[Front inside cover]

IEEE Transactions on Communication and Electronics. Published bimonthly by The Institute of Electrical and Electronics Engineers, Inc., from 20th and Northampton Streets, Easton, Pa. IEEE Headquarters: Box A, Lenox Hill Station, New York 21, N. Y. Address changes must ?be received at IEEE Headquarters by the first of the month to be effective with the succeeding issue. Copies undelivered because of incorrect address cannot be replaced without charge. Editorial office: 345 East 47th Street, New York 17, N. Y. Nonmember subscription $10.00 per year (plus 50 cents extra for foreign postage payable in advance in New York exchange). Member subscriptions: one subscription at $6.00 per year; additional annual subscriptions $10.00 each. Single copies when available $1.50 each. Second-class postage paid at Easton, Pa. The Institute of Electrical and Electronics Engineers, Inc., assumes no responsibility for the statements and opinions advanced by contributors to its publications. Printed in United States of America Number of copies of this issue 9,000.