[time-nuts] Linux PPS clues?

Hi all, I need some clues on the Linux PPS subsystem. I am trying to take some timestamps of events on a GPIO using an ARM SBC, and noticed that the kernel linux can be interfaced to a PPS signal, wanted to sync another GPIO to a GPS receiver for time reference. I need to know how much precise

Re: [time-nuts] Linux PPS clues?

Yo Ilia! On Thu, 20 Oct 2016 06:15:39 + Ilia Platone wrote: > I am trying to take some timestamps of events on a GPIO using an ARM > SBC, and noticed that the kernel linux can be interfaced to a PPS > signal, wanted to sync another GPIO to a GPS receiver for time >

Re: [time-nuts] Linux PPS clues?

On Thu, 20 Oct 2016 06:15:39 + Ilia Platone wrote: > I need some clues on the Linux PPS subsystem. > I am trying to take some timestamps of events on a GPIO using an ARM > SBC, and noticed that the kernel linux can be interfaced to a PPS > signal, wanted to sync

Re: [time-nuts] Linux PPS clues?

From: Attila Kinali [] Yes, but in embedded there are huge differences between the various boards and processors. While an rpi is a great device if you want to do graphics based stuff, it's a very poor choice for control and measurment applications, or anything that needs fast I/O [] Attila

Re: [time-nuts] Linux PPS clues?

the only essential task is sampling and logging into an usb drive. the timestamps must be as accurate as possible with the GPS reference clock. This for an undefined number of devices. Since this 100KHz is a starting point, I must know how fast can be the event rate. Linux Clock tick on some

Re: [time-nuts] 1PPS to 32.768 khz

Hi One problem with a PLL and a 1 Hz input are the values of components you get in the loop. The other issue is the cost of the VCXO that will get you to 32,768 KHz. The PLL as described by the OP would need the 1 pps divided by 2 with a lot of PLL chips. You now are locking 32768 to 0.5 Hz.

[time-nuts] KSC big clock

The KSC clock might just use fluroscent tubes in a 7 segment display configuration.Pretty easy to do, just put a set of relay contacts inplace of the starter in the circuit, close the contact, fluro turns off, current flows through heater / filiment keeping them warm.Open the contact, fluro

Re: [time-nuts] Linux PPS clues?

Thank you Attila :) Actually the system for timestamping is at design stage yet. I expect an event rate of about 100kcps, but I found little infos about the bandwidth variable for the receivers. Since I don't want to fill in the list with off-topic posts, just limit in time-related quests.

Re: [time-nuts] Linux PPS clues?

On Thu, 20 Oct 2016 08:15:03 + Ilia Platone wrote: > Actually the system for timestamping is at design stage yet. > I expect an event rate of about 100kcps, but I found little infos about > the bandwidth variable for the receivers. 100kHz event rate is quite a bit.

Re: [time-nuts] Linux PPS clues?

Thank you. I quickly read the gpsd howto and it explains what I want to do using kpps on a raspberry. From there I can see a typical accuracy of 1uS, but the informations of the live graphs page are precise down to the ns: are these averaged? What do you intend for granularity? Consider

Re: [time-nuts] Linux PPS clues?

On Thu, 20 Oct 2016 07:52:10 + Ilia Platone wrote: > I quickly read the gpsd howto and it explains what I want to do using > kpps on a raspberry. From there I can see a typical accuracy of 1uS, but > the informations of the live graphs page are precise down to the ns:

Re: [time-nuts] PC clock generator without 14.318MHz

Chris, I agree with you that additional HW to avoid interrupt latency is necessary. My NTP servers with stable oscillator and HW card processing PPS (still in use but some mainboards failed after 10 years of reliable service) are described here:

Re: [time-nuts] Need Time Help

Mark, Do you have a likely date for the availability of the new release (other than RSN)? Cheers Dave -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: 04 October 2016 18:40 To: time-nuts@febo.com Subject: [time-nuts] Need Time Help

Re: [time-nuts] Need Time Help

From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Lady Heather has support for setting the system clock from the GPS receiver. The next release has support for analyzing and compensating for the GPS / system / com port message delay. It does not use the 1PPS signal.

Re: [time-nuts] KSC big clock

This may be obvious, but anyone making such a device today would be well advised to use LED strips instead. We just upgraded the lighting in my wife’s office/craft room with an LED panel light. It’s around 4’x1’x1” and puts out 4000 lumens - quite bright and enough to fill the entire room with

Re: [time-nuts] Linux PPS clues?

On Thu, 20 Oct 2016 20:12:12 +0200 Attila Kinali wrote: > So they would need a kind of (hardware) system > to queue up the events to process them in badges. Because of this, an rpi > wouldn't work at all (bitbanging takes several µs for each operation). On Thu, 20 Oct 2016

Re: [time-nuts] leontp offset

Some followup on this. Short version: I do -not- think the problem is with the leontp unit. (actually I never did. I figured there was something I was doing wrong). Not quite so short version: I think that both our very expensive Arbiter Time-Frequency-Deviation-etc GPS clocks are off. By,

Re: [time-nuts] Linux PPS clues?

On Thursday, October 20, 2016 08:12:12 PM Attila Kinali wrote: > On Thu, 20 Oct 2016 10:59:21 +0100 > > "David J Taylor" wrote: > > Actually, of the 15 Raspberry Pi cards I have only one is used in a > > graphics application. > > Yes, the rpi are used for all kind

Re: [time-nuts] Linux PPS clues?

Yo Ilia! On Thu, 20 Oct 2016 07:52:10 + Ilia Platone wrote: > I quickly read the gpsd howto and it explains what I want to do using > kpps on a raspberry. From there I can see a typical accuracy of 1uS, > but the informations of the live graphs page are precise down

Re: [time-nuts] Linux PPS clues?

On Thu, 20 Oct 2016 10:48:28 + Ilia Platone wrote: > the only essential task is sampling and logging into an usb drive. the > timestamps must be as accurate as possible with the GPS reference clock. > This for an undefined number of devices. What kind of events are

Re: [time-nuts] leontp offset

> full disclosure: there were a couple of outlier external clocks I threw out, > one with a 38 ms offset and the other with a 112 ms offset). That's not uncommon. It happens more often when the server is farther away and there are more opportunities for strange network routing. The NIST

Re: [time-nuts] Linux PPS clues?

On 10/20/16 18:12, Attila Kinali wrote: On Thu, 20 Oct 2016 10:59:21 +0100 "David J Taylor" wrote: Actually, of the 15 Raspberry Pi cards I have only one is used in a graphics application. Yes, the rpi are used for all kind of stuff and there is a huge

Re: [time-nuts] Linux PPS clues?

10us deadtime is somewhat excessive for average detection rates much greater than 1kcps (kilo counts/sec).Higher rates will tend to have the correlations between detectors suppressed. This will be particulalrly acute for Intensity correlations.Active detector (Geiger mode APD) quenching is

Re: [time-nuts] Linux PPS clues?

i...@iliaplatone.com said: > These events are random photon arrivals (converted to 5vTTL pulses), their > rate was measured using the pulse width of the smaller detected, which was > 5~10 uS during an observation in low-light environment. The photon arrival > and pulse width were random with a

[time-nuts] Linux PPS clues?

Yes, and it can be quite easy to do. A friend whipped one out in day. Has 16 inputs (used to be 8 inputs) and time stamps any selected edge transition and queues up the time stamp counter/channel values which get written into a bigger RAM buffer queue which gets periodically dumped out via

Re: [time-nuts] Linux PPS clues?

On 10/20/16 22:08, Hal Murray wrote: i...@iliaplatone.com said: These events are random photon arrivals (converted to 5vTTL pulses), their rate was measured using the pulse width of the smaller detected, which was 5~10 uS during an observation in low-light environment. The photon arrival

Re: [time-nuts] Linux PPS clues?

On Fri, Oct 21, 2016 at 2:12 AM, Attila Kinali wrote: > > Going for an uC is easier in that regard as they have very little interrupt > latency (usually just 5-10 cycles), but then you have problems with > getting the output out of the uC as their I/O subsystems are usually >

[time-nuts] Manual wanted for

___ 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.

Re: [time-nuts] Linux PPS clues?

I'm not sure if you were asking for scope adive or not, but to look for the minimum seperation (also runt pulses) you would want to set your trigger threshold as low as possible without false triggering on noise, and set trigger hold off to a minimum. National Instruments has lots of litteriture

Re: [time-nuts] KSC big clock

On 10/20/16 9:28 AM, Nick Sayer via time-nuts wrote: This may be obvious, but anyone making such a device today would be well advised to use LED strips instead. We just upgraded the lighting in my wife’s office/craft room with an LED panel light. It’s around 4’x1’x1” and puts out 4000 lumens

Re: [time-nuts] 1PPS to 32.768 khz

On Wed, Oct 19, 2016 at 8:32 PM, Lee - N2LEE via time-nuts < time-nuts@febo.com> wrote: > > A lot of my other clocks are 6 digit NTP POE clocks so they are not GPS > accurate but I would at like them to all agree. > Can you point all of those POE NTP clocks to a common LOCAL NTP server? Time

Re: [time-nuts] Linux PPS clues?

i...@iliaplatone.com said: > sorry, no attachment, this mail contains two images, one is the previous > attempt, the second (IMG_003.JPG) was taken at 5us/div, 1v/div with a > different oscilloscope setup. The first one looks like you are triggering on noise or runt pulses. What does it look

Re: [time-nuts] Linux PPS clues?

Hi Gabs, everyone, On 2016-10-21 1:53:55, Gabs Ricalde wrote: The events can be timestamped by polling the PPS and event pins and using the cycle counter. A better approach would be to use the 100 MHz eCAP timers. The Beaglebone has two accessible eCAP pins, the PPS goes to one and the event

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Nick had mention that the -12V rail on the thunderbolt has the poorest PSRR with respect to frequency output, so I first took a look at the venerable 7912. The first data-set was taken with a -13.5 VDC input. Attached is the 0.1 Hz to 10 Hz noise of an essentially quiescently loaded 7912, only a

Re: [time-nuts] Linux PPS clues?

On Thu, 20 Oct 2016 10:59:21 +0100 "David J Taylor" wrote: > Actually, of the 15 Raspberry Pi cards I have only one is used in a graphics > application. Yes, the rpi are used for all kind of stuff and there is a huge community around them that helps with all kind

[time-nuts] MM5314 remote setting

This long thread reminded me of a technology that my employer used from the 1970's till just a few years ago. Our system had hundreds of HH:MM LED clocks for the public and we opened in the 70's so of course they were digital clocks. I had always imagined that there was some fancy electronics