JPH11168640A - Fpu device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of parts to shorten adjustment time and to realize miniaturization by switching two channels through a video modulator of a transmission control part by a transmitter side and a receiving demodulator of a reception control part by a receiver side and transmitting video and sound. SOLUTION: A sound signal which is inputted to a transmission control part 1 is modulated with a range of 5 to 8 MHz frequency with a sound modulator 5 to be composited with a video signal, modulated by a modulator 6 and sent to a transmission high frequency part 2. Channel change is performed by selecting a condenser 20 in the modulator 6 with a channel changeover SW. An SHF signal of a selected channel is up-converted with a local signal 9 of the part 2 by a mixer, is amplified by a PA 10, and a radio wave is outputted. A radio wave that is inputted to a high frequency part 3 passes through a low-noise amplifier, is down-converted with a local signal 13 by a mixer 12 and is sent to a reception control part 4. A video signal is demodulated by a channel that is selected by an oscillator 15, and a sound signal is demodulated by a sound demodulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a system for switching two channels (frequency) of an FPU device.

[0002]

2. Description of the Related Art As a conventional technology of an FPU which can switch between two channels (frequency), there are the following technologies.
As shown in FIG. 2, the video signal input to the transmission control unit 1 and A
The audio signal modulated by MOD is 500MHz by VMOD.
, And sends the signal to the transmission high-frequency unit 2 via the coaxial cable 7.
In general, the OCAL oscillator and the mixer 8 upconvert to about 7 GHz and output a designated channel radio wave (SHF signal).

[0003] In the receiving apparatus, the receiving high frequency section 3 has a frequency of about 7 GHz.
receiving the radio wave of z, down-converted to 450 MHz by the LOCAL oscillator selected by the channel switching SW, sent to the reception control unit 4 by the coaxial cable 14, and
The video signal and the audio signal are demodulated by DEM and ADEM.

[0004]

In the above-mentioned prior art,
When switching between two channels, LOCAL with a C / N of 70 dB or more at a high frequency of about 6.5 GHz
Two oscillators are required for the transmitter and the receiver. This L
The OCAL oscillator requires high adjustment man-hours and parts cost from the above-mentioned frequency and C / N conditions, and requires a wide mounting space.
In addition, a switch of the LOCAL oscillator needs to have a low LOCAL level attenuation, and therefore has a disadvantage that the cost of parts is high.

An object of the present invention is to eliminate these disadvantages, shorten the adjustment time, reduce the cost of parts, and reduce the mounting space.

[0006]

FIG. 1 is a block diagram showing the overall configuration of the present invention.

The video signal input to the transmission control unit and the AMOD
Is modulated by VMOD. At that time,
The capacitor shown in FIG. 3 is selected by the channel switching SW, changed to a designated frequency, modulated, sent to a transmission high frequency unit by a coaxial cable, locally mixed, up-converted to about 7 GHz, and outputs a radio wave of the designated channel.

The receiving device receives a radio wave of about 7 GHz at a receiving high frequency, down-converts the signal by a LOCAL oscillator, sends the signal to a receiving control unit by a coaxial cable, selects a capacitor in the VDEM by a channel switching SW, and changes the capacitor to a designated frequency. To demodulate the video signal and the audio signal.

[0009]

As a result, only one LOCAL oscillator is required for each of the transmitter and the receiver, and a switch for the LOCAL oscillator is not required, so that the adjustment time can be shortened and the parts cost can be reduced.

Also, the mounting space for one LOCAL oscillator is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

1 is a transmission control section, 2 is a transmission high-frequency section, 3 is a reception high-frequency section, 4 is a reception control section, and each high-frequency section and the control section are connected by coaxial cables 7 and 14. The audio signal input to the transmission control unit 1 is modulated by a 5 audio modulator at a frequency of 5 to 8 MHz, combined with a video signal, modulated by a 6 modulator, and sent to a transmission high frequency unit 2. Figure 3
20 capacitors in the modulator (modulator 6 in FIG. 1)
7 is selected by the channel switch SW. The SHF signal of the selected channel is up-converted by the local signal 9 of the transmission high-frequency unit 2 and the mixer 8 and amplified by the PA 10. Outputs radio waves.

The radio wave input to the high frequency unit 3 passes through a low noise amplifier 11, is down-converted by a local signal 13 and a mixer 12, and is sent to a reception control unit 4.
The video signal is demodulated on a channel selected by 15 oscillators, and the audio signal is demodulated by 16 audio demodulators.

[0014]

According to the present invention, the cost of parts can be reduced, the adjustment time can be shortened, the number of local oscillators can be reduced by one in each of the transmitter and the receiver, and the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention.

FIG. 2 is a block diagram showing a conventional FPU device.

FIG. 3 is a circuit diagram of a VMOD oscillator.

[Explanation of symbols]

1: Transmission control unit, 2: Transmission high-frequency unit, 3: Reception high-frequency unit, 4: Reception control unit, 5: Audio modulator, 6: Video modulator, 15: Video demodulator, 16: Audio demodulator, 17: Channel changeover switch, 20: condenser.

Claims (1)

[Claims] In a FPU in which a transmitter and a receiver are separated into a control unit and a high-frequency unit, switching between two channels is performed on the transmission side by a video modulator of the transmission control unit and on the reception side by the reception demodulation of the reception control unit. An FPU device for transmitting video and audio in a FPU.