There are a number of relatively independent base band processing units and carrier processing units in the system. The working frequency carrier of each carrier processing unit is fixed, the service information of each communication path is processed by fixed base band unit, and then the processed information is transferred to carrier units of different frequency carriers for processing and transmitting through bus structure according to time sequence and specific frequency hopping principles. This hopping mode is called “base band hopping”.
In base band hopping, each transmitter works at a fixed frequency, the bursts of the same voice channel are sent into respective transmitters under control for switching based on base band signal. Since the frequency of each transceiver is fixed, no change is needed on the combiner, while both broadband combiner and cavity combiner can be used.
The maximum numbers of hopping frequencies are limited by the number of TRX. The problem of base band hopping is that if one TRX board failed, the corresponding code will be lost and the communication performance will be affected.