Xastir—Open-Source Client for the Automatic Packet Reporting System
A very useful recent addition to Xastir is the capability to assign tactical call signs to stations and to transmit them across RF or the Internet to other APRS clients (Xastir and APRS+SA are the only two clients that currently decode and display tactical call assignments).
We added this capability just prior to the Seattle Marathon in November 2008 and used it to great effect at that event. It allowed us to assign call signs, such as LEAD and TAIL, to APRS stations helping in the event, without having to change their tracker configurations. This aids reliability when we're not tweaking tracker settings before the event. The old “if it ain't broke, don't fix it” method really does work when dealing with mobile trackers. Don't touch a working tracker unless you have to.
Xastir also was used to good effect in the New York City Marathon. Officials love it for its instant and eye-catching tactical display. You'll see them hanging around the Xastir display when they're not otherwise engaged.
SAR tactical call signs provide similar advantages, assigning TEAM 1, HELO 2, DOGTEAM 3 and similar monikers to teams in the field. Special features have been added to Xastir to support SAR operations.
Example: Seattle Marathon
For the Seattle Marathon, I (Curt) sit in the net control vehicle with the “route” and “start/finish” radio guys. Xastir is running on a Linux laptop with Internet access, along with a remote LCD display for the radio operators to view the current event map. Bob Donnell, KD7NM, has a similar station several hundred feet away at the first-aid station. Trackers are assigned tactical call signs like SAG 1 prior to the event or at the beginning of their assignments.
I listen for runner pick-up or aid requests from the radio operators and send instant messages to Bob. Bob then dispatches vehicles (SAG wagons) via voice radios to pick up the runners. Positions of all SAG wagons appear on both of our maps.
SAG vehicles can't cross the course, so it's tricky getting them to the correct locations. The map display allows Bob to dispatch the vehicle that would be quickest to pick up the runners—you must know how to route vehicles when Seattle is bisected by this event.
We place trackers on the lead vehicles for both the full and half marathons—problematic due to the choice of electric vehicles, which so far haven't completed the mission. If these trackers become unavailable, we shift to monitoring voice reports on the route network and create objects to represent them on the map. The trailing vehicle is driven by a ham who usually can keep its tracker running, although we have the same fallback plan.
Event organizers use the trailing runner information to adjust support needs at the finish line, and we use the information to keep the volunteer hams up to date on the approach of the final runners. The volunteers then share this information with the rest of the marathon volunteers in their area. This helps ensure that we don't leave anyone behind on the course at the end of the day and lets us know when to open streets and when to pick up ham volunteers and equipment.
From its meager beginnings as a Linux-specific application, Xastir has grown significantly in capability but is still tied to OpenMotif or Lesstif for its widget set. Xastir is a large multithreaded and multiprocess program. Developers have talked about splitting Xastir into an SQL database back end plus a dæmon with multiple clients to handle user interface functions. Such clients could use different widget sets, such as Qt, GTK+ or WxWidgets, with correspondingly better integration with modern-day window managers. Rewriting to use Qt without the X11 layers underneath might allow for running on Qtopia embedded devices. In any case, whether we refactor Xastir, it has a bright future as its user base continues to grow and useful features are added continually. See you on the mailing list!
Note: the Open Group, Motif, Making Standards Work, OSF/1, UNIX and the “X” device are registered trademarks, and TOGAF and Boundaryless Information Flow are trademarks of The Open Group in the US and other countries.
Amateur Radio has been doing digital communications literally since there has been wireless communications. We first used CW (Continuous Wave) or On/Off keying with Morse code. Abbreviations quickly became commonplace. After WWII, surplus teletypes (the heavy, loud electromechanical monsters you see in old movies) became available at reasonable prices and ham radio RTTY (radio teletype) was born, and keyboard shortcuts and abbreviations became even more commonplace.
We use a lot of abbreviations—Q-codes during voice and especially CW conversations (CW or Continuous Wave means Morse code). Even the word conversation has an abbreviation: QSO.
Quite a few of our abbreviations have roots in the Morse code world, spilling over into our e-mail and instant messaging. If we type “hi hi” to you, that means laughter. “QTH” equals location. This is similar to instant-messaging abbreviations that many of you use with SMS messaging or e-mail.
Here are some other common terms:
APRS: Automatic Position Reporting System.
AX.25: the packet radio link-level protocol we use.
digipeater: single-frequency store-and-forward digital repeater for radio.
KISS mode: Keep It Simple Stupid protocol. A simplified protocol used in a TNC for computer control (yes, that really is the name of the protocol).
soundmodem: software to turn a soundcard into a TNC.
TNC: Terminal Node Controller or radio modem.
tracker: a GPS/radio/TNC that emits positions while moving. It may or may not have two-way messaging or a map display.
|August 2014 Issue of Linux Journal: Programming||Aug 01, 2014|
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