Hi Helena,
Yes, quite a lot of questions! Also, take my input with a pinch of salt, as I’m not an engineer, although I sometimes have to become fairly technical to understand what is best for my research.
I think there are actually quite few wildlife radio-tag suppliers globally (see below). Also, the battery-life figures are usually manufacturer estimates, and in practice there can be substantial variation depending on tag construction, animal behaviour, temperature, batch, etc. So I would interpret them conservatively.
For example, if a tag is estimated as lasting 100 days, that will depend on the pulse rate and characteristics of the transmission, such as pulse width (for simple beepers) or the amount of digital data transmitted per transmission (for digital tags). Sometimes companies can change transmission power as well which affects detection range but also negatively correlates with lifespan. I would probably want at least a 20–30% margin for all estimates.
If you’ve already spoken to Lotek, they may be able to provide more information or perhaps offer configurations with longer battery life. There are a few smaller suppliers of beeper tags as well, although I’m not sure they would offer anything better than NanoTags. You could speak with ATS, Wildlife Materials, Plecotus, American Wildlife Enterprises, Telenax & Holohil. Need to confirm with companies about 1g tags. Also these make only beepers as far as I know so no coded tags so these tags will be only received by your stations not the wider Motus network in Europe. The only coded tag supplier is LOTEK as far as I know. So if you “must” have the ability to detect location using other peoples stations in Europe then it is indeed only CTT/LOTEK. If you can sacrifice that for the ability to have a lifespan of tags 1 yr or longer you can use only your station’s infrastructure and choose beepers. But maybe you can combine and go for 433 MHz (though bear in mind there are not too many 433 MHz receivers in Europe atm).
I also think it would be useful to build a database of radio tags’ manufacturers (one of our many COST Action tasks - just need to get Horizon funds - small details!). For the choice of tags, you need to consider the receiver, settings, background noise, and especially how many animals you want to track simultaneously. With >100 animals, using beepers becomes problematic and frequency spacing becomes important. I would aim for at least ~7 kHz, preferably ~15 kHz, between beeper tags, which means the receiver needs to scan across multiple frequencies and makes data processing more complicated. WIth coded or digital tags it is easier - just use one frequency.
In simple terms, a basic beeper just sends a regular pulse that you hear as a beep. A coded tag (we commonly use only LOTEK ones) still uses beeps, but the pattern of peaks (eg 3 time spacing between 4 peaks or the same principle for more peaks) identifies the individual tag, so the receiver can tell animals apart (presuming each receiver has a database of registered coded tags pre uploaded). A digital tag (commonly 433 MHz or other higher-than-VHF frequencies like CTT 433MHz/Blu Series 2.4GHz) is more like sending a small data message with a package of few bits, so it can potentially carry the tag ID plus other information (payload).
Also, 433 versus 150 MHz isn’t simply a frequency comparison. You need to consider whether the tags are beepers, coded tags or digital tags. NanoTags are coded, while CTT uses digital transmission, which allows additional information such as ID and potentially battery or temperature data to be transmitted. Bluebat also supports digital information.
In theory, 433 MHz has a shorter range than 150 MHz at the same transmission power, but in practice detection range depends heavily on the whole system: antenna design and orientation, line of sight, vegetation/terrain, cable and connector losses, amplifiers, and overall RF noise. So the nominal tag frequency may not be the main limiting factor in a real deployment.
Lots of information. You may stick to comparing BluBat 433 MHz vs Lotek Nano tag but you can do range detection testing with one dual-band station and see whether the detection range for BluBat tag in your area is contrastingly different (shorter) than NanoTags and then decided whether you are happy to go with either. It may be that you see much longer detection range with coded NanoTags and given the size of the area you need to cover and the budget you have you may then decide for NanoTags/150 MHz and then you may ask LOTEK to squeeze max lifespan out of those by setting longest pulse rate for ex.
Best,
Dmitry
