The visibility of signals on radar range presentations

An investigation has been made of the dependence of the minimum detectable signal on a radar range presentation, on parameters of the equipment. Brightness, size of deflection pattern, and the distance of the observer from the screen caused little or no variation in signal visibility over ranges of practical values. A horizontal time base was found to be significantly better than a vertical time base. Visibility was found to increase with repetition rate by about 2 db per octave. A detailed investigation has been made of the effect of the more important variables, viz.:¿pulse length, band-width, and time-base speed. An optimum band-width equal to the reciprocal of the pulse length was found, the variation of visibility with band-width being small near this optimum value. Visibility was found to fall off rapidly for time-base speeds so slow that the width of the signal on the screen was less than the line-width of the trace. The product of pulse length and peak transmitter power should be made as great as possible. The work was carried out between November, 1942, and August, 1943.