Generation of Test Signals for IS-136 (NADC) with Signal Generator SME

Communication systems according to IS-136 (NADC) use Time Division Multiplex Access (TDMA) for the communication between base station and mobile stations. There are 6 time slots available. Depending on the amount of data, which have to be transmitted, the system uses full rate channels or half rate channels. A full rate channel means, that the mobile is accessed every 3rd time slot (e.g time slot 1 and 3, time slot 2 and 4 or time slot 3 and 6). With half rate channels the mobile is accessed every 6th time slot. Full rate and half rate channels may be mixed on demand. The base stations transmit continous on their frequency. Depending on the used combination of full rate and half rate channels the base station uses a different sequence of synchronisation words. The mobile stations use bursted transmission with one of the synchronisation words S1 to S6 defined in the standard. Signal Generator SME is excellently suited to generate these signals to test either base station receivers or mobile phone receivers. Together with the modulation data supplied with this application note the SME serves as a signal source for various test and measurement applications in the whole frequency range of IS-136 (NADC).