A vehicle system interface comprises an antenna configured to receive a
digital radio signal, a digital radio receiver circuit configured to
receive the digital radio signal from the antenna and to obtain digital
audio data from the digital radio signal, an FM modulator and transmitter
circuit, and a microprocessor in operable communication with the digital
radio receiver circuit and the FM modulator and transmitter circuit. The
microprocessor is configured to generate a first message requesting a
series of FM radio signal levels corresponding to a series of FM radio
frequencies being received by an FM radio receiver. The microprocessor is
configured to send the first message through an electrical connector to a
control system in operable communication with the FM radio receiver. The
microprocessor is configured to receive a second message from the control
system through the electrical connector indicating the series of FM radio
signal levels. The microprocessor is configured to select a suitable FM
radio frequency from the series of FM radio frequencies based upon the
corresponding series of FM radio signal levels. The microprocessor is
configured to generate a third message instructing the control system to
tune the FM radio receiver to the suitable FM radio frequency. The
microprocessor is configured to send the third message through the
electrical connector to the control system. The microprocessor is
configured to transmit the digital audio data from the digital radio
receiver circuit to the FM modulator and transmitter circuit. The
microprocessor is configured to induce the FM modulator and transmitter
circuit to broadcast the digital audio data in an FM radio signal over
the suitable FM radio frequency.