The in-band characteristics of the vestigial side band emitted signal for ATV digital terrestrial broadcasting

摘要

The characteristics of the signal emitted from the vestigial side band ATV digital terrestrial broadcast transmitter is examined as regards the parameters which determine the quality of the broadcast signal. Only inband characteristics are examined. The band edge characteristics-both upper and lower-are defined in terms of the frequency domain and the resulting time domain data pulse shape is examined. Intersymbol interference affecting eye closure is treated using an example of a transmission line VSWR caused by antenna reflections. The error vector magnitude is shown to fully characterize the quality of the emitted signal. Included in the error vector magnitude is the above intersymbol interference caused by linear distortion such as echoes, channel magnitude ripple and tilts which have not been removed by pre-equalization. Also included are noise-like components caused by non-linear high power amplifiers and random noise caused by transmitter circuits using solid-state devices and electron beams. An error vector magnitude limit value is proposed for the terrestrial broadcast signal.