PC based oscilloscope

No direct experience here. However, in general terms, I often despair at how much faith people seem to have in the myth that the PC is the Ultimate Troubleshooting Tool for any electronics workbench.

You would do far better, IMO, to take the funds that you're thinking of blowing on PC-based device and put them towards a real O- scope, preferably one bearing the Tektronix name.

You can still do an awful lot with even the older Tek 7000 series instruments, and we're getting to the point where a lot of the early digital and digitizing instruments are becoming available on the surplus market.

Without knowing your specific requirements, I can't really make any in-depth suggestions. However, again, I would avoid PC-based 'scopes on general principles. I would be stunned if any of them can perform as well as a good dedicated 'scope for a comparable price/value figure.

Happy hunting.

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR, 
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"

I'd hate to be without mine, which I've used for many years. It's a Pico ADC-200/50, with PicoScope and PicoLog software.

In fairness, I can't make a direct comparison with a high end digital storage 'scope, as I've never been able to afford one. But I now use my conventional dual-channel Hameg only when I suspect some software problem (PicoScope or Windows) is giving me a misleading result on the Pico, or on the very rare occasions when I need an additional simultaneous waveform or two. (A 'Channel-Splitter' has been on my list of future projects for a couple of years ).

The Hameg takes up an unjustifiable chunk of my scarce bench space, but so far I've resisted relegating it to a dark corner of the workshop.

Major appeal to me is the ease of use through its familiar PC GUI interface, with full mouse and keyboard access to all settings. And being able to capture and annotate a waveform and file/display/publish it on my PC (with or without an appropriate schematic) within minutes.

--
Terry Pinnell
Hobbyist, West Sussex, UK

Dunno about that. I think the most important feature of a DSO, even beyond temporary waveform storage, is recordability. Increasingly, I find that if I don't save a measurement for recall perhaps months later, I might as well have never made it. That, and the user interface. If I hate the UI, I'll try not to use the scope in the first place.

The features that differentiate a Tek DSO and a cheap PC DSO are all secondary to these two factors. Where the Teks shine is in the details, not the feature set. When you select Ch1-Ch2 mode, for instance, where does the math happen? Even Tek's cheaper current scopes do it in image space, which means both Ch1 and Ch2's waveforms need to be entirely onscreen. You don't want that. Where does the cheap PC DSO adapter do it? And when the waveform *is* driven far offscreen, how long does it take to recover? Etc.

Keep in mind that commodity components available to the PC DSO adapter vendors today are in most cases better than the exotic stuff available to the designers at Tek in the early Eighties, when most gear accessible to current hobbyists on the surplus market was built. Certainly nobody would build a DSO with a 1K record length today (I hope).

Price is important for most folks, too, and for the price of the GPIB card and cable I have to use with my Tek 2430A DSO if I want to keep waveforms around, you can get a full-featured PC scope with similar specs.

If you're serious at all, you pretty much either have to buy a high-$ DPO scope, or you still need an analog scope on the bench right next to your DSO. I would be tempted to tell people to put the money into the

*analog* scope, and buy the cheapest PC DSO that fits your needs at any given moment.

-- jm

------------------------------------------------------

Note: My E-mail address has been altered to avoid spam

------------------------------------------------------

I've got the velleman PCS500

. I like it and you can't fault it for the price. You have a twin channel scope, spectrum analyser, and if you have the velleman sig gen as I do you can also do frequency plots e.g. for filters etc. You can save the data, take pictures etc as you would expect with a PC scope.

The sig gen can also generate arbitrary waveforms BTW. Takes a bit of programming though since you need to generate a list of data points which is not something you want to do by hand :-).

--

Malcolm

 Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
 (mreeves@fullcircuit.com, mreeves@fullcircuit.co.uk or mreeves@iee.org).
 Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
 electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

 http://www.fullcircuit.com      or    http://www.fullcircuit.co.uk

NEW - www.CharteredConsultant.co.uk - The Consultant A-List

If you want to do spectrum analysis and don't care much about what's above 1MHz, get a model with 16 bits. Gives you more dynamic range and you often need that.

I've got pico adc216 since I wanted 16 bits and the spectrum analyzer function has saved my life a couple times already. I've got Tektronix 496P, but its not suitable for 0-100KHz work.

One more thing, PC based scope lets you capture long waveforms, just like a digital storage scope. Comes handy in studying communication protocols etc. Kind of like a logic analyzer.

You've now got integrated PC based solutions with signal generator, a scope and logic analyzer in one box (I think its USB), check last issue of Elektor magazine.

--
Siol
------------------------------------------------
Rather than a heartless beep
Or a rude error message,
See these simple words: "File not found."

The difference is the liftime. A standalone scope can be working for 15 years and more. A PC based could too, but :

- the interface, USB, serial, ethernet tends to outdated then

- the software is outdated too, and you'll need an old pc just for the scope by then

Just some ideas, though.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

I disagree with both your points:

- The hardware becomes dated no faster than that in a conventional 'scope.

- Pico's software is far from perfect, but it is updated regularly.

--
Terry Pinnell
Hobbyist, West Sussex, UK

Hello John,

Well, that is why I bought a digital camera for the lab after a few folks here in the newsgroup said it would work. And it does!

I just got tired of that HPIB stuff with cables that are about as flexible as a reinforced garden hose. At least after one flung backwards and sent the coffee mug sailing.

There is some more to the picture here. One is channel-to-channel crosstalk, the other is triggerability. So far I have not seen a PC based scope that came close to the Tek 7000 series. Most of the Tek scopes can trigger on a piece of dog hair floating by. Even some of their serious competitors don't match up.

Regards, Joerg

[...]

The Binary Sampler with a Motorola NBSG53A d-flop probably exceeds this bandwidth easily. You can use a ramp timebase like the 7000-series, or heterodyne with a small frequency offset, perhaps from one of the inexpensive YIG oscillators coming on the market. This would be well within the capability of many people in this newsgroup.

Is the bandwidth needed? Yes, I think so. With logic rise and fall times in the

150ps region, a low bandwidth scope lacks the detail needed to troubleshoot problems in transferring the signal from one place to another.

Mike Monett

The PC scope becomes useless as soon as you cannot connect it anymore or as soon as you cannot run the software anymore. Modern PC don't have a serial port anymore for example. Yes, there still are USB to serial converters. My PCs tend to finally die at age 7 or 8.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Only see someone use one once, and can't recall the name, but it was pretty useless.

I've also seen cheap A/D boards that plug on a serial (or was it parallel) port, and again these were next to useless.

I, like some others, would look for a Textronix scope used, or perhaps an HP or similar.

The Textronix 7000 series with the right plugin has a bnadwidth of DC to

14GHz. Yes, not MHz, but GHz, using a sampling head with a 25ps risetime. There are some pictures in my PhD thesis taken using one of these and a 35mm camera.

Take a look in chapter 6 for some pictures. See Fig 6.34, with the

200ps/div, timebase. This was before the days of digital cameras, but 35mm film worked fine.

Is you PC scope going to be able to do that? Of course not. (You might well argue you never need it anyway!!)

Hello SioL,

1MHz,

Which brings up a question that I had asked here and there but nobody knew one: Is there a USB based spectrum analyzer that goes to 1GHz? Nothing fancy, just for pre-compliance checks in the field. Thing is, if you haul the big one as carry-on they'd make you check your pilot's briefcase as luggage which isn't so great. If security lets the analyzer on board in the first place, that is.

Regards, Joerg

timebase. This was before the days of digital

argue you never need it anyway!!)

Your 14GHz tektronix may have FFT function, but its limited to 10-12bits capture, right?

Sure, PC based stuff is generally crappy and cheap, but I use my pico only for its spectrum analyzer option where 16 bits are an advantage. Making snapshots is also easy.

Analog osc. is what I use 99% of the time.

--
Siol
------------------------------------------------
Rather than a heartless beep
Or a rude error message,
See these simple words: "File not found."