; Discussion of precise time and
frequency measurement time-nuts@febo.com
Sent: Thursday, October 23, 2014 9:18 PM
Subject: Re: [time-nuts] GPS for ntp
OK, I see source of the confusion. There is a difference of one character
in the two part numbers. The RYN25 has the older Ublox chipset. The RY725
has
- Original Message -
From: Joseph Gray jg...@zianet.com
To: brian.ing...@systematicsw.ab.ca; Discussion of precise time and
frequency measurement time-nuts@febo.com
Sent: Thursday, October 23, 2014 9:18 PM
Subject: Re: [time-nuts] GPS for ntp
OK, I see source of the confusion
On 24/10/2014 21:33, Joseph Gray wrote:
Timestamping a message to the nearest 100 ns is what I am after. If I can't
do it directly with the ublox, I'll have to look at the PRU on the
Beaglebone. It has a 200 Mhz clock and single cycle instructions.
The BBB has no less than 8 peripherals that
On 2014-10-22 21:07, Joseph Gray wrote:
Now I'm confused. Both the ebay listing and the linked specsheet clearly
state that the Ublox Neo-7N is used. Is this true or not?
On Wed, Oct 22, 2014 at 2:50 PM, Tom Van Baak t...@leapsecond.com wrote:
The USB interface will give you unpredictable
OK, I see source of the confusion. There is a difference of one character
in the two part numbers. The RYN25 has the older Ublox chipset. The RY725
has the Neo-7N chipset. There is only a $6 difference in price. I think
I'll get a few to play with.
Joe Gray
W5JG
On Thu, Oct 23, 2014 at 2:41 AM,
Thanks for the great explanation.
Is there any data on the performance ?
Cheers
Simon
On 21/10/2014 22:29, Dennis Ferguson wrote:
On 21 Oct, 2014, at 08:58 , Simon Marsh subscripti...@burble.com wrote:
How do you map the timer counter value in to a PPS timestamp ?
(that is, how do you turn
On 2014-10-20 19:39, Joseph Gray wrote:
What does everyone think of this GPS module for ntp use? According to the
specsheet, it uses a Ublox Neo-7N.
http://www.ebay.com/itm/RY725AI-10Hz-UART-USB-interface-GPS-Glonass-QZSS-antenna-module-flash-memory-/181562403752
Does anyone want to take a
The USB interface will give you unpredictable timing and you still have to
hook
up the PPS output somehow, so can only really be recommended for navigation
uses.
No, both versions of this board have a very nice 1PPS output pin.
Use the serial or USB interface for NMEA sentences only; use
Now I'm confused. Both the ebay listing and the linked specsheet clearly
state that the Ublox Neo-7N is used. Is this true or not?
Joe Gray
W5JG
On Wed, Oct 22, 2014 at 2:50 PM, Tom Van Baak t...@leapsecond.com wrote:
The USB interface will give you unpredictable timing and you still have
What does everyone think of this GPS module for ntp use? According to the
specsheet, it uses a Ublox Neo-7N.
http://www.ebay.com/itm/RY725AI-10Hz-UART-USB-interface-GPS-Glonass-QZSS-antenna-module-flash-memory-/181562403752
I'm thinking about using it for a Beaglebone ntp server. I know there
Running the BBB as an NTP server is a breeze and has a couple of
advantages over the Pi. Specifically, on the BBB, the kernel module is
pre-built and configuring the PPS driver is done at runtime using the
device tree. No kernel re-compilation is required to get up and running,
just plug and
From: Simon Marsh
No claims are any good without being backed by data, so attached are a
couple of plots showing my NTP performance from the past 4 hours.
'Sheliak' is the BBB with the PCI-5S and 'Albali' is a Pi with an
adafruit ultimate GPS breakout (MTK3339). It's easy to see the heating
On Mon, Oct 20, 2014 at 10:50 PM, Neil Schroeder gign...@gmail.com wrote:
The one thing that hasn't yet happened is making the beaglebone timestamp
on the linux side in a way that works for ntp.
Custom code no problem. Freebsd PPSAPI no problem. Linux, nothing there
yet.
I have been working
From: Simon Marsh
[]
No claims are any good without being backed by data, so attached are a
couple of plots showing my NTP performance from the past 4 hours.
'Sheliak' is the BBB with the PCI-5S and 'Albali' is a Pi with an
adafruit ultimate GPS breakout (MTK3339). It's easy to see the heating
Check lightningmaps.org, mentioned on this list before for lightning location
via TOA using STMicro Cortex -M4 devices.
Didier KO4BB
On October 20, 2014 8:39:16 PM CDT, Joseph Gray jg...@zianet.com wrote:
What does everyone think of this GPS module for ntp use? According to
the
specsheet, it
Andrew-
I'm actually referring to using either the eCAP function or one of the
integrated dmtimer triggers - which are, from some accounts, more accurate
than a gpio.
Google beaglebone dmtimer pps.
NS
On Mon, Oct 20, 2014 at 11:56 PM, Andrew Rodland and...@cleverdomain.org
wrote:
On Mon, Oct
Perhaps the programmable realtime unit (PRU) is what you're looking
for. It's used in the 5370 CPU replacement.
--
Paul
On Tue, Oct 21, 2014 at 8:33 AM, Neil Schroeder gign...@gmail.com wrote:
Andrew-
I'm actually referring to using either the eCAP function or one of the
integrated dmtimer
It's been done on FreeBSD. See:
http://lists.freebsd.org/pipermail/freebsd-arm/2013-February/004769.html
Patch is now in recent FreeBSD releases/snapshots
And yes, it's far superior to than using the GPIOs, or UARTS
There was some work done on Linux, but I'm not sure it was ever finished
or
I missed the lightningmaps mention the first time. That is very helpful.
Joe Gray
W5JG
On Tue, Oct 21, 2014 at 5:22 AM, Didier Juges shali...@gmail.com wrote:
Check lightningmaps.org, mentioned on this list before for lightning
location via TOA using STMicro Cortex -M4 devices.
Didier
I wasn't sure if ntp would be the way to go or not. OTOH, wasn't PHK
getting nanosecond accuracy with FreeBSD on the Net4501, or is my memory
faulty?
Joe Gray
W5JG
On Mon, Oct 20, 2014 at 11:03 PM, Chris Albertson albertson.ch...@gmail.com
wrote:
NTP is not nearly good enough to use for
Iain,
How do you map the timer counter value in to a PPS timestamp ?
(that is, how do you turn the HW counter value in to what the OS thought
the time was when the event occured ?)
Cheers
Simon
On 21/10/2014 13:54, Iain Young wrote:
It's been done on FreeBSD. See:
It just turns up as /dev/pps0 like any other PPS source, so you
configure ntp in the same way you would for any other PPS source,
or build ppsapitest to test it manually
(Although be aware you -may get a Invalid argument error from
ppsapitest after running it more than once. Reboot solves it,
Sorry, I wasn't clear.
The /dev/pps0 devices output a timestamp corresponding to when the event
happened.
The GPIO driver does this very simply by waiting for an interrupt event
and then asking what (current) time it is. This leads to the problem
that there is a non-deterministic time
Hi Simon,
Ah, slightly different question :)
I'm afraid I didn't write the code, so I can't really answer that
question. What I can say is that it does appear to be as good as Ian
(Lepore's) ntpq output shows.
To be honest, I just use the code :)
Iain
On 21/10/14 15:39, Simon Marsh wrote:
With HW capture, you can get an accurate view of when the event took
place but only relative to the counter in the particular timer/capture
unit that is being used.
True.
You have to synchronise between the counter
value and what the OS understands is 'system time' in order to create a
On Tue, Oct 21, 2014 at 6:58 AM, Simon Marsh
How do you map the timer counter value in to a PPS timestamp ?
(that is, how do you turn the HW counter value in to what the OS thought the
time was when the event occured ?)
He is running NTP. NTP's job is it keep the system time in sync with
a
t...@leapsecond.com said:
You have to synchronise between the counter
value and what the OS understands is 'system time' in order to create a
retrospective timestamp for when the event occured.
Also true.
One solution to the problem is use two independent HW capture inputs. One
for a
Here's some more info Joe
My Blitzortung.org station 1162 reboots daily.
It is located at 42 degrees latitude.
GlobalTop PA6H GPS module. The antenna is a Motorola patch in
the attic, looking through wooden boards and tar shingles. I
have the antenna against the underside of the roof,
One solution to the problem is use two independent HW capture inputs. One
for a GPS 1PPS and the other for your event.
In this case the system clock does not need to be synchronized -- since it
is used only to interpolate between the two events. The event timestamp is
little more than
On 21 Oct, 2014, at 08:58 , Simon Marsh subscripti...@burble.com wrote:
How do you map the timer counter value in to a PPS timestamp ?
(that is, how do you turn the HW counter value in to what the OS thought the
time was when the event occured ?)
On the NetBSD prototype I have the clock
What does everyone think of this GPS module for ntp use? According to the
specsheet, it uses a Ublox Neo-7N.
http://www.ebay.com/itm/RY725AI-10Hz-UART-USB-interface-GPS-Glonass-QZSS-antenna-module-flash-memory-/181562403752
I'm thinking about using it for a Beaglebone ntp server. I know there
Hi
There is a *lot* of detail on this in the archives.
Quick rundown - the Soekris has some custom code and “stuff” that makes it
better for NTP than any of the other boards.
For any normal use, a couple of microseconds is likely “good enough. For that,
many boards and GPS’s will do just
The one thing that hasn't yet happened is making the beaglebone timestamp
on the linux side in a way that works for ntp.
Custom code no problem. Freebsd PPSAPI no problem. Linux, nothing there
yet.
I have been working on it but if anyone has some insight its appreciated.
On Monday, October 20,
NTP is not nearly good enough to use for measuring speed of light
delays. It works at the microsecond level at best. I think what you
want is each station to have a local oscillator that runs in phase
with the 1PPS signal that comes from GPS receivers. Then you measure
the incoming signal
34 matches
Mail list logo
