Browse Prior Art Database

Digitizing Noise Level

IP.com Disclosure Number: IPCOM000097427D
Original Publication Date: 1962-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Rumble, DH: AUTHOR

Abstract

This circuit digitally measures the noise level in a communication channel. When coupled to a magnetic tape recorder having channel and time markers, it produces a record. This is susceptible of statistical analysis of the incidence of noise for correlation with the record of transmission error rate recorded from other sources.

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Digitizing Noise Level

This circuit digitally measures the noise level in a communication channel. When coupled to a magnetic tape recorder having channel and time markers, it produces a record. This is susceptible of statistical analysis of the incidence of noise for correlation with the record of transmission error rate recorded from other sources.

The output, including the transmitted data and noise, from receiver 10 is passed through narrow band pass filter 11 to rectifier 12 to yield an analog voltage V. The magnitude of V is proportional to the overall noise in the channel. Voltage V is converted into pulses whose width is proportional to V through use of the phenomenon of the storage delay of the carriers across a transistor junction. If V is negative, the short, fixed amplitude negative clock pulse to which V is added causes a large base current in transistor 13, driving it deeply into saturation.

Since the recovery time of 13 is a function of the depth of saturation, the length of the pulse output from it is proportional to the magnitude of the analog V, and thus, the system noise. This varying width output pulse from transistor 13 is digitized by gate 14, oscillator 15, and counter 16. V, an analog measure of the system noise, produces a depth of saturation in transistor 13 to yield a recovery delay time proportional to it. The pulse width output from 13 gates pulses from the oscillator to the counter 16. Thus, the count in the counter 16 represents the...