GPS data for mobile receiver station

Stations
1

Hello everyone,

I’ve been wondering about certain properties of mobile receiver stations. As found in this and this thread, a station can be deployed as a mobile station, with various options (aircraft, ground-based, vessel, …). In the second threat, Josh says that:

“Note that the main thing this does is bypass some of the location based data validation and alerts in your Data Issues page that normally would be triggered if a particular station moved so much. And of course, it reminds the operator (and others, if their tag happens to be detected by it) that thing is actually moving!”

I was wondering what the consequences are for a Motus station if it is classified as a mobile station. A few questions in particular on this:

  • Assuming a station gets regular GPS fixes - from which it would also be apparent that the station is mobile - does the station’s position change at all in the stations portal? I think I read once that, for a mobile station, you have to define coordinates that represent the start or endpoint of its route.
  • It it possible to easily access a station’s GPS fixes as a function of time? (In fact, this would be useful regardless of whether the station is classified as mobile). I can’t find any option to download GPS fixes under the Download project data option in the Manage project tool.
  • Are Lotek tag detections linked to the station’s most recent GPS fix in the Motus database, or would this have to be done manually?

I’m sorry if this has been asked before, but I couldn’t find this information in the Motus docs or in other forum threads.

2

Hi Lynn,

The “mobile” status is actually set at the deployment level, and not the station. Location, on the other hand, is set at the station level. So there’s a bit of a disconnect there. For that reason (and for the obvious one that they aren’t fixed in one place) stations with mobile deployments shouldn’t be displayed on the station map.

All GPS data collected by a receiver is available via the Motus R Package. Tag hits are not automatically associated with GPS location, though they are present in the two existing views, alltags and allruns. In both cases, the location used by default is the one provided in the station metadata, which obviously doesn’t work very well for mobile stations.

There is a alternate version of each of these views that does incorporate GPS: alltagsGPS and allrunsGPS. For these, the view joins the hit on the GPS record nearest in time to the hit. (Depending on the volume of data you’re working with, these views can be very slow and bog down your system considerably.) There is a dedicated chapter in the documentation that goes into much depth about working with GPS records.