covert@CASTOR.DEC (John Covert) (10/19/85)
The first two tones can vary, but the last tone is always the same. This provides a binary encoding indicating four different meanings. Tone 1 Tone 2 Tone 3 Low: 913.8 Hz 1370.6 Hz High: 985.2 Hz 1428.5 Hz 1776.7 Hz Low tone is always 274 ms, High is 380 ms Category: Reorder Low High Vacant Code High Low No Circuits High High Intercept Low Low /john