skip navigation

PUBLICATIONS

Register for Latest Research

Stay Informed
Register with NCJRS to receive NCJRS's biweekly e-newsletter JUSTINFO and additional periodic emails from NCJRS and the NCJRS federal sponsors that highlight the latest research published or sponsored by the Office of Justice Programs.

NCJRS Abstract

The document referenced below is part of the NCJRS Virtual Library collection. To conduct further searches of the collection, visit the Virtual Library. See the Obtain Documents page for direction on how to access resources online, via mail, through interlibrary loans, or in a local library.

 

NCJ Number: 43218 Add to Shopping cart Find in a Library
Title: EXPERIMENTAL MEASUREMENT OF PATH NOISE IN ULTRA-NARROWBAND RADIO SYSTEMS (SYNCTRAN)
Author(s): ANON
Corporate Author: US Dept of Justice
LEAA
National Institute of Law Enforcement and Criminal Justice
United States of America

Aerospace Corporation
United States of America
Date Published: 1977
Page Count: 62
Sponsoring Agency: Aerospace Corporation
El Segundo, CA 90245
US Dept of Justice

US Dept of Justice NIJ Pub
Washington, DC 20531
Contract Number: J-LEAA-025-73
Publication Number: ATR-77(9970)-1
Format: Document
Language: English
Country: United States of America
Annotation: USE OF NARROW (ABOUT 30MHZ) RADIO BANDWIDTHS TO TRANSMIT ALARM SIGNALS THROUGH URBAN AND SUBURBAN NEIGHBORHOODS TO A CENTRAL SECURITY LOCATION WAS TESTED. NOISE INTERFERENCE COULD BE CONTROLLED.
Abstract: IN THIS SERIES OF EXPERIMENTS, 30MHZ BANDWIDTHS WERE USED TO TRANSMIT ALARM SIGNALS FROM TYPICAL URBAN AND SUBURBAN LOCATIONS TO A CENTRAL RECEIVER USING A LOCAL RADIO BROADCAST STATION SIGNAL AS A REFERENCE POINT FOR BOTH TRANSMITTERS AND RECEIVERS. THIS SYSTEM, CALLED 'SYNCTRAN', AN ACRONYM FOR 'SYNCHRONOUS TRANSMISSION,' WAS DEVELOPED TO OFFSET THE FACT THAT LOW-COST, READILY AVAILABLE NARROWBAND EQUIPMENT DRIFTS GREATLY AS THE RESULT OF TEMPERATURE VARIATIONS. IN THESE TESTS MAJOR SOURCES OF PATH NOISE WERE MOTOR VEHICLES, AIRCRAFT, AND VARIOUS UNIDENTIFIED PHENOMENA WHICH CREATED SIDEBAND NOISE. THIS INTERFERENCE COULD BE CONTROLLED BY TRANSMITTING IN SIDE BANDS LOCATED APPROXIMATELY 10 TO 50 HZ FROM THE CARRIER AND OPERATING AT FREQUENCIES IN THE 25-50 MHZ RANGE. WHILE LOW TRANSMITTER POWER MAY BE ADEQUATE IN MANY SYNCTRAN ALARM APPLICATIONS, A MORE RELIABLE SYSTEM COULD BE ACHIEVED IF THE TRANSMITTER HAD VARIABLE POWER OUTPUT OVER A RANGE OF 0.5 TO 5 WATTS. THIS WOULD INSURE A SIGNAL TO NOISE RATIO OF 30DB OR BETTER AND MINIMIZE LONG-TERM FADING. SYNCTRAN LINKS TO, FROM, OR BETWEEN MOBILE STATIONS ALSO APPEAR FEASIBLE.
Index Term(s): Alarm system technical information; Facility security; Telecommunications equipment; Testing and measurement; Transmitters-receivers
To cite this abstract, use the following link:
http://www.ncjrs.gov/App/publications/abstract.aspx?ID=43218

*A link to the full-text document is provided whenever possible. For documents not available online, a link to the publisher's website is provided. Tell us how you use the NCJRS Library and Abstracts Database - send us your feedback.