A project hosted by the Zoological Society of London ZSL

Do the devices use GSM, mobile networks or satellites?


Posted on January 17th, by Robin Freeman in . 4 comments

The devices do not relay data via mobile networks or satellite. They use satellite signals to determine position (GPS), but do not send data to satellites. Each devices has a small radio antenna that can transmit and receive data. Data can then be transmitted between devices. This can be used to download data to devices configured as base-stations in the field. Devices retain logged data, and can also be manually recovered.





4 thoughts on “Do the devices use GSM, mobile networks or satellites?

  1. Question 1: what is experience with the maximal range between base and tracking device? e.g. in forest? in mountains?

    Question 2: is it possible to get into the range with a base and initiate a download cycle at that time?

    • Hi Duke,

      1 – I’ve only tried the range between devices (the base and trackers are the same device, just reprogrammed) in quite clear environments (islands). Using a small wire antenna (just a 10cm wire) we were able to get 300-500m range with line of sight. I would expect this to be similar in many environments (with line of sight). This degrades as you get obstructions, but it would be hard to predict for any given environment – we’d have to try it out!

      2 – I’m not sure what you mean by ‘at that time’. The current method is to have trackers send a ‘heartbeat’ (a small signal relaying memory size, battery voltage) at a user selectable intervals, and the tracker will then listen for a response from a base. So if you configured the tracker to send a signal every 30 minutes, and to listen for 10 seconds – you would then have to have a base within range at that time. You can have multiple bases (just reprogrammed trackers) which you can scatter throughout the environment to maximise contact.

  2. Hi there,

    We have been working with the behavioural ecology and ecological “function” of large herbivores, primarily Malayan tapir, in tropical rainforest habitats for the past 10yrs. We have made use of VHF as well as GPS (both with GSM and Satellite download), but neither has worked satisfactorily.

    The main challenge is a) GPS-fixes below dense canopy, b) practicalities in keeping the transmitter on the target animal and c) unable to “communicate” with other transmitters.

    We are currently exploring options on how we can study the social and reproductive interactions of this very illusive species, and the modest size of your device offer various options for progress, e.g. attaching it to the ear. So here are a few questions:

    a) have you tested the GPS accuracy/function in dense canopy conditions and if so, how is the % of fixed points? Currently, our units have a coverage of about 40% at a 90sec “search” setting.
    b) for obvious reasons, we have to operate the units for a minimum of 12 months, and preferably 24months to get a full reproductive cycle. Our current transmitters can be extended to 30 months, weigh about 500gr incl battery, but do not communicate with other transmitters. They also have “drop off” function, which is important for us. With the mAh drawn for your device, is it possible to operate it for 24months without adding a 5kg battery?
    c) Inter-transmitter communication is an important new component in this study, because it will provide us with data of proximity (breeding/mating) and occasional encounters. What information does your transmitters transmit to each other?
    d) To measure possible hormonal fluctuation related to reproductive activity/cycle, or body temperature, we would like to be able to measure such parameters too. Can a such additional technology be part of the transmitter too?

    Best regards
    carl

    • Hi Carl,

      > a) have you tested the GPS accuracy/function in dense canopy conditions and if so, how is the % of fixed points? Currently, our units have a coverage of about 40% at a 90sec “search” setting.

      No, we haven’t yet had the opportunity to do so (most of my work has been on seabirds). Do you happen to know the sensitivity of the GPS receiver we were using. We’ve selected a relatively new chip with high sensitivity (-165 dBm), so it should have a good chance, but it’s hard to tell without testing (which is one of the reasons for the call for collaborations).

      > b) for obvious reasons, we have to operate the units for a minimum of 12 months, and preferably 24months to get a full reproductive cycle. Our current transmitters can be extended to 30 months, weigh about 500gr incl battery, but do not communicate with other transmitters. They also have “drop off” function, which is important for us. With the mAh drawn for your device, is it possible to operate it for 24months without adding a 5kg battery?

      It should be possible, by selecting the appropriate duty cycle (how often to take a fix). How often were you taking fixes on your current units?

      > c) Inter-transmitter communication is an important new component in this study, because it will provide us with data of proximity (breeding/mating) and occasional encounters. What information does your transmitters transmit to each other?

      At present they can communicate ‘heartbeats’ (how much data, voltage, etc). However, we’re currently working on enabling the devices to synchronise complete logs with each other (but this is a new feature beyond what we’ve tested to far). I’ve also considered this for recording occasional encounters, and having complete GPS traces should allow these encounters to be inferred. Furthermore, if you were just using device contact as evidence of interaction, the range of the device (up to 500m) would also have to be taken into account (whereas GPS would let you determine the distance).

      > d) To measure possible hormonal fluctuation related to reproductive activity/cycle, or body temperature, we would like to be able to measure such parameters too. Can a such additional technology be part of the transmitter too?

      It’s certainly possible, but isn’t something we’ve considered as yet. However, we’re keen to explore new ways we can extend the device

Leave a Reply

Your email address will not be published. Required fields are marked *


− four = 1

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>