| 摘要 |
PURPOSE:To transmit PCM(pulse code modulation) audio data to a remote place with a weak radio wave equipment by providing a spread spectrum transmitter which subjects PCM audio data to spectrum spreading with a spreading code and modulates and sends it and a spread spectrum receiver which demodulates the received signal with the spread code. CONSTITUTION:PCM audio data Da is subjected to spectrum spreading in the transmitter with a spreading code RND generated by a code generating circuit 8, and a carrier wave is modulated by the signal obtained as the result and is sent. With respect to the signal received by the receiver, a correlation detection signal Sa is delayed by a time corresponding to one period of the spread code RND and is outputted when the input signal is matched to a preliminarily set phase pattern in a matched filter 19, and the received signal is demodulated to PCM audio data Da. Thus, the power density is spread in a wide frequency range to transmit the signal, and the communication distance is extended even when the allowable power is weak. |
