Cart (Loading....) | Create Account
Close category search window
 

An Improved Decision Technique for Frequency-Shift Communications systems

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

1 Author(s)
Thomas, E. ; Page Communications Engineers, Inc., Washington, D.C.

This paper describes a new circuit technique called a decision threshold computer, which enables a frequency-shift-keyed receiver system to use information in mark and space channels. independently, resulting in an improvement in circuit quality where fading exists between the mark and space frequencies. Frequency selective fading observed on ionospheric-scatter circuits and on high-frequency communication circuits is discussed. The results of a correlation study are presented which show such fading to be relatively uncorrelated a large portion of the time. Typical FSK demnodulators, with a fixed decision level set halfway between the long-term average amplitudes of the received mark and space frequencies, are shown to result in a high error liability when deep fades occur on either the mark or space frequency. It is further shown that such errors are unnecessary since the complete message is available on either frequency. The device discussed in this paper has been designed to make use of the normally deleterious effects of frequency selective fading, to provide up to a 30-fold reduction in teleprinter error rates over that which is theoretically possible when flat fading is assumed. Additional orders of diversity are shown to result where low correlation exists between the mark and space frequencies. Theoretical error rate equations and resulting error rate curves for the new technique are compared with those resulting from a fixed threshold device of conventional design.

Published in:

Proceedings of the IRE  (Volume:48 ,  Issue: 12 )

Date of Publication:

Dec. 1960

Need Help?


IEEE Advancing Technology for Humanity About IEEE Xplore | Contact | Help | Terms of Use | Nondiscrimination Policy | Site Map | Privacy & Opting Out of Cookies

A not-for-profit organization, IEEE is the world's largest professional association for the advancement of technology.
© Copyright 2014 IEEE - All rights reserved. Use of this web site signifies your agreement to the terms and conditions.