A system includes a radio frequency (RF) receiver having an input, and an antenna terminal configured to connect to an antenna. The system further includes one or more switches that switch the receiver input of the RF receiver to connect to a terminating load that is not an antenna or to an internal antenna, and noise level measurement circuitry that measures a first RF noise level across the terminating load or the internal antenna. The one or more switches further switch the receiver input of the RF receiver to connect to the antenna terminal, and the noise level measurement circuitry further measures a second RF noise level received at the antenna terminal. The system also includes a controller that determines whether an external antenna is connected to the antenna terminal based on the first RF noise level and the second RF noise level.