The Design Of Comprehensive Digital Simulation Sources In Telemetry System

In recent years, with the rapid development of space technology, there are a wide variety of the ground telemetry data receiving equipments. It’s very important that the digital simulation sources provide synthetic data for the test of ground telemetry data receiving equipments. Most of existing digital simulation sources are specially designed for the different ground telemetry data receiving equipments, they just provide data that only have a few data rate, single frame structure and output data type. Therefore, the design of a type of digital simulation sources which can be in common use in the ground telemetry data receiving devices test has the important practical significances, the digital simulation sources have the characteristics of programmable, high scalability, and strong universality.This paper does some researches on the design of comprehensive digital simulation sources in telemetry system. The digital simulation sources produce the synthetic data stream which has the programmable frame structure, the output comprehensive data types include sinusoid, rectangular wave, saw tooth wave and triangular wave, also can be fixed number or pseudorandom code. Aiming at the technology requirements of digital simulation sources present the total design scheme. Analysis and design of the hardware circuit of digital simulation sources, detailed discuss the design of the LVDS bus, the FPGA configuration circuit, single ended output circuit, differential output circuit and power supply circuit. Describing the generated of synthetic data and the designed of control logic inside the FPGA, include the LVDS control module and data generation module, designing the communication protocol between source and host computer. Analysis of technical requirements, proposed and solved three key technology:the technology of comprehensive data code rate can be adjusted continuously; the technology of programmable frame structure; the technology of comprehensive data code conversion between NRZ-L/M/S、Bi-ΦL/M/S six code type. By using the technology of digital frequency synthesis to achieve the continuously adjustable code rate, using the PC configuration parameters to design the programmable frame structure, by using the transformation rules between NRZ-L/M/S, Bi-ΦL/M/S codes to achieve the transform output of codes. We assembles and debugs the hardware circuit of digital simulation sources, and test its performance. The digital simulation sources achieve the design requirement of technical index, it can realize the output of synthetic data stream, and the code rate, frame synchronization, output data word and code pattern can be adjusted.