Theory of Frequency Counting and Its Application to the Detection of Frequency-Modulated Waves

Electronic circuits of the "frequency-counting" type furnish, in response to a sinusoidal signal of frequency ω/27π, a continuous signal proportional to ω. It may then be expected that, within certain limits, if the frequency ω is modulated, this "continuous" signal output will reproduce the modulation. In this paper are studied, first, the validity of this principle of detection of frequency-modulated waves, with observations on the subject of detection in general, and second, the methods employed for carrying into effect the electronic counting.