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Oscilloscope specs - which are really important

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Hydrawerk:
Long memory (more than 1MB) is good if the scope has proper tools to handle it. There should be posibility to place marks or search automatically. Wave Inspector

hans:

--- Quote from: AndyC_772 on January 15, 2013, 09:06:34 pm ---
--- Quote from: EEVblog on January 15, 2013, 10:00:59 am ---I'd consider the Rigol 2000 series the current front runner by far in under $1K 2 channel scopes.
As someone else said, 4 channel is handy, and you'll never regret getting a 4 channel.

--- End quote ---
Shame the 2000 series doesn't come in 4 channel. I don't know how anyone manages with just two channels; how do you probe clock, data and chip select, for example? Any kind of stimulus / response uses up two channels straight away, even if both are a single signal. Add anything more complex and you're hosed.

There's the 4000 series, of course, but they're twice the price.

--- End quote ---

The 4000 series does have additional features (although the 2000 seems decent equipped for a hobbyst) and has 2 more channels. So if you calculate the 2 extra channels for 25-50% extra cost, the more sample memory, more wfm/s is the extra cost.

Have to say, I'm also disappointed. 50kwfm/s and 14MPts for me would be more than enough, but I really like to see 4 channels for the reasons you mentioned.

On a 2 channel scope it's hard to measure SPI, I2C is okay. For SPI I would compare ChipSelect vs Clock and then Clock vs Data, but each time you program a firmware update, things change, stuff shifts around, and so assumptions are made, which is the mother of all fuckups. |O

alm:
I tend to use a logic analyzer for protocols like SPI. SPI is usually slow enough so even the cheap 24 MS/s max USB logic analyzers can easily keep up. They are much cheaper than the premium of a four channel scope. I use a scope for the signal integrity stuff, but that doesn't normally require monitoring a lot of channels.

nctnico:
There is more to life than SPI. When measuring in circuits I often find myself using 3 channels. Sometimes 4. I actually have two almost identical 4 channel scopes. In one case I stacked the scopes and connected the trigger out on the first to the trigger input on the second to get an 8 channel scope.

marmad:

--- Quote from: nctnico on January 16, 2013, 02:19:21 am ---There is more to life than SPI. When measuring in circuits I often find myself using 3 channels. Sometimes 4. I actually have two almost identical 4 channel scopes. In one case I stacked the scopes and connected the trigger out on the first to the trigger input on the second to get an 8 channel scope.

--- End quote ---

Sure, but let's face it - in the long history of oscilloscopes, 2 channels has been the most standard - and most tasks can still be handled with it. Honestly, I remember when an External Trigger input was a premium feature. Of course, the more you have of almost anything (channels, bandwidth, sample speed, memory, update rate, etc) the better, so if you can easily afford 4 channels (or 8 or 12  :) ) get it - but I agree with alm that, for many users, the premium you pay for 4 channels (especially given the tiny sizes of most oscilloscope displays) would be better spent on equipment better suited to looking at and analyzing a larger number of signals.

And I do exactly what you describe with your 2 scopes - but with my scope and a logic analyzer.

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