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

一种高分辨率图像记录系统。构建了TAT带宽压缩算法，并成功论证了其可行性。7 MHz带宽的高分辨率图像信号经TAT系统压缩为半带宽的信号，录在录像机中。带宽压缩后的图像信号由调频系统记录，用于图像重构的控制信号在较低频带采用QPSK或M^2（米勒平方）编码记录。由于对带有抖动的再现图像信号采用OPSK再现载波后的时钟或M^2码的时钟进行重采样，从而抑制了录像机的抖动，稳定地再现了图像。重建图像的分辨率比非压缩系统提高了1.6 ~ 1.8倍。SN比约为35db。控制信号误码率范围为10^<-7> ~ 10^<-5>。由于在重构图像中观测到的谐波失真是由调频系统的传输特性引起的，因此开发了一种利用调频信号进行传输特性测量的系统。测量结果表明，相位特性近似线性，随调频记录电平变化很小。引起谐波失真的奇函数分量在幅值特性上较大，且随调频录音电平的变化而变化。当记录电平为450 mV_<p-p>时，最大谐波失真小于6.6%。在重构图像中观察到的控制信号的干扰主要是由三阶畸变引起的。调频信号和控制信号。虽然M^2码的干扰比QPSK小，但与QPSK相比，M^2码对磁系统低频截止特性的均衡要求更严格。

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.