An Experiment with Polarization Diversity Combining for Aeronautical Mobile Telemetry

Abstract

The post-equalizer bit error rate performance of SOQPSK-TG operating maximum ratio combined RHCP and LHCP antenna outputs is compared to the case of combined vertical and horizontal polarized antenna outputs. To perform the comparison, an experiment was conducted to measure multipath channels in an indoor environment using a single monopole transmit antenna with a variable orientation and two receive antennas in a cross-polarized configuration. The impulse responses where computed from the received signals and used in computer simulations to estimate the post-equalizer bit error rate. The results show that the post equalizer bit error rate performance of maximum ratio combined RHCP and LHCP channels is the same as that of maximum likelihood combined and maximum ratio combined vertical and horizontal channels. The current practice in ground stations (maximum ratio combining of RHCP and LHCP antenna outputs) is capable of achieving optimal performance.