Posts Tagged ‘EMCOM’

Ham Radio and Mesh Networks

Lately I’ve been fascinated by the capabilities of mesh networks. The ability to quickly create ad-hock computer networks could be an invaluable resource for amateur radio operators in general and particularly for emergency communications (EMCOM)

Linksys WRT54GL Router

The particular device and software I have been experimenting with is the Linksys WRT54G router and HSMM-MESH firmware from http://hsmm-mesh.org/.

Installing the HSMM-MESH firmware changes the way the Linksys router functions and allows it to automatically connect to other HSMM routers in a mesh network. No special configuration is required after setting your callsign. All TCP/IP configuration is pre-configured, even down to automatically assigning addresses to connecting clients.

Mesh Network Diagram

Mesh networks are highly fault tolerant. Every router in the network is aware of every other router and has the ability to move network packets through from one unit to another provided there is a link, or chain of linked routers, between them.
In the diagram to the right each router is represented by a numbered circle. If router number 6 were to fail then network packets that needed to move between router 1 and 7 would travel through routers 2 & 3 or 5 & 10 until 6 was repaired. All this happens automatically and quickly enough so that there is no disruption to the traffic.

Anything you can access on a normal computer network can be made to work on a mesh network. Some of the services that have been demonstrated include email, voice over IP (VOIP), video conferencing, file sharing, web servers & groupware applications.

With simple modified antennas the modest output power from the WRT54G (100 to 200mW) can be used to reach distances of many miles or tens of miles with directional antennas. Mounting the router on a mast in a sealed enclosure can reduce losses from long cable runs while running off 12V power makes them compatible with ham radio power sources including solar and wind power.

The example to the left is from NG5V located on hsmm-mesh.org and consists of an omni-directional external antenna and a lawn sprinkler controller box from a popular home improvement store.

Did you know that … Frequencies used by channels one through six of 802.11b and 802.11g fall within the 2.4 GHz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not commercial content or encryption.

I hope to acquire a few more WRT54G routers and put together a mesh network in the Katy TX area as a resource for experimentation and education in an area not normally touched upon by regular amateur radio operators. Who knows what the future holds & it behooves us to investigate this technology and bend it to our own needs.

The Amateur is Progressive … He keeps his station abreast of science. It is well built and efficient. His operating practice is above reproach.

LHS Episode #074: The Great Hobo Migration

2012 is rolling along nicely and Linux in the Ham Shack is rolling along with it, bringing you new ways to use your computer with amateur radio, and sometimes just technology for fun (and maybe profit). This time around, the guys break into politics — just slightly — and get a few grievances of their chests. In the middle segment, Richard and Russ discuss terminal emulation, something a radio amateur might need for accessing modems built into rigs or running packet TNCs. Finally, our intrepid co-hosts open up the mail bag and respond to listener feedback. If you would like to contribute feedback, please do so by sending us e-mail at [email protected] or calling in on our voice line at +1-909-547-7469.

73 de The LHS Guys

LHS Episode #067: The Left Hand of ARES

And we are back. In this installment, Richard tells us all about his renewed interest in emergency communications and his dealings with ARES in the Texas county where he now lives. On the Linux side of things, Russ talks about some security issues: the hacking of kernel.org, emacs violates the GPL and how to get cheap certificates for your Web sites. Throw in a dash of humor, some general screwing around and you have the formula for pretty much every episode of Linux in the Ham Shack. Thanks for sticking it out with us, everyone. We love each and every one of you.

73 de The LHS Guys


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