Wireless signal transmission systems, methods and apparatus

A transmitter apparatus for transmitting stereo multiplexed audio signals from a received television signal having a horizontal frequency f.sub.H, comprising:

• input means for receiving right and left channel audio signals obtained by demodulation from the received television signal;
• means for adding the right and left channel audio signals to form a first combined audio signal;
• means for subtracting the right and left channel audio signals to form a second combined audio signal;
• means for modulating a subcarrier with one of the first and second combined audio signals, the subcarrier having a frequency substantially equal to 3f.sub.H to form a subcarrier modulated signal;
• means for combining the other of the first and second combined audio signals with the subcarrier modulated signal to form a stereo multiplexed audio signal;
• and
• transmitter means for transmitting the stereo multiplexed audio signal.