[ntp:questions] how do you like the Trimble Resolution T
Ron Frazier (NTP)
timekeepingntplist at c3energy.com
Wed Feb 29 14:16:23 UTC 2012
Thanks for the info. I really want to run my antenna indoors if
possible, so this unit might not be for me. It's good to know about the
sawtooth correction stuff though.
I forgot to post the original link to the Ebay auction. It's item #
260769578277. The link below should work, but, if not, you can put the
item number into the Ebay search box.
Other than the Sure board which has been mentioned, are there any other
modern, hi sensitivity, timing GPS's which cost less than $ 100. Many
of the ones mentioned seem to be older technology like this Trimble.
On 2/29/2012 3:36 AM, Terje Mathisen wrote:
> Ron Frazier (NTP) wrote:
>> Hi all,
>> Is anyone using the Trimble Resolution T GPS for timing? I was looking
>> at an ad for one on ebay. For my purposes, any accuracy under 1 ms is
>> great. I don't have to have 15 ns. Of course, smaller numbers are always
>> better. Is this device hard to setup and program for PPS and use with
>> NTPD? What accessories are needed?
>> This is what the ad says is included:
>> quote on ->
>> The Resolution T Starter Kit provides everything you need to start
>> integrating the module into your application. The kit includes an
>> active, external 5-VDC Bullet-style antenna
>> 50 feet of RG-59 cable, and an AC/DC power adapter. The starter kit
>> enclosure includes a mother board that provides serial output, and a
>> serial interface cable. A reference manual and monitor programs are
>> provided on CD-ROM.
> I could not get to that taobao link...
>> <- quote off
>> I notice the unit only tracks 12 satellites and has 141 dbm sensitivity,
>> which seems to be less than some units. Is that a problem?
> Should not be as long as you can get an outside antenna location.
>> Finally, what is sawtooth correction?
> Most GPS chipsets run off a 10 MHz clock, which means that the best
> they can do is to locate the actual PPS edge on the nearest 100 ns
> boundary, i.e. you'll get an error of +/- 50 ns which the gps knows
> Timing gpss like the Oncore UT+ sends the known PPS offset as part of
> the serial timestream, telling NTPD (or any other recipient) how
> early/late the pulse actually did arrive.
> This is nice to have if you also have a stabilized clock source for
> your motherboard, along with hw to detect and measure the interrupt
> latency, i.e. the time between the PPS pulse and when the OS driver
> wakes up and notices it.
(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
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timekeepingdude AT c3energy.com
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