WoW, thanks for all the replies/suggestions!
My main requirements for the scope are:
- 4 channel
- 200 Mhz (or 100 expandable to 200 Mhz)
- SPI & I2C at a minimum upgradable to I2S (I dabble in music / guitar / instrument effects)
If you want I2S then it probably has to be the Keysight as neither the Rigol DS4000 nor the LeCroy WaveSurfer support I2S.
But I'd consider if not just getting some cheap USB device as I2S decoder isn't a better alternative anyways.
- FFT or spectrum analyzer ability at lower frequencies (typically audio, but occasionally higher -- say 100Mhz at most)
FFT is really bad on the Rigol as it only supports a few thousand points (IIRC 4kpts). The DSOX3kT uses up to 64kpts for FFT which isn't great but still a lot better than the meagre 4kpts of the DS4000.
The LeCroy WaveSurfer uses 1Mpts.
- Various trigger / math functions that all scopes come with now so I won't list them
Well, the Rigol is pretty primitive in this regard (few triggers and primitive math). Both Keysight DSOX3kT and LeCroy WaveSurfer 3000 offer much more in these areas. The WaveSurfer also comes with WaveScan which is a very flexible tool to find glitches or any other signal anomaly. It's probably best described as some kind of very flexible trigger, although it works with realtime data as well as data in the sample memory.
Here is what I'm reading from above:
Rigol
- Don't bother at this price range
Keysight
- Can't go wrong with the 3000T, solid contender
- Current free software upgrades include the AWG, freq counter, all decoding, etc.
- Can buy 100Mhz and upgrade to 200Mhz
- Very nice hardware FFT (not software)
As to FFT see above. It's much better than what the Rigol offers but that's because FFT on the Rigol is so poor for a scope of this day and age and not because it's that great on the Keysight. 64kpts is still pretty low for FFT, but I guess that (similar to the low sample memory of only 4M) is a limitation of the old scope platform and its slower processing architecture (the DSOX3kT is a slighlty improved DSOX3k which came out around 2012).
Teledyne/LeCroy
- I haven't researched these because I heard they are rebranding a cheap Chinese scope as their own. No idea which models are good.
Yes, they do. The LeCroy WaveAce Series are rebranded Siglent scopes, and they are crap (the hardware is fine but the Siglent firmware is shit), plain and simple. But these are bottom-of-the-barrel scopes, and I guess LeCroy slowly realized that it burnt their reputation.
The WaveSurfer 3000 is manufactured by Siglent for LeCroy but the software comes from LeCroy, and it's a really good scope at a decent price. There have been a few discussions here so use the search function and you'll find more information.
However, the WaveSurfer 3000 is more a competitor to the Keysight DSO-X4000 Series than the 3000 Series.
- People have suggested their 3000 series, but they don't show scope prices or option prices so it's hard to compare (maybe I missed it on the site?)
- Are they bandwidth software upgradable? Can I get a 100Mhz and upgrade it later to 200 or more?
Yes, they are.
However, I recommend to just forget about bandwidth upgrades. They are rarely worth their money, no matter what manufacturer. Buy the bandwidth you need in the foreseeable future now, and later when you find that you need even more then sell the scope and get a new one which has the larger bandwidth. There's little point investing hundreds of dollars in the upgrade of a scope that by the time you want to upgrade is pretty much outdated when you can sell the old scope and use that money plus the money for the upgrade to buy a new model which will also perform better.
- Obviously I have homework investigating these
A good starting point are the spec sheets:
Keysight DSO-X 3000T:
http://literature.cdn.keysight.com/litweb/pdf/5992-0140EN.pdf?id=2545408LeCroy WaveSurfer 3000:
http://cdn.teledynelecroy.com/files/pdf/wavesurfer-3000-datasheet.pdfhttp://cdn.teledynelecroy.com/files/pdf/wavesurfer-3000-fact-sheet.pdfBTW: the WaveSurfer recently got a DVM display mode (similar to the one on the Keysight) as a free upgrade for all WS3k scopes, and the optional signal generator in the scope is now a full Arbitrary Waveform Generator, again through a software update (which is free for owners of the FG option). Both things aren't mentioned in the data sheets.
Tektronix
- Well, after watching Dave's review of the MDO4000 ... more bad points than good points IMO.
- Let me know if anyone uses this scope please. I could use another opinion
Back in the day Tektronix was the bees knees; if you were anyone you owned a Tektronix scope (or HP). It's funny nobody mentioned them on this thread ... must indicate something...
Tektronix really was the technology leader in analog scopes, which also earned them their reputation which they are still benefitting from. But as far as DSOs are concerned, Tek was never a front runner. They had some decent scopes, and were the first offering scopes in the typical lunchbox format, however technology-wise they were mostly trailing behind others, notably LeCroy which is probably closest to being Tek's equivalent for DSOs.
The MDO3000/4000 might not be a bad scope if you need a single device which includes scope and spectrum analyzer, however the specs of the latter part is pretty poor, and for the price of a MSO3k with 3GHz SA you'll probably get two separate devices with overall better performance.