Date: Thu, 03 Jul 1997 09:27:09 -0400 From: "Stephen F. Combs [Network Services]" <steve.combs@gemis.ge.com> To: Wes Peters <softweyr@xmission.com> Cc: "Andrew K. Adams" <akadams@wraith.psc.edu>, questions@FreeBSD.ORG Subject: Re: TrueTime GPS... Message-ID: <33BBA8AC.3F1B76CE@gemis.ge.com> References: <199707020030.UAA05757@wraith.psc.edu> <199707030716.BAA04660@obie.softweyr.ml.org>
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I've been evaluating a "TrueTime" Model NTS-100 for the last couple of weeks (GPS Receiver with a network interface so you don't have to have any specific S/W, just point your ntp S/W at it as a "server") and I must say I haven't been tooooo terribly impressed. It locks on to the satellite(s) just fine (after I FINALLY found a good location for the antenna!) but it's network response Sucks! I've put it's AUI i/f on a Cisco Catalyst switched-hub (it's own dedicated connection) wich is directly attached to our FDDI campus ring. 10 pings of 100bytes result in response times of 39ms to 256ms with AT LEAST 2 packets dropped! I attach a FBSD PC to the same port (using the SAME Twisted-Pair-to-AUI tranceiver AND the same CAT-5 Cable) and get sub-2ms response times for 1000 packets of 100bytes with NO dropped packets!! I have three "stratum-5" ntp servers which sync to three machines in our corporate FireWall office which work just fine. The NTS-100 is currently driving 3 other NTP servers (it's a 'stratum-1' server, so the three machines I have sync'ing to it are at 'stratum-2') which CONSTANTLY loose syncronization with it! For $4300 I'm NOT impressed!!!! I'm using a combination of FreeBSD and Sun Sparc systems as my NTP servers for BOTH set-ups! Running 'xntp3-5.90' on ALL systems. Wes Peters wrote: > Andrew K. Adams writes: > > I would like to attach a GPS to a FreeBSD box (for network > > synchronization) and would be very appreciative of any information > > anyone can offer. I am currently looking at a model manufactured > by > > TrueTime (XL-DC 600), since it (and my PC) is rack-mountable and it > > > provides a serial port for communication -- I am unsure if the > latter > > is useful with FreeBSD. > > Chances are pretty good it is a NMEA-0183 port, which uses RS-422 > signalling levels. You should be able to plug it into a PC serial > port, > unless you have really bad hardware. > > You'll have to contact the manufacturer for information on the > protocol > they use. There is *some* standardization in this area, but I > wouldn't > count on your software working with it. Most manufacturers are pretty > > good about releasing protocol specs, though I've never heard of > TrueTime. > > (I'm known as Barnacle Wes in another, *much* slower dimension. ;^) > > -- > "Where am I, and what am I doing in this handbasket?" > > Wes Peters > Softweyr LLC > http://www.xmission.com/~softweyr > softweyr@xmission.com -- ---- Stephen F. Combs Internet: CombsSF@Salem.GE.COM GE Industrial Systems Voice: 540.387.8828 Network Services Home: CombsSF-Home@Salem.GE.COM 1501 Roanoke Blvd FAX: 540.387.7106 Salem, VA 24153 LapTop: CombsSF-Mobile@Salem.GE.COM
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