Accession Number : AD0819362

Title :   AUTOMATIC EQUALIZED DATA MODEM.

Descriptive Note : Final technical rept. 21 Jan 66-15 Mar 67,

Corporate Author : AUTONETICS ANAHEIM CA

Personal Author(s) : Motley, D. M. ; McAuliffe, G. K.

Report Date : JUL 1967

Pagination or Media Count : 194

Abstract : The objective of this contract was the development of a 2400 or 4800 bit/sec automatically equalized data modem for operation over 4 KC/sec telephone circuits. The major problem was the development of an automatic and continuous data equalization technique. The use of a feedback channel was not allowed. The selected equalization technique, which is called ADEM II, is a tail concellation system which utilizes the impulse response of the channel for intersymbol interference elimination. Among the research objectives were the derivation of the channel learning limits of the ADEM II equalization technique, the derivation of the excepted impulse response characteristics of Schedule 4B telephone circuits, and the computer simulation of the ADEM II equalization technique. Upon verification of the performance capability of the equalization technique the ADEM II digital data modem was constructed. When completed, the ADEM II data modem was tested over simulated and leased Schedule 4B telephone circuits and performed within 1 db of theoretical at both 2400 and 4800 bit/sec. It also met the performance requirements of a bit error rate of less than 1 x 10 to the minus 7th power at 4800 bit/sec over a leased Schedule 4B telephone circuit. No major difficulties were encountered during the contract, however, some reduction in the possible servicing requirements could be achieved through the replacement of some analog circuits with their digital equivalents. (Author)

Descriptors :   (*DATA TRANSMISSION SYSTEMS, TELEPHONE LINES), DIGITAL COMPUTERS, OPERATIONS RESEARCH, CIRCUITS, PERFORMANCE(ENGINEERING), FLOW CHARTING, DIGITAL TO ANALOG CONVERTERS, SIMULATION.

Subject Categories : Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE