Are low/lower cost USB Oscilloscope's any good?
in [Design]
|
Prev: 74C925 alternative?
Next: 12 and 16-bit oscilloscopes
From: Nico Coesel on 14 Dec 2006 15:43 Joerg <notthisjoergsch(a)removethispacbell.net> wrote: >Hal Murray wrote: > >>>I've been impressed with these guys: http://www.cleverscope.com/ -- they seem >>>to have a solid understanding of what terms like "noise" and "jitter" mean, >>>unlike many of the cheap scopes out there. >> >> >> A friend has one. He's very happy with it. >> >> One of the advantages of a PC based scope is that it doesn't take >> up much room on your desktop. >> > >But why are they so slow? At least the ones I have seen were. We >designed 400MSPS converter boards even back in the late 80's and early >90's. It ain't rocket science. The problem is what to do with the data. Sampling and storing data in some memory is the easy part. Gettting it from the memory onto a screen in a meaningfull way is not so easy. I'm working on one and everything is about ready except for the sampling itself. -- Reply to nico(a)nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl
From: Joerg on 14 Dec 2006 15:56 Nico Coesel wrote: > Joerg <notthisjoergsch(a)removethispacbell.net> wrote: > > >>Hal Murray wrote: >> >> >>>>I've been impressed with these guys: http://www.cleverscope.com/ -- they seem >>>>to have a solid understanding of what terms like "noise" and "jitter" mean, >>>>unlike many of the cheap scopes out there. >>> >>> >>>A friend has one. He's very happy with it. >>> >>>One of the advantages of a PC based scope is that it doesn't take >>>up much room on your desktop. >>> >> >>But why are they so slow? At least the ones I have seen were. We >>designed 400MSPS converter boards even back in the late 80's and early >>90's. It ain't rocket science. > > > The problem is what to do with the data. Sampling and storing data in > some memory is the easy part. Gettting it from the memory onto a > screen in a meaningfull way is not so easy. I'm working on one and > everything is about ready except for the sampling itself. > Back in those days that was even worse because fast static RAM was incredibly expensive. So, we often used lower cost RAM and staggered it. Data was written into it in a round-robin fashion, read out in a normal way one bank at a time and then pieced together by software. Or in our cases mostly by a scan converter hardware. And yes, these were realtime systems where there was very little pause between acquisitions. -- Regards, Joerg http://www.analogconsultants.com
From: Phil Allison on 14 Dec 2006 18:17 "Phil Allison" > "Joel Kolstad" > >> ** Maybe one of these is all you need. >> http://www.dse.com.au/cgi-bin/dse.storefront/45809b3e05c4671c2740c0a87f9c0727/Product/View/Q1803 >> >> The long number in that link is apparently a session ID that has expired, >> but searching for "Q1803" from dse.com.au gets you there. > > > ** Try this instead: > > http://www.dse.com.au/cgi-bin/dse.storefront/4581d4e80084b7a22744c0a87f9c077d/Product/View/Q1803 > > >> Here in the U.S., I've seen same 'scope on eBay, e.g., > > ** That is not the same scope and it is priced much higher. ( delete troublesome Ebay link ) >It is rather cute and might make a lot of sense to keep around a lab >forsome quick troubleshooting, but for someone's first and only scope I >reallythink the money would be better spent on a used Tek box. ** What you "really think" is not of much value to anyone. Old Teks are basically boat anchors. > I wonder how much storage tubes cost to manufacture? The Q1803 would > probably have a lot more takers if it could > freeze the trace so that it would work for troubleshooting, e.g., > non-repetitive serial communications. ** Not a requirement at all for most scope users. Digital geeks have an extraordinarily narrow idea what "troubleshooting" is. .......... Phil
From: Barry Lennox on 14 Dec 2006 19:21 On Wed, 13 Dec 2006 13:27:01 -0600, "news.valornet.com" <nospam38925(a)forme.com> wrote: >Hi, You might want to start off with a real scope, I still use Tek 453 and 454s I got a few years ago for $100 and $125. No doubt they are even less now. Both are still excellent performers and are used most days. However, as another poster pointed out the ones at http://www.cleverscope.com/ are very good if you want a "all-digital" USB scope. I have trialled one against a low end Tek scope and the Cleverscope was superior in nearly every respect. Cleverscope has a good comparison chart against the low end Agilent and Tek scopes on their website. As far as I can see, it has not been "selectively tweaked" to present a true, but misleading picture. Barry Lennox.
From: Joel Kolstad on 14 Dec 2006 20:27
"Phil Allison" <philallison(a)tpg.com.au> wrote in message news:4ue4ccF17clfmU1(a)mid.individual.net... > ** That is not the same scope and it is priced much higher. You're correct, I looked closely and there are some minor differences. The actual specs appear the same, though -- I'd wager they're made by the same OEM, and it's the same basic design. The price is double, but comparing the price of anything on eBay to the pricing in a brick and morter store (especially when you have to throw in a currency conversion!) is irrelevant. > ** What you "really think" is not of much value to anyone. You're entitled to your opinion. :-) > Old Teks are basically boat anchors. Depends on how old you get... I'm not thinking the really old 465s, more like the 2000-series. (I'd say 2465B, but that costs a *lot* more than what the OP is after.) >> I wonder how much storage tubes cost to manufacture? The Q1803 would >> probably have a lot more takers if it could >> freeze the trace so that it would work for troubleshooting, e.g., >> non-repetitive serial communications. > ** Not a requirement at all for most scope users. That's a very arbitrary statement. We could both come up with lists of applications where being able to freeze the display is anything from pretty worthless to an absolute necessity, but it's a reasonable statement that -- everything else being equal -- I can't imagine anyone would *not* want to have such an ability in their scope. > Digital geeks have an extraordinarily narrow idea what "troubleshooting" is. For many of them, sure... but consider that these days the "high-end" digital guys are doing things like troubleshooting 10Gbps data streams, and this requires plenty of extraordinarily high-end equipment. There's a good reason why Tek's "Which oscilloscope is right for you?" page -- http://www.tek.com/products/oscilloscopes/selection_chart.html -- lists "high-speed serial" first on their 15GHz real-time scopes. ---Joel |