[time-nuts] Trimble T Lassen 2 - suitable antenna....advice.....questions
Hal Murray
hmurray at megapathdsl.net
Mon Jul 23 17:36:19 UTC 2012
squirrox at gmail.com said:
> While i am on, can anyone suggest a reasonably priced unit that has a 1pps
> output, NMEA and a built in antenna. Because I want to use this with an 8
> bit embedded system I am probably not going to be able to hack one of the
> many cheap USB dongle GPS's.
Garmin GPS 18x-LVC
GlobalSat MR-350
http://support.ntp.org/bin/view/Support/InexpensiveOemGps
azelio.boriani at screen.it said:
> ...And don't forget that the PPS pulse is very narrow so you have to use a
> 'scope with memory, a digital 'scope or turn the brightness at max.
Most scopes that I've used have some sort of indication if they are/aren't
getting triggered, so even if you can't see the pulse you can tell if there
is a pulse there.
Sometimes, it helps to run in Triggered mode rather than Auto. If you are
using Auto, at least with the Rigol DS1102E, it may take a while to lock up.
I assume it searches for a while, doesn't find anything, so it stops to
display the current buffer. While it is stopped, the pulse happens. I don't
know how big the blind spot is, but it takes several seconds to show a PPS
signal. Works fine in Triggered mode as long as you are happy without seeing
anything when the trigger doesn't happen.
bownes at gmail.com said:
> The pulse from my T-Bolt is on the order of 1uS wide.
Interesting. Mine is 10 uS wide.
Rev E, 5/31/05
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