MS
Mark Sims
Mon, Jan 30, 2012 5:47 PM
The Tbolt does not have any sawtooth error or corrections. Its' GPS receiver LO is generated from the 10 MHz oscillator. That's what makes it the best GPSDO out there.
I'm also thinking of porting over much of the Lady Heather t-bolt monitoring stuff to the Arduino.
One thing you can do with a uP based controller is look at the t-bolt's saw tooth error correction and remove a few nS of error.
The Tbolt does not have any sawtooth error or corrections. Its' GPS receiver LO is generated from the 10 MHz oscillator. That's what makes it the best GPSDO out there.
----------------------
I'm also thinking of porting over much of the Lady Heather t-bolt monitoring stuff to the Arduino.
One thing you can do with a uP based controller is look at the t-bolt's saw tooth error correction and remove a few nS of error.
CA
Chris Albertson
Mon, Jan 30, 2012 6:22 PM
The Tbolt does not have any sawtooth error or corrections. Its' GPS receiver LO is
generated from the 10 MHz oscillator. That's what makes it the best GPSDO out there.
Inside "Packet 0x8F-AC" (supplemental timing packet) there are two
data fields named "PPSOset and 10MHZOset. Each is a 4-bit signed
integer with units of nanoseconds for PPSOset and in pars per billion
for 10MHZOset. They are used to report an estimate of the PPS and
10MHz signals offset from UTC. Typically the values reported are not
constant and in the single digit range. (I'm reading from section
A.10.31 of the Thunderbolt manual.)
This is what I meant when I said "sawtooth". Maybe the wrong term.
But I think theses numbers can be used in a controller.
Chris Albertson
Redondo Beach, California
On Mon, Jan 30, 2012 at 9:47 AM, Mark Sims <holrum@hotmail.com> wrote:
>
> The Tbolt does not have any sawtooth error or corrections. Its' GPS receiver LO is
> generated from the 10 MHz oscillator. That's what makes it the best GPSDO out there.
Inside "Packet 0x8F-AC" (supplemental timing packet) there are two
data fields named "PPSOset and 10MHZOset. Each is a 4-bit signed
integer with units of nanoseconds for PPSOset and in pars per billion
for 10MHZOset. They are used to report an estimate of the PPS and
10MHz signals offset from UTC. Typically the values reported are not
constant and in the single digit range. (I'm reading from section
A.10.31 of the Thunderbolt manual.)
This is what I meant when I said "sawtooth". Maybe the wrong term.
But I think theses numbers can be used in a controller.
Chris Albertson
Redondo Beach, California
DJ
Didier Juges
Tue, Jan 31, 2012 1:50 AM
Mark,
If you feel adventurous, my GPSMonitor (written in C for the 8051) source
code is available. Development tools including C compiler are free.
Didier KO4BB
On Mon, Jan 30, 2012 at 11:47 AM, Mark Sims holrum@hotmail.com wrote:
The Tbolt does not have any sawtooth error or corrections. Its' GPS
receiver LO is generated from the 10 MHz oscillator. That's what makes it
the best GPSDO out there.
I'm also thinking of porting over much of the Lady Heather t-bolt
monitoring stuff to the Arduino.
One thing you can do with a uP based controller is look at the t-bolt's
saw tooth error correction and remove a few nS of error.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Mark,
If you feel adventurous, my GPSMonitor (written in C for the 8051) source
code is available. Development tools including C compiler are free.
Didier KO4BB
On Mon, Jan 30, 2012 at 11:47 AM, Mark Sims <holrum@hotmail.com> wrote:
>
> The Tbolt does not have any sawtooth error or corrections. Its' GPS
> receiver LO is generated from the 10 MHz oscillator. That's what makes it
> the best GPSDO out there.
> ----------------------
> I'm also thinking of porting over much of the Lady Heather t-bolt
> monitoring stuff to the Arduino.
> One thing you can do with a uP based controller is look at the t-bolt's
> saw tooth error correction and remove a few nS of error.
> _______________________________________________
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
AK
Attila Kinali
Tue, Jan 31, 2012 3:52 PM
The Tbolt does not have any sawtooth error or corrections.
Its' GPS receiver LO is generated from the 10 MHz oscillator.
That's what makes it the best GPSDO out there.
I just wonder, whether one could take a GPS module, like the LEA-6T
and replace the TCXO they have with a VCXO that is phase locked
to the 10MHz reference. Or would that cause too much of the hanging
bridge problem?
Attila Kinali
--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin
On Mon, 30 Jan 2012 17:47:54 +0000
Mark Sims <holrum@hotmail.com> wrote:
>
> The Tbolt does not have any sawtooth error or corrections.
> Its' GPS receiver LO is generated from the 10 MHz oscillator.
> That's what makes it the best GPSDO out there.
I just wonder, whether one could take a GPS module, like the LEA-6T
and replace the TCXO they have with a VCXO that is phase locked
to the 10MHz reference. Or would that cause too much of the hanging
bridge problem?
Attila Kinali
--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin
CA
Chris Albertson
Tue, Jan 31, 2012 5:32 PM
.... one could take a GPS module, like the LEA-6T
and replace the TCXO they have with a VCXO that is phase locked
to the 10MHz reference....
I'm trying to figure out your goal. The above assumes one already
has a 10MHz reference.
Chris Albertson
Redondo Beach, California
On Tue, Jan 31, 2012 at 7:52 AM, Attila Kinali <attila@kinali.ch> wrote:
>.... one could take a GPS module, like the LEA-6T
> and replace the TCXO they have with a VCXO that is phase locked
> to the 10MHz reference....
I'm trying to figure out your goal. The above assumes one already
has a 10MHz reference.
Chris Albertson
Redondo Beach, California
AK
Attila Kinali
Tue, Jan 31, 2012 5:40 PM
.... one could take a GPS module, like the LEA-6T
and replace the TCXO they have with a VCXO that is phase locked
to the 10MHz reference....
I'm trying to figure out your goal. The above assumes one already
has a 10MHz reference.
Let's say, i'm building a GPSDO with a high quality OCXO.
Wouldnt it then make sense to lock the reference clock of the GPS
receiver also to that OCXO?
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
On Tue, 31 Jan 2012 09:32:22 -0800
Chris Albertson <albertson.chris@gmail.com> wrote:
> On Tue, Jan 31, 2012 at 7:52 AM, Attila Kinali <attila@kinali.ch> wrote:
>
> >.... one could take a GPS module, like the LEA-6T
> > and replace the TCXO they have with a VCXO that is phase locked
> > to the 10MHz reference....
>
> I'm trying to figure out your goal. The above assumes one already
> has a 10MHz reference.
Let's say, i'm building a GPSDO with a high quality OCXO.
Wouldnt it then make sense to lock the reference clock of the GPS
receiver also to that OCXO?
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
B
bg@lysator.liu.se
Tue, Jan 31, 2012 5:50 PM
.... one could take a GPS module, like the LEA-6T
and replace the TCXO they have with a VCXO that is phase locked
to the 10MHz reference....
I'm trying to figure out your goal. The above assumes one already
has a 10MHz reference.
Let's say, i'm building a GPSDO with a high quality OCXO.
Wouldnt it then make sense to lock the reference clock of the GPS
receiver also to that OCXO?
Attila Kinali
Exactly that is the appeal of the Tbolts. What frequency does the uBlox
6T TCXO have? Let us know your progress.
--
Björn
> On Tue, 31 Jan 2012 09:32:22 -0800
> Chris Albertson <albertson.chris@gmail.com> wrote:
>
>> On Tue, Jan 31, 2012 at 7:52 AM, Attila Kinali <attila@kinali.ch> wrote:
>>
>> >.... one could take a GPS module, like the LEA-6T
>> > and replace the TCXO they have with a VCXO that is phase locked
>> > to the 10MHz reference....
>>
>> I'm trying to figure out your goal. The above assumes one already
>> has a 10MHz reference.
>
> Let's say, i'm building a GPSDO with a high quality OCXO.
> Wouldnt it then make sense to lock the reference clock of the GPS
> receiver also to that OCXO?
>
> Attila Kinali
Exactly that _is_ the appeal of the Tbolts. What frequency does the uBlox
6T TCXO have? Let us know your progress.
--
Björn
AK
Attila Kinali
Tue, Jan 31, 2012 7:43 PM
Let's say, i'm building a GPSDO with a high quality OCXO.
Wouldnt it then make sense to lock the reference clock of the GPS
receiver also to that OCXO?
Attila Kinali
Exactly that is the appeal of the Tbolts.
Yes, but can this be replicated with a standard GPS module?
And does it have side effects?
What frequency does the uBlox
6T TCXO have?
48MHz as stated in the Timing AppNote.
Let us know your progress.
My current progress is that the uC i wanted to use does not
do what i want. Can anyone recommend a uC with 32bit timers
and IEEE 1588 support?
The alternative would be to use an FPGA, but i'm reluctant to
do that as it makes the whole system a lot more complex.
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
On Tue, 31 Jan 2012 18:50:08 +0100
bg@lysator.liu.se wrote:
> > Let's say, i'm building a GPSDO with a high quality OCXO.
> > Wouldnt it then make sense to lock the reference clock of the GPS
> > receiver also to that OCXO?
> >
> > Attila Kinali
>
> Exactly that _is_ the appeal of the Tbolts.
Yes, but can this be replicated with a standard GPS module?
And does it have side effects?
> What frequency does the uBlox
> 6T TCXO have?
48MHz as stated in the Timing AppNote.
> Let us know your progress.
My current progress is that the uC i wanted to use does not
do what i want. Can anyone recommend a uC with 32bit timers
and IEEE 1588 support?
The alternative would be to use an FPGA, but i'm reluctant to
do that as it makes the whole system a lot more complex.
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
JH
Javier Herrero
Tue, Jan 31, 2012 8:06 PM
El 31/01/2012 20:43, Attila Kinali escribió:
My current progress is that the uC i wanted to use does not do what i
want. Can anyone recommend a uC with 32bit timers and IEEE 1588 support?
El 31/01/2012 20:43, Attila Kinali escribió:
> My current progress is that the uC i wanted to use does not do what i
> want. Can anyone recommend a uC with 32bit timers and IEEE 1588 support?
You can have a look on these
http://www.ti.com/mcu/docs/mculuminaryfamilynode.tsp?sectionId=95&tabId=2597&familyId=1756
Some of them have IEEE-1588, like the LM3S9B96
Regards,
Javier
C
cfo
Tue, Jan 31, 2012 8:23 PM
On Tue, 31 Jan 2012 20:43:35 +0100, Attila Kinali wrote:
My current progress is that the uC i wanted to use does not do what i
want. Can anyone recommend a uC with 32bit timers and IEEE 1588 support?
On Tue, 31 Jan 2012 20:43:35 +0100, Attila Kinali wrote:
> My current progress is that the uC i wanted to use does not do what i
> want. Can anyone recommend a uC with 32bit timers and IEEE 1588 support?
>
Some of the ST's supports IEEE-1588
http://www.embeddedstar.com/weblog/2011/09/21/stm32-f4-mcu/
www.mouser.com/pdfdocs/BRSTM32F4_v7final.pdf
I'd suggest a $20 STM32-F4-Discovery (Digikey etc)
http://parts.digikey.com/1/parts/2484058-eval-kit-stm32f-discovery-
stm32f4discovery.html
And a Phy (The mac is in the F4) $10
http://www.ebay.de/itm/DP83848-Ethernet-Physical-Transceiver-RJ45-
connector-control-interface-Board-Kit-/260868624339
Some www-sw is here (German use google translate)
http://www.mikrocontroller.net/topic/237223#2491080
The F4 even supports "Single precision" Floats in HW ,
and has both ADC & DAC (with the ADC/DAC vref pin on external pin).
1G flash , 192k Ram , and it runs 168Mhz.
I think there is 2 x 32bit timers (Fclock/2) , and a fair amount of 16bit
timers.
It comes with build in debugger (proprietarary) , but the debug protocol
has been reversed ... (see texane project) , and afaik it is now suported
in openocd. So arm-gcc & arm-gdb can be used (ie codesourcery).
ST suggests Atollic as "gcc" toolchain , but that's imho "handicapped" in
the free version.
I have earlier suggested the F4-Discovery , as a "Tnut" GPSDO/OCXO/RBXO
controller board.
CFO
