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

一种高分辨率的图像记录系统。构造了TAT带宽压缩算法，并成功地论证了其可行性。TAT系统将带宽为7 MHz的高分辨率图像信号压缩为半带宽的信号，并记录在VCR中。带宽压缩的图像信号由调频系统记录，重建图像的控制信号在较低频段用QPSK或M^2(米勒平方)编码记录。由于利用OPSK重放载波后的时钟或M^2码的时钟重采样具有抖动的重放图像信号，因此VCR的抖动被抑制，图像被稳定地重现。重建图像的分辨率比非压缩系统提高了1.6~1.8倍。信噪比约为35分贝。控制信号的误码率范围为10^-7~10^-5。针对调频系统传递特性引起的重建图像中的谐波失真问题，研制了一种利用调频信号测量传递特性的系统。测量结果表明，相位特性近似为线性，且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度特性上很大，并且随调频记录电平而变化。当记录电平为450 mV&lt；p-p&gt；时，最大谐波失真度小于6.6%。在重建图像中观察到的控制信号的干扰主要是由的三阶失真引起的。调频信号和控制信号。虽然M^2码的干扰比QPSK码小，但M^2码比QPSK码对磁系统截止特性的均衡性要求更严格。

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.