Research And Development Of Baseband Signal Processing Module In TETRA Protocol Analyzer

ABSTRACT:TETRA protocol analyzers, which are used for the protocol conformance test of TETRA equipments, can guarantee the interconnection between the infrastructure and terminal equipments in different manufacturers. Because the baseband signal processing module in the TETRA protocol analyzer has the function of digital downconversion, demodulation, synchronization and decoding, it is an important part in the TETRA protocol analyzer. Therefore, the research and development of the baseband signal processing module is one of the key technologies in the development of the TETRA protocol analyzer.Based on summarizing the development situation of protocol analyzers for kinds of mobile communication systems, first of all, the functional requirements of the TETRA protocol analyzer are analyzed, and the overall structure of the TETRA protocol analyzer is stated in this paper. Then according to the basic principles of digital downconversion, π/4-DQPSK modulation and demodulation, synchronization, descrambling, deinterleaving, RM code, RCPC code and CRC check, the overall design of the baseband signal processing module in the TETRA protocol analyzer is given, the processing procedure of the digital downconversion module, the π/4-DQPSK differential demodulation module, the synchronization module, the time base module, the logical channel identification module, the descrambling module, the deinterleaving module, the RM decoding module, the RCPC decoding module and the CRC check module are designed in detail. Next, on the xc6vlx240t hardware platform based on look-up table, the digital downconversion module, the π/4-DQPSK differential demodulation module, the synchronization module, the time base module, the logical channel identification module, the descrambling module, the deinterleaving module, the RM decoding module, the RCPC decoding module and the CRC check module are developed by the VHDL programming language, in order to implement the baseband signal processing functions in the TETRA protocol analyzer. Finally, based on chipscope online testing solutions, the digital downconversion module, the π/4-DQPSK differential demodulation module, the synchronization module and the decoding module of baseband signal processing module are tested, and the resource utilization of the baseband signal processing module and the maximum system clock are given, and the results of tests show that the functions of TETRA signal’s digital downconversion, demodulation and synchronization are implemented by the baseband signal processing module, and the logical channel can be automatically identified and decoded, which can satisfy the demands of users.