University of St Andrews SMRU Instrumentation
SMRU Instrumentation
Sea Mammal Research Unit

Gen2 GPS Phone Tag

Our original GPS phone tag offered a major advance in marine mammal telemetry, combining GPS quality locations with efficient data transfer using the international GSM mobile phone network. Our Second Generation (Gen2) GPS Phone Tag now offers the same quality locations and broadband M2M data uploads in a streamlined package with no external antenna.

A pair of Gen2 GSM/GPS Tags on a beach


  • Collects accurate high-resolution location and behavioural data at a rate determined by the user.
    Typical daily data from a harbor seal:
    • 200 dives, each with 25 depth profile points
    • 180 GPS locations
  • Complete, detailed individual dive and haulout history archived on the tag
  • Data is relayed via quad-band GSM mobile phone module when animal is within GSM coverage. This results in:
    • Lower data cost compared to other platforms
    • International roaming capability
    • High energy efficiency
    • High bandwidth

Fastloc® GPS offers the possibility of a location at every surfacing. Less than a second is needed to acquire the information required for a location. The tag also uses precision wet/dry and pressure sensors to form detailed individual dive (max depth, shape, time at depth, etc) and haulout records along with more synoptic summary records as in earlier SMRU SRDLs. Both location and behavioural data are then stored in memory.

For species that come near shore within GSM coverage the entire set of data records stored in memory can be relayed via the mobile phone system. Visits ashore may be infrequent, so up to six months of data can be stored on-board the tag and these data may also be downloaded if the tag is retrieved. GSM data relay offers very high data bandwidth and is over one hundred times more energy efficient than Argos — all for the cost of a couple of hours of phone calls!

Quad-band ensures that our Gen2 GPS Phone tag operates on all continents, wherever GSM coverage is available.

Seal track along the Scottish coastline uploaded from Gen2 GSM/GPS Tag
Dive profiles & GPS track of harbour seal swimming from Orkney to Moray Firth, Scotland.
Dive and track data: SMRU-IG GPS-Phone tag; Bernie McConnell, Marine Scotland, Marine Mammal Scientific Support Programme.
Bathymetry data (exaggerated): EMODNET. Coastline: EEA Europe. Visualisation: SMRU-IG MamVis software. Graticule ticks at 10 km intervals.


  • GSM engine: Sierra Wireless HL8548-G module
  • GSM bands: 850 MHz, 900 MHz, 1800 MHz, 1900 MHz
  • Depth rating (m): 2000
    • Pressure (dbar) range: 0 to 2000
    • Accuracy: max ±0.15% @ full scale
    • Resolution: 0.06 m
  • Tag Size: 100mm (L) x 70mm (W) x 32mm (H)
  • Weight in air: 300g

Power options

  • A high energy density Li-SoCl2 C-cell configuration is now standard, allowing for a lighter, more hydrodynamic device.
Data uplinks are typically attempted every 6 hours. When at sea, only an SMS can normally be sent; this provides the most recent GPS location. Bulk data transfer occurs during a haulout, or possibly during extended surface events in very calm conditions. An additional connection attempt is therefore allowed at the beginning of the first haulout in each 6-hour period. If it is important to monitor the location of the animal in near real-time, more frequent uplinks may be attempted at the cost of tag longevity. Conversely, a longer deployment can be achieved if the frequency of uplinks is reduced.

For details of pricing and how to order, please see our Contact & Sales section.

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