Abstract: A noise blanker circuit protects a signal processing circuit from unwanted noise spikes by interrupting the signal path when it exceeds a preestablished threshold or reference level. The detector itself is a two branch detector that has in one branch a variable gain amplifier that is controlled by an automatic gain control signal and a comparator. The other branch of the circuit has a delay network which delays the signal by the propagation delay of the variable gain amplifier in the comparator and applies it to a switch, which when activated by the output signal from the comparator, will interrupt the second branch to ground and thus protect the remainder of the circuit.

Abstract: An automatic gain control circuit utilizes sampling techniques to vary the time constants of the automatic gain control circuits. The time constants are easily programmed by changing the sample rates instead of changing the RC time constants contained within the differentiator of the prior art circuits.

Abstract: Variable rate digital control of a frequency synthesizer is afforded by periodically generating a digital signal from among a plurality of such digital signals representative of various tuning rates, converting each digital signal to a digital control word through a rate decoding means in which each control word is associated with at least one of the digital signals, applying the control words to a digital counting means having a plurality of counting rates, with each rate being determined by a different one of the control words, and applying the digital count of the digital counting means to the frequency synthesizer to control its frequency.