| 摘要 |
A frequency hopping MFSK radio system which transmits one symbol on each channel is arranged to transmit a header control block encoded using a powerful error correcting code on all available channels before message transmission commences. This header control block contains a sequence of flags identifying a subset of the available channels which are least occupied. The information from which the flags are set is contained in a probability table which is updated from at least one of the following: the output of a receiver decoder for decoding an error correcting code applied to the data to be transmitted relating to the presence and channel position of errors detected in received data; channel spectrum information derived from an MFSK demodulator at the receiver; and the setting of an automatic gain control device at the receiver. |
