Radio telegraphy monitor with visual display - stores signal and repeatedly replays it at adjustable speed to analyse transmission

摘要

A radio telegraphy signal is monitored by measuring the times between each transition and entering them in a digital store. The signal is displayed on a TV screen with alternate times appearing as bright lines, by repeatedly reading out the stored data. The real time represented by each line of the display is continuously variable. The display can thus be adjusted to align the bright lines vertically, similar to a Hell-diagram. Hence the speed and type of transmission can be determined. The display is rolled up as transmission proceeds so that the latest signal is always being written on the bottom line. The phase of the start point can be varied, to shift the pattern sideways without changing line length or speed. The advantage of the method is that no information is lost while adjustments are being made.