A saturable-core modulation differentiator

In signal transmission systems employing suppressed-carrier modulated signals, it is often desirable to operate on the modulation in order to stabilize the system or alter its performance. The circuit discussed in this paper is an illustration of techniques which employ saturable-core reactors (SRs) for operating directly on the modulated carrier.¹ It is based on the ability of an SR to convert a voltage integral to a magnetic flux and store it until needed. The experimental circuit is a differentiator having a zero voltage gain at zero frequency and an output linearly proportional to the rate of change of the modulation voltage up to frequencies approaching that of the carrier.