Aeronautic Telemetry Channel Estimation Using Field Data

Aeronautic telemetry is prone to channel impairments like noise and multipath fading. The system under study uses PCM/FM scheme. Understanding the channel behavior will help the link designer in applying suitable mitigation mechanism like equaliser or FEC. In this paper, field data obtained from this channel is used to estimate and characterise the wireless channel, exploiting the frame sync patterns in the PCM format, without performing channel sounding experiment. The channel excitation signal is obtained by performing PCM/FM on the sync pattern. The channel response is obtained by retrieving portion of the IF signals at receiver, containing the frame sync pattern, using signal correlation. Using LMS technique, the coefficients of the assumed FIR filter model of the wireless channel are estimated. The estimation is performed on known FIR filter coefficients for validation of the process. All the algorithms are implemented in NI LabVIEW.