Wideband Coherent Communication at VLF with the Experimental Transmitting Antenna Modulator (ETAM)
Abstract
A 1-kilowatt Experimental Transmitting Antenna Modulator (ETAM) was tested on-air at RADC. This on-air performance evaluation at 29.5 kHz employed a VLF transmitting station at Camden, New York and a receiving station at RADC, Griffiss AFB, New York. Using the ETAM, an 800 baud coherent FSK (Modulation Index of 1/2) signal was efficiently transmitted over the 160 Hz 3 dB static bandwidth transmitter/antenna system; concurrently, the signal was received and coherently demodulated with negligible evidence of intersymbol or other system degradation. On the other hand, when the ETAM was removed from the transmission system, it was necessary to derate the transmitter output by 10 db to preclude destruction of the transmitter output transformer caused by the high-Q mismatched output load; under this operating condition, it was impossible to obtain bit error rates less than 6% because of the ambient atmospheric noise and intersymbol distortion. This report describes the equipment configurations at the transmitter and receiver, the test procedures, and the quantitative results.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1973
- Accession Number
- AD0916687
Entities
People
- John T. Gamble
Organizations
- Rome Laboratory