THE EVOLUTION FOR MONTE VISTA The earliest successful test site our project installed, was the 14.2 mile 115Kbps link between the commercial Rocky Mountain Internet POP in Alamosa and the Monte Vista Middle School. Except for outages caused by severe winds, and equipment failures, this link has run for 2 years. Originally, this link was accomplished by using two FreeWave 115DRG, serial-ported frequency hopping radios operating in the 902-928Mhz range. ALAMOSA END At the Alamosa end, which was in a two story building - The Carter House - an 8 dBi gain yagi antenna was installed on the roof of the building, aimed at Monte Vista to the west. Large mature deciduous trees, much higher than the antenna, rimmed the downtown Alamosa location, and we thought, might antenuate the signal. In the computer room of RMI-Alamosa, where Ken Sweinheart had his DSU/CSU and routers for his dialup service, we placed the FreeWave radio, running an RF cable approximately 25 feet to the roof antenna. The radio was connected by 9 Pin RS232 cable into the COM1 port of a custom NSF Field Test Router, which in turn was connected to the RMI router by Ethernet. The Custom Router - which we replicated for all the sites using the FreeWave radios (including 8 of them in Mongolia), were basically a minimim-installation of Linux in an Intell computer chassis with 8 Mbs of RAM, a hard disk, 3.5 inch floppy drive, and removable monitor and keyboard, with standard RS232 serial ports using 16650 UARTS (which could handle 115Kbps) and a standard Ethernet card. This was in a flat box only about 3 inches high. Essentially this was just a low profile IBM PC clone, running Linux, which, once configured as a router would occupy only 3 vertical inches of shelf space, generally with the smaller radio sitting on top of it. With stable Linux (in our case the Debian release), it was capable of rebooting itself back into router mode in case of extended power outages. The systems cost approximately $1,000 to be custom assembled by Silicon Valley Connection in Colorado Springs. MONTE VISTA END At the Middle School site in Monte Vista, we put up a 30 foot guy wire anchored vertical mast, the top of which was an 8 foot omni antenna tuned to the 915Mhz radio range on the one-story school roof. However, in this case, we experimented with a highly modified radio configuration to permit us to put the radio up on the mast as close as possible to the omni antenna, in order to eliminate as much as possible the RF line loss in the run to the computer room, which would be at least 100 feet. This was only considered necessary in this configuration because (1) the original FreeWave radios only produced 300 milliwatts of power (2) the distance between radios was 14.2 miles (3) the ground in between the two radio points contained scores of mature trees (4) 100 feet of RF cable would lose at least 4 dB of signal if we put the radio in the computer room close to the router, and ran the RF cable from that point to the roof antenna. In order to do this, it would require that the radio be modified to (1) fit in a weatherproof metal case for fixing to the mast outside (2) a 25 pin waterproof connector would have to used to carry the serial data, the power, the manual switches (reset), and the lights down the 100 feet from the radio to the computer room. We contracted with a firm who could do circuit-board level modifications, and had him make the necessary modifications. Then we mounted the radio box high on the outdoor antenna mast, ran the 25 line cable down into the computer room of the school, where one set of wires was interfaced to a female 9 pin RS232 connector - replacing the 6 foot modem cable that comes with the radio - for connection into the router. And another set of wires were connected to a male RS232 connector, by which the radio up the mast could be 'reset'. And finally the 110V powersupply was connected to appropriate lines, to power the unit on the mast. Then between the School's NT Server in the computer room, which was linked to the class workstations, and the radio, we put a second thin chassis Linux router like the one in Alamosa. The radio on the mast being connected to it via the serial cable, and to the NT, via a standard ethernet cable coming from the Ethernet card in the router. After assigning IP addresses from the Monte Vista set of Class C numbers sold through RMI, we launched the system. PROBLEMS The best thing to be said about the complete wirelessly linked network was that it worked. The signal travelling 14.2 miles across the flat San Luis Valley plain between Monte Vista and Alamosa, through scores of trees, was solid. The linkage to the Internet from the 25 classroom computers - initially running Workplace for Windows, then later Windows 95 - worked. Within about 6 months of the installation, very high winds aross the valley blew down the antenna mast on the school roof. It took three men to get it back up and fastened better. A strong electrical storm passed over Monte Vista, and a charge built up in the circuitry, so that the FreeWave radio - unusually set high on the exposed antenna mast - was reset from those entered into its non-volitale ram - into a bizzare mode. It had to be brought back into it link state. Being unable to see the led lights on the radio made it more difficult to diagnose. And we had to teach the school techs new procedures to trouble shoot and reset the radios locally. Sweinhart of RMI had problems with the telephone company getting him enough lines for his growing RMI internet dial-up business, so he was compelled to move his entire ISP operation to another building in Alamosa, which he bought. Of course that required a total relocation of our radios and outside antennas. Once the move was made he had to erect a 30, then 60 foot tower on his building. Which further delayed and disrupted things. Some of these changes were made during the summer when school was out. Then, RMI and Sweinhart parted company, as Ken decided to go seperately as Amigo.Net. Which change, however, required a change in all the routing tables, and IP numbers, as he was issued new IP Addressing blocks as an independent provider. During this additional changeover, while the Monte Vista school techs were attempting to reconfigure the routers, the NT, and the radios without our help, they caused the radio to go into a locked up state. From which it only could be released when the mast was lowered - a two man job. A DIFFERENT SOLUTION Having experienced all these problems over a two year period, many caused by the experimental arrangement of the radio on the mast to maximize the robustness of the long link with radios only producing one third of a watt, and with less-than-standard connections, we decided to install the later 1 watt versions of the FreeWave radios, remove the modified radio and cables from the mast, install the radio in a power-switching room above the computer classroom, and make the connections standard. The last week of November, 1997, we made the changes at the Monte Vista School end of the link. But, with the radio in Alamosa, still only a one third watt radio, we could not get link. So we changed out the radio there also. With only omni antennas at both ends of the 14.2 mile link we got a solid link. Another problem arose, when the custom router's ethernet card failed, so in another trip to the Valley, we replaced that router with one that had been at Center School, and was no longer needed. Thus the week of December 1st, everything was up and working from the Internet POP in Alamosa, via the pair of 115Kbps FreeWave 1 watt frequency hopping spread spectrum radios 14.1 miles via 902-928Mhz omni antennas, to the Middle School in Monte Vista, then through a custom router and an NT server, is serving 25 workstations in the classroom. At the end of this NSF Project, we will formally transfer ownership of the two radios, omni antennas, one custom router, to the Monte Vista School District. Afterwhich it will be their sole responsibility. Although we expended far more in this test site, both materials and labor, than a straightforward effort to get a connection up without experimentation would cost, the cost to replicate this wireless Internet link armed with the knowledge all have now, would be roughly: 2 FreeWave 115DRG 1 Watt Radios - $2,500 1 30 foot antenna mast - $ 150 2 Omni 915Mhz antennas - $ 250 1 RF cable $ 50 1 Linux router $ 500 Misc connectors etd $ 50 -------- Parts $3,500 Commercial Installation - 2 days $1,000 Total $4,500 Monthly Operating cost for wireless substitute for local loop 56Kbps telco charges. $ 0 Dave Hughes Principal Investigator