Increasing transmission range of missile telemetry data with compression techniques

Dictionary definition of the word 'telemetry' is 'measurement from a distance'. Telemetry notion thus has been used to define the applications aiming to control or observe a system remotely, to record instantaneous data obtained from these systems (via various measurement devices) and to collect all relevant performance data in a data center. Currently, electrical facilities, natural gas production facilities, communication systems, biomedical systems, space stations and vehicles are some of the major areas that use telemetry for their measurements. Also; the design stage of aircrafts, rockets and missiles require telemetry applications as they require validation of design by comparing performance data from actual vehicles. Telemetry data of a missile in design stage, typically include measurements of various on-board sensors, GPS (Global Positioning System) data, guidance commands created by the missile computer, position of flaps and so on. These data are collected by an internal processor and later transmitted via wireless communication to a ground station, where they can be investigated by the design engineers to see if they align with pre-flight predictions. In Turkey, there are on-going design and production work for different types of missile projects; created by the needs of Turkish Armed Forces and the state. For the flight tests, different test ranges are assigned according to the requirements of different projects and many telemetry tests are performed with success each year. The collected telemetry data are then used to see if the design engineering was performed in the right way to obtain a missile meeting the requirements of that certain project. This critical role of telemetry tests lead to the importance of collecting as much data as possible with minimum error. Compression of telemetry data pre-transmission shows itself as an answer to the question of increasing the amount of data obtained per-flight. Literature search for usage of data compression methods for missile/rockets, show results in mostly applications of compression in the data recording/storing stage. However, data bandwidth in missile telemetry tests limit the communication range of the test and amount of information obtained in the test and data compression performed on-board might be a solution for this problem. This study aims to investigate the effects of data compression, thus decreased data bandwidth on the RF communication range in missile telemetry tests. For this purpose, different data compression methods are performed on fabricated (assumed) telemetry data, the decrease in data amount are compared and effects on RF parameters are investigated using link budget calculations. Other communication parameters such as signal modulation type, receiver specifications, antenna types, etc. are accepted as constants to see the effect of data size only. The results are compatible with the hypothesis; as they show increase in communication range after a decrease in data bandwidth, as expected.