To quote the ARRL,
"Narrow Band Emergency Messaging System (NBEMS) is an Open Source software suite that allows amateur radio operators to reliably send and receive data using nearly any computer (Windows, Mac, and Linux) and any analog radio without requiring a dedicated digital infrastructure or specialized modem hardware. NBEMS works on both VHF/UHF FM and on HF."
NBEMS is the standard digital emcomm package for Contra Costa County's Auxiliary Communications Service (ACS), Walnut Creek's CERT communications team and others.
The System uses Fldigi, the Fast Light Digital modem application, a free, open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem.
A Digital Practice Net is held in Contra Costa County every Tuesday evening at 8:00 PM using the W6CX 2-meter and 220/440 repeaters: 147.060 /+ (100PL); linked with 224.780 MHz, PL 77.0 & 441.325 MHz, + PL 100.0. Everyone with an interest in NBEMS is welcome to join in, ask questions and test your system.
Quickie Guide to Fldigi. (PDF, 19 pages)
by Klaus Brerkner, K6KHB
A short 19-page guide to quickly configuring the Fldigi software basic settings for most Contra Costa County use.
NBEMS Fast Start Guide. (PDF, 2 pages)
by Harry Styron, K6HS
Another short guide for downloading, installing and configuring the software, and a few settings on your PC that may be needed.
Beginner's Guide to Fldigi. (PDF, 12 pages)
From the Fldigi source web site.
A Tour of Fldigi. (PDF, 72 pages)
A much more detailed guide to the software.
Introduction to NBEMS. (PDF, 50 pages)
by Harry Bloomberg, W3YJ
A slide deck from the ARRL web site.