my open-hardware design for frequency and pulse distribution is on ohwr: https://ohwr.org/project/pda-8ch-fda-8ch/wikis/home The PPS distribution uses IDT (now named something else?) 5PB1108 logic buffers with 7-800 ps rise-time. AFAIK the only way to match outputs is to use trimmer-caps before the last output-stage and tune each output while measuring with a time interval counter. Depending on your counter and patience you get within 10-20 ps quite quickly.
+1 to endrun for publishing a phase-noise spec on their website - most others don't do that. A possible improvement for the ohwr frequency-distribution board would be to use many LMH6702 (or similar) in parallel for each channel - but I haven't had time (or a project that needs the performance) to test. the results posted for the ARTIQ clocker board look good https://github.com/sinara-hw/Clocker/wiki and https://github.com/sinara-hw/Clocker/issues/4 (I haven't verified them) Anders On Fri, Jun 2, 2023 at 1:37 AM Marcus D. Leech <patchvonbr...@gmail.com> wrote: > On 01/06/2023 15:56, John Ackermann N8UR wrote: > > Hi -- > > > > There's some fairly old data about the Octoclock here: > > > http://www.anderswallin.net/2016/09/ettus-octoclock-distribution-amplifier/ > > > 200ps of timing dispersion among different gates isn't that weird, when > the switching time can take up to > 15nsec on the non-'F' variants of the 7404. I don't know which of > many variants of the 7404 were used on > the Octoclock. But if they're garden variety HC or LS or something, > the switching time dispersion on the > 1PPS may be fairly high. > > > > > > > > In the shameless plug department, the TADD-1 distribution amplifier > > from TAPR: > > https://tapr.org/product/tadd-1-rf-distribution-amplifier/ > > > > has very good additive noise, and is inexpensive. It has six channels > > but two or more boards can be stacked and driven from a common input. > > The downside is that it's a kit (through-hole parts). > > > > I compared the additive phase noise of several distribution amps here: > > https://www.febo.com/pages/amplifier_phase_noise/ > > > > (that data is also fairly old; currently-shipped TADD-1s use a newer > > amplifier chip that seems to have a couple of dB better performance). > > > > Best, > > John > > ---- > > > > On 6/1/23 15:16, Eugene Grayver wrote: > >> Hello, > >> > >> I am building a high-end testbed and trying to decide on a 10 MHz > >> distribution option. I've used octoclock for other systems and it > >> 'works.' However the datasheet is pretty sparse. Does anyone have > >> detailed specs (that you measured or from Ettus). I am interested in > >> the non-GPSDO version since my 10 MHz comes from outside the system > >> > >> * port-to-port delay variation > >> * phase noise increase if any (assuming external source) > >> > >> My other option is > >> > https://endruntechnologies.com/products/distribution/10-MHz-low-phase-noise > >> < > https://endruntechnologies.com/products/distribution/10-MHz-low-phase-noise>, > > >> which is about 5x more expensive. > >> > >> Thanks. > >> > >> ________________________ > >> > >> Eugene Grayver, Ph.D. > >> Aerospace Corp., Principal Engineer > >> Tel: 310.336.1274 > >> ________________________ > >> > >> > >> _______________________________________________ > >> USRP-users mailing list -- usrp-users@lists.ettus.com > >> To unsubscribe send an email to usrp-users-le...@lists.ettus.com > > _______________________________________________ > > USRP-users mailing list -- usrp-users@lists.ettus.com > > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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