After Sales Technical Documentation TACS SYSTEM OVERVIEW Original, 09/94 NMP Part No.
TACS System Overview After Sales Technical Documentation AMENDMENT RECORD SHEET Amendment Number Page 2 Date Inserted By Comments Original, 09/94
After Sales TACS System Overview Technical Documentation TACS SYSTEM OVERVIEW CONTENTS Page No Cells 5 Channels 5 Control Channels 5 Voice Channels 6 Tone Signalling 6 Power–up Mode 6 Idle Mode 6 Access 7 Transmitter Power Control 7 Hand–off 7 Call Termination 8 Cellular Initiated Call 8 Original, 09/94 Page 3
TACS System Overview After Sales Technical Documentation [This page intentionally left blank] Page 4 Original, 09/94
After Sales TACS System Overview Technical Documentation Cells The Cellular System allows a large number of users to perform direct dialling from a cellular or portable telephone. The main difference between a cellular system and the older radio telephone systems is the re–use of the channels which allows more efficient use of the allocated frequency spectrum giving rise to a much larger number of users.
TACS System Overview After Sales Technical Documentation Voice Channels Voice channels are used for both conversation and data transfer such as Hands–off, Telephone Output Power Control and special local control features. Data transfer between the Cell Site and the telephone is at a rate of 8 kbits/s using FM. Data is formatted into groups of words with a binary preamble for synchronization purposes.
After Sales TACS System Overview Technical Documentation Access The telephone uses the access channel to acknowledge the paging message, at the same time notifying the system of its identification and cell location. The system responds by assigning a voice channel together with power level and SAT code information. The telephone receives the command, tunes to the assigned voice channel, adjusts its transmitter power level, then transponds the SAT back to the cell site.
TACS System Overview After Sales Technical Documentation Call Termination On termination of the call by the party calling the telephone, the MSC transmits, via the cell site, a release order which the telephone acknowledges by sending a signalling tone prior to ceasing transmission. If the call is terminated by the user of the telephone, a burst of signalling tone informs the MSC to terminate the connection.
