Thanks Arie, Yes, very true, it depends on your application!
My statement about what makes a good clock is very subjective. This all depends on your application, your measurement and of course your jitter. - For Wireless AV, a 10ms gps clock is fine. - For Wireless Earbuds, a 10us clock is required with 1us phase max drift. - For Photon measurements, you're in the nano/pico domain... Accuracy costs money, how well do you need to measure? So the message is to know your application! Your application will have varying time requirements. The infrastructure and machinery for relaying and exchanging time is all PTP provides as a tool. The 802.1AS spec specifies how to manage that clock across multiple time domains. Related, know your latencies! https://gist.github.com/jboner/2841832 Best regards -James On Thu, Dec 8, 2022 at 3:37 AM Arie de Muijnck <nu...@ademu.com> wrote: > Beware of that 1PPS signal. A few years ago I bought several GPS modules > and compared the signals. Some differ by exactly 100ns (within 2ns, the > accuracy of my scope) from others, and that is not the width of the pulse, > that is much wider, I compared only the edge that are comes close to the > others. Maybe I will test again, have a 1 GHz LeCroy now, should be able to > do jitter measurements too. > Oh, and yes, before someone asks: all antenna and scope cables were the > same length... ;-) > > Arie > > > On 2022-12-08 06:33, James Dougherty wrote: > > Related to this, I have a GPS receiver generating PPS interrupts on > SAME70. It would be a perfect GMC - Atomic clock sync! > > I will look at this when I get a chance. I have a lot of upstream > contributions from HW platforms I have done over the last 5 years or so > with myself and others ... I need some time to > > patch master on upstream -- something for 2023 and now that NuttX has > graduated! Yay! > > >
