Accession Number : AD0654351

Title :   A VARIABLE ATTENUATION NOTCH FILTER FOR USE WITH THE ANALOG COMPUTER,

Corporate Author : JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB

Personal Author(s) : Jordan,J. D.

Report Date : 10 MAR 1959

Pagination or Media Count : 8

Abstract : A sample model of a notch filter was constructed with uniformly excellent results up to where the depth of the notch reached about 35 DB's. The failure above 35 DB's was attributed to the noise level of the amplifiers. This was demonstrated by obtaining an output signal with no input. Figures 1 and 2 represent notch filters using the loaded and unloaded values of resistors and capacitors respectively. Both were designed to produce a 20 DB notch at 10 cps. The unloaded filter will give a depth of notch at the prescribed frequency essentially the same as if it were unloaded. There are, however, two differences. The width of the notch is increased with loading and there is a slight gain when the higher frequencies are reached. With the values of R sub 2 and C from Table II, this later effect is a gain of roughly 0.5 DB's at the high frequencies. A study was made to determine whether or not the width of the notch might be controlled by juggling the loading in some way. This did not seem promising as long as regular REAC units are used. The assumptions made, and the results obtained, seem to indicate that the end justifies the means. It is believed that this filter will be of value where it is desired to shift the position or depth of a notch during the process of solving a problem. (Author)

Descriptors :   (*ELECTRIC FILTERS, ANALOG COMPUTERS), ATTENUATION, ELECTRICAL PROPERTIES

Subject Categories : Electrical and Electronic Equipment
      Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE