I tried a pulse-stretcher using a 555 [found on the net, not my design] with
both a Trimble unit and a Sure development board. Neither of them had any
success ;-(
OTOH, the 555 isn't the best chip to use for this job. I just happened to
have some in the junk-box. Anyway, I've ordered new processors for my
Ultimates, so I hope my problems will be behind me soon.
By the way, I want to use my Ultimates as portable units. Having a separate
antenna makes it possible to put the transmitter in a strong metal box, but
nearly all the 'recommended' GPS units appear to have integrated antennas
which need delicate surgery to the case and make waterproofing more
difficult. Any thoughts on that?
David
G8XBZ
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-----Original Message-----
From: QRPLabs@... [mailto:QRPLabs@...] On Behalf Of
andyfoad@...
Sent: 16 June 2013 10:05
To: QRPLabs@...
Subject: [QRPLabs] Those GPS 1pps problems. (Some bystander thoughts)
Yesterday I thought I'd try to do a bit of research regarding the GPS
modules used by kit owners.
Now I'm not sure if I've got all the model numbers correct but from what
I've seen so far, all the modules have a very narrow 1pps width output.
For example I've seen figures of nanoseconds and microseconds quoted on the
troublesome modules, yet my Reyax UP501 which works flawlessly has a whole
100ms width for the 1pps output.
From where I am standing it does seem that this pulse width is the key to it
all.
I remember some month ago some work by KA7OEI regarding using and RC network
across the 1pps outputs might help broaden the pulses to work.
Maybe a trawl through this groups archive might reveal some more ?
Just thinking aloud...
73 de Andy G0FTD (Reyax UP501 GPS user with zero hassles)
