[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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This paper deals with the theoretical analysis and the experimental results of the characteristics of an improved synchronous detector in which the reference carrier phase is varied according to the phase modulation component of the received signal.
It is shown that the characteristics of this proportional-phase synchronous detector are more suitable for video demodulation compared to those of the envelope detector which produces quadrature distortion or of the conventional constant phase synchronous detector which generates differential phase resulted from the phase modulation component produced in the television transmitter by its AM to PM conversion characteristics.
As the reference signal in the improved synchronous detector is generated from the received signal by the amplitude limiter consisting of ring connected diodes to reduce the phase shift error of the circuit, the experimental visual demodulator has been realized with simple construction and improved stability.

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The authors have developed an SHF television converter of new circuit structure using a Microwave Integrated Circuit (MIC) module.
A wideband Rat-Race circuit, in which an additional output port is incorporated to eliminate the crossover structure, is employed in the mixer section of this con-verter.
The fluctuation of the Gunn diode local oscillator frequency is stabilized within±297kHz (-20°C-55°C) by implementing an AFC circuit consisting of a dielectricresonator housed in a small oven and a phase discriminator.
The conversion loss of the experimental mixer is measured to be less than 3.9 dB including the insertion loss of the input bandpass filter, and the overall noise figure for 150 MHz bandwidth is 5.2 dB.

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A fame recording method is experimentally applied to improve the image quality of the intermittent X-ray television which has been used to reduce the exposure does in fluoroscopy.
This method includes the frame biasing technique applied to the cathode potential of the pick-up tube, and the gamma correction technique applied to the second field output signal.
The working principle is analyzed, and the calculated results are confirmed by the experiments which are made using the system newly developed for this purpose.
It is shown that the image quality is considerably improved with respect to resolution and signal to noise ratio as observed on the picture monitor, and that the effect of flicker is suppressed almost completely by the gamma correction at all pulse rates.

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[in Japanese]

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