RadioJay: open-source tag development (Motus & GPS)

[TvE]

Sometime in march someone asked what it would take to make DIY/open-source tags for Motus and I wondered “hmmm, lemme try…”

This soon morphed into wondering what it would take to add altimeter data to the tag transmissions in the context of tracking bird collision risks around ocean wind farms.

It’s now a bit over half a year later and I’m reaching a milestone, which is an AOS 2024 conference poster presentation next week .

What I’ve done since march is to produce a small number of 1 gram tags that are fully Motus compatible (433Mhz) and have a pressure sensor as well as an accelerometer on-board. At each ‘beep’ the tags transmit their ID and the pressure reading, from which the flight altitude can be estimated. Here are two photos of a tag laying on top of a programmer board and inserted into the programmer:

In this process the three main learnings were:

1. it’s indeed possible to make sophisticated DIY tags that weigh 1 gram and cost only $30-$60 a piece
2. it’s possible to extend the 434Mhz protocol in a backwards compatible manner
3. the really interesting question here is how useful the real-time data is

There’s a huge divide between tags that transmit real-time data, which is lost if the transmission is not received, and tags that store sensor data and upload it via radio when in range of a station. I got the impression that the real-time data works to study collision risk around wind turbines but not for many (most?) other studies due to the fact that it’s difficult to ensure a reasonably continuous data set.

(Maybe this is a good time to insert a disclaimer: I have a PhD but it’s in computer science, not ornithology, so I know nothin’ about bird-related studies!)

All this lead me to wonder: how about replacing that altimeter by a GPS? (There are good reasons to have both, but that’s another topic.) Long story and lots of testing of latest generation GPS devices later I’m pretty convinced it’s possible to make 1 gram GPS tags that upload the data via radio when in range of a station. Moreover, I believe it’s totally feasible to upload to emerging public LPWAN networks (Low-Power Wide-Area Networks). I don’t have such a tag made yet so it’s still in the “I believe” category: I’ll find out in the coming weeks…

Overall I’m interested in figuring out whether I can help projects with new tags and how new localization technologies like snapshot GPS can work with Motus. All this is non-commercial.

If you are interested in this topic I’d love to hear your ideas, especially if you might be interested in collaborating to test some 1g-1.5g GPS tags in the near future! If you are going to AOS 2024 please stop by at the poster session (wed evening) or at any other time, if you won’t be there please get in touch here!

All the info is available at https://radiojay.org : details about the tag development as well as a couple of whitepapers on topics around the technology, including some of the options I see around Motus. (Keep in mind that I’m just a volunteer, not affiliated with Motus HQ.)

[Pat_Lorch_SSRS]

Very cool. Look forward to reading the poster at AOS 2024

[user972]

Hello, this is really interesting! Do you know if this type of transmitters exist and are commercial? How this tag will last?

[TvE]

Hi Helena, I’m not sure I understand your question correctly. The tags I’m making are non-commercial. If you are asking whether there are tags that combine similar functionality that are made commercially then the closest ones I know of are the tags that were used by a U of East Anglia project to track Griffon Vultures in Portugal. One of their papers is the first reference in the related work section of the radiojay.org website. Their tags were made by MiroMico if I remember correctly but I’m not sure they’re pursuing that business,

In terms of tag lifetime, I making tags with solar recharge because I don’t know of any non-rechargeable battery technology available commercially that can support GPS at these tag weights. This means that lifetime is really bounded by tag reliability and attachment method.

[user972]

Hi Thorsten, I open again this conversation because I am interested in knowing more about this tags. I would like to know the lifespan and the options to buy or do it ourselfs.

Thank you very much, Helena

[TvE]

Hi Helena. The status is “slow progress”…

I’ve been traveling and managed to catch a long lasting virus but I’m finally gearing up again and am working on the tag software. A lot of software is required to make this stuff work…

With the last prototype I was not satisfied with the GPS antenna performance and I have some new PCBs to assemble and evaluate.

Overall this will take a good number of months before I have something I can send out to others to test out.

What is the tag weight limit you are looking for?

Also, I assume you have looked into Lotek and CTT GPS tags, both have very lightweight ones, but they generally require recapture.

[user972]

Hi, I hope you’re doing well. We are currently working with 1-gram Lotek Nanotags, which have an approximate lifespan of a year. However, we are experiencing a significant loss of tags, and we are unsure whether the birds are leaving the area and not returning or if the tags are malfunctioning. For this reason, we are interested in a tag that includes GPS functionality to track the birds’ movements. However, I may not have fully understood how this type of tag works. Additionally, lifespan is a crucial factor for us… Are we still far from having access to this kind of technology?

Thank you Best regards

[user1235]

For community college usage we would love to have access to tags that could be that inexpensive as the $200 tags are quite cost prohibitive for us. I could think of some applications in non-migratory birds where an altimeter could offer some useful insights on behavior even if the data is not being stored. I assume this would require some tweaks to the data processing pipelines to extract this information from the radio packet data?