Digital AM transmitters

Digital amplitude modulation (AM) generates a high-quality AM signal with an overall efficiency of greater than 80%. Digital AM was introduced in March 1987 with a 10-kW solid-state transmitter. Also completed are 25-kW and 50-kW transmitters, and plans exist for transmitters up to 2000 kW. The digital AM system utilizes a high-speed 12-bit analog-to-digital converter (A/D), a digital modulation encoder, and a power-multiplying digital-to-analog converter. The latter reconverts the digital information back to analog to form an AM signal. Use of this system results in an AM transmitter with outstanding efficiency, audio performance, and reliability