DocumentCode :
1407213
Title :
A visual selectivity meter with a uniform decibel scale
Author :
Sturley, K.R. ; Shipway, R.P.
Volume :
15
Issue :
45
fYear :
1940
fDate :
9/1/1940 12:00:00 AM
Firstpage :
215
Lastpage :
220
Abstract :
Visual examination of the selectivity or frequency response of a filter by means of a frequency-modulated oscillator cathode-ray tube is well known, but few attempts have been made to produce a selectivity curve to a decibel scale. A very successful method, which depends on A. G. C.¿ action (virtually negative feedback), has been developed to give logarithmic delineation of frequency response, and the apparatus is described with particular reference to decibel scale production. The carrier or mid-frequency range of instrument is capable of variation from 50 to 1 500 kc./s., frequency-modulation ranges, giving band widths of 100, 20 and 10 kc./s. are possible. The decibel frequency response scale is ¿linear¿ over a range of 60 db. Check tests at three different carrier frequencies, 1 500, 500 and 100 kc./s., are described and show the performance of apparatus to be satisfactory and its degree of accuracy to be good.
fLanguage :
English
Journal_Title :
Wireless Section, Institution of Electrical Engineers - Proceedings of the
Publisher :
iet
Type :
jour
DOI :
10.1049/pws.1940.0027
Filename :
5245859
Link To Document :
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