Controlling a tower-top low noise amplifier (TTLNA) without transmit mode or receive mode timing control signals from a base station. The TTLNA system and associated components autonomously determine the proper mode of operation (transmit/receive), and automatically control the operation of a low noise amplifier (LNA) to prevent signal distortion and/or damage to the wireless system hardware. A preferred method comprises: at a TTLNA, measuring a transmit time period based on detecting radio frequency (RF) transmit signal energy; determining a receive time duration based on the measured time period and a predetermined frame time; and, configuring the TTLNA to a receive mode by placing a low noise amplifier into a receive signal path during the determined receive time duration.