We have developed HDTV CODEC (encoder and decoder) applyed to the digital transmission system through the satellite channel of 36MHz bandwidth Ku band transponder. In the encoder, input data, 1 channel of video and 4 channels of audio, are compressed efficiently and are multiplexed. Then, Reed- Solomon coding is performed to the multiplexed data. Video compressing scheme is based on frame / field adaptive motion compensated prediction and DCT algorithm. In the decoder, reconstracted images have excellent quality in spite of its 1/30 compression ratio.
We have developed and introduced "Frequency Synchronizing System" for our Am broadcasting to reduce Co-channel interference. The carrier beating and the platform-motion are the two embarrassing aspects in listening to an Am broadcasting in existence of the co-channel interference. We have thought up this device with and intention to reduce such harmful phenomena. The frequency difference between the transmitting and the interfering signal is measured at a remote place. The frequency synthesizer at the transmitting station is adjusted according to the measured data so that the transmitting frequency is synchronized to the interfering signal.
In Am stereo broadcasting suing the C-QUAM format, a rigorous technique has not yet been established for measuring the degree of phase modulation when modulating the difference signal and left or right signal. This has become and important item of investigation among those involved in implementing AM stereo systems In response to this situation, the authors use Lissajous waveformes drawn our by the nonmodulated propagation wave and the modurated waves to clariful measurement principals, and propose a method for measuring the degree of phase modulation in AM stereo that has sufficient accuracy and no measurement-system variable factors.
Reception system of terrestrial television broadcasting for vessels is studied. The computer automatically controls direction of recieving antennas using location data of the vessels and broadcasting stations, and so on. The validity of this system is proved by the experimant on the ferry boat to which this system was loaded. Further, we have studied the methods how to transmit recieved signsls to existing television signals distribution system of vessel.