Transmitter and automobile audio apparatus using the same

An automobile audio apparatus, comprising:

• an automobile FM radio and a transmitter for transmitting an audio signal derived from an audio appliance to the automobile FM radio, said transmitter comprising
• a transmitter circuit for converting said audio signal derived from said audio appliance into an FM signal within an FM broadcasting band and transmitting said FM signal,
• a receiver circuit having at least a tuner circuit, said receiver circuit detecting an unused frequency within said FM frequency band,
• a control circuit for controlling a transmission frequency of said transmitter circuit by setting a frequency corresponding to said detected unused frequency to said transmission frequency of said transmitter circuit, and
• a memory connected to said control circuit for storing said detected unused frequency, so that upon initial operation of said transmitter said transmitter circuit is turned off, said receiver circuit is turned on, and the transmission frequency of said transmitter circuit is set to said detected unused frequency read out from said memory, and
• a display for displaying thereon said set transmission frequency;
• and
• channel selecting means for tuning said reception frequency to said transmission frequency displayed on said display.