A Decoder with VSB Compensation and Field-Sequential Transmission System of Chrominance Signals Improves Picture Quality

Abstract

In the NTSC system, high frequency characteristics of chrominance signals are degraded by simple decoding of chrominance signals transmitted by VSB (Vestigial Side Band). Color sharpness therefore deteriorates. A system is proposed that expands the bandwidth of the Q-signal (narrow bandwidth chrominance signal of the NTSC system) up to 1.5 MHz-the same as the I-signal-by field-sequential transmission of high frequency chrominance components. The design of a decoder with VSB compensation, and its improvement of picture quality, are discussed.
The characteristic required of a decoder filter are analyzed, and a suitable circuit requiring minimal hardware is proposed. As evaluated by subjective tests, field-sequential transmission and VSB compensation improved picture quality.