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Browse Prior Art Database

Narrow Band, High Resolution Filter

IP.com Disclosure Number: IPCOM000093838D
Original Publication Date: 1966-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Alspaugh, GR: AUTHOR [+2]

Abstract

The upper drawing shows timer circuits. These are connected to obtain a filter which has response to an arbitrarily small band of frequencies and virtually completely rejects all other frequencies. This is obtained by use of the time out of the various timers when compared by the And.

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Narrow Band, High Resolution Filter

The upper drawing shows timer circuits. These are connected to obtain a filter which has response to an arbitrarily small band of frequencies and virtually completely rejects all other frequencies. This is obtained by use of the time out of the various timers when compared by the And.

The four timers T1...T4 have the following characteristics. Any down input initiates the time out process, after which the output goes up. Any up input resets the timer, whether during or after the time out process setting the output to a down level.

In the upper and lower drawings when the input frequency is f1 or higher, T1 is selected to have a time out period such that it never times out. Hence, T2, which goes up because of a previous time out remains up continuously while the input is f1 or higher. T3 is also selected to have a time out period such that it never times out with an input of f1 or higher. Therefore T4 remains up continuously.

Since the output of T2 is inverted no output indicative of an and condition appears at the output of the And when the frequency is f1 or higher.

When the input frequency is a lower frequency f2 the time out period of T1 is such that it does time out. The up signal from T1 brings T2 down, where it remains because it is periodically restarted by up inputs. The time out period of 12 is so selected that at frequencies in the order of magnitude of f2 T2 does not time out. T3 is selected so that it has a period w...