Dynamic Image Quality Analysis and Comparison between 6MHz and 8MHz Bandwidths for DVB-C Digital TV System

Abstract

The object of this research is to analyze and compare the dynamic image quality between the DVB-C digital TV systems with bandwidth of 8 MHz and 6 MHz, in Europe and in Taiwan, respectively. Under the RF output level from -50dBm to-79dBm, with carrier modulation of either 64QAM or 256QAM, we simulate the dynamic image transmission over the digital TV system with standard measuring equipment on the following criteria, namely, the picture quality rating (PQR), the differential mean opinion score (DMOS), and the peak signal to noise ratio (PSNR). The standard measuring equipment, which is the property of the Telecommunication Technical Center (TTC), is composed of the instruments from the Tektronix and the Rode & Swazi (R & S). Based on our experiment setup, under the 64QAM carrier modulation at -78dBm level, the scores for the above three criteria, i.e., PQR, DMOS, and PSNR, are 4, 11, and 33, respectively for the European DTV system. Under the 64QAM carrier modulation at -72dBm level, the scores for the above three criteria, are 5, 14, and 38, respectively for the Taiwan DTV system. Under the 256QAM carrier modulation at -73dBm level, there is observable mosaic on the image for the European system. However, under the 256QAM carrier modulation at -68dBm level, there is serious mosaic on the image for the Taiwan system.