ABSTRACT
The measurement of the fidelity of a digital transmitter is an expression of the variation of the waveform from the ideal. Digital transmission is deterministic—the Radiofrequency energy has precise and well-defined values at defined periods of time. The modulation error ratio is a measure used to quantify the performance of a digital television transmitter or receiver in a communications system. Single-frequency networks require that all transmitters have identical waveforms transmitted at the matching frequency. Solid-state transmitters for UHF and VHF are highly similar. In the real world, a transmitter, when operated in a temperature-controlled environment, will operate with no significant variations in performance over a long period of time. In many ways, the transmitter control systems are the most important and most difficult-to-design piece of a transmitter. The transmitter might be shipped with the amplifiers and other components installed, but it is more common for them to be integrated on site.
