[in Japanese]

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[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

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This paper describes the output SNR (Signal-to-Noise Power Ratio) and noise characteristics of the wide-band analog FM communication system in the m-distributed fading environments, where the output noise consists of random noise and click noise.
The improvement effects due to the diversity are also investigated, and three kinds of linear diversity combining techniques, such as Selection Combining (SC), Equal-Gain Combining (EGC), and Maximal-Ratio Combining (MRC), are compared from the viewpoint of the improvement effects including the correlation between two diversity branches.
The main results obtained by the analysis are as follows.
1. The fading affects the click noise more strongly than the random noise.
2. Much more diversity improvements can be obtained in the click noise than in the random noise.
3. The better SNR performance can be obtained for the case with smaller correlation between two diversity branches.
4. The MRC is the best diversity technique.
5. This analysis is also applicable to the case without fading.

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This paper describes a theoretical analysis of the characteristics of direct color correction of NTSC color television signal and the development of a new NTSC color corrector.
First, the desirable characteristics of NTSC color television signal correction which is equivalent to the adjustment performed in primary color channels is studied.
Correction curves which can be realized with simple circuit configuration having small correction errors are derived for the adjustments of pedestal level and gamma characteristic respectively. The error in color reproduction is evaluated for the proposed correction curves by calculating the chromaticity errors for the representative hue samples.
A new NTSC color signal corrector is developed based on the above study and considerations and successfully applied in the actual program production, and it is confirmed that the new method of color signal detection and processing employed in the equipment functions satisfactorily.

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When the input data change, D/A converter using 2^-1, 2^-2…, 2^-m-weights suffers from large impulsive noises (Glitch) owing to short-time data errors resulting from delay differences among registors and switches, which must be rejected by expensive and power consuming resample-and-hold circuit. And also it demands very precise weights only to maintain monotonicity.
To solve these problems, it is pointed out that we can use Parallel Expansion method. The upper m input bits are expanded into 2^m-1 Thermometer Godes which have as many High Levels as the input binary number and each of which has equal weight of 2^-m. And they are strobed into registors together with the lower bits to switch the weights simultaneously. Then, the glitch is suppressed to less than 2^-m and the allowable weight error for monotonic conversion is expanded to ±2^{- (n-m)} . To design TV signal D/A converters by this method, the allowable limit of the glitch is experimentally found and the increases in DG and DP owing to weight errors are calculated.

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