I bought one of the early models when they first came out and I have found
it handly at various times. Certainly even a base model Tek storage scope with
built-in LCD and "analog feel" knobs is a lot more handy and more powerful
than the bitscope but then even a basic Tek costs about 5 times as much.
The main limitation of the bitscope is that it only handles up to
50 megasamples per second, and you don't have as many other sample
options as you might like (e.g. 10 megasamples). On the other hand,
I was using it mostly for motor and large inductor measurements where
everything happens reasonably slowly and the bitscope is really good
for slower signals.
Comparing a pure analog scope with a bitscope is a bit like comparing an
apple with an orange because the analog is easy to set up and to get some
visibility into the signal but hard to take real measurements off and the
analog obviously can't see single shot pulses. In addition, the bitscope
gives you more complex triggering options along with a simple expansion
mechanism to build your own triggering circuits.
So I downloaded the DSO1.1 software and connected it over the Internet to
there "SYDNEY" BitScope to do some mucking around.
I must say my first thoughts were gees this looks complicated, after a
couple of e-mail's to BitScope I was back on track and making sense of the
trigger setups and time base zooming etc, etc
The bitscope setup IS kind of complicated, especially the various
delays and time base adjustments. The triggering is unusual but not too
difficult since it is basically a digital detector working on the ADC
output. Expect a bit of a learning curve if you have only worked with
analog scopes in the past.
I've been told BitScope are actively enhancing the software and I was asked
by BitScope to suggest any enhancements. Here what it could not do right
now and hence I've suggested
Define a logic trigger event that has to exist for a certain amount of time
before it's true. limited to 50us
Be able to look at the data before the trigger event occurred.
The bitscope changes time-base at the moment of the trigger so it always
runs balls to the wall (i.e. 50 megasamples) until trigger time and then it
switches to whatever time base you are working in. The buffer is a simple
circular SRAM block and it DOES store data while it is waiting for a trigger
so if your after-trigger delay is short then you will still have pre-trigger
data in your buffer. However, the pre-trigger data will always be sampled
at full sample rate (and single channel).
This behaviour may have changed, mine is an early model that had a later
transplant to upgrade it.
Try the DSO1.1 software connected to the "SYDNEY" BitScope, that will give
you a real good idea of what to expect.
I think that the real charm of the bitscope is that you can program it
yourself. I never once used their standard front-end and found it easier
to knock together my own perl scripts. Admittedly those scripts are a bit
buggy and need work but as I needed a feature I worked on that part of
the script until it was good enough. For setting up repeatable experiments
this is amazingly useful because you can use the PC parallel port to
fire off whatever starts your experiment, then fetch your results back
and process the data all in the same perl script. That is something that
you can't get your analog scope to do and even the expensive Tek will
require a lot more expensive hardware and software before you can run any
sort of automated test environment.
- Tel