DIY Emergency Cell Tower

Chris Paget, KJ6GCG has over a decade of experience as an information security consultant and technical trainer for a wide range of financial, online, and software companies. Chris' work is increasingly hardware-focused, recently covering technologies such as GSM and RFID at venues such as Defcon and Shmoocon.

At the recent Defcon 18 conference he displayed a spoofed GSM cellphone tower using a Universal Software Radio Peripheral (USRP) transmitting 25 milliwatts, to present a GSM air interface to a standard GSM handset and uses the Asterisk software PBX to connect calls. The combination of the ubiquitous GSM air interface with VoIP backhaul could form the basis of a new type of cellular network that could be deployed and operated at substantially lower cost than existing technologies in the developing world.

http://openbts.sourceforge.net/

FCC rules aside, this is some powerful stuff. Imagine being able to restore cellular coverage in a disaster area using the foundation he has laid.

You can read more here:

http://www.networkworld.com/news/2010/083010-open-source-voip-cell-phones-at-burning-man.html

Here is a video that shows a test call being placed from a softphone talking to an Asterisk PBX in conjunction with GNU radio and a USRP to create a Part 15 signal level call to a cellphone.




Regarding using HSMM style techniques for running an amateur cell site:

http://www.innismir.net/article/513


Here is a similar project which modifies android phone to use asterisk running on something called a mesh potato. This would be great for developing areas. Just drop some of the MP's with a battery and a solar cell and poof... a phone system.

http://www.villagetelco.org/

Another favorite is using asterisk with amateur radio and repeaters

http://ohnosec.org/drupal/

EmComm & AMSAT's Geostationary Satellite

A very interesting overview of AMSAT's phase IV Geostationary Satellite and the possible emergency communications implementations is in the Fall issue of CQ-VHF.

As you can tell I don't have a lot of love for Emcomm, but here is something that actually makes sense. A high speed multi-media capable, geostationary satellite.

AMSAT has recently begun negotiating with INTELSAT to get amateur radio communication payloads “piggybacked” on commercial geosynchronous communications satellites. This would be a first for amateur radio. It would allow earth stations to have 24/7/365 communications over a very large area using small fixed antennas. A small dish antenna would be able to access voice communications and text messaging. A larger dish antenna could provide access to video and high speed data. Because this has obvious value for emergency communications, AMSAT hopes to get considerable funding for this project from emergency communications agencies.

Hams are well acquainted with radio coverage problems while providing emergency communications. The high frequency bands suffer from hourly to daily propagation challenges. VHF and UHF simplex channels have limited geographic coverage. A repeater improves coverage while restricting all operations to its fixed channel pairs. Most of our current operating modes offer voice communications only. If data is transmitted it is supported at low rates such as 300, 1200, or 9600 baud.

I hope this gets some backing from the ARRL ARES directors. I honestly don't understand why and how all these recommendations come down the EC line to promote stuff like WinLink. They should all get behind something like this that makes sense, and help promote development and deployment of terrestrial HSMM networks.