by the concert group on FM,
Is the audio signal of audio f3 at the TV broadcasting station? Characteristic J: A television broadcasting system that converts the audio intermediate frequency signal into an intermediate frequency signal and inputs it to the main circuit of a television transmitter without adjusting the door, converts the audio intermediate frequency signal into a desired television audio carrier wave, and broadcasts the signal.