[ntp:questions] lots of GPS modules and info at SparkFun

Ron Frazier (NTP) timekeepingntplist at c3energy.com
Thu Feb 9 23:41:33 UTC 2012

On 2/9/2012 12:43 PM, Chris Albertson wrote:
> On Thu, Feb 9, 2012 at 1:08 AM, Ron Frazier (NTP)
> <timekeepingntplist at c3energy.com>  wrote:
>> OK, so I'm replying to my own message, what's strange about that?  8-)
>> VERY preliminary data, after running an hour with my USB GPS without PPS
>> outputting only GPZDA sentences, I'm getting ~ +/- 5ms peak offsets of the
>> computer clock vs GPS.  I'm liking it so far.  It initially looks more
>> stable than when I was using GPGGA sentences.
> Warning: This is addictive.   After you get some improvement then you
> try for more and so on and so on.   Before your most recent change you
> were about three orders of magnitude from the state of the art so you
> have room for a great number of those "and so on and so on" cycles.
> Before long you'll take seriously the old joke that a man with a watch
> knows what time it is, but a man with two watches is never sure of the
> time.  So you end up with three or five GPS systems and a couple
> rubidium standards as well.  Then you'll be measuring cables to
> account for propagation delays and placing your equipment in
> temperature controlled enclosures,..... The spiral  does not have an
> end.    Now your emails have many uses of "ms" but later we will be
> reading "us" and even later "ns" and "ps"   This is the normal
> progression for most addicts.
> Chris Albertson
> Redondo Beach, California

Hi Chris,

You've got a point. ... ... Maybe I should start running away now!

On the other hand, my latest incarnation has been running stably for 15 
hours.  Might as well get the next unit conversion out of the way.  The 
biggest offset peak on my current chart is 6753 us.  My wallet's 
relative emptiness will keep me from getting into any exotic technology 
any time soon.  However, I might be able to get a few more toys.  As I 
mentioned, I don't have any pressing need for "us" accuracy, but 
learning about the technology is very interesting.  I find most anything 
related to GPS to be just fascinating.  I guess I'm getting hooked.  8-)




(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT c3energy.com

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