haas@cs.utah.edu (Walt Haas) (11/10/89)
Greetings All, We are considering options for a high-speed data link between our campus network and the computers in LDS Hospital, about three miles away. There is a good clear line-of-sight between here and there, which would suggest that some sort of microwave or laser link would be useful. However for a number of weeks each winter the air in between is filled with thick freezing fog. Is anyone out there familiar off-hand with a good technology for dealing with this stuff? Thanks in advance -- Walt Haas haas@cs.utah.edu utah-cs!haas
eric@ists.ists.ca (Eric M. Carroll) (11/11/89)
>We are considering options for a high-speed data link between our campus >network and the computers in LDS Hospital, about three miles away. There >is a good clear line-of-sight between here and there, which would suggest >that some sort of microwave or laser link would be useful. However for >a number of weeks each winter the air in between is filled with thick >freezing fog. Is anyone out there familiar off-hand with a good technology >for dealing with this stuff? ISTS has installed a LCI Lace laser from one building to another, about 0.85 km away. After lots of trouble with low serial number design problems, we have got it settled in and it performs very well. We are quite happy with it. Compared with the microwave (way out of budget) or T1 (ludicrously expensive in Canada), it was the clear choice. As to the fog issue, it is the one weather condition that actually brings the link down. Rain has not been much of an issue. Intense fog has brought it down once in 4 months. Generally the fog has to be enough that you have very limited visibility, but the situation has not occurred enough to make any definite statements about fog survivabilty.
illgen@hq.af.mil (Keneth..Illgen) (11/13/89)
In article <1989Nov9.175018.26644@hellgate.utah.edu> haas@cs.utah.edu (Walt Haas) writes: >We are considering options for a high-speed data link between our campus >network and the computers in LDS Hospital, about three miles away. There >is a good clear line-of-sight between here and there, which would suggest >that some sort of microwave or laser link would be useful. However for >a number of weeks each winter the air in between is filled with thick >freezing fog. Is anyone out there familiar off-hand with a good technology >for dealing with this stuff? We presently use RF radio modems that support our LAN traffic for small distances. However, I know the company that we deal with (ARLAN) makes a model of this radio modem that can travel, up to, six miles LOS. Normally you MIGHT see problems at these frequencies (around 950MhZ) with the fog and cold weather you mentioned but these modems use spread- spectrum technology (SST) which basically stretches out the signal on transmit and crunches it back on the receive. At the distance you mentioned weather really wouldn't pose a problem. That's a pretty elementary explaination of what it does but I haven't finished my first cup of coffee yet. Anyway, SST provide for a reduction of noise interference; the kind of interference you might see with your type of weather. If you're not too worried about budget then you might find a laser system that is better but for the money you can't beat a good RF LOS with SST. We use ARLAN's but there might be something better out there. If you want more info on ARLANs drop me a line. Kenneth Illgen HQ Air Staff LAN Pentagon, Washington, DC (202) 695-5090 AUTOVON 224-6136 illgen@hq.af.mil
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (11/14/89)
In article <1989Nov9.175018.26644@hellgate.utah.edu> haas@cs.utah.edu (Walt Haas) writes: > >We are considering options for a high-speed data link between our campus >network and the computers in LDS Hospital, about three miles away. There >is a good clear line-of-sight between here and there, which would suggest >that some sort of microwave or laser link would be useful. However for >a number of weeks each winter the air in between is filled with thick >freezing fog. Is anyone out there familiar off-hand with a good technology >for dealing with this stuff? > You can consider private laser or microwave. I think that laser will be ruled out as all the vendors quote one kilometer maximum. Fog is a killer for infrared laser. Less so for microwave. 23 GHz microwave should work well on a three mile link with two foot dishes, depending on your definition of "thick". Three miles is well within nominal delay spec for Ethernet on microwave, so that should work without special kludges. Ethernet is cheaper than T1 last I looked, and you get more bandwidth. If you want to talk to a vendor, call: Microwave Bypass, Inc. 25 Braintree Hill Office Park Braintree, MA 02184 (617) 843-8260 dtheombs@eagle.mit.edu If I knew another turnkey Ethernet-on-microwave vendor, I would tell you. Motorola resells MBS gear, and perhaps Microwave Networks in Houston is still in the business. DEC and M/A Com never did work. LAN Connection never got off the ground. I never heard of anyone else. This technology has been used to good effect in NEARnet in the metro Boston area, where there are 8 of these links installed to date. I am getting another one to get to our Medical Center on the other side of Boston. Mass General also uses two links. All from MBS. --Kent England, Boston University [Disclaimer: I have no affiliation with MBS and this is not intended as a sales pitch. Your mileage may vary. Second opinions always advised.]
ray3rd@ssc-vax.UUCP (Ray E. Saddler III) (11/14/89)
The summary says it all.....'nuff said! -- Ray E. Saddler III UseNet ___ ___ ___ ___ ___ CAD System/Network Admin uw-beaver!ssc-vax!ray3rd /__// //__ / /\ // _ P.O. Box 3999 m.s. 3R-05 PhoneNet /__//__//__ _/_ / //__/ Seattle, WA. 98124 USA +1 206-657-2824 Missile Systems Division