[in Japanese]

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[in Japanese]

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An experimental model of a high speed data recorder which records compressed HDTV images is developed. This data recorder is capable of recording digital data up to 140 Mbps in a cassette-type half-inch tape for 60 minutes, and is applicable to various transmission rates less than 140 Mbps by changing an interface board. In this data recorder, a double Reed-Solomon code is used as an error correction code. Record equalization is employed to reduce the channel bit error rate. With this method, a channel bit error rate of 10^-5-10^-4 is obtained. An off track margin of ± 5μm is obtained, to keep the channel bit error rate at less than 10^-4. The channel bit error rate degrades in a low humidity condition caused, in our estimation, by an increase of a rubbing noise. When recorded HDTV image data is compressed with HDTV-CODEC, our experimental model gives playback data without degrading the coded picture quality.

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A new method for fast transformation is described in this paper. The purpose is real-time transformation at low cost, low power and with small size hardware. Real-time processing is impossible without special hardware. A simple DDA can be easily generalized to an implicit function DDA. The DDA plays a very important role in carrying out fast three-dimensional rotations and projections. Address control memory and brightness control memory, which belong to a lineage of Logic-in-Memory, also do speedy, not only linear transformations, such as affine ones, but nonlinear ones such as mappings. A complex method combining the advantages of both DDA and control memory is proposed. Through concrete examples using digital pictures from a VTR, the effectiveness is confirmed.

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This paper describes how to protect power devices of the transmitter against transient voltage and current due to load changes.
When the load condition of the transmitter changes because of antenna-induced lightning surges, large transient voltage and current, which can damage the power devices, occur in the transmitter.
These transient votages and currents are analyzed using computer simulation. If the load impedance seen from the power amplifier with the grounded antenna base is extremely small, both voltage and current can be very large to exceed the ASO of the power device.
This paper also shows that in order to protect the power devices, the load impedance seen from the power amplifier with the grounded antenna base should be approximately equal to (inductive load), or twice (capacitive load) the absolute value of the matched load impedance.

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[in Japanese]

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