Diary # 21

MULTIPLE DATA LOGGER RIDDLE SOLVED, AND DATA FLOWS AT TROUT LAKE

There is a solution to the multiple Campbell Data Loggers of the class CR10X, CR21X, or CR23X and a multiple Freewave Radios. Its really a kludge, and leaves lots of disadvantages, but it does work. It took 3 of us at Trout Lake 6 hours, including multiple telephone calls to both Campbell and Freewave - neither of whom had the full knowledge of what was required. Though Campbell sent us, via email, a set of Notes that helped get us started, it still took lots of work to get it to work properly. They are included, edited and annotated for completeness, at Report #22.

To restate the problem, if the users of Campbell Data Loggers and Freewave DRG115 radios want to set up a network using two or more data loggers each connected to one Freewave, and be able to run PCW208 software to fetch data from selected data loggers, the essential requirements are these:

The Radios have to be set up in a mode, controlled by the radio set up as Master as a "Point to Point Switchable" mode, which in effect creates separate 'point to point' communications links (rather than Point to Multipoint) each time one wants to access one data logger.

This holds true whether there is just one Master talking to 2 or more Slave radios directly, or whether there is a Relay radio also involved.

Read Report 22 for details of configuration. It is a bear.

But it works. As soon as we got radios talking to each other in the Center, and to a lab data logger, we planned to go out to the key Weather Station Raft on Friday, and install a radio, and terminate the cell phone, intermittent access arrangement.

Because of the changing weather, we had to act rapidly to assemble all the items, and the right tools. Once out on the boat we could not afford to be missing anything. We didn't.

While we got away on the boat by 9:30 AM - Tim Meinke, John, and me - while Tim Kratz stayed back in order to test the link and data capture when we were ready - the weather started to get windier and windier. We found it over 10 mph, with gusts higher by the time we got to the raft - a small (about 8 feet by 8 feet) floating platform with only about 8 inches of freeboard. It tilts when a man stands on it.

It took over an hour and a half of all three of us, Tim and John, most familiar with the installed equipment doing most of the work, to get it all done. While the waves slapped water up and the boat had to be held on both sides of the raft. These tasks had to be accomplished:

    • a. Radio placed and positioned in the Pelican box along with the CR21X Data Logger and its sensitive equipment.
    • b. Hole drilled in box rear to run power and antenna wires through it.
    • c. Disconnecting the serial cable to the cell phone modem, and connecting it to the serial cables running to the radio cable. Adding the Campbell SC932 DCE to DTE interface, with 25 pin to 9 pin adapter.
    • d. Mounting a Cushcraft 915mhz antenna on the existing mast without interfering with the air flow past the ananometers.
    • e. Running the antenna cable to the antenna, and the radio, sealing the exposed connectors, and using tie downs to hold the wires close to other equipment.
    • f. Installing the 40 inch Siemans solar panel on a plywood lid, running its power lines, and ground line (a bare copper wire a foot deep in the water). With much drilling.
    • g. Opening and rearranging equipment in another Pelican box on the other side of the raft, to put the 12volt Marine battery in it.
    • h. Drilling another hole in that box, through which to run both power cables from the solar panel to the battery, and from the battery to the Freewave 115W Radio across on the other side of the raft.
    • i. Install 6 amp, inline fuzes, between the solar panel and the battery, and between the radio power input and the battery.
    • j. Sealing the holes.
    • k. Applying power to the radio to check whether the radio responsed correctly. It didn't the first time (intermittent) until it was discovered a plug was too big for a connector pin, which resourceful Tim Meinke solved with a tiny copper shim.
    • l. Checking everything for connectivity and water seal.

Before closing the cases, I then called Tim Kratz at the Trout Lake station by cell phone (the Motorola's would not reach it through the dense woods) and he then ran the test from the NT server. It worked first time! He reported not only the connection messages, but watched data flow. He repeated this several times. We could observe the change in status lights on the Freewave. We then closed up the cases, padlocked them, and came back in. Later we ran several repeated tests on it, to be sure it was still operating OK.

And we called Paul Hanson, in Madison, for him to test it by his 'PC Anywhere' method - wherein, over the Internet, he logs into the NT Server at Trout Station, and PC Anywhere software grabs control of the NT computer. So he then runs PC208W and commands it to fetch the data from Sparkling Lake data logger by issuing the same commands on his screen that we are seeing and sending. We could even see his cursor move around the screen. So he was seeing exactly what we were seeing.

He too had no problem with fetching the data through the radios.

Next will be the task of getting the whole process automated, so that the data is fetched automatically on some schedule, then the retrieved data added to some data base, which itself is accessible by the web.

That work must be done in Madison, and not at Trout Lake, which is the main repository for the data bases for all LTER data collection efforts.

The Sparkling Lake radio was still operating fine, with real data being logged at the station, at the late end of the last day I was there.

 

World Wireless Experiments

I left a pair of very small 100mw, 19.2 speed, serial-access spread spectrum 902- 928 World Wireless 'Hopper 900' radios, in special waterproof cases, and with external antenna connectors at the Station. So that Paul Hanson can experiment with the technique of connecting up the temporarily deployed 'small buoys' that he puts out in the summer and fall, by these radios which cost closer to $300 each, (rather than the $1,500 for Freewaves) to a laptop running PC208W software, from a car next to the shore. If they work properly we can report big progress in 'scaling' with wireless. 5 Hopper 900s configured for the price of 1 Freewave. Where data rates are low - 9,600 - and ranges required are short - a mile or less.

 

The Trout Lake Big Buoy Radio Project

While there I got very familiar with the efforts of Paul Hanson, and two graduate students this project partly paid for, working under his supervision during the summer, connecting up the Big Buoy, reported on in Report 13.

On the Buoy is a device fabricated in Madison that connects up the RUSS Buoy (Remote Underwater Sampling Station) special data logger made by Apprise Technologies, to a PCMIA PC card carrier, with an Aironet PC 4500 (2 Mbps)radio. And a mast antenna.

Then, at the Trout Lake station is an Aironet BR100 (2mbps) radio and roof antenna, that connects to the University wide Internet network. The server for collecting the data is now at Madison, in a Linux system, running Apache web software.

While eventually it is planned that the incoming data flow automatically, and be available on the LTER Web site, for now anyone can 'read the data' being currently connected by using a web browser to

ftp://198.150.174.249/russdata

On Tim Kratz request, I attempted to get the data by putting the BR100 on the garage at the base of the 120 foot antenna tower, an AP4800 one-mac address Aironet in the Center, connected to the net, via the Ethernet connection, and thus communicate with the radio on the buoy and the data behind it, through one Aironet in the Center, to a relay Aironet acting as repeater, then to the PCMIA Card Aironet on the Buoy.

It did not work, even though the radios talked to each other and the IP addresses pinged fine. And the 'association' diagnostics showed all radios were talking properly to each other. Efforts to run the ftp command failed, however.

Since Hanson, on the phone, reported some timing problems that they were encountering trying to feed the data to a web site, I suspect that is the problem also here.

This can eventually work however, opening the door to wider ranging 2.4ghz, much faster - than 115Kbps Freewaves - wireless LAN radios.

 

SUMMARY

With the primary Sparkling Lake data being fetched wirelessly, and the Big Buoy Trout Lake data coming in, with Trout Lake Station technical staff now able to install radios on their own, Tim Kratz and I discussed future wireless projects that are essentially different from the ones we have accomplished. One promising one is to rig 7 water depth sensors in the 7 lakes of the LTER Study area, attached to special small and cheap radios, and then link all of those, simultaneously readable, back to Trout Lake Station and the net. In this case Muskie Tower could come into play. We will pursue that next trip.

From an old photograph at Trout Lake of a young researcher in the 20s or 30's before computers, wireless, or even phones to the northern Wisconsin were around.