| 摘要 |
In a communications system employing HF radio transmission a message to be transmitted is subjected to time spreading modulation prior to transmission. The time spreading modulation results in processing gain at the receiver with either resultant transmission range increase, which is particularly beneficial in the case of inefficient antennae, or limited transmitter power, or permitting lower power to be used for a predetermined transmission range. A message 5 at a first bit rate is multiplied at 6 by a pseudo random spreading sequence 7 at a higher bit rate, and the resultant data stream is modulated at DPSK modulator 4 prior to transmission. <IMAGE> |
