Use case scenarios
Who is nearby?
An amateur radio operator with limited computer skills interested in exploring APRS obtains a copy of xastir and installs it on their non-internet connected computer. They connect their TNC to the computer, tune their radio to 144.39, and are presented with a map showing stations nearby stations as they are heard. The user provides their callsign and location to xastir, and it begins transmitting their location through the TNC. Mobile stations are shown with their tracks, and weather stations are shown with current weather data. The operator can view details of each station heard, including graphs of the weather history for weather stations.
Who is nearby? [internationalized]
An amateur radio operator who does not speak English downloads and installs copy of xastir. They connect their TNC to the computer, tune their radio to the local APRS frequency, and are presented with a map showing nearby stations as they are heard. The operator provides their callsign to xastir, connects a GPS to their computer, and provide access information for an internet APRS server. Xastir begins transmitting their location over the TNC and passes both their location and heard stations to the internet APRS server. Xastir retrieves heard stations from the internet APRS server and displays them on the map for the operator. The operator zooms in on the map, and since they have an internet connection, satellite or aerial images of the area they are zooming in on are shown through openareialmap's WMS service. The operator explores stations in the area by zooming the map in and out,by panning the map north, south, east, and west, and stays oriented to scale by the inclusion of a scale bar on the display. The operator saves a local map view of the area immediately around their station, and another map view of an area further away with lots of APRS activity. The operator can easily switch from one map view to the other, or as they move around the map can move rapidly to one of the stored map views.
Resource tracking for a served agency
An amateur organization providing communications support for a served agency managing a road race deploys a computer, a TNC and a radio in the command post, and sets up map displays with the served agency on the served agencies computers (in the command post and elsewhere). An operator, working with a served agency representative, plots a route and a series of distance markers along the route. The route and distance markers, along with the current positions and trails of resources that are transmitting their position by APRS are visible both on this computer and on other served agency computers in the command post.
During the event, there is a power failure, and the computers in the command post are all shut off. After reboot, xastir is brought back up, and the previous session is easily restored on each workstation, including heard stations and their trails.
During the event, a mobile station along the route sets its APRS transmitter to signal an emergency, and calls in to the command post on a voice frequency. The status of the mobile station and its location along the route are immediately visible on the computers that are monitoring the map of the race in the command post.
GIS Asset for SAR
A volunteer SAR organization plans to deploy a set of computers (including laptops and mobile devices) and an xastir installation to help provide GIS support for searches. Members of the organization install xastir on several of the computers, obtain a set of raster and vector GIS layers covering their area of responsibility. They train with xastir as a standard GIS tool, and deploy APRS trackers with task teams in training. Several members of the organization's overhead team are cross trained to use xastir and other GIS software in support of a search.
GIS layers collected by the SAR organization and installed in their xastir installations include one byte geotiff images of older USGS DRG scanned topo quads, three byte geotiff satellite images, recent jpeg2000 air photos, a high resolution raster digital elevation model, vector roads from Tiger census data, geocoded placenames from GNIS, ESRI shapefile vector layers of county boundaries, municipal boundaries, streams, water bodies, geological hazards, wetlands, and land use.
Called in to a search, the SAR organization deploys the computers and xastir as part of its GIS support capability in the incident command post. Terminals are provided to logistics and operations for monitoring resources, another to investigation for, and several, along with a color map printer and a GIS support technician to planning. A video projector is also set up on a computer to allow the display of digital maps and APRS during briefings. APRS trackers are deployed with task teams, including in some cases, handheld devices that serve as APRS mapping stations.
During the first operational period, the GIS technician sets up the computers and sets a default display of the search area on each. The technician then produces maps and 3d visualizations (draping topo maps and air photos over the digital elevation model) of the search area for the planning section. As search segments are developed, they are created as vector layers in xastir (including their initial probabilities of area), and maps of each search segment are printed as part of the task assignment forms developed by the planning section. Easily available and printable information for each search segment includes its area in acres, a UTM grid with easily read and understood markings on the map border, a scale bar and a north arrow.
A decision is made to mark one search segment boundary with a flag line along a compass bearing, so a task team is deployed with an APRS tracker and their progress and their transit along the correct segment boundary is monitored by operations. The operator in the operations section opens a map display in xastir, provides it with the tactical call sign of the task team laying out the flag line, and sets it to keep that station centered while the map moves around it. The operator leaves this map display open and opens another map display to monitor the movements of several other task teams.
A task team with a tracker calls in a clue, and their voice transmissions of compass bearings triangulating their position are correlated with the APRS packets from their tracker providing the investigation section a highly reliable indication of the location of the clue. The investigation section chief decides to send an investigator to examine the clue, so the GIS technician marks up a map with an automatically generated compass bearing and distance from a nearby access point, generates and prints a map to provide to the investigator and support team. The investigation section chief calls an investigator at a local police department by land line and has a conversation with them about the clue including an URL that the other investigator can visit in their web browser to see the location of the clue on a map of the area.
As task teams return during the first operational period, their probabilities of detection are attached by the planning section to the search segments in xastir. New probabilities of area for each segment can be readily produced, and operators at each computer can easily visualize (or print maps of) the changing coverage and probabilities of the search area.
During the second operational period of the search, a county GIS technician called in as a resource by incident command makes a set of municipal GIS layers, including property boundaries from tax maps, available to the search team, an operator adds these to the set of maps being used by xastir to manage the search, and rapidly configures the property boundaries to display as a vector layer of one pixel solid black lines with each parcel able to be marked with the name of the landowner.
During the second operational period, the logistics section addresses areas where there were radio communications problems during the first operational period, The locations of key communications assets including repeater locations are selected in xastir, their height, power, and frequency characteristics are entered, and a propagation model for is generated for each site. Areas with poor coverage are identified. Based on these, a location for the deployment of a portable repeater and digipeater is identified and tested with the propagation model. A communications task team is sent to deploy a portable repeater and digipeater at this location.
During the third operational period, a task team finds the missing subject, their location is visible to each of the workstations. A rescue task team is sent in to extract the subject, this task team is equipped with a mobile device that serves as an APRS mapping station, so that as they proceed to the location of the find, they can see both their current location on the map, the location of the find, and the location of other nearby assets with trackers. As they move around terrain hazards, they can use the handheld to work out compass bearings and distances to travel to most efficiently get to the find.
Distributes knowledge of changing internet map services.
The Open Street Map project resumes their WMS service and adds a WFS service. An xastir user becomes aware of these new services, adds them to the list of map sources they are using in xastir, and marks these new services as to be shared with other xastir users. All other xastir users have these new services automatically added to their list of potential map sources [there are potential malicious variants of this scenario that suggest this might be best handled in a centralized vetted manner, such as the new services being posted to a central source for review, and then added to a (to give a too close to implementation example, rss) feed (to which all xastir installs can subscribe) after human validation (which could also have updates periodically distributed as APRS messages), though peer to peer communication amongst xastir installs would eliminate this source as a single point of failure]. Distribution of knowledge of changes to weather and callsign data sources are familiar variants of the issue in this scenario.