Inventors:
John R. Cressey - College Pk. MD
Stephen A. Miller - Baltimore MD
Assignee:
Case Communications Inc. - Silver Spring MD
International Classification:
H03B 372
Abstract:
Characteristics of a pulse sequence, such as frequency, are controlled in a simple circuit without requirement for specific storage components. The cumulative effect of a sequence of control signals is maintained by providing a phase shift between a pair of waveforms. The phase shift between the waveforms is used to provide a number of control pulses to the circuit for varying the desired characteristic. In a particular embodiment, control signals are externally provided for varying the phase shift between two waveforms. In response to the phase variation, a number of control signals are provided for adding or deleting pulses to a pulse stream. The use of feedback control loops results in repeated addition and/or deletion of pulses to or from the pulse stream, thereby varying the output frequency in accordance with a one time input of the external control signals. In accordance with the principles of the invention, serial or parallel control signals may be provided, and ripple counters (or a combination of ripple and presettable counters) may be used for the frequency control function.