Pressure & depth

Depth sensors

The very first nanoFix® tags that we produced in 2014 for tracking seabirds had onboard immersion sensors to log immersion behaviour and to avoid wasting GPS power when submerged. Increasingly knowledge of seabird immersion has evolved into more detailed characterisation of their underwater behaviour through use of depth sensors. We have been providing miniature, lightweight depth sensors on our range of both logger and wireless download tags for over 5 years now and have an ever growing range of sensors available for customers. The most popular depth sensor that we supply is highly compact and lightweight, but with a depth rating of 290m is suitable for use on even the deepest diving species (with adequate tag protection). As the demand for wireless download tags with depth sensing have increased we have developed a range of data compression formats to allow for highly efficient wireless offload of depth data from those devices.

Depth data can be provided at sample rates of up to 1Hz, together with configurable depth logging thresholds which can be set to provide the optimal data capture for a given species and deployment period. Temperature data from the sensor can also be provided, depending on the amount of additional data that the tag is able to offload. Our tags with depth sensing have been used on a very wide range of species around the world, with many different tag configurations selected by customers.

Combined pressure sensors

An area of key interest to seabird researchers is the measurement of accurate barometric pressure to help characterise flight heights. Although many standard barometric pressure sensors can survive operation to depth in saltwater, they do not recover very quickly when they leave the water, resulting in long periods (tens of minutes) when they cannot provide accurate air pressure readings. To address this issue, we have developed a range of tag configurations that use specialist combined depth and barometric pressure sensors. These combined sensors are particularly well suited to deployment on diving seabirds as they can operate at the large pressures experienced when submerged in water, whilst then being able to react instantaneously to provide very precise and accurate air pressure measurements upon surfacing.

In addition to providing this range of combined pressure and depth sensors with our standard logger and wireless download tags we have now developed an ultra small and lightweight solution for use on small and medium size seabirds that incorporates such a sensor. As a result we are now able to provide tags for small seabirds that can provide GPS, pressure, immersion and accelerometer data starting at just 1.0g in weight. The sensor that we use is able to provide depth data when submerged (to 30m) and barometric pressure data when above the water. Further details of this new ultra lightweight multi sensor tag, together with examples of other standard depth tag configurations are provided below.

Ultra lightweight GPS & depth tags

A picoFix® 1.0g mini GPS, depth, immersion and barometric pressure logger. This brand new tag has to date solely been deployed on storm petrels. It measures 20x10x5mm plus ~50mm external whip antenna. It can provide up to 320 GPS location attempts (pressure and accelerometer data may reduce this slightly – contact us for further details). Barometric and depth pressure data can be sampled at up to 1Hz. Immersion data can also be stored. Burst or continuous accelerometer data capture is available at rates of 1Hz, 12.5Hz, 25Hz or 50Hz. This 1.0g tag is depth proof to 2m. Increased depth proofing, as well as increased battery capacity options, can be provided with an appropriate increase in weight.

A picoFix® 2.3g GPS and depth logger. This tag has been successfully deployed on a number of species including Peruvian diving petrels and puffins. It measures 24x13x7mm plus ~50mm external whip antenna, with an additional 4mm height to the top of the depth sensor. It can provide up to 1600 GPS location attempts (depth and accelerometer data may reduce this slightly – contact us for further details). This tag is depth proof to 50m. Burst or continuous accelerometer data capture is available at rates of 1Hz, 12.5Hz, 25Hz or 50Hz. This tag has an extra large onboard memory to allow high rate depth and accelerometer data capture for extended time periods.

A picoFix® 2.6g GPS, depth with UHF download tag. This tag has been successfully deployed on diving petrels. It measures 34×12.5x8mm plus ~50mm external whip antenna. On battery alone it can provide up to 700 GPS location attempts including regular UHF download attempts, but with no depth data. See Table A for illustrations of the impact depth data transmission would have on the battery capacity of this tag (excluding solar). This tag utilises our new solarPlus technology and therefore can provide up to 360 GPS location attempts per day in UK summertime conditions. The daily volume of depth data to be wirelessly transmitted will impact this capacity – please contact us for more details. This tag is depth proof to 30m.

Deep diving GPS & depth tags

A picoFix® 28g GPS and depth logger. This tag has been successfully deployed on various penguins, including: gentoo penguins, king penguins and macaroni penguins. It measures 60x24x18mm plus ~50mm external whip antenna (length includes 4mm depth sensor). It can provide up to 24000 GPS location attempts (depth and accelerometer data may reduce this slightly — contact us for further details). This tag is depth proof to 400m. Burst or continuous accelerometer data capture is available at rates of 1Hz, 12.5Hz, 25Hz or 50Hz. This tag has an extra large onboard memory to allow high rate depth and accelerometer data capture for extended time periods.

A picoFix® 28g GPS, depth with UHF download tag. This tag has also been successfully deployed on penguins: gentoo penguins, king penguins and macaroni penguins. It measures 53x24x17mm plus ~50mm external whip antenna (length includes 4mm depth sensor). It can provide up to 20000 GPS location attempts including regular UHF download attempts, excluding depth data. See Table F for illustrations of the impact depth data transmission would have on the battery capacity of this tag. This tag is depth proof to 400m. Burst or VeDBA accelerometer data options are now also available for this tag configuration.