An Experimental Study on the Recording System Using TAT Bandwidth Compression for High-Resolution Pictures

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A high-resolution images recording system using the. TAT bandwidth compression is constructed and its feasibility is successfully demonstrated. High-resolution picture signal with 7 MHz bandwidth is compressed to the signal with a half bandwidth by the TAT system and recorded i. n VCRs. The bandwidth compressed picture signal is recorded by FM system and the control signal for the reconstruction of the picture is recorded by QPSK or M^2 (Miller Square)coding in the lower frequency band. Since the reproduced picture signal with jitter is resampled using the clock following the reproduced carrier of OPSK or clock of M^2 code, the jitter of the VCR is suppressed and the picture is reconstructed stably. The resolution of the reconstructed picture is improved 1.6 to 1.8 times over that of the non-compression system. The SN ratio is about 35 dB. The bit error rate of the control signal ranges from 10^<-7> to 10^<-5>. Since harmonic distortion observed in the reconstructed picture is caused by the transfer characteristics of the FM system, a transfer characteristics measurement system using FM signal is developed. The results of measurement show that the phase characteristic is approximately linear and varies very little with the FM recording level. The odd function components which cause the harmonic distortion are large in the amplitude characteristic and vary with the FM recording level. When the recording level is 450 mV_<p-p>, the maximum harmonic distortion is less than 6.6 %. Interference of the control signal observed in the reconstructed picture is caused mainly by the third order distortion of. FM signal and control signal. Although the interference of M^2 code is less than that of QPSK, M^2 code needs more strict equalization of the cut-off characteristic of magnetic system in the-low frequency than QPSK.