Designing And Implementation Of Telemetry Real-time Processing System Based On IP Multicast Technology

Telemetry technology is a comprehensive technology which includes sensing, data acquistion, communication, and data processing, and is widely used in military test and civil field. Real-time pre-processing for telemetry data system means that telemetry data, which central transmitted to the data processing center through the network, is recorded, displayed, picked and processed. And pre-processing for telemetry data must be demodulated after received by telemetry ground station. In the flight test, the system is used to give accurate real-time status data, so that before launch the commander could make a decision whether to transmit; during the flight, the critical telemetry data could be processed in real time, and the results are transmitted to the command center for monitoring, and as a basis to control testing; uplink remote control commands could be checked up in real time; telemetry processing results could be quickly provided to help to analyze fault in case test fail happens. IP multicast technology can transmit telemetry data to the processing system remotely and is a very important way to ensure test security and shorten the period. It not only plays important role in the telemetry parameter processing, the GPS processing of exterior ballistic measurement and the display processing of telecontrol data, but also has huge value in decision and evaluation for aircraft test.This issue researches on transmitting without frame dropping multiple streams of telemetry data to a processing central by IP multicast protocol; on establishing telemetry data processing channels for single-stream and finishing real-time preprocessing; so management and coordination jobs could be realized by monitoring terminals. In the process of system implementation, by mainly using the programming methods of object-oriented, multithread, dynamic link library and the technology of IP multicast, information sharing. The real-time storage, display and processing are realized by the system. Compared with the traditional telemetry processing method which is single data stream and low code rate, this system can complete more complex processing job on the real-time condition to be ensured. This system has a breakthrough in systematic flexibility and compatibility which make itself no longer a special software, so repeated development could be avoided and construction investment could be saved.Real-time pre-processing for telemetry data system guarantees in real-time the measurement and control method of telemetry?exterior ballistic measurement and remote control in the test; solves the problem of losting frames and large delay in real-time network transmission for multi-stream telemetry data; and realizes the function which preprocess various types of telemetry parameters and pick up GPS or telecontrol data; so that the real time and versatility for TT&C system are ensured. At present, this system has been tested many times. Testing results show that this system could get to the technical requirements in the data storage, display, communication, picking road processing. Therefore it can meet the test needs.