Browse Prior Art Database

Variable Frequency Square Wave Clocking System

IP.com Disclosure Number: IPCOM000094575D
Original Publication Date: 1965-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Leonardi, JR: AUTHOR

Abstract

The drawing shows a conventional system for demodulating pulses that represent binary data by their phase relationship to a clock signal that is kept synchronized with the data. The system has an improved clock and clock frequency control circuit.

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Variable Frequency Square Wave Clocking System

The drawing shows a conventional system for demodulating pulses that represent binary data by their phase relationship to a clock signal that is kept synchronized with the data. The system has an improved clock and clock frequency control circuit.

In this system, a demodulator receives data pulses that are appropriately shaped by an amplifier limiter. It also receives signals from an oscillator and a sample and squelch pulse generator. It produces a binary output according to the input data.

For providing a reference for the clock frequency, such systems also usually include a circuit to derive from the input data a pulse for each bit period. A peak pulse circuit is connected to receive the signal at the amplifier limiter output and to produce a signal at the beginning and middle of each bit period. A delay device connected to the output of the oscillator produces a signal that corresponds to about the middle of the bit period. A logic circuit is connected to the output of the peak pulse and responds to signals from the delay device to transmit pulses that appear at the peak pulser output in the middle of the bit period.

The clock for this system is a square-wave oscillator of the type that varies its frequency in response to an input signal. The frequency control for the oscillator includes a delay and width compensation circuit that receives pulses from the logic circuit and produces complementary pulses P and P. T...