Program swallow counting device using a single synchronous counter for frequency synthesizing

Claim 1

A high speed programmable swallow counting device for dividing repetitive high frequency pulses to produce a predetermined frequency ratio, said counting device including a prescaler means coupled to a source of high frequency pulses, said prescaler means being capable of providing division of said high frequency pulses by either of two moduli in response to control input signals, comprising: a single synchronous counter coupled to the output of said prescaler means; memory means containing information related to two preselected numbers, said first number being a counter state at which the prescaler is to be directed to change to divide by the lower magnitude of said two moduli, said second number being the counter state at which the predetermined frequency ratio is achieved; and comparator means, coupled to said single synchronous counter and said memory means, supplying a control signal to said prescaler when said single synchronous counter reaches said first state and a second control signal to reset said single counter when it reaches said second state, whereby said first number is temporarily stored in said single counter as a counter state during the change of modulus in the prescaler with synchronous counting continuing from the counter state, and swallow counting is thereby achieved by means of a single synchronous counter.