> Is there any way for a USB device to synchronise with the CPU clock (perhaps
> via the USB framing) so that a special-purpose device could timestamp the PPS
> occurrence with respect to CPU time ?
If you were designing a special purpose device, just add a counter to measure
the time from
There's a lot of lore out there that, for instance, HP would put
oscillators with good long term stability in counters, but for things
like a spectrum analyzer or signal generator, you'd use an oscillator
with good close in phase noise, because absolute frequency accuracy
isn't as
Is there any way for a USB device to synchronise with the CPU
clock (perhaps via the USB framing) so that a special-purpose device could
timestamp the PPS occurrence with respect to CPU time ?
On Mon, Jul 13, 2020 at 9:51 PM Trent Piepho wrote:
> On Mon, Jul 13, 2020 at 8:54 AM Petr Titěra
It is taken
In a message dated 7/13/2020 4:56:05 PM Eastern Standard Time,
time-nuts@lists.febo.com writes:
I was given a working with new capacitors EEG TS RFS. Have no use for it but if
some one wants it for the cost of shipping be glad to send it . Off list please.
I opened it up, impressed
I have an 8640B in the lab. Bizarre instrument.
David
On 7/13/20 2:57 PM, Richard (Rick) Karlquist wrote:
On 7/13/2020 11:34 AM, jimlux wrote:
There are also "frequency locked" devices that are not "phase locked"
- they essentially discipline an internal oscillator by adjusting its
I was given a working with new capacitors EEG TS RFS. Have no use for it but if
some one wants it for the cost of shipping be glad to send it . Off list please.
I opened it up, impressed with the optical unit, has any one analysed it,
with EEG space history is it more than what we find in
On Mon, Jul 13, 2020 at 8:54 AM Petr Titěra wrote:
>
> All Prolific chips I saw claimed to be USB 2.0 Full-speed. That means
> they are polled only once in 1ms and there is no way how to change it
> (poll rate is selected at hardware level).
Looking at the UHCI specification, for USB 1.1 HCIs,
Petr,
Is the variance plot based on PPS timestamps, or on NTP's smoothing of the
timestamps?
Have you measured the offset?
On Mon, Jul 13, 2020 at 10:54 AM Petr Titěra wrote:
> On 12.07.2020 3:57, jimlux wrote:
> > On 7/11/20 1:30 PM, Steven Sommars wrote:
> >> Using GPIO with an RPi is a
On 7/13/20 11:27 AM, paul swed wrote:
Taka
I firmly believe the first answer to your question is cost.
Was the counter an economical unit or higher quality.
My 5335 counters have seriously cheap xtal clocks and an external reference
makes a big difference.
But the larger costly generators and
On 7/13/2020 11:34 AM, jimlux wrote:
There are also "frequency locked" devices that are not "phase locked" -
they essentially discipline an internal oscillator by adjusting its
frequency, but not with any sort of phase locked loop.
The 8640 famously worked (sort of) this way. The
Good question; answer is not so simple. Here goes:
Signal generators and spectrum analyzers have to have a low phase
noise oscillator inside to be able to generate/detect spectrally
pure signals. Unlike counters, the 10811, etc has to be standard
equipment, not an option.
Therefore, in order
On 7/13/20 9:58 AM, Taka Kamiya via time-nuts wrote:
I'm sorry to interject a newbie question I changed the title to
distinguish from rest of the conversation.
I have heard this both ways about external references - whether it's used to
phase lock internal source and used directly after
Taka
I firmly believe the first answer to your question is cost.
Was the counter an economical unit or higher quality.
My 5335 counters have seriously cheap xtal clocks and an external reference
makes a big difference.
But the larger costly generators and counters seem to use the phase lock
I'm sorry to interject a newbie question I changed the title to
distinguish from rest of the conversation.
I have heard this both ways about external references - whether it's used to
phase lock internal source and used directly after some conditioning. Both
come from people on this list
On 7/13/2020 9:46 AM, Wes wrote:
Thanks again for your insight Rick. I'll be passing on acquiring one of
these.
Wes N7WS
I'm so glad you asked before buying.
I hate having to tell something they wasted their money.
Rick
___
time-nuts mailing
Thanks again for your insight Rick. I'll be passing on acquiring one of these.
Wes N7WS
On 7/13/2020 9:02 AM, Richard (Rick) Karlquist wrote:
On 7/13/2020 6:26 AM, Wes wrote:
Hi Magnus,
I did have the manual when I posed the original question but I had not delved
into the cal procedure
On 7/13/20 9:02 AM, Richard (Rick) Karlquist wrote:
On 7/13/2020 6:26 AM, Wes wrote:
Hi Magnus,
I did have the manual when I posed the original question but I had not
delved into the cal procedure until you mentioned it. It seems to be
a bit complicated for what it does. I wonder how
On 7/13/2020 6:26 AM, Wes wrote:
Hi Magnus,
I did have the manual when I posed the original question but I had not
delved into the cal procedure until you mentioned it. It seems to be a
bit complicated for what it does. I wonder how stable this is and how
often might it need to be
On 12.07.2020 3:57, jimlux wrote:
On 7/11/20 1:30 PM, Steven Sommars wrote:
Using GPIO with an RPi is a good direction, of course. That wasn't my
question. Some data may help explain.
Configuration =
RPi4 (raspbian buster)
Uputronics RPi GPS board (includes PPS) connected to GPIO
On Sun, Jul 12, 2020 at 11:51 AM jimlux wrote:
>
> Is the PPS via USB CTS stamped at interrupt time? or is it stamped
> higher up in the stack?
>
> I started tracing this out, but then decided I'm not going to be writing
> Linux USB drivers any time soon, so gave it up.
>
> I could easily
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