On the practical side, the 5345 is HEAVY due to its older technology—doing what it does with first-generation ICs required HP jam an enormous amount of circuitry into a fairly small physical package.
Jeremy N6WFO On Tue, Apr 3, 2018 at 2:39 PM Bob kb8tq <kb...@n1k.org> wrote: > Hi > > I would add the HP 5335 to the list of counters to look for. The surplus > market can be really > weird. A 5334 *should* be less than a 5335, but on any given day, that may > not be true. The > 5370 and 5345 are also worth looking for. Target price (at least for me) > wold be < $150 for a > quick buy and < $70 if I was willing to shop for a while. > > Getting data *out* of the older counters will involve GPIB. If you are not > already set up to do > that, there will be the cost of a cable and a simple adapter. > > If you want to move up a generation, the 53131 and 53132 are higher > resolution devices than > the 5334 and 5335. They give you the benefit of a serial port. No GPIB > stuff to bother with. > Finding one at price lower than the TAPR counter …. probably not. > > Bob > > > On Apr 3, 2018, at 3:04 PM, Tom Van Baak <t...@leapsecond.com> wrote: > > > > Hi Gary, > > > > One solution is to look for used hp, Fluke, or Racal time interval > counters on eBay. 1 or 2 ns is pretty easy to find with a $100 or $200 > budget. Look for Racal 1992 or hp 5334B as examples. If you plan to collect > lots of data, you'll want GPIB (or RS232 / USB) connections to a PC and > that will add to your net cost. > > > > Another solution is to homebrew your own 1 ns counter. The downside is > you will spend a month working out the bugs before you trust the data. Plus > if you don't already have another counter to compare it against it makes > development even harder. > > > > Third solution is the TICC from TAPR. It's new and works out of the box. > Lots of us use them. John did a very good job with the design. Highly > recommended. It's a dual-channel *time stamping* counter so you can collect > 1PPS data on two separate GPS receivers at the same time if you want. In > that respect it's 2x as useful as a commercial *time interval* counter. > > > > You mention jitter, not ADEV. I don't think you need a fancy timebase if > all you want to measure is jitter. You can get a good feel for the jitter > of a GPS / 1PPS output within a few samples. Even a minute of data is > usually enough to establish the rms jitter value. If you want a full ADEV > plot, then yes, you'd probably want at least an Rb for your reference. > > > > See paragraph "Timing Stability" at http://leapsecond.com/pages/MG1613S/ > for an example of what jitter from a GPS receiver looks like; in this case > it's primarily sawtooth. > > > > Right, the picPET has 400 ns resolution and so it is not the right tool > for your nanosecond needs. I do have a 10 ns version that I use, but that's > still a bit coarse for GPS work. > > > > I have spare FEI Rb here; I'll send it if you want it. That way you can > afford a TICC. > > > > /tvb > > > > > > ----- Original Message ----- > > From: "Gary E. Miller" <g...@rellim.com> > > To: "time-nuts" <time-nuts@febo.com> > > Sent: Tuesday, April 03, 2018 10:47 AM > > Subject: [time-nuts] Cheap jitter measurements > > > > > > Time-nuts! > > > > With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec > > resolution. That is the smallest increment of the RasPi 3B clock with > > a 64-bit kernel. That is clearly not time-nuts accuracy. > > > > What would you guys suggest as the cheapest way to see jitter down to > > around 1 nano second? > > > > I'm thinking maybe something like a rubidium standard (FE-5680A) and > > a TICC-TAPR? But that would put me out around $400. > > > > The picPET does not look accurate enough. Maybe a clever way to use it > > for more accuracy? Is there a picPET like thing cheaper than the > > TICC-TAPR? > > > > Ideas? > > > > RGDS > > GARY > > > --------------------------------------------------------------------------- > > Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 > > g...@rellim.com Tel:+1 541 382 8588 > > > > Veritas liberabit vos. -- Quid est veritas? > > "If you can’t measure it, you can’t improve it." - Lord Kelvin > > _______________________________________________ > > 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. > > > > _______________________________________________ > > 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. > > _______________________________________________ > 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. > -- Sent from my iPad 4. _______________________________________________ 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.