Accession Number:

AD0815855

Title:

HF ADAPTIVE MODEM TEST.

Descriptive Note:

Final technical rept. 15 Jan 66-30 Jan 67,

Corporate Author:

COLLINS RADIO CO NEWPORT BEACH CA

Personal Author(s):

Report Date:

1967-05-01

Pagination or Media Count:

60.0

Abstract:

This report presents an accumulation of experimental data from which was determined the relative performance of several modem modes for various HF channel conditions. In addition to these results, thresholds are defined for each channel condition which specifies the criteria for modem mode switching. The experimental data utilized in this report was obtained from a one-way digital data transmission test. In this test data was transmitted at rates of 1200, 1800, and 2400 bps. The tested modes include one full rate mode and three distinct half rate modes all utilizing phase-shift keying modulation with non-diversity operation. These modes are as follows 1 full rate -- multitone quaternary encoding 2 half rate -- multitone binary encoding 3 half rate -- double bit length of full rate mode 4 half rate -- half the number of tones of full rate mode. The channel conditions are identified by the processing of digitized analog sensors within the modem standard circuitry. The sampled circuits include the quadrature and in-phase detectors, and keyed filter ring outs, both on a per tone basis. The identifying channel parameters are fade rate per tone, mean phase offset per tone, phase standard deviation per tone, coherent bandwidth, and signal to noise ratio. These are used in connection with the recorded BER per mode to relate the performance with the channel condition. Author

Subject Categories:

  • Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE