TROUT LAKE

 

On April 12, 2000 as the weather began to move into spring, Mike Willett, our NSF project technical assistant from Dallas, and I, as Principal Investigator from Colorado Springs, rendezvoused at Trout Lake, northwest of Rhinelander, Wisconsin, to accomplish several things.

1. Make a joint decision, with Tim Kratz, Site Manager, for North Temperate Lakes Long-term Ecological Research Site at the University of Wisconsin, and Joe Sanfillipo of Northern Technical Services who would do the construction, exactly where to site the 110 foot tower we had determined, on earlier visits, would be required to enable FCC Part 15 type data radios to link up both to a higher tower on Muskie Mountain, and to close in Data Collection sites near or on Trout Lake itself.

2. Make a decision through consultations with Tim Kratz, Paul Hanson, Technological Manager of the University of Wisconsin Center for Limnology in Madison, and technical and support staff of Trout Lake, what the exact architecture of the wireless data collection network should be, and how it will interface with both Trout Lake Station, the Madison Center, and the Internet in general.

3. Do a series of field tests of the radios we had selected to be the backbone of the network, to both get a rough 'benchmark' for the ability of these radios to penetrate the mix of deciduous and pine trees that exist throughout the research area as forests, and to map out a profile of the areas radiating outward from the Research Station that could be reached directly by these radios, without using radio relay stations.

4. Get, install on our own computers, both the Campell Scientific software that the Center uses to control their Campbell Data Collectors - principally the CR21X's which are used to collect data from a complete weather/water station on a raft on Sparkling Lake, the unique, compiled, programs created at the Station that runs on the CR21Xs there, and become intimately familiar with the LTER's data collection procedures, and how the data is stored, and communicated to Madison. In this, Tim Meinke, the Station's long time chief Technician would be the key man to work with.

5. Become familiar with the $83,000 data collecting 'Apprise Buoy' that the Station had recently acquired with an NSF grant, that Paul Hanson was responsible to get operating, and which he had determined could be connected by advanced wireless from its place on the water.

In spite of a snowstorm that swept over the area, dumping 2 inches of snow the night we arrived at the cabins at the center - after a perfectly beautiful day when we came in on Wednesday the 21st - we accomplished all the tasks I had set out for the two working-day trip.

 

THE LOW-COST WIRELESS CHALLENGES

In previous reports - which can be accessed on http://wireless.oldcolo.com

under the Progress Reports section - Reports 4 and 6 - the geographical layout of the Trout Lake Research Area is described, accompanied by maps and photographs. I won't repeat those here.

Suffice it to say that the main characteristic of the Research Area, currently embracing 7 lakes and bogs, the furthest of which is only 3 miles from the Research Center on the southern end of Trout, the largest, lake - are the forests.

Distance, or range, for the data radios to traverse is not a problem. The entire area can easily be reached by almost all Part 15 radios, operating at, from 100 milliwatts, to 1 watt, of power. The problem is the uniform coverage of the entire area by tall trees, whose branches and leaves will sharply reduce, with wide variations caused seasonally, the useful range of the radios that are sited to penetrate them parallel to the ground.

The technical reasons that thick stands of trees are a challenge - which for environmental biological field science areas throughout the world are to be expected - are twofold. First, the current FCC Rules for use of Part 15 no-license radios, particularly spread spectrum radios limit the devices to a maximum of 1 watt of radiated power at the radio, and no more than 36dB of radiated power gain at the associated antennas in the US. (it is as low as 100milliwatts in numerous other countries.) The second reason is that no-license radios whether spread spectrum in design, or under UNII rules, are currently confined by the FCC to three frequency bands which are relatively high on the spectrum of usable frequencies - 902-928Mhz, 2.4-2.483Ghz, and 5.725-5.85Ghz. This means they must - as a function of both power and frequency - operate pretty much as 'Line of Sight' radios beyond any but the closest distances - such as inside buildings, or after a few hundred meters between buildings, or trees. Low power and obstacles, whether trees or hills, sharply reduce the ability of the radios to communicate reliably.

These factors were well known to myself and radio engineer Mike Willett from our years of experience deploying such radios, both commercially, and through my findings via the 'Education by Wireless' NSF Grant ANI 9527664, that I supervised between 1995 and 1999. Just 'how limiting' the specific types of trees, and their densities in the Trout Lake 'North Temperate Zone' region would be, was yet to be determined - but it did not take an elaborate engineering analysis or costly spectrum analyzers, for us to know that the best strategy for dealing with the trees that rimmed all the lakes and bogs in the area, was to get above them at strategic points, striving to get direct sight lines between the antennas mounted on masts or towers (or even cooperating trees!) and the data collection floats or devices put on or near the water. Or, at the very least, by calculating the number of meters or kilometers of average density trees that a signal would have to pass through when it comes down from a high point at a slant angle, stay within the penetrating-power capabilities of the radios to sustain a link. Another strategy could be the use of radios for 'relaying' signals through forested areas at ground level, or from various high points.

On prior trips to the region we had decided that one new tower was needed in the close vicinity of the Research Station. It would have to be at least 110 feet to comfortable clear the trees that averaged 85 feet in height. Northern Services was capable of erecting such a tower under contract to the NSF Project, but it would have to be guyed both for practical safety and government regulatory purposes.

 

THE RESEARCH STATION TOWER

The first order of business on Thursday, the 13th, was to decide on the exact location for the main tower, and its required concrete base - which could not be emplaced until the ground had thawed - April at the earliest. Joe Sanfillipo of Northern had already made two trips to the Station, and discussed tower locations with Tim Kratz, and had given the Project an estimate ($5,700 for a 110 foot tower). Two possible locations had been discussed - one right next to the main research center building at the Center, the other at the far end of the row of cabins on the property.

The Station personnel, headed by Tim Kratz, were concerned about the environmental impact of the tower - both its appearance, and the degree to which trees on the property would have to be trimmed or cut down. While the Trout Lake Research Center consists of many buildings, and considerable amounts of equipment and vehicles, care had been taken to make the facility blend in as much as practicable with the surround sylvan wooded setting. A tall metal tower would be intrusive. In turn we had to be concerned about the distance from the nearest building, for power and antenna cables - which reduce the throughput from the radios the longer they reach - and the point on the premises that the data signal can enter the local area network - LAN - and thus the Internet. So a compromise was indicated.

There was a brief jocular discussion about camouflaging the tower, and we mentioned the costly Cell Phone towers on Monument Hill in the midst of the Black Forest along the Interstate between Colorado Springs and Denver, in Colorado. They are designed to look as much as possible like, and blend in with, the surrounding Ponderosa Pines. One has to look for a few seconds at the structures before one realizes they are not natural. When passing by at 75mph they do not attract attention to the man made structures. However they cost $250,000 each. I mention this, because environmental suitability of antenna towers - whether in rural natural or urban settings has already become a legal and regulatory issue at the FCC. Wireless demands towers and tall antennas. Aesthetics calls for their minimization or elimination. One solution is to make them blend in better. However few companies have specialized in that potential market. Other than possibly painting the 120-foot bright metallic colored tower, nothing much can be done at Trout Lake to mask the new structures, which is one aesthetic price of wireless.

After tromping around in the snow for about an hour, everyone agreed on a third, compromise, location - behind a garage in what might be termed the 'industrial' area of the complex. About 100 meters from the main research building, which would require a link from there to the tower or the radios at its base. But the main advantage of the site was that there is one heated room in the garage, where preserved plankton samples are stored. We could put our small radios in that room, where there is also 110v wall power, and still only have about 130 feet of RF cable running to the antennas on top of the mast. (There is 3-4 dB of loss per 100 feet in even the best RF cables, so minimizing that loss was a consideration for us.) Joe Sanfillipo still had concerns about just where he could run the angular guy wires, which had to be on the garage side of the tower site, and legally 120 degrees from the other two legs of guy wires. Only a minimal number of branches might have to be trimmed from the trees in the woods around the tower, no large trees having to be cut down. Which was a relief to all.

At first we thought we should dig a 100 meter ditch through the woods between the garage and the Research building, to bury CAT5 cable or fiber to link the radio at the base, to the POP in the main building. But Mike and I decided, later, that, given the low data rates coming from the Campbell Data Loggers - 9,600 baud being routine - we could make the entire wireless network comprised by Freewave DRG115 Serial-Port 1 watt 902-928Mhz radios. And we could use a pair of such radios link the garage/tower radio site to the main building at tolerable cost - probably less than construction cost of the cable ditch. We also decided to go up 10 more feet - to 120 feet on the tower height.

So the first major decision was reached.

1. The tower would go on the north side of the garage, 120 feet high, giving it 35 feet clearance over the surrounding trees, approximately 30 feet from the garage building, and 100 feet from the main Research Center building.

2. Joe Sanfillipo would come back on his own and lay out the exact spot the base pad would be built, and where the three guy wires needed to be emplaced. He would first get Tim Kratz approval for that exact scheme.

3. Joe would fax the bid for the work and materials to me, and we would execute the agreement for the tower to be erected in May. Joe estimated it would take from 2 to 3 weeks after the contract was signed for the tower to go up.

4. The work would include Joe affixing the 915Mhz capable antenna and cable to the tower at the top, and running it down to the vicinity of the heated room in the garage. While we were capable of doing that work ourselves, it was desirable for Joe to do this, since, later, other towers might be erected for the general research area, and it would be desirable for a local contractor to become quite familiar with the special requirements of these low power radio networks and the care and permanency with which the RF cable lines and antennas had to be installed, waterproof.

5. The heated room in the garage would be used for the base radio or radios at the Research Center, using wall, or grid, power, supplemented by an UPS - Uninteruptable Power Supply, powering the radios.

 

THE WIRELESS NETWORK

During an hour-long discussion with all interested Station personnel present, the Architecture of the entire wireless network emerged, represented by the following diagram.

1. We decided on the key role of Muski Tower, whose owners, the Wisconsin Power Company had already indicated by return letter to me, they were willing to permit an antenna array to be placed high up on it, and use power in their 'radio shack' at the base for our low-power drawing, radios. This is still subject to final approval, but they appeared to be very cooperative. We avoided asking the owners of the taller tower at the same general site - a communications company, in which telephone company equipment is used - for permission. We were aware that, in general, telephone companies are uncooperative to requests to put even small, and very small wind-loading radio antennas on towers they control. Their lack of familiarity with spread spectrum radios, and their often expressed views about such no-license (therefore no commercial service cost) radios as being in 'competition' with them dissuaded us. There is no competition in the case of utility companies.

At Figure 1 is a digital view up the 200 foot Wisconsin Power tower.

Tower on Muskie Mountain tower

 

We would seek to put an omni antenna with 8db of gain, tuned to 915mhz region high on the tower, and run LMR-400 low loss RF cable down into the Radio Shack, where a Freewave DRG115 1-watt radio, operating only as a 'Relay' radio would reside.

Freewave DRG115 Radio

 

Freewave DRG115W Professional - in Waterproof box

 

This antenna has a radiation pattern suitable for being so high on the tower/mountain (small hill). The higher the gain the antenna the 'flatter' its effective envelope of coverage. Since the relay radio would have to communicate with 7 or more radios, from as close as 1 mile, out to as far as 10 miles, the 'envelope' of coverage needed to reach the ground had to have sufficient depth. Thus our choice.

3. The Relay Radio at Muski Mountain would be set to communicate with the Freewave radio at the base of the tower at the Trout Lake Center operating as the 'Master' radio. Perhaps a 4db Cushcraft omni antenna. Since, even if the Center radio could reach many points around Trout Lake, it was clear, because of interfering terrain - low hills - it could not reach several of the lakes. Thus the Relay Site on Muski Mountain would be the key radio to reach all sites on the 7 lakes. A single radio at the relay point, working in 'both directions' cuts the effective thrupt in half. Thus it can be expected that the thruput from the Slave radios back to the Master will be no more than 56kbps, half-duplex. Since the data loggers only operate at 9,600 baud out their serial ports, this appears to be plenty of capacity.

4. The Freewave radios at the 7 lakes, whether on rafts, or buoys, or not, would be set to communicate in "Slave Mode" - a characteristic mode for the Freewave radio. This might require a directional antenna on each of the rafts, pointing back to Muski Mountain. Given that the rafts can move, bob up and down in the wind and small lake wave action, the antennas chosen for the Slave radios would have to be a compromise between highest gain, with the narrowest beam path, and a wider and deeper, while still directional, zone of coverage. Swings of a raft beyond 90 degrees would be beyond the ability of the radios to communicate at the 1 to 10 mile distances, even without the consideration of trees up to the water's edges.

5. The Slave Radios, on the lakes, would be powered by external 12-volt batteries shared with the Data Loggers at those sites, and the solar panel array which would keep the batteries sufficiently charged. One benefit of spread spectrum radios generally is their low power draw. The Freewave radios are rated at an average of 180 milliamps, 100 to receive and 600 to transmit. The Campbell Data Loggers also operate at 12 volts, DC, so the shared battery approach is quite feasible and economic.

6. Because the Freewave Radios can be configured to operate on any of 15 'channels' within the 902-915Mhz range, it then, with the above configuration of up to 9 radios (Master, plus Relay, plus 7 Lake Radios) on one hopping pattern, we can put another pair of radios between the Garage and the Main building, and interconnect only by RS232 cable, the two radios sitting side by side in the Garage radio site. They will be set to operate on different hopping patterns from the Master and Muski Tower/Slave patterns. In the event that either the thruput, or data response time from the slave radios and data collectors back through the relay radio is inadequate, we can, thanks to the design of the Freewave, configure it as a third network. This would consist of the Slaves talking to the Muski Tower Radio as a Master, then, in the radio shack, connecting the RS232 ports on the Master, to a second radio as a Slave to the Master back at the Garage, which then connects to a third Master radio talking to a Slave inside the Center, only 100 feet away. All three sets on different hopping patterns, thus not interfering with each other, even though their antennas and the radios are co-located. This of course would require a second RF cable and antenna, on the Muski Mountain tower. So we will probably ask Joe Sanfillipo to emplace two cables, and antennas, rather than one, on the Muski Mountain Tower.

Thus the Trout Lake initial Wireless Network will look like this:

 

Proposed Wireless Network

 

 

FIELD DATA MANAGEMENT

One issue arose during the discussions, which has to be thought through - largely by the Trout Lake and Madison LTER staff. And that is, who can access the data via the wireless, where does the data reside, and how the interaction between data storage server at Trout Lake and those operated by the U of W Data Management staff in Madison.

Currently the Trout Lake staff can dial up the raft and Weather Station's Data Logger on Sparkling Lake using a PC with the PC208W software twice a day. The LTER staff in Madison also, separately, dials, long distance, the cell phone on the raft, and collects the data in Madison's computers, makes it accessible with a Web interface from its Oracle data base which all LTER researchers have access to. The data does not pass through Trout Lake facility enroute to Madison. The public - 'citizen science' including students, can only access this data until after Madison puts it, periodically, on their web site.

Once the Wireless links are up, the data CAN be delivered, or requested by, Madison, over the T-1 Internet link to Trout Lake - at no added cost (cell phone and service). It can also be polled more frequently - even down to every 5 minutes or so, giving nearly 'real time' data from all the sensors. We discussed alternate ways that Science students in K-12 schools, might have access to the data, and/or substantively assist in the data gathering, storage, analysis, or representation on web servers accessible to the Public, as well as Science students anywhere.

The technical capability, policies, security procedures, to deliver that data from the Data Loggers, first wirelessly, then via the Ethernetted Internet, has to be decided before the final 'interface' is installed.

Paul Hanson agreed to work on that matter before the final design of the network is finally decided.

The wireless links both enable new ways to gather and distribute the data, and poses new management questions, for science.

 

THE APPRISE BUOY

After these decisions were made, we spent a little time examining the sophisticated Buoy by Apprise Technologies, which was stored in the garage, and discussed with Paul Hanson, who had to return to Madison, his ideas on linking it by radio.

The Buoy consists of three metal rectangular tanks that float in the water, connected to each other in a star formation, each leg being 120 degrees from the other. Inside each tank are batteries, and on top is a solar collector panel. In one tank is space and openings for the data collector. A mast for a weather station is included.

But the main value of the Buoy, resides in a pair of cylindrical tubes attached to each other, between which are inserted 3-foot long cylinders which contain 6 sensors each, or a total of 12. Then the apparatus is lowered into the water under the Buoy which being loosely tethered to it on the surface, and a proprietary system of pressure valves for air and water, keep the device at any selected level in the water beneath the Buoy, so it can gather data at various depths. Even if the Buoy bobs around, the sensors remain at a constant level in the lake.

While the Buoy is shipped with a Motorola radio system, Paul Hanson, realizing the greater power and flexibility of a pair of Part 15 data radios, procured a set of Aironet Radios - BR100, which operates in the 2.4Ghz frequency bands, at 100 Milliwatts of power, at 2Mbps of rated speed. To be the base station on shore. And a PC4500 Aironet, designed to operate in a desktop computer, into a chassis of his own design, which includes a complete processor, to put on the Buoy.

This arrangement can be further interconnected to the router and T-1 link to the Internet in general, but more particularly to the Center for Limnology at Madison, 250 miles away. Data can be read real-time from there.

By using this radio system, rather than the analog Motorola radio, which is mated to the Data Logger low rates of throughput, it becomes possible to add devices, such as digital video cameras on, or suspended under, the Buoy, which requiems substantially higher data rates. (Full motion video can require 384Kbps to 1.1mbps of throughput)

Since the Buoy in this case will operate out on Trout Lake, there will be no difficulty in communicating from the vicinity of the shore where the Center is, out across the lake to its furthest reach with this radio pair, even though the power is one tenth that of the Freewaves, and at a less tree-penetrating set of frequencies.

Unassembled Apprise Buoy with Hanson holding one sensor set.

 

This system will be launched onto Trout Lake this summer.

 

BENCH TESTS

We spent several hours on Thursday after the above work, bench testing the operation of the radios I brought with me, linking the Campbell Scientific software on PCs, to a CR21X Data Logger.

 

Working Group at Trout Lake Station

 

Tim Meinke at the Trout Lake Center is largely responsible for set up, operations, and maintenance of the data loggers. He operated a Center's PC on which was mounted the Campbell PC208W30 software - which is the key data gathering and analysis software for all of Campbell's Data Loggers.

As designed by Campbell, the Data Loggers are connected to the Computer running the software, via a RS232 cable, terminating in the data logger in a DB9 port. However this is not a completely standard RS232 port. It is connected to an SC32A Optically Isolated RS232 Interface, which is in turn connected to the computer, or serial port on a modem for use with a cell phone.

In the simplest configuration, on the table, or in the field where it is desirable or necessary to get the data via a physical visit to the location of the data logger, or to set it up with changed software, an RS232 cable is run between the computer's DB9 serial port and the SC32A device, and another RS232 cable is run to the DB9 port on the data logger. The Software is commanded to 'Connect' upon which the custom software loaded onto the Data logger responds, showing a connection, and transfers the initial data.

On the raft on Sparkling Lake, this can be done, but there is also a Cell Phone on the raft, which is connected into the Data Logger there, via a modem operating at 9,600 baud.

The Data Logger's program is programmed to turn on the cell phone for 30 minutes twice a day, to be able to receive calls from the Trout Lake Station or Madison. A PC then captures the data at the Center. It is also possible for the Data Base Managers at the Madison, WI campus, to call the same way, long distance, and capture the data. This is done as the primary means by which the Madison campus gathers the data to put it into the North Temperate Lakes LTER data bases - not through the T-1 Internet connection with exists between the two locations.

This arrangement of course, works satisfactorily where there is cell phone service at the field sites where a data logger is deployed. If, however, there are many sites - such as the '7 lakes' scenario, 7 different cells phones and contracted services would be necessary, one for each. This might be tolerable for one-a-day calls to the rafts and data loggers. However, as efforts to gather the data every 5 minutes, as was suggested as an option, was done, the costs would go up substantially. And of course if any data logger is out of range of the cell service, no data could be collected. If the same data could be gathered via the Part 15 no license, therefore free, data radios, and fed into the Internet at Trout Lake, the costs would be limited, and data could be gathered on any desirable frequency of schedule.

We substituted a pair of Freewave Data Radios for the RS232 cables, set down to port speeds of 9,600 baud, and the Data Collector <-> PC208W software link worked perfectly. We did this with both the Computer owned by and configured by the Trout Lake Center, and to/from the laptop Dell Computer I brought, and had mounted the PC208W3.1 version of the software (one revision higher than the Center's copy).

Whether or not that continues to work well, when we increase the distance to miles between the radios, and/or go through a Relay radio, remains to be seen. But the critical test of a pair of radios acting as a standard 'serial' cable between them, was passed using the radios we intend to use in the area. We did not have such good luck with a second set of radios which I brought.

While not completely familiar with their characteristics, since they were received only the week before, I brought an interesting, lower cost, set of 1 watt, spread spectrum, Part 15 no-license, 56kbps radios named the World Wireless 900 SS Hopper Data Radio.

What is interesting about these radios, are that they are much cheaper than the Freewaves, which list at $1,750 each in the weatherproof model. Together with necessary external antennas, mountings, cabling and power supplies, the Freewave solution can reach $4,000 for a pair of installed radios. The 990 Hopper radios, including a weatherproof Nemo enclosure, with sealed leads coming out of the box, power supply, small directional antennas, cost us $920 the pair. One-fourth the price. But you get what you pay for in radios.

When we tried to make them link the CR21X Data Collector and the PC208W software in a PC, they would not work properly. I spent some time then, and the next day, systematically altering cables, connectors, and settings in the radios to make them work. They never did. I suspect, there is a timing problem somewhere. There are few status lights on the 900 Hopper boards, they cannot be set up in relay mode, and their configuration choices are somewhat limited. The problem could also be with the 'optical interface.' If we get that solved, If these radios prove to have the same range as the Freewaves - which can only be verified by comparative field testing we could not do there - they would be a more economical solution that would scale for many data loggers. More testing is needed.

 

GETTING A ROUGH WIRELESS BENCHMARK

The last day, we determined to (1) establish a rough benchmark for 'how far' in miles and tenths the Freewave radio would work through the trees of the Trout Lake area and (2) see what points around the perimeter of Trout Lake we could expect to get a good connection.

We did not have time to test different sets of antennas in this 3 hour effort, so we determined to put one antenna up on the roof of the garage with a vertical 6dB gain antenna, and drive the second radio around, powered from the 12volt DC car battery through its cigarette lighter. And to stop periodically when the green 'link light' indicator on the radio went out, and test it outside as far as the power line would stretch. The antenna on the Freewave - a 3-inch rubber duck - has only 2dB of gain, but I wanted a good bench test at that level first.

Over the next two hours we drove 15 miles around Trout Lake, observing the reaction of the data radio, both inside the vehicle when the radio signal would have to pass through the glass and metal of the car, and outside. We kept exact distances line of sight with a GPS that was keyed to the original point and base radio at the garage. As expected, the results were quite variable. However, we consistently could see that the radios would lose link after about .8 of a kilometer, or one half a mile, through solid stands of trees.

Thus our Rough Benchmark is .8 Km for trees of the type shown in Figure 7, using the lowest gain antennas.

Figure 7

Woods Surrounding Trout Lake Station

 

However, since the garage is only about 50 meters from the shoreline of Trout Lake, with only sparse trees in between, we also found we could satisfactorily connect up at many points on the perimeter of the lake, even back from the shoreline through trees until about .5 of a km of trees was reached. As shown at Figure 8, we had a link at 2.5 miles on the western shore, 4.3 miles on the extreme northern shore at a site called Camp Fiesta, which had to pass through a pensile about one quarter mile wide, and its trees, and at 2.72 on the eastern shore, including behind a quarter mile of trees, where the State Forest Headquarters has a facility and offices. We also got a good link at the edge of the research site Bog about 100 meters beyond the lake shoreline.

Good Coverage from Camp Fiesta

 

So it is clear, even at the lowest antenna gain, it will be possible to reach almost any point on Trout Lake itself from the Garage location (not just from the high antenna on Muski Mountain, and onto the shore from variable distances. However, because the land drops away to the east of Trout Lake, we were not able to get a link at or near the four smaller lakes two miles east of Trout Lake (3 miles from the garage radio). But these lakes are directly north and at distances of from 1 to 3.5 miles from Muski Mountain. The antenna mounted there will clearly be able to reach these lakes, including through from .1 to .4 km of trees.

All these baseline findings however, will improve as higher gain antennas are used, and high tower mountings of the antennas are made. And, as is usual for specific Wireless Installations, the ability to establish reliable links is a function of a specific engineering site survey of that individual site. The rough benchmark can be used for general planning and estimating, but the final plan needs to come from a carefully engineered and surveyed layout. At the low power levels Part 15 radios work, and at the high frequencies they must use, only a careful site survey, with actual radio emissions data can insure that a site will operate year round, reliably.

And it was also clear from our survey, that we can use Freewave Radios as relays in places where small hills, or depths of thick trees blocks our signals from either the Trout Lake Station, or Muski Mountain sites. In fact, we could even rely on one of the two radios we planned to link the garage tower radio, to the Main building, to be in Multi-Point Mode, from where it could serve many points out on Trout Lake or its periphery.

The main findings we made were that (1) the 1 watt, 902-928Mhz radios can penetrate approximately .8 of a km through prevailing tree stands in winter at the lowest level of antenna gain and (2) the Freewave DRG115 Radio has good receiver sensitivity (3) Freewave DRG115 Radios will be suitable for the Trout Lake Research Station work, and will scale to at least 7 lake data collection sites.

As soon as the 120 foot tower at Trout Lake Station, and permission is obtained from Wisconsin Power Company to install on their Muskie Mountain Tower, we can commence the installations.

 

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