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A Publication Featuring The Information Services Technology of Maine State Government
Volume IV, Issue 6 |
June 2001 |
By Tom Cromwell and Martin Murphy
During April, Bureau of Information Services employees, Flint Bachelder and Tom Cromwell set up the State’s first wireless bridge link at the Northern Maine Juvenile Center in Charleston. This is also the State’s first production use of Voice Over Internet Protocol (VOIP) technology.
During the construction of the new Department of Corrections’ Juvenile Facility in Charleston, the administration section needed to be relocated to a former restaurant several hundred feet from the facility. The standard solution would have been to dig a trench and drop a fiber line. Due to the unknown future of the old restaurant building, the cost of a permanent, buried line was questionable. We decided to pursue a "reusable" wireless method. In the event that we abandon this temporary administration area, we will not have a fiber line left in the ground that we cannot use. The VOIP/wireless idea seemed to be the right answer for the Department of Corrections in that location.
Last Fall, Tom Cromwell made a site visit, and agreed conditions were adverse and generally cost prohibitive to the installation of traditional copper and fiber cable for voice and data services to the "restaurant" building. After a considerable review of numerous wireless products, Tom settled on the Western Multiplex Tsunami system. He says "I had some prior knowledge of Western Multiplex and their larger microwave communications systems. I was confident that they turned out high quality products, and after reviewing the Tsunami product and its capabilities, it seemed like a good fit for what we were trying to accomplish in Charleston."
The Tsunami wireless system provides a 20 MB full duplex Ethernet/TCPIP link for the data, as well as a T1 channel for voice connectivity. This is accomplished through combining or "multiplexing" multiple signals onto one radio link. The radios are based on spread spectrum technology, where the information within the radio signal is spread over multiple frequencies. This, combined with the highly directional antennas used in the system, make it virtually impervious to interception and therefore affords "built in" security of the information on the radio link. The data connection was basically "plug and play", in that once the radios were optioned and the link established, it was simply a matter of plugging the Ethernet connections into hubs and the Local Area Network (LAN) was effectively extended to the former restaurant.
The Northern Maine Juvenile Facility, seen here on the left side of the picture, is connected to the temporary administration building (formerly a restaurant on the right side of picture) using wireless technology. One of the Tsunami antennas is on the small cupola atop the Juvenile Facility. Photo by Shannon Shea 5/21/01.
The voice side was slightly more complicated. The Avaya R300 product, which allowed us to provision up to 24 phone connections through the use of VoIP technology, was selected. The R300 affords connection directly to the LAN, via an Ethernet port, or by a serial T1 connection via a T1 port. We opted to go the T1 route and keep the voice out of the data portion of the radios, as the T1 bandwidth was already available as part of the Tsunami system, and we did not want to slow down the LAN side of the link with voice traffic.
Part of the new addition to the Northern Maine Juvenile Facility is in the foreground, and the former restaurant, now the administration offices, is in the background, several hundred feet away. As you look at this photo, the other Tsunami antenna is on the back (right side) of the restaurant. Photo by Shannon Shea 5/21/01.
The most exciting and adventurous part of the installation was scaling the snow-covered roof of the juvenile building in chilly breezes to install and align the antennas! The antennas used in this installation are of the flat-panel design, and are generally six inches square. They are highly directional, so they require a fine alignment to one another for maximum performance. Incidentally, these antennas are made right here in Maine by Gabriel Electronics of Scarborough. Tom says, "In the end, I was thoroughly impressed with the overall ease of installation of this product, as well as with its performance. I believe that this can be a rapidly deployable solution for any situation in which we are inhibited from the installation of traditional cable connectivity, or where it makes more economic sense, such as for temporary service requirements. Its quality, reliability and reuse capability make it a very attractive investment".
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Martin Murphy has worked for the MIS section of the Department of Corrections for four years, as an Information Support Specialist. Previous employers include Strategic Weapons Facility, Pacific (Martin worked as a computer specialist there in the Network Support group working with various networking solutions), and the US Navy as a Submariner. He may be reached with questions or comments by e-mailing martin.murphy@state.me.us.
Tom Cromwell has worked for the Network Services Division of the Bureau of Information Services for the past 11 years. Prior to coming to BIS, Tom had worked in Norfolk/Virginia Beach and Alexandria, Virginia for Atlantic Research Corporation, a research, engineering and electronics firm that supported programs for the Department of Defense and other government agencies. Tom is a 1979 graduate of Eastern Maine Technical College. He may be reached by e-mailing tom.cromwell@state.me.us.