[time-nuts] Chinese Scopes

Tue Apr 17 19:21:06 UTC 2012

True, the LeCroy I have has +/- trigger, which is sometimes invaluable and very hard to emulate if your scope does not have that feature.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: Tom Knox <actast at hotmail.com>
Date: Tue, 17 Apr 2012 08:33:35 
To: <shalimr9 at gmail.com>
Subject: RE: [time-nuts] Chinese Scopes

I also like the LeCroy I have because of the deep memory, but I also find the advanced trigger options are equally important in capturing many events. 

Thomas Knox

> To: jfor at quikus.com; time-nuts at febo.com
> From: shalimr9 at gmail.com
> Date: Tue, 17 Apr 2012 13:56:43 +0000
> Subject: Re: [time-nuts] Chinese Scopes
> 
> I agree that memory depth is an under appreciated parameter, but even 2,500 points like what's available on the cheap Tek scopes is quite useful. 
> 
> On the other hand, I had a few LeCroy with 50k deep memories and there are cases where that is very useful too. I can't imagine real life use cases when I would need multiple MB. It would be nice to have but seldom used.
> 
> One issue is that most DSOs don't have displays that let you take advantage of the higher memory depth other than by letting you zoom in on a narrow time window. I have found that on the TDS 200 and 2000 series, downloading the data to a PC will let you display and print higher resolution pictures and I wrote a utility to do that.
> 
> Didier KO4BB
> 
> Sent from my BlackBerry Wireless thingy while I do other things...
> 
> -----Original Message-----
> From: "J. Forster" <jfor at quikus.com>
> Sender: time-nuts-bounces at febo.com
> Date: Mon, 16 Apr 2012 13:58:09 
> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
> Reply-To: jfor at quikus.com, Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] Chinese Scopes
> 
> OK. IMO, there is another, perhas a more important, issue....  memory depth.
> 
> Most digital scopes I've seen, and some LAs too, just don't have enough
> depth for my taste, so they undersample and guess.
> 
> Tek did make the RTD-710A high speed transient data digitizer that had 64
> MB of 12 (?) bit RAM. That is beginning to be useful, IMO.
> 
> -John
> 
> ==================
> 
> 
> > Sorry john, that's more what I meant, by accuracy and precision I imply
> > its faithful to the signal you choose to examine, free of artifacts
> > induced by the scopes timebase or vertical amp, but with DSOs its limited
> > by Nyquist sampling rules.
> >
> > Thus, sampling rate is as important a feature as a scopes rated bandwidth.
> >  For best results, its should be 10x the analog bandwidth.  Below it, one
> > has to beware of artifacts, it worsens as the ratio signal bandwidth/
> > sampling rate < 10.
> >
> >
> > At 14:32 04/16/2012, time-nuts-request at febo.com wrote:
> > ------------------------------
> > Message: 2
> > Date: Mon, 16 Apr 2012 10:59:16 -0700 (PDT)
> > From: "J. Forster" <jfor at quikus.com>
> > To: "Discussion of precise time and frequency measurement"
> >         <time-nuts at febo.com>
> > Subject: Re: [time-nuts] Chinese Scopes (was: Re: LORAN-C at MIT)
> > Message-ID: <56387.12.6.201.2.1334599156.squirrel at popaccts.quikus.com>
> > Content-Type: text/plain;charset=iso-8859-1
> >
> >> At eevblog.com forum Chinese scopes are a daily discussion for over 3
> >> years.
> >>
> >> In summary, in the <= 100 MHz level they are ...
> > ...snip...
> >>... less.  The criteria for rating them are
> >> measurement accuracy and precision, UI, construction quality and tech
> >> support.
> >
> > Measurement accuracy is a ruse, IMO. I don't care if a 'scope is
> > "accurate". I want the waveform to be a faithful representation of the
> > electrical behaviour of the circuit, free oif sampling artifacts and
> > aliasing.
> >
> > If I want to accurately measure a voltage, I'll use a differential
> > comparator or DVM. Anything timing, an appropriately gated counter.
> >
> > Some years ago Tektronix had a digital camera package with RS-170 output
> > and some aardvaark frame grab board for a PC and a SW package. It was
> > designed to do waveform measurement.
> >
> > I would actually like to know why many seem to feel that a 500 MHz analog
> > 'scope is not "good enough" for what you really do in your lab?
> >
> > The more I hear about 40 GSps or whatever 'scopes, the more I'm convinced
> > it's like comparing car engines or top speed. So, I have a car that'll do
> > 160 MPH and yours will do 172? So what? Can you use it? No.
> >
> > YMMV,
> >
> > -John
> >
> >
> > Best Wishes,
> >
> >
> > Marv Gozum, Philadelphia Pa
> >
> > [ sent via Outlook webApp]
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at 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 at 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 at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.