A Personal Packet Station
An Emergency Response
By: KS4NY
As ham radio operators, many of us have volunteered for service during emergencies. Some have manned shelters during evacuations and others have operated as Net control. We all try to prepare for the worst and make sure our stations are up to the test. Recent years along the Gulf coast have given new meaning to the term "disaster". Instead of a two day stint in a shelter and subsequent after action review, we have seen one and two week activations with outside help arriving usually 72 hours after the storm. The need to have a working station that can stay on the air for that time is clear and recent moves to develop packet radio for emergency use cannot be ignored. The ARRL has been urging the adoption of Winlink 2K, an email server over amateur frequencies. It can operate on HF as well as VHF and UHF and holds promise for passing a lot of traffic for agencies such as the Red Cross and Salvation Army. Here in Escambia County, there are folks already studying the applications of Winlink. During hurricane Dennis, a test of winlink was performed at one of the shelters. This test pointed out several problems that should be addressed before the county agencies will adopt its use. First and foremost is the issue of technical capability. The folks at the ESF table don't want complexity. While the EOC leadership liked what they saw in the demos, the guys at the working end didn't want to be bothered with having to learn how to communicate through a winlink client operated by a ham. While this can be addressed at future training session for county personnel, this does not solve our immediate need for reliable digital comms. After discussing the problem with Gene Bannon the Emergency Coordinator for Escambia County, I set about to build a reasonable Personal Packet Terminal (PPT) with extended battery life and reliability. The first requirement was to make a packet station specifically design for the shelter communicator. It should be compact yet easy to use. No complex setup procedures for the ham to figure out. It should be reliable. Turnkey operation is critical. Not many of us are IT specialists. It should also be expandable in its capabilities. As our needs change from shelter to shelter, so should the terminal's ability to convey data about the demographics and conditions of each.
The hardware design follows the KISS (Keep It Simple Stupid) approach to lower cost and yet provide reliability and simplicity. The PPT consists of a simple Palm Pilot PDA with a serial link to a TNC designed by John Hansen (W2FS) which is a KISS mode kit. The TNC controls a five watt ht chosen for good battery life and ease of use. Tests using nickel metal hydride batteries showed that the HT could operate for twenty-four hours in standby with one report sent every hour. The TNC can operate for nearly thirty six hours on a single 9 volt transistor battery and the PDA can last a week or more on a pair of AAA batteries.
So now we have a portable station capable of packet. Now what? Software that can gather the needed info and send it along its way to the EOC where a waiting computer accepts the data and generates a report automatically and then resets itself to await another report. With the aid of a Palm platform basic interpreter I was able to create a program which can query the operator with a preset list of questions so that the operator need only answer each question concerning the shelter population and conditions there. Once complete, the software sends the data out to the TNC and the packet is transmitted. These packets are formatted just like APRS packets and can be sent over an existing APRS network using the available WIDE n-n digis. As each packet is received at the EOC an acknowledgement is transmitted back to the shelter PPT. Upon receipt of the ack, the PPT transmits the next line of data until the report is complete at which time it ends and the PDA can be powered down to conserve energy.
While not everyone would agree that digital radio has a place in Amateur Emergency response, this simple approach to getting accurate data where it is needed most is worth trying. If only for the exposure to some of the technology used in the more comprehensive modes such as Winlink 2K
THE COMPLETE PACKAGE
Screen Shot of The Palm Program