If the bandwidth is really limited to 2 MHz, that is a rise and fall time of 175ns. Some of those PPS signals are barely wider than that.
On Thu, 23 Feb 2012 22:26:47 +0100, Azelio Boriani <azelio.bori...@screen.it> wrote: >Yes, in my opinion the connectors are MCX and I totally agree with Attila >about the 20MHz limit. Nice toy to just take a look at low speed signals, >for example GPSDOs 10MHz and PPS, serial lines and so on. > >On Thu, Feb 23, 2012 at 9:49 PM, Attila Kinali <att...@kinali.ch> wrote: > >> On Thu, 23 Feb 2012 20:01:18 -0000 >> "Rob Kimberley" <robkimber...@btinternet.com> wrote: >> >> > I'm looking at Item: 300658066641 on EBay, and wanted to know if anyone >> in >> > the group had any experience of this product. I know this is way off >> topic, >> > but as a group it's nice to know what's out there and possibly useful in >> our >> > mutual hobby. >> >> It depends what you want to use it for. If you just want to have >> something protable that can show you roughly what's going on, >> then this might be a good thing. For anything else, especially >> measurements, >> i wouldnt trust it further than i can throw it. >> >> It's actually quite nice that they put the schematics online too, >> so their claims can be verified. >> >> First that jumps out is that they are using a AD9288-40 as ADC. >> Note the -40 there? It means it's an 40Msps ADC. Ie the maximum >> usable BW you can have is 20MHz (actually a bit lower). The analog >> circuitry doesn't seem too bright either, but i guess you should be >> able to get the 20MHz. I havent checked the exact circuitry so >> i cannot say whether the input circuit does filter at 20MHz. But >> as they claim to have 72MHz analog bandwidth, i would be very carefull >> about aliasing problems >> >> The input circuitry isn't very impressive either and has an undefined >> input capacitance (there is a trimmer there) somwhere between 5pF and 30pF >> (plus stray capacitances). I find it a it strange, that they disconnect one >> input of the frontend opamp... it might anything from going into saturation >> to start bouncing around... >> The analog switches are rather on the cheap side, nothing you'd expect >> in an DSO, but well.. for that price :-) >> >> Also notice that the connectors used look like SMB or MCX antenna >> connectors. Ie those would not be able to withstand many mating/break >> cycles. >> >> Overall, i'd say a good portable gauge, but not much more. >> >> For a more indepth analysis i'd have to take the schematics apart >> into a readable format... >> >> Attila Kinali >> >> -- >> Why does it take years to find the answers to >> the questions one should have asked long ago? >> >> _______________________________________________ >> 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.