Test experience using marine radiobeacons for DGPS communications

Using prototype DGPS (differential Global Positioning System) modulator-demodulator hardware, a radio beacon was modified for interference testing of a representative set of manual and automatic direction finding units. DF (direction finding) bearing errors were recorded with and without the DGPS subcarrier, while subcarrier offset, data rate, and subcarrier power levels were varied. In a second test, DGPS channel bit error rates were studied using actual atmospheric noise and a prototype modulator-demodulator with error correction. Details of both testing efforts are given and test results are compared to previous theoretical analyses