USB Oscilloscope/Spectrum Analyzer

[MegaWatt]

Hello everybody!
I am building my own lab at home, but I'm still in need of an oscilloscope and a spectrum analyzer. Do you think it would be a good idea to buy a USB oscilloscope. With this device it would be possible to have a scope and a spectrum analyzer in one. Analog/Digital scopes/spectrum analyzers are really expensive, and it seems that for like 100 € you can already get a decent USB oscilloscope that includes also a spectrum analyzer. So i was wondering, where is the catch? I'm a hobbiest, so I was wondering, why spend 1000 € on a scope and a spectrum analyzer if I could just buy a digital usb oscilloscope. I hope to get some opinions on this! Thank you! 

[Simon]

hm from what I hear people say the one word answer is NO, it depends on the specs really, read them thoroughly make sure there are no catches (phanton "virtual" specs) and go for it if your happy. I think the usual issue is real time viewing of signals, you can't put 1 GS/s down a USB connection (essentially 1GB/s of data plus communication overheads)

Standalone units are also easily carried around, I can throw my Rigol in my rucksack and take it anywhere along with a few DMM's and anything else i may need, do you really need a spectrum alalyzer ? the best thing is to buy stuff as and when you need it, setting up a lab does not have to mean spending money on equipment you may not need for years to come and making do is part of a good engineer to be. Get a couple of reliable multimeter's and a scope, analogue scopes are cheaply obtained and you can get low end digitals for reasonable prices and of course do you need a digital ?

[DaveW]

The big question is what kind of electronics do you want to do?
I'll second Simon, a spectrum analyser is a niche bit of kit, useful for RF development, but not much else besides; if you're doing RF work, most the the usb oscilloscopes won't have the bandwidth to see most RF signals. As for USB equipment, it tends to have compromises in it, in particular the cheaper stuff will have inferior analogue front ends compared to a decent scope. Also, I've used bitscopes, picoscopes and the stingray oscilloscope, and having to use a mouse to change settings always becomes a pain.
Personally, I'd say the times its worth looking into a usb device is if you need to carry it around every day, and have to fit it into a laptop bag or suchlike, or if you're only going to use it occasionally. Beyond that, get a good analogue scope if you're looking at repetitive signals (analog circuits etc), and a DSO is particularly useful if you want to look at digital data, capture single shot events etc.

[Simon]

the bottom line is that on a like for like basis of manufacturer in their standard/quality you get just what you pay for

The Rigol and other low end scopes are a first choice for many, not a lot of bells and whistles and I'd like a nice display (more pixels) but they are basic machines that get the job done for a reasonable price

[MegaWatt]

Hello,

well maybe you are right and I don't need a spectrum analyzer. It is just, I have been doing some radio projects in school, and there I had to use it all the time. But I guess you are right, other than RF electronics it's pretty much useless. And also I do not need a digital scope indeed. I guess the best thing to do is to try and grab off an analog scope off ebay or something like that?

[DaveW]

Whereabouts are you? And ebay is a good bet, make sure its at least a dual channel, 20MHz is enough for most electronics

[MegaWatt]

I live in belgium, I've been trying to snip a scope a long time, but really can't find anything under 100 € 

[Mechatrommer]

you can't put 1 GS/s down a USB connection (essentially 1GB/s of data plus communication overheads)

of course we cannot put 1Gs/s on USB, but random jiggling graphs on DSO display could be useless as well. maybe the point is we should rely on the hardware Gs/s spec to catch the trigger and later stream it on the USB. just a thought.

[slburris]

Hello,

well maybe you are right and I don't need a spectrum analyzer. It is just, I have been doing some radio projects in school, and there I had to use it all the time. But I guess you are right, other than RF electronics it's pretty much useless. And also I do not need a digital scope indeed. I guess the best thing to do is to try and grab off an analog scope off ebay or something like that?

You can build your own spectrum analyzer:

http://www.scottyspectrumanalyzer.com/

Not me, although I've been working on building one of these for at least a year.

Scott

[btipton]

Whereabouts are you? And ebay is a good bet, make sure its at least a dual channel, 20MHz is enough for most electronics

I just bought my first scope on eBay - a 20MHz dual channel for $30, plus $17 shipping.  It looked like there were quite a few 20Mhz scope to be had for <$50.

Bob Tipton

[the_raptor]

USB/portable Oscilloscopes are either not high enough resolution for "real work" or so expensive you may as well put in an extra $100 and buy a bench scope which is an order of magnitude better.

I recently bought a DSO Nano v2 (I can hear Dave groaning in the background) because I wanted something that would allow me to do basic examination of signalling and to aid my learning of electronics (ie it can tell me whether my project is actually putting out roughly the right output).

I think the market for "hobbyist" scopes is growing though based on the success of the DSO Nano (even if Dave hates it) and for example SeeedStudio who made the DSO Nano are working on the "DSO Quad" which might hopefully have enough bandwidth to be useful but still be cheap enough that it is a good deal.

P.S. And contrary to what Dave has said I can't find a 20Mhz eBay.au scope for less than $200 with p.p and those that low are dodgy or broken. $100 for the DSO Nano v2 was a good deal in comparison to what I could get off eBay.

[Simon]

I think for a beginner one of the cheap Rigol's is fine, it has decent spec and is not too exspensive, of course there are other options out there

[Mechatrommer]

I think for a beginner one of the cheap Rigol's is fine

do i have to second this? "more" than fine actually, for a beginner. imho.
but to be used as a spectrum analyzer (esp for RF system), i dont think so.
and SA is no way a beginner tool, i've not find any sub $300 (1K our currency) for a usable SA (for 433MHz RF in my case)

[aat24]

Just stumbled across this old thread but I think it is still relevant today. Most USB scopes include meanwhile a spectrum analyzer and other functions such as logic analyzer or waveform generator. Also prices dropped since then. Therefore this kind of instruments might be an ideal all-in-one solution for beginners. A product overview of USB scopes was recently published here: http://oscopes.info/market/2256-usb-oscilloscopes-product-overview-low-end

[jimon]

Btw, I've understand why one wants bench top oscilloscope with prober knobs and interface, it's your everyday instrument in the end, so it needs to have proper UX.

But what if one only use spectrum analyzer like 2 times a year, then are usb spectrum analyzers any good ?
I often see this one on ebay http://www.ebay.com/itm/USB-RF-Spectrum-Analyzer-4-15-GHz-TSA4G1-by-Triarchy-Technologies-/151218540507?pt=LH_DefaultDomain_0&hash=item233553cfdb and I see big limitation - no tracking generator, but on other hand, is it any good at all ?

PS. Or should I just buy Rigol DSA815-TG and don't bother with it ? 

[Howardlong]

Resolution bandwidth (minimum 50kHz) and minimum span (1MHz) are limiting factors. Depending on what you're doing it's likely to mean it might end up sitting in a drawer.

Not sure how well calibrated it is across its frequency range.

I'd also be interested to see the sweep rate in various configs.