The two-antenna problem in aeronautical mobile telemetry is created by the reception of two copies of the same RF waveform with different phases and time delays. Alamouti and Alamouti-like space time block codes can solve the two-antenna problem, but the decoder/detector needs to account for the different time delays between the signals received from the two transmit antennas. In this thesis, a comparison is made between the performance of Alamouti space-time block codes and time-reversed space-time block codes with 16-APSK to solve the two-antenna problem. The maximum likelihood decoder/detector for Alamouti-encoded 16-APSK is a sequence detector operating on a trellis with a large number of states. A practical state-reduction technique is presented. The results produce a trellis with 256 states and a small loss in bit error rate performance as long as the delay difference is not too big. The decoder/detector for the time-reversed space time block requires only waveform manipulations and channel matched filtering in the case where the two channels are simple delays. For the more general case of multipath propagation between the two transmit antennas and the receiver, the decoder/detector requires an equalizer; simulation results using a channel pair measured at a test range show that the decoder/detector is capable of achieving near AWGN performance with a modest equalizer.