DIARY #19

TOTAL FOREST WIRELESS COVERAGE

July 23d - July 26th, 2000

The second major task we undertook on this visit was to install a Repeater Radio somewhere on the top of El Yunque Peak. Which radio could not only link to the Slave-Repeater radio on the El Verde Tower, and thence to the Master Radio inside El Verde Center and its computers, and later link to the Internet, but also reach other Tower data loggers in the Forest, and sites yet to be set up elsewhere in the entire El Yunque Rain Forest.

This was as much a bureaucratic and business problem as it was a technical radio problem.

El Yunque in a U.S. National Forest. As such it is under the jurisdiction of the National Forest Service. As is somewhat common in National Forests across the nation, the tops of some peaks are very desirable for commercial, and not only government, placement of antenna farms. On El Yunque Peak there are a pretty large number of antenna arrays, and buildings supporting them. Here are some:

Castle Communications had been granted a long term permit by the USFS to install and maintain commercial radio services on part of El Yunque Peak.

When we (our NSF Wireless Field Test Project) directly approached Castle Communications, months earlier, first to test, then to make a deal for putting at least one of our small antenna-small radio installations up there, things appeared at first to go smoothly. But - and partly because Castle Communications is not locally (Puerto Rico) owned, it because very frustrating to deal with them. Even though we (the NSF project now) and the LTER later, were willing to pay the normal $400 a month for the 'right' to place an antenna on one of Castle's masts, and use wall power for our small inside radio, it was just moving too slowly for me - and had an uncertain long term future.

Reasoning that the US Forest Service itself used the top of El Yunque for some of its own administrative voice radios so they could reach all corners of the forest, and knowing that the El Yunque LTER is a 'collaborative' NSF funded research project, in which Dr. Fred Scatena, USF, and the Sabana USF Work Center is involved with some of the research also (water studies, parrot, Coqui, and weather), as well as the University of Puerto Rico's work under Dr. Jess Zimmerman, and that our installation would be 'nonprofit' and eventually owned entirely by the LTER, I decided to ask the Forest Service directly for permission to place a system on the peak in places other than that controlled by Castle Communications.

Fred Scatena was able to secure temporary permission for us to put up a test installation, before we decided on a permanent location, and sought a long term permit.

So our team went to the top of El Yunque on Sunday, the 23d of July, and scouted out other sites than Castle's.

There was another practical consideration - having run some mobile tests on our previous two visits from some of Castle's building and towers, we observed heavy RF interference. For one thing, somebody was running Glenayre 2.4Ghz no-licence radios at the facility. These radios have one bad feature - they are always in a transmit mode. They virtually blanked the Aironet radios we took there to test, ruling them out. (Aironet's listen before they transmit - much more efficient use of the spectrum). The further we could get away from such interference sources, the better. Even a 100 meters can make quite a difference.

So we went to the westernmost tip of the peak-ridge of El Yunque, where an odd structure exists.

The structure, designed to look like what an 1521 Spanish lookout tower may have looked like - when El Yunque was a place from which approaching hostile - such as British - warships could be spotted, and a runner dispatched down the mountain, was actually built in 1934 by the CCC - work-making Civilian Conservation Corps, during the Great Depression. In fact the very tortuous road to the top of El Yunque itself was built then - a very difficult feat.

The picture above shows Mike Willett, Andrew McFadden, my technical assistants, and Dr. Fred Scatena, USFS Researcher on the crenelated (castle like) structure, with a small farm of antennas, some abandoned and old, some apparently in use, on it.

From the top of the structure, however, using binoculars, USGS maps, and Fred Scatena's knowledge of the Pico del Este and Bisley site locations, we finally managed to spot in the far distance, hidden in the trees, the very tops of the three weather tower sites. With the critical one - to El Verde Tower which has to be reached as a 'relay' to the El Verde Research Center and thence, later, to the Internet - just peeping over a near rocky outcropping. I immediately worried about the 'Fresnel Zone' effect - where the elliptical shape of RF radiation between two points must clear the intervening land and obstacles sufficiently, or there can be too much loss of RF energy diffused, and the link can be down.

But to our immense - and almost accidental - joy, for a critical cable was missing from our bag of tricks which we carried to the mountain top which let us connect up progressively more powerful antennas, we got a solid green link on our hand held Freewave DRG115 radio with ONLY a small rubber duck antenna. Down to the DRG115 radio and its uphill looking Yagi at El Verde Tower! We even got it on all sides of the peak, even when we did not have an absolute line-of-sight.

THAT told us volumes about the value of that location on El Yunque peak for a 1 Watt DRG115 radio connected to a 6 dB omni antenna up there. Much much better than we expected. But critically important.

We were a bit nervous whether or not intense RF in the 915Mhz range already on the peak might be causing our apparent single-green light radio indication of link to El Verde. But our fears were unjustified. (The only other way we could have validated it further, would have been to set up an actual data-passing session, from a laptop on the peak, and with someone back in El Verde getting it. Not easy to arrange on this Sunday outing.)

As a bonus, we also had a clear sight line from that easternmost part of the peak, to the summit of El Toro! The place that Forest Service researcher Victor Cuevas would like us to link up the sounds of the rare Richmondi Species of Coqui - which requires, otherwise, 4 hour, in the night, hard hikes to reach to capture those same sound by tape recorder after midnight. This could work for that 'data collection' use also!

Because the Forest Service was considering tearing down the obsolete tower on its part of the peak, we then looked for some way OTHER than using the stone structure to mount our system, solar panel, and antenna. Also, since hardy Puerto Rican's sometimes hike to the top of El Yunque on holiday, we wanted to get it out of the reach of too-easily tampering.

We found a VERY rusty old iron pole, unused, that went up about 20 feet high, from which all our critical points could still be seen. Here is a look at it, first with Mike Willett and Andrew contemplating it, then Andrew up on it a ways.

 

We decided to try it with an installation on Monday, after Fred Scatena either got us temporary permission from the Forest Management staff, or they wanted to accompany us back up there. As it turned out they permitted a temporary installation which, if it worked for us, could probably be extended to a long term permit.

Doubts About El Pico del Este

On our way down from El Yunque, we went out on the long twisting, and closed to the public roadway toward Pico del Este, beyond which is the Naval Radar Station. We wanted to see if we could see back from the exact location of the Fog Drip Data Logger, to the peak of El Yunque.

We couldn't. One last hill mass seemed to block our path to where the radio would be. But because we had no radio installed yet on El Yunque, we could not test it yet.

We also were unable to open the data logger locked case (padlock) to see if we could repeat the way we installed the radio and battery at El Verde - putting them all in one case, rather than having to have two waterproof cases. We needed to see inside the case - how much room was available. We also decided we might better be advised to put a small wind generator, rather than a solar panel in the vicinity of the logger. There is constant north to south wind over the ridge, but constantly overcast skies.

We decided to visit Pico del Este again in the next two days, with Fred's Sabena Work Center data manager assistant, Carlos, who had the keys, and who had to come up there at least twice a week to fetch the data logger modules for downloading. In this case not a hard climb, but a long slow drive up and down.

Surprising Good Signals

All Monday morning the 24th was spent in various directions, assembling the solar power brackets and pole-fastners needed to put an entire system on El Yunque Peak. While I trained, first Andrew, who will be technically supervising the installed radio network when done, and then some of the Researchers. And then Andrew and I went up the 120 foot El Verde tower to complete the interfacing connections, reconfigure the radio from 'Call Book' to 'Network ID' configuration, and prepare for final, hammered down, installation of the El Verde equipment. As usual, we had computer problems, connector problems, and therefore configuration problems, all eventually solved. But with several trips up the tower.

It takes a lot of attention to detail to prepare for a remote site installation - radio, cables, connectors, antennas, brackets, cases with the right sized holes in them, batteries, power connectors, and then means to test whether the connection will work properly. So Mike Willett assembled those things, some parts being hard to find on the eastern tip of Puerto Rico. And then he prepared everything for a trip with he and Andrew to the top of El Yunque to install what would be our most important radio, which would have to relay everything, reliably.

Late in the afternoon, they set forth, and I fetched from Radio Shack in Farjdo area, better serial connectors. And I firmly ordered two solar panels, and bought two more West Marine batteries for the Bisley and Pico del Este installations on the next trip.

It was falling dark by the time they finished on top, reported by cell phone good connections by the radio configured for that relay location, and we all made plans to gather for supper in a restaurant near the beach at Luquillo, several miles further east.

Intrigued by the success we had with the small antenna portable test DRG115 Freewave two days before, when I got to my hotel room, right on the beach, I plugged the radio in, walked to the window facing the mountain range and cloud-hidden El Yunque and I got a solid green-light link! With the tiniest antenna possible! THAT told me volumes, about coverage of the forest. If I could get a 7 mile link with the 0 dB omni rubber duck antenna at my end, and only a 6 (some would argue 4 dB or less, true) omni on El Yunque, in spite of spurious interference from there, we certainly could reach most of the forest with stronger antennas, even down in the trees, if the angle from the top down were sharp enough. That still remains to be seen, however, as actual data flow over wireless is not the same as 'just a link.'

So I took the radio to the dinner gathering, 10 miles from the peak, and we STILL had a link. Which, since two of the researchers live in Luquillo, opens the possibility that they could, from their studies in their homes, fetch the data or do other work, including linking to the Internet through the El Verde Center directly! Everyone was very pleased. And to the research staff which had watched us overcome one problem after another over months of time, and several visits, were delighted to see, at last, solid, practical, use of the wireless for fetching their data.

Much Better Coverage Than Expected

The last two days of this trip, established several other things.

First of all we showed Andrew McFadden, our assistant while we are in Puerto Rico, but a key data system manager for the LTER at other times (and who will, in the long run, have to maintain all the radios, and even expand the network as needed - which underscores why I set out to train him in RF as much as possible from the beginning), how to make 'coverage maps'. By, first, driving around the periphery of the Rain Forest in a car, with a colleague holding an omni antenna out the window, while running the radio off the cigarette lighter. Seeing just where we had a good link, a marginal one, or nothing.

We drove over to Sabena Work Center, on the other side of the north end of El Yunque Forest, to get the keys to the Pico del Este Fog Drip data logger case. We were sure we would NOT get a good signal there, since the center is down in a hole in the forest. But we did! And only encountered a few dead spots enroute. This was a total surprise. For it says that the data managers at Sabena may be able to download the Bisley and Pico del Este data directly, themselves, from their field office!

Since the USFS researchers also use Sutron, and not just Campbell Scientific data loggers - which we must master also in a wireless context, this opens up more possibilities.

We went back up the mountain to Pico del Este while Andrew held the mobile radio antenna out the window. And we saw even more tracts where it will cover. Including the hill-mass blocked site right at Pico del Este! So we CAN reach it from the repeater site, already. Very good news. Our job is being made simpler all the time, as the great little 1 watt Freewave and a good installation on El Yunque Peak does its thing!

Inside the Pico del Este Data Logger box - that is a CR21X data logger inside. We saw that there was enough room to put our larger battery, radio, interface, and cables.

Andrew is holding the portable DRG115, which, though it doesn't come through in the smaller frame, shows link light green, even with the small antenna.

So I gave one important task to Andrew to do before we make the next trip - after the back ordered solar panels, and wind generator arrive on the island. Make, as we have Margot at Trout Lake, Wisconsin, a 'Coverage Map' by systematically visiting all the reaches of El Yunque rain forest, and the private land outside the forest, right down to the beaches on the Caribbean, to see where, first with the 6 db Omni, then with a 10 dB directional Yagi, and plotting the coverage, and dead areas, served by this first scientific data gathering radio on the Island of Puerto Rico.

The coverage we observed even in our informal survey, is very impressive indeed, and tells me that data loggers and other devices linkable to the network may be deployable all over the entire El Yunque National Rain Forest.

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