FM transmission system and method

An RF transmission system comprising:

• an RF transmitter receiving a base band media signal and generating a broadcast signal on a broadcast frequency, the broadcast frequency being a one of a plurality of transmission frequencies within a frequency band;
• a radio data control module:
• periodically performing an interference detection measurement to determine whether an interfering signal at the broadcast frequency exceeds a threshold criteria, and
• selecting an open frequency if an interfering signal at the broadcast frequency exceeds the threshold criteria, the open frequency being one of the plurality of transmission frequencies wherein RF interference is within predetermined acceptance criteria;
• and
• driving the RF transmitter to transmit an identification of the open frequency on the broadcast frequency and, following such transmission, to switch the broadcast frequency to such open frequency;
• and
• further comprising an RF receiver:
• receiving a tuning frequency identification signal from the radio data control module, the tuning frequency identification signal indicates an identified frequency, the identified frequency being a one of the frequencies within the frequency band;
• receiving an RF signal on the identified frequency;
• providing an indication of the received RF signal to the radio data control module;
• and
• selecting an open frequency comprises determining RF interference at each of a plurality of transmission frequencies within the frequency band by:
• providing a sequence of frequency identification signals to the RF receiver;
• receiving an indication of the received RF signal at each of the sequence of identified frequencies;
• and
• the acceptance criteria is the frequency with the weakest interfering signal.

An RF transmission system comprising:

• an RF transmitter receiving a base band media signal and generating a broadcast signal on a broadcast frequency, the broadcast frequency being a one of a plurality of transmission frequency within a frequency band;
• a radio data control module:
• determining RF interference at each of a plurality of transmission frequencies within the frequency band;
• selecting an open frequency, the open frequency being one of the plurality of transmission frequencies wherein RF interference is within predetermined acceptance criteria;
• and
• driving the RF transmitter to transmit an identification of the open frequency on the broadcast frequency by mixing, onto the base band media signal, a digital indication of an alternate frequency command and a digital indication of the open frequency, and, following such transmission, to switch the broadcast frequency to such open frequency.

A portable device comprising:

• a media application generating an audio media signal;
• an RF transmitter receiving the audio media signal and generating a broadcast signal on a broadcast frequency, the broadcast frequency being a one of a plurality of transmission frequencies within a frequency band;
• a radio data control module:
• periodically performing an interference detection measurement to determine whether an interfering signal at the broadcast frequency exceeds a threshold criteria,
• selecting an open frequency if an interfering signal at the broadcast frequency exceeds the threshold criteria, the open frequency being one of the plurality of transmission frequencies wherein RF interference is within predetermined acceptance criteria;
• and
• driving the RF transmitter to transmit an identification of the open frequency on the broadcast frequency by mixing, onto the base band media signal, a digital indication of an alternate frequency command and a digital indication of the open frequency, and, following such transmission, to switch the broadcast frequency to such open frequency.

A portable device comprising:

• a media application generating an audio media signal;
• an RF transmitter receiving the audio media signal and generating a broadcast signal on a broadcast frequency, the broadcast frequency being a one of a plurality of transmission frequencies within a frequency band;
• a radio data control module:
• periodically performing an interference detection measurement to determine whether an interfering signal at the broadcast frequency exceeds a threshold criteria,
• selecting an open frequency if an interfering signal at the broadcast frequency exceeds the threshold criteria, the open frequency being one of the plurality of transmission frequencies wherein RF interference is within predetermined acceptance criteria;
• and
• driving the RF transmitter to transmit an identification of the open frequency on the broadcast frequency and, following such transmission, to switch the broadcast frequency to such open frequency;
• and
• further comprising an RF receiver:
• receiving a tuning frequency identification signal from the radio data control module, the tuning frequency identification signal indicates an identified frequency, the identified frequency being a one of the frequencies within the frequency band;
• receiving an RF signal on the identified frequency;
• providing an indication of the received RF signal to the radio data control module;
• and
• selecting an open frequency comprises determining RF interference at each of a plurality of transmission frequencies within the frequency band by:
• providing a sequence of frequency identification signals to the RF receiver;
• receiving an indication of the received RF signal at each of the sequence of identified frequencies;
• and
• the acceptance criteria is the frequency with the weakest interfering signal.