Hi David, Dan,
Thanks for the explanation, my English failed me this time around (problems
of a non-native speaker ¯\_(ツ)_/¯ )
Regards,
Franco
On Mon, Mar 11, 2019 at 1:19 PM Dan Werthimer wrote:
>
> hi franco,
>
>
> i think we picked the word "arm" because it's similar to arming a gun,
>
hi franco,
i think we picked the word "arm" because it's similar to arming a gun,
getting it ready to fire, but not firing it.
"arm" is not the signal that directly resets the elapsed time counter.
the arm signal is a software command that says:
on the next 1 PPS, the elapsed time counter
Hi, Franco,
> On Mar 11, 2019, at 07:37, Franco wrote:
>
> why you call "ARM" the signal/register that resets the time-tracking counter?
One of the many definitions of the verb “to arm” is...
to equip or prepare for any specific purpose or effective use:
to arm a security system; to arm
Hi,
Yes! Very clear. Thank you very much James, Jack and Dan. Just the last
little question, why you call "ARM" the signal/register that resets the
time-tracking counter?
Thanks,
Franco
On Mon, Mar 11, 2019 at 4:27 AM James Smith wrote:
> Hello Franco,
>
> Jack's email explained more
Hello,
We use a different scheme for datation, not using any GPS. Our ROACH2 is bind
to a rubidium clock, then:
1/ Each 8K acquisition packet is taged with a 64 bits counter in the FPGA reset
only at firmware init. The acquisition is continuous, the dispatching of
relevant data is delegated to
Hello Franco,
Jack's email explained more explicitly what I tried to convey. Did it make
it clear?
Regards,
James
On Sat, Mar 9, 2019 at 12:44 AM Jack Hickish wrote:
> Hi Franco,
>
> The general principle is generally this --
>
> We assume that the system has
> 1. A CPU-based control
In my defence, <100ns is also <100us :)
On Fri, 8 Mar 2019, 2:54 pm Dan Werthimer, wrote:
>
> hi franko:
>
> i think jack meant "<100ns" in his email below. (not "<100us").
>
> here's another description of the technique used in casper instruments to
> get accurate time stamps:
> from peter
hi franko:
i think jack meant "<100ns" in his email below. (not "<100us").
here's another description of the technique used in casper instruments to
get accurate time stamps:
from peter mcmahon's thesis, section C.5:
https://arxiv.org/pdf/1109.0416.pdf
C.5 Precise Timing using ARM and 1PPS
Hi Franco,
The general principle is generally this --
We assume that the system has
1. A CPU-based control computer (a laptop / desktop / posh server /
whatever) which has a standard NTP client running. NTP allows this computer
to know the time good to some number of milliseconds.
2. FPGAs in
Hi John,
Thank you for the answer. I see, so reading the network packages directly
from FPGA using the GBE core, would be the way to go if using PTP or NTP.
Thanks,
Franco
On Thu, Mar 7, 2019 at 10:11 AM John Ford wrote:
> Hi Franco.
>
> We have normally time-stamped the data using a
Hi James,
Thank you for your answer. Yes, I use and ADC for data acquisition. I
understand the general idea of your system. What I don't understand is
where you get the start time of the ROACH2. Is generated by the TRF? Is
there a different system that initialize all the synchronized devices and
Hi Franco.
We have normally time-stamped the data using a hardware 1 Pulse per Second
digital input as a sync source, which gives us << 1 microsecond timing
precision. PTP requires hardware support in the LAN hardware, and I don't
recall for sure but I don't think it's in the PHY/MAC on the PPC,
Hi Franco
Simon Lewis in the RRSG at UCT has White Rabbit hardware and expertise (PhD
incubating). Snag is that it runs on 1GE Fibre. We also have a GPS version.
The former gives sub ns precision, the latter about 4 ns rms. Send me a
message off line and I can link you. We also have a scheme of
Hello Franco,
As I understand it, PTP wasn't terribly useful in our application (though I
wasn't involved with this directly). You can probably sync the little Linux
instance that runs on the ROACH2, but getting the time information onto
your FPGA may prove somewhat tricky.
Are you using an ADC
Dear Casperiites,
I was given the task of timestamping ROACH2 spectral data in a telescope
that uses PTP (precision time protocol) as a synchronization protocol. I
understand that ROACH's BORPH come preloaded with NTP (network time
protocol) libraries/daemos, but PTP is preferred because is
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