hello.

A few people asked for the story of my visit to Tony Di Fiore’s research site in chronological order.  Here are all the posts in order:

• Part 1
• Part 2
• Part 3
• Part 4
• part 5
• part 6
• part 7
• Part 8
• Part 9
• Part 10
• coda

I’m home now, after a couple days of traveling back from Tiputini.  The trip home was calm, but not without a few interesting moments.

The trip home was basically a repeat of the trip downriver, but with a lot more people.  In addition to Tony and I, two of the student groups were leaving, as well as Diego, the station manager, who was going back to Quito for a break.

Leaving at 7:30 AM, we took a boat two hours and change upriver to another research station, where we waited for a truck.  The truck took us an hour or so down a road cut by the oil company through the forest to a checkpoint at the edge their territory.  There, we got stuck for a couple of hours waiting for another boat because of the rain.  The second boat was delayed because it was bringing another group of undergrads to Tiputini station, and their flight was delayed landing in Coca.  We sat around in a garage at the oil company checkpoint waiting, while the students chatted, flirted, grouped off to play cards, show off, and so forth.  Watching it all, Tony turned to me and said with a smile, “You really don’t need to go to the forest to see primate behavior, it’s all right here.”

The boat finally came, and we headed up the last stretch of the river to Coca.  We got stuck on a sandbar at one point, and the boat driver had to do some fancy motor work and poling to get us back in the channel.  By that time we were almost late for the plane. Fortunately, they held it for us (since our group was the majority of the people on that particular flight) and we made it back to Quito safe and sound around 7PM. 12 hours from station to hotel.

Photos from the trip are finally online on my Flickr site, for those interested.  All in all, a great trip, and one I hope to repeat in the future.

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.

GPS tests

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

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.

17 Jan 09

As to how the new undergrads are: loud.  I know all about the dating lives of the guys in the next cabin now.

It’s another sunny day, hot for walking, but very pleasant otherwise.

Not much to report today, it was a pretty relaxed day for me.  Tony went out with his assistants to identify plants and check on how they’re flowering as a way to be able to estimate monkey diets.  I stayed in, and with no net and no radio work to do, spent time working on Arduino examples. A little pedestrian for the location, perhaps, but it was a nice break.

About 11 or so, he came back in, and shortly thereafter we took a walk up to canopy tower 2. It’s further away, about 2600 meters, which seems like nothing at home, but here, for me, it was a long hike.  Worth it, though, because the view from there is fantastic.  It’s a taller tower than the other one, I think, and larger. It’s wooden instead of metal scaffolding like tower 1, and surrounds the tree for more stability.  At the top there are three levels, a veritable tree fort.  It’s on the top of a ridge overlooking a lagoon, and as I said, has a great view.  I can see why the bird people love it.

On the way there, we ran across some leafcutter ants.  Pretty cool to see a long trail of leaf bits marching off into the forest. I got a few pix to be posted later.

While we at the tower, Heidi, who’s researching the photosynthesis of palm trees, came out to collect some samples.  In order to do this, she had to climb a palm, drag a saw up after her, and saw off a leaf.  No mean feat since the palm is 15-20m high and has no branches except at the top.  What she used was a pair of leg braces that clamp on to the tree and allow you to climb it one step at a time. The braces are attached to the tree by a loop of wire, and when you push your foot down on the brace, it tightens the wire loop and secures the brace whereever it is on the tree.  Lift your foot and you loosen the wire, allowing you to slide your foot up the tree. We had a good time watching her and catching the palm leaves.  Then we went down to the lagoon, had a quick paddle, and came back.  The shower I had when I got back was second only to last Saturday’s shower in its greatness.

Didn’t see any monkeys while we were out there, but Tony picked up one of the wooly groups, L group, on the telemetry unit, and was mighty happy. No one’s picked them up in a few days.

The main generator is still out, so all A/C is gone, and only the lab and the kitchen have power. There’s the occasional breeze, and a fan, so it’s plenty cool in the lab.

When many people are using the internet here, loading a web page is a bit like watching grass grow. I’ve been editing the same wiki page for the last hour and have almost made one change.

I’ve had crazy dreams since I’ve been here. Not sure why, but they’re all over the map. Some anxious, some amusing, most just plain weird.

16 Jan 09

Big generator still out today so we’re still operating on the small one. Conserving power, and no internet this morning. Running on battery power as long as I can.

Proxmity Tracking paper

Reading the proximity paper I mentioned a few days ago. A few interesting things stick out:

The collars had a weight of 125g. That’s too high for us. Are they less now?

The error rates look high to me. In the field, 34% exhibited problems they could not correct in the field. Apparently this is similar to the rates for GPS collars. Given my own experience with small GPS units, I wonder if that’s due to the size of the GPS collar. In any event, a 34% failure rate for proximity collars seems high.

The number of erroneous contacts is worth noting. Below a 15-second sample rate, they saw many continuous contacts show up as multiple contacts. That’s not so useful, though they do note that as the sample rate is taken higher, the number of erroneous multiple contacts decreases.

The number of “phantom radio detections” they had seems high too. I wonder if they are all analog radios, which is what’s causing the error?

They state that “because this was the first field deployment of these collars, such problems were not unexpected and determining their causes should enhance design modifications to limit similar problems.” In other words, they might be functioning much better now. This paper is from 2006, meaning there’s likely been another revision or two of the collars.

Their tests were all for the 1 – 1.5m range, though the collars can supposedly go out to 100m. I wonder if any research has been done on the longer ranges.

Further research: “Passive integrated transponder (PIT) tags have been used successfully to monitor individuals’ proximity to structures or use of certain areas (Prentice et al. 1990, Harper and Batzli 1996, Boarman et al. 1998, Kunz 2001, Gibbons and Andrews 2004) but have not been used to document individual-to-individual contacts. To our knowledge, the only previous attempt at proximity detection has been the MateID system (Sirtrack Ltd.; Ji et al. 1999, 2005)….. This system is limited in that contact can be estimated between, but not within, the 2 groups (e.g., genders) and only at very close ranges.”

“One-way systems may be available in the future, utilizing fixed-location receivers and animals carrying only transmitters, which would be similar to some current PIT tag applications (Gibbons and Andrews 2004). Such an arrangement would have positive implications for power consumption and collar size.” It would also have positive implications for our relay idea.

The rest of the day

In other news, it was a fairly quiet day. After a morning reading up on animal telemetry, we had a nice small lunch — only two tables out of about twelve were filled, because it’s Friday, and the boat took the last large group of undergrads back up the river after breakfast this morning. We had a leisurely lunch, filled with stories from Rudy the ornithologist about his travels around Bolivia, the hallucinogenic effects of ayahuasca and San Pedro cactus, and so forth.

After lunch, I finished off a little code and some email, then went for a walk on my own. It was a gorgeous sunny day, and the view from the canopy tower was spectacular. Lots of butterflies, but sadly, no monkeys. Then, on the way back, I ran across a group of wooly monkeys and got the chance to take some more pictures. Finally got a half decent one of a monkey staring down at me while he wrestles with another monkey. Those little bastards are hard to get pictures of!

Came back to camp and coded a little more, then did a quick run into the forest with Tony and Margaret looking for a wooly group she had been tracking earlier in the day. We didn’t find them, unfortunately. There is some confusion at the moment as to which monkeys are in which groups, because both Margaret and Peter have run across at least two signals at the same time. Tony’s not sure what it means, but he’s intrigued.

A new batch of undergrads have arrived this afternoon. We’ll see what they’re like at dinner.

15 Jan 2009

There’s a group of howler monkeys voicing their opinions nearby as I type.  I can hear them through the window. It’s pretty quiet, so they’re probably several hundred meters away in the forest, I’m guessing.

Saw tamarind monkeys today on the way back from breakfast.  There’s a group that hangs out in the camp and I had never noticed them before, but Tony pointed them out.  It was a group of about 9.  They’re tiny, maybe the size of a large rodent.  They ran all through the trees from the stream by the dining hall to beyond the lab.

It’s a frustrating technology morning for Tony.  First, he downloaded nearly six days of data from his GPS only to find that the memory holds three days, and defaults to wrapping around. This means that the most recent three days overwrote the previous three days.  That sucked.  Then, we had planned to walk out to one of the camera traps by the river, about 2km, and replace the batteries and memory card on the camera.  We hiked out there, longer than we thought because one area was flooded out and we had to skirt around it, and when we got there, he realized the batteries were not in Tony’s pocket.  A wasted trip for him. But hey, I enjoyed the walk, and the spot is really beautiful, right by the river.  I didn’t get any shots though, too much foliage.

Update on José: we ran into him in the forest today, taking down his traps.  He told us it turns out there’s no room on the Friday plane from Coca (where the boat lands) to Quito is full, so he’ll have to stay a day in Coca before he gets to Quito.

Did another test with the GPS unit, this time on the dock of the river.  Results:  nothing.  Sigh. It was pleasant to sit out by the river while it collected data though.  Got through a couple more chapters of Moby Dick while butterflies landed on my legs.

The big generator went out this afternoon, so they’ve got the lab on a small generator.  Now we have the fragrance of gasoline exhaust wafting in the window.

The food here is pretty good. It’s simple, rice with most meals, and all the bread is the same sandwich buns (hamburger buns, basically). This morning we had French toast made with the buns, and tonight we had broccoli and cauliflower over noodles in a cheese sauce, with garlic bread from the same buns.  Lunch was a to-go pack for the forest, two ham and cheese sandwiches on, you guessed it, the same buns.  The folks cooking are pretty creative with a limited set of staples to work with.  We’ve also seen an amazing variety of uses of bananas.  Tonight they were poached in a sugar sauce, I think. Sometimes there are banana chips, or grilled bananas.  There are always mangoes and some other fresh fruits available, usually apples and passionfruit.

Tonight for fun, I explained how GPS works, and Tony played human evolution raps from his class. Now there’s a more serious conversation about how to identify individual monkeys from the coloration of their genitalia.

14 Jan 2009

Radio Tests and Camera Traps

Today was a day of camera traps and radio tests.  Tony and I  went out to replace two of the camera traps that are used to cover a mineral lick where the monkeys come to eat the dirt in a cave.  I guess it’s rich in minerals and bugs, so they get a lot of monkeys there.  It’s also rich in bats, and as we were working, one flew out of the cave.

Thanks to Younghyun Chung for the following note on Canon cameras that may be worth looking into for future camera trap development:

“CHDK, Canon Hack Developers’ Kit, seems worth to look at to take a picture of monkeys. I just heard about this and it includes “Motion detection – Trigger exposure in response to motion, fast enough to catch lightning.”

While we were on the trail to the camera traps, we saw a stinky phallus.  It’s a pretty mushroom, snow white with large holes in the side, and tubular. Got some pictures I’ll post when I get home.

We had some actual sunshine today.  The forest looks gorgeous in the sun, and gets much warmer. Rosser and Nataliya were happy because they finally got a few more dragonflies.

What’s the maximum range on active RFID?  Wonder if it’s worthwhile to give the monkeys the equivalent of EZ-Pass. I know, Charleton Heston would say the minute they can get over the bridges easily, it’s all over for Manhattan.

Radio tests:  We looked at whether we can tell the difference between 5m, 10m, 25m, all the way out to 75m. We typically lost signal between 57 and 75m, just as we did the day before.  The signal was very noisy, so I’d say it was inconclusive.  There’s definitely a difference between 5m and 10m, but less so beyond that.  However, I wasn’t plotting it on a log scale either, where the plateaus will show up more sharply.  Will look again later.  Tony had fun bounding down the trail like a monkey.

On the way back from camp, we ran across a group of wooly monkeys very close to camp. I was able to get my camera out and get some monkey shots, finally.  Most of my shots are useless, because I hadn’t yet been able to work out settings to shoot them, but at least I have an idea of settings now.  It was pretty exciting.  Of course this was the one time I went out with no pack, only camera, and it started to rain as we were out there.

Some of the cabins ran out of water this evening. Kevin had no water, so came over to use our shower. He had been processing monkey poop using a “DIY centrifuge” — aka tie the vial on a string and spin it around for a few minutes — when one of the vials popped open and sprayed him in the face with poop.  Hopefully no ill effects, but good to wash it off right away.

One thing I’m learning is how much of my life involves high bandwidth.  The number of everyday requests I’ve gotten via email from colleagues, friends, etc. that involve transfers of more than 1MB is a lot larger than I thought.  At home I wouldn’t even think about this, because I always have a nice fat connection.  Down here, every byte counts.  And not being able to do some of those everyday things inconveniences people I work with.  So if you’ve been inconvenienced, sorry.  On the other hand, if you design websites, try going back to 1995-era home connection rates and looking at your sites.  You’ll be amazed.  Even something as innocuous as an online application form has stopped me cold down here. Take a look back through your mail for the last day and see which ones were either greater than 1MB, or referenced a web page that was.  It’s higher than you might think.

There’s not a ton of sleeping getting done in our cabin, it’s a bit of an infirmary. I’m still up and down on the toilet every couple of hours, and our cabinmate José is very ill.  He’s been achey and had a fever for days, yet has still been out in the field chasing birds.  He says the aches are worse at night, and after consulting a doctor (conveniently, his mom is one), he’s afraid he might have malaria.  Though there is no malaria in this region, he was on the coast before this. He’s planning to take the Friday boat out and see a doctor in Quito.  He’s hoping it’s less serious, and that he’ll be able to come back on the Monday boat following. The boats only go on Monday and Friday, except in cases of extreme emergency, so those are his only choices.

13 Jan 2009

Question: what are the regulations on long-range 2.4GHz and associated bands in this area?

25-30 animals in a group typically, although spider monkeys typically move in smaller groups ( less than 5-6?)

Didn’t go into the field today, stayed in to read up on wildlife telemetry.  Found an interesting product from Sirtrack that already does proximity detection. These collars have to be retrieved from the field, though. It’s not clear from the Sirtrack site what the range on the collars is, but there’s a decent paper on them:  New Radiocollars for the Detection of Proximity among Individuals, by Suzanne Prange, Trevor Jordan, Colin Hunter and Stanley D. Gehrt in the Wildlife Society Bulletin, Vol. 34, No. 5 (Dec., 2006), pp. 1333-1344 Published by: Allen Press. I think these are worth some experimentation. I started to work up a simulation of what we might do with them in Processing.

Today is laundry day, oh joy.  Clean clothes tomorrow.

The rain last night was very intense at two points, strongest I’ve heard other than a hurricane or nor’easter.  No wind, though, which probably made it all the more intense.  There’s been much more rain than everyone expects (this being the dry season), so most everyone’s tracking is less productive than they’d like.  The dragonfly researchers (Rosser and Nataliya) have found only half the species they expected to so far, and spend much of their time in camp because it’s just not worth going out, for them.  The monkey folks go out most of the time, though.
A typical day around here for most of the researchers looks like this:
6:30 AM breakfast. 7 – 7:30ish prep for fieldwork. Most of the morning is spent in the field.  Some come back for lunch at noon, others take lunch and keep going. Afternoon is more fieldwork until about 5 or 5:30, followed by checkin at the lab, shower, and dinner at 7.  Most head back to the lab after dinner (8ish) and work until the electricity goes off at 9:30.  Then bed. By then it’s very dark, and you’re going to be up early, so you might as well go to sleep. Sometimes people head out earlier.  For example, I’ve seen Tony’s team head out at 5:45 some mornings to get to the monkeys earlier.

Electricity is on twice a day, from 10:30 until about 1 I think, and 6 or 6:30 until 9:30.  In the labs, the power comes on earlier, about 8:15 AM, and stays on later.  The network connection is up from about 8:30 until 9:30 in the labs, when it’s working.   There’s no media that I’ve noticed: no TV, haven’t heard any radio.

The showers are cold, but after a hike they’re refreshing once you get past the initial shock.  The cabins are all open to the air (curtained and screened, but that’s it), so you’ve got a pretty good idea what everyone else is saying in your group of cabins, and can hear the forest all night.  It’s a rich soundscape, and pretty loud, I’ll try to record it one night.

In addition to the researchers, there are a number of school groups that come through.  All the ones I’ve noticed so far are undergrads from the US, on biology fieldtrips.  They’re typically in the field all day, and have night classes after dinner.

There are ants crawling across my screen as I sit here programming.

Camera Traps

Tony brought two camera traps back in from the field today. One’s a video camera trap and the other’s a still camera trap. They’re about the simplest things I’ve seen so far, it’d be easy to build them from scratch.  The video camera trap is just a Sony Handycam in a Pelican case attached to a microcontroller.  The microcontroller’s got a PIR motion sensor in it, and a photocell.  The photocell is there to tell if it’s day or night.  The PIR, of course, is for motion detection, and when it detects motion, the microcontroller sends a signal to the camera using the Sony LANC protocol.  There are a series of DIP switches on the back of the controller board to set the operating mode, and tuning potentiometers to adjust the sensitivity of the sensors.  Couldn’t get a look at the controller, but it looks like an 18-pin PIC. There’s also an IR LED array attached to the front, but they don’t use it since the monkeys aren’t nocturnal.  The still camera trap is about the same thing, except it’s using a different protocol for the different camera, also a Sony (PSC41).  The controller on that one is a little fancier in that they incorporated an LCD display for feedback about the operating modes.  I took some pictures which I’ll post on Flickr when I get home.

One thing that fascinates me about the gear they’re using in the field is how old the battery technology is.  Most of it relies on AA, C, or 9-volts. Seems like converting the stuff to something with a higher energy density, or easier recharging, would be an easy first step. Even some of the new equipment I read up on was using C cells.

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.  They’re at the resort where we waited for the boat the first time.  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:  my camera (Nikon D70) emits RF noise that interferes pretty heavily with the telemetry units.

I love this tree.  It’s huge.  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.

Vertical tests

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.

Horizontal tests

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.

11 Jan 2009

Not much to say about today. I spent the whole day in camp, and much of it in the bathroom, getting intimate with the local microflora.

The researchers use dictaphones to record vocal notes on their observations. My first question was why not use the PDAs (model Palm Z22) to record vocal notes as well as the written notes?  Tony pointed out that the dictaphones are very small and easy to hold up to your mouth to speak into quietly, whereas the PDAs are not, particularly when they are in a dry bag.

Another item that could be handy: Coaxial cable repair kit. The coax cables that attach the telemetry antenna to the base unit go bad a lot.  Repair would save money on new cables.

We did a very slapdash test of the XBee radios in the forest today. I was hoping to see what kind of penetration we can get out of 2.4GHz radios in the forest. I put a receiver radio (XBee series 1 radio as a receiver) on a datalogger, and a second radio (XBee series 1 pro as a sender) on an accelerometer.  The received signal strength was surprisingly noisy considering that the distance between them was relatively constant.  We could see a clear dropoff, though, when he climbed the canopy tower. Will do more rigorous signal strength tests later on, I hope.