A trainable transceiver for learning and transmitting an activation signal that includes an RF carrier frequency modulated with a code for remotely actuating a device, such as a garage door opener. The trainable transceiver preferably includes a controller, a signal generator, and a dynamically tunable...http://www.google.com/patents/US20060234670?utm_source=gb-gplus-sharePatent US20060234670 - Transceiver with closed loop control of antenna tuning and power level
