Thank you for a good tip, and it could have been a great opportunity but=20
it=B4s equipped with a RS232 and the distance from DCE to DTE could maximum=
=20
be about 30meter. The demand I have is more like 200meter. In one place I=20
have to place a measure-point in the basement of a skyscraper in NY and the=
=20
distance between the PC and the antenna will demand that the interface is a=
=20
RS422 or so because it can reach at least 300meter. I have at RIPE NCC seen=
=20
a antenna from Trimble that is equipped with that interface and RIPE have=20
made an PC-interface that converts the signal between 232/422 in the PC=20
with power supply to the antenna from the PCI-bus.
Do you know if the GPSClock Model 200 could be delivered with RS422 in=20
stead of RS232? The price on GPSClock Model 200 seem to bee more attractive=
=20
than the Trimble antenna.

yours
Krister

krister@ruthblad.com


At 06:17 2001-05-10 +1000, you wrote:
> >Hi,
> >
> >I=B4m planning to use a PC with netBSD measuring IS-IS updates in a WAN=
 and
> >I=B4m going to use a GPS-system to synchronize the different measurement
> >probes, I=B4m planning to place them in various places in the WAN so that=
 I
> >can get the convergence-time from the measurements.
> >I wonder witch support there is in the OS for getting time from a GPS?=
 and
> >how does it work?
>
>sure it works and is fairly easy to do.
>
>For the GPS, you might want to look at www.gpsclock.com with the special
>offer running for five more days. I've only recently noticed this product
>and haven't used it myself. People might have reported experiences on the
>comp.protocols.time.ntp newsgroup, so a search through dejanews could be
>worthwhile.
>
>these pages need updating, but have a look at:
>   http://www2.imb.uq.edu.au/Computing/Tech/GPS_NTP_Setup.html
>   http://www2.imb.uq.edu.au/Computing/Tech/NTP_GPS_Setup.html
>
>one tip: when first connecting the GPS, use a terminal like minicom
>(available as a NetBSD package) and set it to use the right serial port, at
>4800 bps
>
>as soon as the settings are right, you'll see several lines of output from
>the GPS every second, like:
>
>$GPGSA,A,2,02,,,07,,09,,,,,,,3.5,3.5,*11
>$GPGSV,2,1,08,02,38,094,38,04,60,044,,05,05,240,31,07,45,148,41*75
>$GPGSV,2,2,08,08,09,031,,09,35,226,43,24,30,354,,26,19,303,*77
>$GPRMC,084420,A,2729.9587,S,15300.8460,E,000.0,000.0,070501,011.3,E*61
>
>the '*xx' at the end of every line is an optional checksum
>
>the $GPGSV lines list all satellites that could be in view
>$GPGSV,2,1,08,02,38,094,38,04,60,044,,05,05,240,31,07,45,148,41*75
>        ^ two $GPGSV lines
>          ^ this is number one (of 2)
>            ^^ total of 8 satellites
>               ^^ satellite 02 (each GPS satellite has a number 1..32
>                  ^^ 38 degrees elevation
>                      ^^ 094 degrees azimuth
>                         ^^ signal strength of 38
>                            ^^ satellite 04....
>
>the $GPGSA tells you whether the GPS is achieving a fix
>$GPGSA,A,2,02,,,07,,09,,,,,,,3.5,3.5,*11
>        ^ automatic
>          ^ 2 means a 2D fix  initially this will be '1', no fix
>            ^^^^^^^^^^^^^^^^ these fields correspond to the satellites
>                             in the GPGSV lines. Here satellites 2,7,9
>                             are deemed good enough to use for the fix
>
>when you first switch the GPS on, it will output lines like
>$GPGSA,A,1,,,,,,,,,,,,,,,*11
>which means it's not fixed, and probably isn't outputting the PPS signal
>
>cheers,
>Danny Thomas