Bert wrote:
The thunderbolt is one of the best timing devices but not for
frequency, if you want high resolution. Over time it is ok but high
resolution short gate times and you see the frequency changes. They
use the OCXO to correct for timing error
I concur with Tom's comments -- I
In message CAKyJ6kZqOiByDU_CwkZpPiuvzigGh+mqe4O=dpwzz4wo9gr...@mail.gmail.com
, Paul writes:
Sawtooth (quantization) correction is probably the defining characteristic.
Position Hold is what makes a GPS receiver timing, the sawtooth correction
is icing on the cake.
--
Poul-Henning Kamp
On 04/27/2014 04:15 AM, Tom Van Baak wrote:
The thunderbolt is one of the best timing devices but not for frequency, if
you want high resolution. Over time it is ok but high resolution short
gate times and you see the frequency changes. They use the OCXO to correct for
timing error and if
On Sat, 26 Apr 2014 22:36:27 -0700
Chris Albertson albertson.ch...@gmail.com wrote:
How does the u-bloc's performance compare to the M12+T?One of these is
on my list of things to buy someday. I thought the M12+T had a 1-sigma
error in the single digit nanoseconds.The u-bloc is newer
Hi
You might want to actually measure the GPS modules to look at their
performance. Some of them (like the uBlox) can do much better than the
published specs.
Bob
On Apr 27, 2014, at 4:25 AM, Attila Kinali att...@kinali.ch wrote:
On Sat, 26 Apr 2014 22:36:27 -0700
Chris Albertson
For a nice comparison of the M12+T, M12M, and ublox-6T, start with page 34, and
especially note the ADEV plot on page 40:
http://www.cnssys.com/files/tow-time2013.pdf
The ublox-6T performs at least as well as the M12+T does. They are both in the
1 to 2 ns/day ballpark. The advantage is that the
The Pendulum GPS-88 and GPS-89 have a button on the front you push when
you want to force it into hold-over to do your measurement, for this
very reason.
PPS steering and OCXO steering is the same thing once you forced the PPS
into the right range. Some *really* depend on the
Bert Kehren wrote :
The thunderbolt is one of the best timing devices but not
for frequency, if you want high resolution.
Bert,
Would my old HP Z3801A be better for frequency than the Thunderbolt?
Could you put some quantitative difference to it?
Thanks,
... MartinVE3OAT
Hi
There are an enormous lot of variables when you do all of this. You also need
to figure out what you are really looking for. Often that relates to system
specs.
A WAAS enabled receiver will probably give you a better fast survey than a
simple receiver. Are you doing a 48 hour survey or a
I unplug the antenna from my fury boards. I hope this is an effective
alternative.
Sent from mobile
On Apr 27, 2014, at 9:02 AM, Tom Van Baak t...@leapsecond.com wrote:
The Pendulum GPS-88 and GPS-89 have a button on the front you push when
you want to force it into hold-over to do your
Tom,
There is an important error in your message below. The Motorola designed
M12M receiver is still in popular and in full production mode. You can get
them from Synergy Systems, LLC in San Diego. They are very friendly to
time-nuts members. The M12M has been used continuously by commercial
Bill,
There is an easier method that does not jiggle the board mechanically:
The command:
sync:hold:init
Disables the disciplining.
sync:hold:rec:init
Re-enables disciplining.
The sync:tint? command can be used to check the drift while in holdover..
Bye,
Said
Sent From iPhone
On
Hi Rick,
Thanks very much for the correction, and for the additional information.
Glad to hear the M12M is still around. That's good news for all of us.
But then can you explain what you meant in your PTTI paper when you said:
Anticipating the need for a M-12 replacement, Synergy examined
I unplug the antenna from my fury boards. I hope this is an effective
alternative.
Bill,
That's probably what I did for my tests. Or maybe I just used a SCPI command to
do it. I don't remember anymore. Sometimes when I test multiple GPSDO at once
it's convenient to just remove the antenna
Tom,
When Motorola decided to get out of the GPS business there was uncertainty
about the future of the products that relied on the M12+ so a market
opportunity presented itself and the SSR-6T series receivers were born. In
the meantime the confusion over the future of the M12M was resolved and
I spent some time reading the uBlox-6 documentation. I found the TIM-TP ubx
message and format. I see that there is also the ability to feed back to
the uBlox-6 time shift info for the PPS in 1ns increments.
Does it make sense to feed the TIM-TP info back this way to provide
correction?
Or is an
Jim,
Most (all?) timing receivers allow you to virtually shift the 1PPS forwards and
backwards to compensate for antenna delay or other factors. But the physical
1PPS output will still have clock quantization and the only way to deal with
this is external h/w or s/w sawtooth correction.
On Sun, Apr 27, 2014 at 2:14 AM, Poul-Henning Kamp p...@phk.freebsd.dkwrote
Position Hold is what makes a GPS receiver timing, the sawtooth
correction
is icing on the cake.
I've been curious about this for a while:
SkyNav says the SKG16 (based on the MT3329) has a timing accuracy of 60ns
j...@jtmiller.com said:
I spent some time reading the uBlox-6 documentation. I found the TIM-TP ubx
message and format. I see that there is also the ability to feed back to the
uBlox-6 time shift info for the PPS in 1ns increments.
Does it make sense to feed the TIM-TP info back this way to
When I was playing with an Adafruit GPS, it appeared that if it thought you
were not moving it would go into a pseudo-position-hold mode and the output
coords would not change. It took it a while to start outputting new coords
when you started moving again. This test was at walking speeds.
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