| 摘要 |
In order to protect transmitted data signals, transmitter-receivers are used that communicate with each other with an unequivocal and synchronous channel switching sequence. In addition to common switches for signal processing, each transmitter-receiver includes for this purpose a program part (22) for a channel switching sequence and a clock generator device (24, 26) synchronized by a public radio time signal as well as a channel select circuit (20) and a channel switch (10). In case of a call, the receiving and the transmitting devices are adjusted to a given channel switching sequence depending on the identification number of the receiving device so that participation of other devices is excluded. Channel switching is effected at a relatively high frequency of approximately 1 MHz with the purpose of excluding any possibility of connection being interrupted by a more powerful transmitter as is the case in conventional CB radio systems. The transmitter and the receiver can be easily and rapidly synchronized on the basis of the public time signal. |
