12 Jan 2009
It’s getting a little easier here, for a few reasons. My stomach is getting stabler (still a ways to go), Tony and co. are only taking me on short baby walks. In fact, it’s quite a pleasant day today.
Have to consider rain in every component. There is always rain.
Everyone’s asked for photos. Here are the largest I can upload at the moment, more to come when I get home.
These monkeys are not in the station.Â They’re at the resort where we waited for the boat the first time.Â I don’t think they’re legal pets, though. I haven’t gotten any pictures of monkeys in the wild yet, because we’re usually on the move (because they’re on the move) and because I am way clumsy in the forest, and likely to throw the camera in the river and end up on my butt.
We learned something interesting today though:Â my camera (Nikon D70) emits RF noise that interferes pretty heavily with the telemetry units.
I love this tree.Â It’s huge.Â One of the canopy towers is in this tree, about 35 meters up.
And here’s the money shots for the geeks:
This was taken from the top of the tree:
This morning, Kevin and Tony and I went to look for titi monkeys. We didn’t find any, but we did manage to get lost, or as Tony prefers to put it, “got to know the forest a little better.” It was a good hike, but frustrating for them because no monkeys were found. I did another test with the GPS micro-mini, and got the same results. I’m pretty sure it’s going to take a bigger antenna to make it work.
This afternoon, we ran some tests of signal strength of 2.4GHz using XBee radios. Transmitter was sending 1 sample of AD0 and AD1 at 80 ms intervals for all tests. I don’t necessarily want to use XBees, but they were the only high frequency radios I had in hand to test with. The current telemetry gear works in the 148 – 152MHz range, which supposedly gives better penetration through the foliage. Details below.
Tonight we’re in the lab seeing if we can get high by putting a mixture of momnkey poop and ethanol in the dry box to evaporate the solution. This is what happens when there’s not a lot of entertainment. We’re eager to see what happens.
Test 1: I climbed from the top of canopy tower 1 to bottom (approx 35m). Used an Xbee as transmitter (chip antenna) and an Xbee as receiver (chip antenna). Got inconsistent signal from top to bottom, but consistent at about 25-30m on down. I climbed from the bottom of canopy tower 1 to top (approx 35m), while Anthony waited at the base. I stayed at the top for a minute or two.using an Xbee pro as transmitter (wire antenna) and an Xbee as receiver (chip antenna). Got good signal from top to bottom. -85dB at approx 35m.
Test 2: I climbed from the top of canopy tower 1 to bottom (approx 35m). Used an Xbee as transmitter (chip antenna) and an Xbee as receiver (chip antenna). Got inconsistent signal from top to bottom, but consistent at about 25-30m on down. -94dB at approx 25 – 30m.
Test 3: I stayed at the base of tower 1 with a transmitting radio while Anthony walked into the forest. He got lost and walked back, then walked out again (The second rise shows his return) Using an Xbee pro as transmitter (wire antenna) and an Xbee as receiver (chip antenna). Continued to get successful transmission out to approx. 60m. There is a sharp dropoff in signal strength, of 20 – 30dB, when he crossed into the trees and out of the clearing.
Test 4: I stayed at the base of tower 1 with a transmitting radio while Anthony walked back to me from the forest (approx 60m). Using an Xbee as transmitter (chip antenna) and an Xbee as receiver (chip antenna). There is a sharp dropoff in signal strength, of 20 – 30dB, when he crossed into the trees and out of the clearing. Signal consistent from about 45m, and gained strength more or less consistently all the way back. There are dips and spikes as he went, possibly due to the thickness of foliage?
Test 5: Using an XBee Pro as transmitter, the receiver walked as far away as he still had signal, then walked in and out of range at the periphery of the range. A noticeable dropoff when he went into the forest, but consistently increased on his return.
Tony mentioned that they don’t always use GPS because the trails and the trees are so well marked and well known that sometimes it’s more accurate to reference your position by the tree than by lat/long
Some weight limits to consider: We can probably go up to 100 grams on a large monkey. Here are the weights of the things we’ve currently got. Small monkey radios: currently 54g (big one), 22g (small one), large monkeys currently 45g. Logomatic v2 plus battery: 51g. Xbee Pro plus LilyPad power supply plus small LiPoly battery: 27g.