On 07/31/2014 02:36 PM, Sova wrote:
I'm probably looking for more confirmation of waveforms and basic
measurements. So calibration is probably not a huge deal, and I'm not
sure if 4 channels is going to be that much more useful than 2,
Most tasks only need 1 or 2 channels, but often the 3rd and 4th channel
are extremely helpful.
For example, I just posted a blog article on the website about recent
work I've been doing on the Arduino SPI library. Try to imagine how
you'd view the timing of when 2 unrelated pieces of code are accessing
hardware with an interrupt signal thrown into the mix, using only 2
channels. I suppose you could feed the interrupt (blue trace) into the
scope's external trigger input, and not see those other 2 signals, but
at least "know" where the rising edge happened.
http://www.dorkbotpdx.org/blog/paul/spi_transactions_in_arduino
What you can't see in that screenshot is the trigger event, which in
that example was a pulse width trigger. Old analog and cheap digital
scopes have only conventional rising/falling edge trigger, which means
you can't really trigger on any specific part of a complex signal.
Modern digital scopes offer lots of other ways to trigger (including
serial protocol analysis, usually as extra-cost options). Some of those
trigger options, combined with the holdoff setting, are extremely
useful. Figuring out how to get the scope to trigger where you want is
often the most frustrating part of actually using a scope.
Of course, the more-than-2 channel and special trigger answer is
probably a cheap USB logic analyzer, for a purely digital problem like
this. But when analog issues are a factor, a logic analyzer can really
trick you into thinking only about ones and zeros, which is why I always
prefer to use a scope.
The Rigol comes with a 3 year warranty but I just don't know anything
about them. The smaller size and portability of the Rigol seems like
a big plus. Anyone have any experience with them?
I have a Rigol DS1052D, which is very similar. I could bring it to the
next meetup, if you'd like to spend a some time playing with it.
I believe in today's market, the 2 "budget" scope options to seriously
consider are the Rigol DS1074Z ($585) or a cheap USB adaptor (about $100
to $150). The people selling those USB things make a lot of tall
promises and misleading claims on models that rival the pricing of real
scopes. Don't get sucked into spending a lot on a USB gadget. But a
$100 USB dongle can give you DC response, with is a LOT better than
trying to use a sound card input as a scope!
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