Ummm think you sent the question to the wrong group perhaps?
On Wed, Feb 26, 2014 at 12:50 PM, <corc...@yahoo.ca> wrote: > I have some problems with My 8505A > Analyzer, it has no RF output, I checked the YTO and other frequency > dividers > and it appears to be OK some times there is RF output only it will not > tune and > it seems to cut out as I tune trough the frequency range. > Thank You > Sal C. Cornacchia Electronic RF Engineer > Ret. > > > > On Wednesday, February 26, 2014 12:33:17 PM, Chris Albertson < > albertson.ch...@gmail.com> wrote: > > It's not going to work. > > If the purpose of running the Thunderbolt is only to drive NTP then > you don't need LH. NTP's only tags the pulses to the nearest > microsecond, nano sec on accuracy is lost on NTP. I'd even say the > TB is the wrong GPS for NTP. It costs to much and uses to much power. > > But if you are also, or mainly, using the Thunderbolt for it's 10Mhz > and NTP is a secondary function then a TB makes sense. > > Yes you NEED the PPS on the serial cable. Thunderbolts do not send > NMEA. Thunderbolts send their own data format that is unique to > Trimble. Don't modify the GPS receiver. Make a special cable > adapter. When you do this pay attention to polarity of the PPS > signal. It is easy to get it backwards. You want the raising edge of > the TB pulse to interrupt the computer. It you invert the signal the > wrong number of times the time will be "off" by the ouse length and I > don't know if the pulse length is controlled to the level the leading > edge is. Remember RS232 uses negative and positive voltage, data > lines use negative logic, control lines positive. The TB's PPS is > TTL level. Many rs232 ports do accept t/l level if you get the > polariy correct. > > Again don't even bother to run an NTP server without PPS. You may as > well just get time from some internet time servers. > > You can NOT control a GPS from two ports. Both NTP and LH will try to > send commands to the GPS. > > Likely, almost certainly you need to build a small circuit board the > has two connectors that face the TB (PPS and serial) and one that > faces the computer. The little perfboard makes a neat way to or > connect cables but you could solder up a y--cable > > The best thing to do is get a cheaper GPS, and one that uses less > power to drive the NTP server. The old Motorola Oncore series are > cheap and the new breed of very small GPSes are good too. DOn't spend > more than $40 or $50 on a GPS to drive NTP as ,again NTP record > microseconds. > > You could free up that Windows PC too. It is not the best platform > for NTP. Asmall ARM based system (even the Rasbery Pi) will > outperform a Windows based NTP server. and use a LOT less power > (Power cost for a NTP server is more than you think, it came to about > $300 a year for me if I used a standard PC and a thunderbolt. > Switching to a very tiny ARM based system and a smaller GPS gave as > good performance and power savings paid for the hardware in 1/2 a > year. $.21/KWH about 170W and 8760 hours per year comes to a $300 > power bill. My current system is powered by a 1000 mw plug-in power > cube and does not need a cooling fan. > > On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge > <david.partri...@perdrix.co.uk> wrote: > > I'm running Meinberg NTP on the Windows 7 x64 machine to which my > Thunderbolt is attached. > > > > I'd like to be able to share the serial port between LH and NTP so that > I can run the machine as an NTP Stratum 1 server locked to the TB, and also > be able to use LH to check things. > > > > I looked around the with Google, and saw *numerous" serial port > splitters. Which is recommended? > > > > Also what's the best way how to configure NTP to lock the the TB on a > serial port? Do I need to modify the TB to deliver the PPS down one of the > serial data lines or will NTP work well by parsing the NMEA time messages? > > > > Many thanks > > David Partridge > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.