Hi
You don’t *have* to go to the “many days” approach if that’s beyond the
accuracy you require.
You *can* go there if you need to. If you don’t have a GPSDO (or something
similar) it may not
make much sense to go quite that far.
Even with less accurate sources, the same approach still works.
Hal Murray wrote:
>
> Internally, Linux (and most other modern OSes) use UTC. The API doesn't
> include the TAI offset. There is no way to talk about the extra second.
See adjtimex(2) for a description of the leap second API.
Tony.
--
f.anthony.n.finchhttp://dotat.at/
Humber, Thames: Sout
dave.martind...@gmail.com said:
> It seems odd that the Garmin receiver got it wrong. The Garmin GPS-20 and
> -25, which I think are both older than the 18x, get it correct.
I haven't played with the -20 or -25, but I have -18 (no x) as well as -18x.
It's easy to tell the -18 from the -18x just
It seems odd that the Garmin receiver got it wrong. The Garmin GPS-20 and
-25, which I think are both older than the 18x, get it correct. The GPS-20
is so old it is a single-channel receiver, the GPS-25 is 12-channel but
still 5 V power.
GPS-20, June 1998:
$GPRMC,235959,A,4913.2184,N,12305.9266,
Oh boy Chris, some good information there. I guess my first step would be to
get a GPS disciplined source. My preference would be to use an external 10 MHz
source. And even if I did, I'd lose it some times of day depending on
propagation. Maybe the 1 pps to set my OCXO as close as I can get
"I logged NMEA from three cheap ($15-$50) GPS/1PPS receivers, the kind
popular with hobbyists: parallax(good), reyax(good), adafruit(bad)."
what is the problem with the adafruit board?
73
KJ6UHN
Alex
On 7/1/2015 4:34 PM, Kasper Pedersen wrote:
On 07/01/2015 05:23 PM, Tom Van Baak wrote:
I log
> Okay that makes some sense. I will have to ponder over this and see how it
> will help.
> But in any case (which I sort of expected) it's a time consuming procedure,
> during which the counter isn't available for other use.
Bob, I suspect you don't quite have it yet.
Make one measurement today
Hi
Take your OCXO and divide it down to 1 pps.
Take the PPS out of your GPSDO
Feed both of them into your counter
Time the “delta” between the two to the resolution of a 40 year old 5335 ( low
ns).
Wait 10 seconds
Repeat
You now have data to a resolution of ~2x10^-10
Shut down the counter, go
On 07/01/2015 05:23 PM, Tom Van Baak wrote:
> I logged NMEA from three cheap ($15-$50) GPS/1PPS receivers, the kind popular
> with hobbyists: parallax(good), reyax(good), adafruit(bad).
>
> 3) Adafruit Ultimate GPS Breakout
> http://www.adafruit.com/products/746
>
> If someone else has dat
Okay that makes some sense. I will have to ponder over this and see how it
will help. But in any case (which I sort of expected) it's a time consuming
procedure, during which the counter isn't available for other use. And when I
go to bed I won't know the next day if I might have missed a cou
So I can measure the time interval, which should be one second. If I measure
10 intervals, my resolution would be 1 part in 10 million. I think I can set
the master oscillator closer than that with beating against WWV. So maybe
buying a 1 pps source won't improve anything for me.
On W
On Wed, July 1, 2015 12:55 pm, Bob Albert via time-nuts wrote:
> I am missing something here. How does one use a 1 PPS signal?
> I see how I can use a 1 MHz or 10 MHz for a time standard but
> the 1 PPS usage eludes me.
Actually you have it backwards. A 1MHz or 10MHz can be a frequency
standard
time-nuts@febo.com said:
> I am missing something here. How does one use a 1 PPS signal? I see how I
> can use a 1 MHz or 10 MHz for a time standard but the 1 PPS usage eludes
> me. Unless the pulse is extremely sharp, a minor uncertainty in the shape
> or amplitude will have profound effects on
subscripti...@burble.com said:
> My linux boxes also did a double 59:
> Wed Jul 1 00:59:58 BST 2015
> Wed Jul 1 00:59:59 BST 2015
> Wed Jul 1 00:59:59 BST 2015
> Wed Jul 1 01:00:00 BST 2015
> Wed Jul 1 01:00:01 BST 2015
That's to be expected (unless you have fancy software).
Internally, Li
ement
Sent: Wednesday, July 01, 2015 10:55 AM
Subject: Re: [time-nuts] Leap Second results: cheap GPS/1PPS receivers
I am missing something here. How does one use a 1 PPS signal? I see how I can
use a 1 MHz or 10 MHz for a time standard but the 1 PPS usage eludes me.
Unless the pulse is extremely
uency measurement
Sent: Wednesday, July 01, 2015 10:55 AM
Subject: Re: [time-nuts] Leap Second results: cheap GPS/1PPS receivers
I am missing something here. How does one use a 1 PPS signal? I see how I
can use a 1 MHz or 10 MHz for a time standard but the 1 PPS usage eludes me.
Unless the pul
On 01/07/2015 16:23, Tom Van Baak wrote:
3) Adafruit Ultimate GPS Breakout
http://www.adafruit.com/products/746
This GPS receiver appeared to mess up the 2015 leap second, with a double 5959
and possible receiver reset:
(I also had serial communications issues with this board today)
If s
I am missing something here. How does one use a 1 PPS signal? I see how I can
use a 1 MHz or 10 MHz for a time standard but the 1 PPS usage eludes me.
Unless the pulse is extremely sharp, a minor uncertainty in the shape or
amplitude will have profound effects on the timing.
I use an HP 5328A
I logged NMEA from three cheap ($15-$50) GPS/1PPS receivers, the kind popular
with hobbyists: parallax(good), reyax(good), adafruit(bad).
1) Parallax PAM-7Q GPS Module
https://www.parallax.com/product/28509
When I powered up this board, I see:
$GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
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