JPS61205078A - Telecasting equipment - Google Patents

Abstract

PURPOSE:To improve the reliability of a telecasting equipment and also to prevent the break of a program signal owing to switching actions of video modulator, by using a rubidium atom oscillator to operate plural different video modulator in parallel with each other and therefore omitting a switch for those modulators. CONSTITUTION:The output of a rubidium atom frequency standard unit 93 is supplied to a reference frequency oscillator 93 for generation of a signal of the standard frequency. The video modulators 111 and 121 apply the frequencies of the output signals of crystal oscillators 13 and 14 as well as the reference frequency to comparators 91 and 92. When the outputs of both oscillators 13 and 14 have variance, the comparators 91 and 92 produce the error signals between the output frequencies of oscillators 13 and 14 and the reference frequency for control of the output voltages of oscillators 13 and 14 of modulators 111 and 121. Thus it is possible to obtain a constant output that is stable and synchronous with the reference frequency. The control is carried out for the output level or modulators even with different modulators 11 and 12 as long as the reference frequency is constant. Then the synthesizing is possible after setting the output levels at the same value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to television broadcasting equipment, and more particularly to a parallel operation method in which a rubidium atomic frequency standard is used to control a crystal oscillator of a video modulator. .

(Prior Art) FIG. 2 is a block diagram showing an example of a television broadcasting machine employing a parallel operation method according to the related art. In Fig. 2, 11.12 are modulators, 13.14 are crystal oscillators, 15° and 16 are local oscillators, 20 is a switching distributor, 21-24, 29 are high-frequency relays, and 25-28 are respectively local oscillators. , 30 are distributors, 31 and 32 are compensators, 41 and 42 are frequency converters, 51 to 54 are power amplifiers, 61 and 62 are CIN diplexers, and 70
is a combiner, and 80 is an antenna.

In FIG. 2, each video signal modulator 11.1
2 outputs and the outputs of local oscillators 15 and 16 are
The signals were distributed and input to respective compensators 31 and 32 and frequency converters 41 and 42.

(Problems to be Solved by the Invention) A television broadcasting device adopting such a system includes switchers 21 to 24.29 and distributors 25 to 24 for the modulator 11.12 and local oscillator 15.16. 2
Just in case you need 8.30. In addition, when the modulators 11 and 12 in use fail, the system is switched to a spare modulator, which has the disadvantage that the program signal is intentionally cut off for several seconds.

In addition, each modulator 11 is connected to high frequency relays 21 to 24 and 29 used for selective switching of different oscillation frequencies.
．． In order to prevent the 12 components from influencing each other, a coaxial switch with a highly separated contact system was used, which caused problems with long-term stability and caused failures.

An object of the present invention is to control the oscillation frequency of a video modulator using a rubidium atomic frequency standard, and to eliminate the above drawbacks by operating two different video modulators in parallel. To provide a television broadcasting device configured such that the system configuration can be simplified by omitting a switching device, and broadcasting can be performed without cutting off the program signal in the event of a failure of one video modulator. .

(Means for Solving the Problems) A television broadcasting device according to the present invention includes a pair of modulators, a pair of compensators, a pair of frequency converters, a pair of power amplifier groups, and a pair of CIN diplexers. The system consists of a pair of transmitting systems consisting of a rubidium atomic frequency standard and a combiner for operating the pair of transmitting systems in parallel to combine the output and guide it to the antenna], and the transmitting system has a rubidium atomic frequency standard and a reference frequency It is equipped with a generator and a pair of phase comparators, and is constructed so that it can be operated in parallel in synchronization.

Rubidium atomic frequency standards are intended for use as oscillation sources.

The reference frequency generator is for generating a reference frequency by dividing and multiplying the output of the rubidium atomic frequency standard.

The pair of phase comparators compare the reference frequency and the output frequency of the crystal oscillators of the pair of modulators, and control the output frequency using an error signal to make it equal to the output frequency of the rubidium atomic frequency standard. It is.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a television broadcasting device according to the present invention. In Figure 1, 11.12
are each a modulator, and 111 and 121 are each a modulator 1.
1.12 is an internal video modulator, 112, 122 is an internal audio modulator of modulator 11.12, 113,
123 are distributors for the outputs of the audio modulators 112 and 122, 13.14 are crystal oscillators, and 15.1
6 are local oscillators, 31 and 32 are compensators, 41 and 42 are frequency converters, and 51 to 54
are respectively power amplifiers, 61° and 62 are CIN diplexers, 70 is a combiner, 80 is an antenna, and 91.9
2 is a phase comparator, 93 is a reference frequency generator, 9
4 is a rubidium atomic frequency standard.

The block diagram shown in FIG. 1 includes a rubidium atomic frequency standard 94 in addition to the configuration of the television broadcasting device shown in FIG.
, reference frequency generator 93, and phase comparator 91.9
2 is added as a friend.

In FIG. 1, the output of a rubidium atomic frequency standard 94' is input to a reference frequency generator 93 to generate a reference frequency signal. Video modulator 111, 121K
The frequency of the output signal of the crystal oscillators 13 and 14 (7) and the reference frequency are connected to phase comparators 91 and 92, respectively.
Add to. When the output of the crystal oscillator 13.14 fluctuates, the crystal oscillator 13.1 is detected by the phase comparator 91.92.
Generate an error signal between the output frequency of 4 and the reference frequency,
The output voltages of the crystal oscillators 13 and 14 of the respective video modulators 111 and 121 are controlled by the error signal to obtain a stable and constant output in synchronization with the reference frequency.

If the reference frequencies are the same, even if the modulators 11 and 12 are different, the output levels and modulation degrees can be adjusted to make the output levels equal before combining.

A similar relationship holds true for local oscillators 15 and 16. That is, if one of the video modulators 111 and 121 fails, broadcasting can be continued without cutting off the program signal by turning off the corresponding modulator 11 or 12.

(Effects of the Invention) As explained above, by operating different video modulators in parallel using a rubidium atom excavator, the video modulator switcher is omitted and the reliability of the broadcasting device is improved. At the same time, there is an effect that cutting off of the program signal due to switching of the modulator can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a television broadcasting device according to the present invention. FIG. 2 is a block diagram showing an example of a television broadcasting machine according to the prior art. 11, 12...Modulator 111.121...Video modulator 112.122...Audio modulators 25-28, 30, 113, 123...Distributor 13.14...Crystal oscillator 15 , 16...Local oscillator 20...Switching distributors 21-24, 29...High frequency relays 31, 32
... Compensator 41.42 ... Frequency converter 51 ~
54...Power amplifier 61.62...CIN diplexer 70...Synthesizer 80...Antenna 91.92...Phase comparator 93...Reference frequency generator

Claims (1)

[Claims] A pair of transmission systems consisting of a pair of modulators, a pair of compensators, a pair of frequency converters, a pair of power amplifier groups, and a pair of CIN diplexers, and the pair of transmission systems are operated in parallel and output. In a television transmitter configured with a synthesizer for synthesizing and guiding to an antenna, the transmission system includes a rubidium atomic frequency standard for use as an oscillation source, and the output of the rubidium atomic frequency standard is divided into two channels. A reference frequency generator for multiplying and generating a reference frequency, and comparing the reference frequency and the output frequency of the crystal oscillators of the pair of modulators, and controlling the output frequency by an error signal. A television broadcasting device comprising a pair of phase comparators for making the output frequency equal to the output frequency of the rubidium atomic frequency standard, and configured to be able to operate in parallel in synchronization.