Development Of Testing Functions For Radio Transmitter Specification In TETRA Digital Trunked Synthesized Analyzer

Digital trunked system is a kind of advanced specialized mobile communication system that is one of the domestic key research projects of the specialized mobile communication system, which not only provides personal mobile communication but also provides lots of wireless commands and scheduling functions to users. Nowadays, the digital trunked system is applied in domestic traffic control, police allocation, air traffic control. At present, the domestic digital trunked system analyzer equipment, which is mainly imported from foreign countries, is particularly expensive. Therefore, the development of independent intellectual property rights of TETRA general analyzer has great economic significance and academic significance.In the specialized digital trunked communication system, the performance of the network is affected by the RF performance directly. The system is limited to the hardware quality and transmission distance, and has several difficult problems to solve:(1) The carrier power leaks to the adjacent frequencies, and results in crosstalk, noise and so on;(2) Due to the lack of modulation accuracy, mistakes would occur in constellation after demodulation, and leading to the increase of demodulation error rate;(3) The signal frequencies drift because of the low accuracy of the phase-locked loop and Doppler shifting.This paper overviewed the domestic and international technical edges and development situations of the digital trunked general analyzer, firstly, analyzing the requirements of emission specifications test, providing specific parameters of emission specification test based on the overall structure of TETRA digital trunked general analyzer. Using VHDL language under ISE platform of XILINX INC., four primary functions that are the communication spectrum monitoring, the adjacent-channel power monitoring, the modulation accuracy monitoring and deviation monitoring are developed.Then, the filter parameters and power estimation methods are proposed, based on Fourier transform, shifting of frequency spectrum, calculation of FIFO and demodulation principle of DQPSK. Circuits of spectrum monitoring, adjacent channel power ratio test, modulation accuracy test, frequency-offset test, eye diagram, and constellation diagram are designed.In the end, the emission specification tests of TETRA digital trucked general analyzer are developed by VHDL language, and many tests were executed for many times. Results show that the technical specifications of emission specifications test of the TETRA digital trucked general analyzer meets the expected requirements.