EMC190 Intro to Trunking 3/3 To: Emergency Communications Units - Information Bulletin To: Emergency Management Agencies via Internet and Radio By: Auxiliary Communications Service (ACS) of the California Governor's Office of Emergency Services EMC190 Intro to Trunking 3/3 For release 6/29/99 "Large users, such as public-safety agencies, may need more than 16 subfleets. Multiple independent systems can be installed and programmed into user radios. In this case, the system number appended to the subfleet (1-A, 4-B) is used to indicate the group. SmartNet, or Type II, systems operate similar to the Privacy Plus systems with regards to ISW/OSW and high and low speed handshaking. In addition, a SmartNet radio affiliates with the system on power on and before processing data from the control channel. This is similar to cellular/PCS phones that require an automated "logon". Affiliation also occurs whenever a user changes talkgroups. De-affiliation occurs when the radio is powered off. System administrators can disable individual radios as needed by setting the controller to refuse affiliation. A non-affiliated radio can not process information from the controller, and will not transmit or receive. A Type II system can have up to 4,000 talkgroups, and the controller must manage all of the talkgroups to avoid overloading the system. Because each discrete talkgroup will occupy a system repeater, talkgroups only become active when two or more radios have affiliated with it. A single radio on a talkgroup will be unable to transmit. This keeps the system load down, especially during multi-select (a transmission over several talkgroups, such as a general broadcast by a dispatcher). The controller transmits to those groups that have radios affiliated, leaving several system repeaters open. A Type IIi system is a hybrid of a SmartNet with some Privacy Plus components. This type of system is commonly used while a department is migrating from Privacy Plus to a SmartNet system and must maintain compatibility with older radios. In the unlikely event of central controller failure, the system will go into Fail Soft mode. Fail Soft conditions are similar to conventional repeaters in that all trunking functions are lost. A faint single beep is heard every 10 seconds to alert users of the condition. Radios are preprogrammed using the system repeaters in a conventional format, and all users share the system's repeaters until the system is back on-line. The controller sends the Fail Soft message in its data stream. As communicators, it is important that we become familiar with the equipment used by the agencies we support. Knowing the basic operating principles of trunking may prove valuable in the future when you may be asked to operate on a trunking system. Motorola and all references to their trunking formats are registered trademarks of Motorola." (Series end: AN INTRODUCTION TO TRUNKING RADIO SYSTEMS By Mike Krueger, N6MIK, Assistant Radio Officer, Training Officer, County of Orange RACES.) --- To subscribe to bulletins, use the Subscription Services web page at . If you don't have web access, just send an e-mail message to . - For training assistance contact the ACS Training Officer at the web site or send an email to larton@garlic.com - Submit suggestions, topics or comments on the bulletins to cary.mangum@macnexus.org or cary_mangum@oes.ca.gov Bulletins are on the ACS Web page: http://acs.oes.ca.gov -and a Landline BBS: 916-262-0856 (graphical & standard interface); and a FTP Archive: ftp.ucsd.edu/hamradio/packet/tcpip/incoming for some bulletins. For earlier ones: ftp.ucsd.edu/hamradio/races