Development Of Telemetry Noise Data Real Time Lossless Compression Equipment

The main purpose of the Telemetry Noise Data Real Time Lossless Compression Equipment is to achieve telemetry noise measurement system lossless data compression at simulation prototype stage and complete the corresponding verification test. The equipment complet the acquisition of noise signals and lossless compression, and finally compressed data will be transported to data integration device through the digital communications interface.Normally, one channel noise data of telemetry data reach the capacity of the general 160Kbps, a large number of noise data occupy considerable volume of the system, but the bandwidth of telemetry channel is limited.In order to complete more of the noise parameters measurement, we need to fully research the characteristics of the noise data and design an effective dynamics and real-time compression equipment, so that the pressure of system capacity and bandwidth will be greatly reduced, and so it can better and more complete measurement of the project and content the overall measurement demand.This paper analysis the target characteristics of real-time lossless compression (telemetry noise) first, which studied the produce mechanism of signal noise, the time domain,frequency domain characteristics, quantify parameters of the noise data, code probability distribution and so on; In the selection of lossless compression algorithm on the basis of these indicators such as decreased rate, compression rate, compression efficiency, according the comparison of several compression algorithms, the final selection of the practical application of this system is the LZARI algorithm. The equipment noise adopt complex programmable logic device (CPLD) and digital signal processor (DSP) architecture based on the telemetry noise data characterics analysis and comparison of lossless compression.The equipment use the CPLD to realize data acquisition, buffering, pre - processing, and coordination the work of the various parts of the equipment.The equipment use DSP to realize lossless compression and upload the compressed data to telemetry system or PC through the 422 bus.Practical application of the equipment in the sampling rate of 27KHz, the average compress decreased rate could reach 60-80%, the quantizing precision could reach 8 bit. Lots of experimentations on compressing and decompressing noise data show that the device could work normal and meet all the design requirements.