Intercept Thresholds for the NRL Microwave Signal Intercept System
Abstract
The signal-to-noise thresholds for the headphones and the acquisition indicator of the NRL microwave signal intercept system have been determined with respect to pulse width and pulse repetition frequency of a pulse -type signal. The S/ N threshold was defined as the second-detector S/ N power ratio in db at which an average observer would detect a signal with 50-percent success. Groups of observers were used in five-frequency position experiments to determine those values of threshold which were of interest. The a c qui sit ion indicator utilized a time-frequency raster with intensity modulation and was investigated while using three different video sections: (a) main i-f video with a 250-kc bandwidth, (b) main i-f video with 10-Mc bandwidth, and (c) second i-f video. The intercept capabilities of the NRL receiver system arebest when the main i-f video section with the 250;.kc bandwidth is incorporated in the acquisition indicator . The headphones have a better S/N threshold than this indicator when the signal has a prf and pw greater than 1500 pps and 10 microsec, respectively. The S/N threshold of the receiver is improved over a limited range of signal characteristics when the second i-f video amplifier replaces the main i-f video amplifier in the acquisition indicator, but the decrease in probability of intercept capability of the receiver with the former video section more than offsets the advantage in threshold, unless a considerable amount of a priori information is available.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 15, 1958
- Accession Number
- AD1225028
Entities
People
- N. R. Garofalo
Organizations
- United States Naval Research Laboratory