18 Jan 2009
Fourth day no big generator. The morning is overcast, and a bit muggy.
Summarizing my project notes from the whole trip so far:
Notes on gear use
Each researcher carries four main pieces of electronic equipment in the field: GPS unit (on lanyard in dry bag attached to backpack, usually); Palm (on lanyard in dry bag around neck or shoulder for easy access); voice recorder (haven’t seen anyone use them, presumably in pack) and telemetry receiver (around neck). None of the devices communicate with each other currently, though it would be useful if each note in the Palm were tagged with GPS coordinates. Likewise, a telemetry unit that logged its readings and geotagged them would be useful.
Again, any communications between devices would have to be wireless, but would also have to avoid interference with the telemetry signals. Worth noting how my Nikon D70 camera generated considerable RF interference for the telemetry unit.
Summary of possible useful items for the lab
- coaxial cable repair kit, along with coax connectors and cable
- Uninterruptible power supply
- Solar panel on roof/battery storage unit in lab
- dry box improvements (?):
- all incandescent lamps for greater heat
- humidity sensor to trigger on/off instead of timer?
Conclusions on radio tests
2.4GHz radios work fine out to about 60m, though there is significant attenuation due to interference from vegetation. Our proximity tests didn’t conclusively show a difference between 1m, 5m, 10m, though the tests were not very rigorous. There was a lot of noise. The data from the tests is here, in Excel format:
(post excel files here)
Things to consider for next tests
I think it’s worth investigating 900MHz solutions for the longer range, which might mean more coherent signal at shorter range. Is the Atmel AT86RF212 worth considering? It’s their only 800/900MHz offering that I could find. Also, look at the Digi XBee Pro DigiMesh 900 radios.
I’d also like to do successful accelerometer tests.
Future height signal strength tests should use tower 2 or the canopy walkways to avoid signal interference of the metal scaffolding of tower 1.
Every device to be tested should be thoroughly sealed. Even on a pleasant day, there’s enough humidity to cause potential interference. Put it in a box, seal the outside, controls on the outside with rubber washers and gaskets.
Antennas should ideally be woven into the collar, or perhaps even be the collar.
RFID and tracking
Early on, I speculated on the idea of using RFID in tracking. After a little reading, I’m skeptical about it. First, because passive RFID is already in use in animal tracking, written up in many papers as “Passive Integrated Transponders,” or embedded RFID tags. For our purposes, passive tags would make no sense, too short range. Active RFID tags would make more sense, and many are even within the frequency range of current telemetry,but there’s no such thing as a reader-tag, which is more or less what we need. The amount of customization we’d need to do is great enough that it makes more sense just to get generic transceivers and build the units that way, or to use something existing like the Sirtrack proximity collars.
The micro mini was a failure, most likely due to too small an antenna. Aaron at Sparkfun notes that they had their best results in testing with no interference, so the canopy here is probably the issue. Worth investigating the EM-406 or 408, maybe, with patch antenna.
The Nokia E71 got signal while on the river, but not under the canopy. Worth trying an iPhone out here, perhaps, or better yet, an iPod Touch with a GPS backpack. Tony mentioned the thought of switching to them one day in the forest.
Camera traps look easy to build; just a camera, microcontroller speaking the camera’s control protocol, PIR sensor, and batteries in a Pelican case. Usually a photocell as well to make adjustments for day/night, and sometimes an IR array for night light (not necessary with the monkeys).
Possible camera trap improvements:
- make your own, for cheaper (publish an instructable)
- Use the same power source for camera as for microcontroller board
- Use more energy-dense power source
- Investigate CHDK, Canon Hack Developers’ Kit, for possible use in camera traps. There is a motion detection script for it.
Things we didn’t get to
- coming up with a way to Access as a database tool with an online DB
- coming up with an automatic upload scheme so that field researchers’ data is automatically available to Tony and Eduardo on a daily basis
- investigating other handheld database solutions
Worth noting that the team here is largely Mac-based, but the software is mostly Windows-based. They do most of their work in Parallels.
Diego, the station manager, just came in with a giant toad, about the size of his palm, brown with a tan back. It was in the bathroom.
Last walk in the forest was good, just a short walk to the canopy walkways (less than 1km out there). They’re rope walkways from a tower like the other two to a couple of large trees in the area. Probably great for watching the canopy, but no way am I getting up there.
Tomorrow, a full boat back to Coca with the undergrads from Bethel University, the ones from Kalamazoo, Tony, and I.