We put up, sleeping bags and all, in one of the Cabins at the Trout Lake LTER Station (Northern Temperate Lakes LTER) the night of November 10th and 11th.

 

Thursday, November 10th, we met with Tim Kratz, the senior PI (Principal Investigator) of the Station, and Tim Meinke, Technical assistant at Trout Lake - both of whom have been at Trout Lake for 20 years. (there is a research, technical, and administrative staff of about 10 at Trout Lake. Tim Meinke handles most of the lake equipment, including the raft on Sparkling Lake - the only lake that has a set of sensors, data loggers, and communicating cell phone system on it. This year they will attempt to leave the raft in the water all winter long, which they have not done before. Obviously the ice and snow that starts in November, and continues through spring, poses many problems for maintaining reliable data collection all winter long.

By agreement with Tim Kratz, our first priority is to connect up the Sparkling Lake data collection system to the Trout Lake facility, wirelessly.

Sparkling Lake is only approximately 1.3 miles from the main building at the Station - where the T-1 line from the University of Wisconsin terminates in a router, an NT server, and a local area network.

The challenge for connecting up the 7 lakes wirelessly, however, is that the ground is relatively flat throughout the area, with the slight exception of 'Muskie Mountain' a few hundred feet higher than the surrounding countryside. And the entire area is covered with sparse to dense trees, both deciduous and evergreen. They average 60' in height. Thus if we use no-license spread spectrum radios, which operate in the 902-928 Mhz and 2.4 to 2.483 Ghz frequency bands, at power levels from 100 milliwatts to 1 watt (at the radios) we cannot put the radios at ground - or lake surface level and expect them to reach the Station, even if there is a tower on the main building. By inspection, from our experience, there will be too much attenuation.

So at first glance it appears we must look for ways to gain height by towers, get the maximum antenna gain, and highest FCC permissible power, and, where necessary, use relay station radios.

And in all lake-site cases, we have to provide for rechargeable power. To drive both the radios and data logger and sensor instruments.

We agreed that we would concentrate on the Sparkling Lake case first, and get all the information we needed to order duplicate data loggers on which to design interfaces here in Colorado between trips to Trout Lake where we expect to visit largely to install radios and interfaces, both hardware and software.

 

SPARKLING LAKE

Out in the middle of Sparkling Lake is a raft built at the station which is approximately 6 feet by 6 feet, under whose timbers are watertight cans that gives it good flotation with about 12" of freeboard. The raft will easily support a man, even two, although working on it while on the water would be awkward and slow. The Station prefers to pull it out of the water and take it back to the work sheds for modification.

Myself, Mike Willett and Tim Kratz took a power boat out to the raft launched and navigated by Tim Meinke. There was a brisk breeze blowing. No ice had formed yet (10 November) but it was clear it would be forming soon. We wore water survival suits.

 

 

Boat and Boaters

On the raft is a locked case containing a Campbell Data Logger and a special interface, to which is connected numerous censors, a battery case, a spare smaller case, and the solar panel tilted at a 45 degree angle to the south.

 

Raft and Gear

The sensors consisted of 3 Anemometers operating at 1, 2, and 3 meters of height above the raft. They are affixed to a metal pole which looks to be about 3/4 of an inch in diameter. Then there are Relative Humidity and Air Temperature instruments above water, and 10 Thermisters hanging below the raft to a depth of 16 feet. These are the sensors which send their data to the data logger, storing it, and awaiting calls over a cell telephone which is rigged to turn on and draw power only when a call comes in.

 

Open Case with Data Logger

Then there is a solar panel about 2 by 3 feet that recharges the 12 volt battery that powers everything.

 

Solar Panel on Raft

Until this year, the raft was pulled from the lake before the ice came in, and put back into the water in the spring. The ice starts forming in November, and the staff cannot go out onto the ice until late December. Because our NSF project was approved and funded two months later than we requested, this makes it touch and go to see if we can get a wireless link installed before the ice makes it impossible for about two months. After which we can get out on the ice with equipment, but the raft will be frozen in, and cannot be extensively modified.

We discussed various ways to solve the most critical problem at the raft, which will be the reliable generation of sufficient power to keep the battery or batteries powering all equipment, plus the radios which must operate continuously. (perhaps)

Our consensus was that it will take a wind generator besides a solar panel, to keep it all functioning even when snow covers the solar panel, and weak winter short day sun cuts down on the solar panel input. But since the anemometers are very sensitive to disturbance, it was also a consensus that we ought to plan on putting a second raft into the water to carry all the wireless equipment - sealed radio boxes, mounted antenna, possibly a 13dB gain directional panel, battery, solar panels, pole and wind generator. Which should kick in to produce effective power at about 6 knots of wind speed. Tim Kratz was going to look up the data on past readings, but felt that on the larger lakes at least, wind would be present much of the time.

The second challenge for the Sparkling Lake site is getting the wireless signal from the lake level to the Station, through or around the dense trees which occupy at least 74% of the ground between. Until we test both 915Mhz radios at 1 watt of power and perhaps a 24db antenna at both ends, with a 60 foot roof tower at the Station, we cannot know to what extent the trees can be penetrated. If they cannot be, we may be able to mount a relay radio, high on a tree halfway between, to get the signal through.

 

Typical Shore Line Trees

Only a later trip with spectrum analyzer and radios we can temporarily install will give us the answers. Even then, the snow build up on trees will inject another unknown-value problem.

Then the main challenge, will be redesigning the interface between the data logger and the wireless, then integrating it into the station computer system as well as the Madison data storage site. For as it turns out, BOTH the Trout Lake site AND the Limnology Center site 'poll' the data logger via telephone modem. The Limnology data center has its system rigged to automatically, every two weeks, 'call' via long distance and modem to the cell phone on the raft. A switch detects the call attempt, power is applied to the cell phone, it answers, and stored data flows to Madison Wisconsin where it is added to the data stored there.

Then, whenever the Trout Lake site wants to know the same data, or to check that the system is operating correctly, Tim Meinke can manually order his computer and modem to place the call, and link the data to the Campbell Scientific Software designed to present and save the data from their loggers.

The problem this presents is whether or not the researchers are going to expect that BOTH the wireless and the cell phone system will operate for a time while the bugs of the wireless are worked out. If so, since the data comes out of the Campbell loggers RS232 port, we may face a tricky 'split' RS232 feed. Many software questions need to be answered here before we can proceed. Some of whose answers are at the Limnology Center, not at Trout Lake.

We concluded our analyses of the Sparkling Lake site by identifying the problems we have to solve.

 

MUSKI MOUNTAIN TOWERS

We then visited all 6 of the other lake sites, starting with a revisit (for me) to the towers on Muski Mountain, about 4 miles south east of the Trout Lake station.

There is a Wisconsin Electric Power large tower, with multiple radios - most looking like cell phone antennas - on it, up to its ringed 200 or so foot top. There is another very tall tower (450') about a 1/4 mile from the Wisconsin Power tower, and lower down. It appears that this tower, with television relay and cell phone antennas extends at least 100 feet higher.

Both towers look very attractive for the placement by us of a relay radio sight that can at once serve the Trout Lake Station with one 4 mile leg, and then reach out to as many lakes of the 7 as are reachable through no trees, or only an edge of them.

We will now contact the tower owners to see under what conditions and at what price we can mount equipment on either of the two towers.

While we were there a crew with many vehicles was working on the tallest tower. This one requires a winch truck with a very long cable anchored at the top, to haul a worker up the tower on a seat. So we will have to contract with someone to do that work.

Climbing up on a lower fire lookout station tower by Tim Kratz to about 100 feet determined that several lakes were visible from it.

As we visited the other 6 lakes, the towers were visible from three of them, and the Trout Lake itself is visible across the water directly to the Station, which is near the water and on a hill of perhaps 50 feet above the water's edge.

So the idea of putting the base radio at the Station, on a 60 foot tower, which then with directional antenna shoots to a radio at the top of one of the high towers on Muski Mountain, and then down to as many lakes as can be 'seen' by lake-level radios, looks like one we will have to follow.

Given the data rates coming out of the Campbell Loggers - which appear to be less than 9,600 baud, we may try the reliable, amd full 1 watt FreeWave DRG115 radios at first.

 

THE 7 LAKES

We drove to the edge of all 5 lakes and two smaller 'ponds' called Bogs, and saw the same essential problem everywhere - 60 foot high trees ringing the lakes close in. With a challenge getting the signal from water level on the lakes high enough to link to the towers, and thence to the Station. The bogs also might pose the problem of insufficient wind to make wind generators useful. But given the distance to all is less than 5 miles, it looks like we can get the job done by next summer. While we will try to get Sparkling Lake connected wirelessly by early spring.

Across Trout Lake

Crystal Lake

Trout Bog

 

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