| Most of leading countries in aviation industry generally adopt IRIG-106 telemetry standards and PCM(Pulse Code Modulation)in the field of filght-test, which can transmit airborne test data from an aeroplane to a ground station in single-direction, and ensure maximum transmission distance of 300 kilometers. Telemetry experts predict an aeroplane’s bandwidth demand in filght-test will increase by 900% over the current bandwidth of 10 M in 10 years. The S-waveband spectrum allocated to flight-test is only 2.2~2.4GHz, and the total bandwidth is too narrow to tramsmit large amounts of airborne test parameters and videos from aeroplanes to ground station.In order to relieve the urgent demand for telemetry frequency resources in filght-test, a single-direction wireless link which can transmit airborne test data is designed and implemented upon the basis of commercial wireless network.The advantages and disadvantages of PCM telemetry in flight-test are analyzed, and wireless network protocol IEEE802.11 b is analyzed, the system architecture of the single-direction wireless link suitable for airborne data transmission is introduced.The single-direction wireless link budget is made, its hardware are designed, including the combination of MIPS32 M14 K processor and Atheros AR6101 x chips. Also the Linux drivers for wireless network card are developed.The overall tests are made, and on the basis of ground tests the single-direction wireless link is installed on an aerotransport and the filght tests have been carried out. The test results show the design ideas of the system are correct, each module and the function of the system achieve the expected purpose of the design. It’s able to meet the demand for airborne flight-test real-time telemetry, and find a new way to tramsmit airborne test parameters and video. |
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