speed = 25
Humanoido
Posts: 5,770
The PropScope is a two-channel oscilloscope that is capable of reading 25 million samples per second with ten bits of resolution over one, two, ten, or twenty volt peak-to-peak waveforms.
Is this exactly the same speed as a 25MHz oscilloscope?
humanoido
Is this exactly the same speed as a 25MHz oscilloscope?
humanoido
Comments
-Phil
The PropScope can continually take 25Msps on two 10 bit analog channels and 4 digital inputs while outputting a completely customizable signal at the same 25Msps. All while looking for a trigger. Once the trigger has been found, it takes over a thousand samples and then streams them back to the pc. Assuming you have enough trigger points and you've set your timescale fast enough, it does this 30 times/second. Back to the questions- you'll need at least 2 samples per cycle to detect the waveform- so the fastest wave you'll see without artifacts is 12.5MHz. If you want to see more detail- you'll want more samples- 5 samples/cycle results in a decent representation.
What types of signals are you trying to analyze?
Hanno
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Co-author of the official Propeller Guide- available at Amazon
Developer of ViewPort, the premier visual debugger for the Propeller (read the review here, thread here),
12Blocks, the block-based programming environment (thread here)
and PropScope, the multi-function USB oscilloscope/function generator/logic analyzer
I'm interested in pin pulses, measuring fractional volts .1v on up to 5 volts, checking the
accuracy of power supplies for clean regulated signals, PWM calibrations, clock frequency,
on Stamps and the prop chip which will be set to vary from the slowest possible speed
(both internal rc circuit and external crystal), as well as measuring the effects of increasing
the speed up to around 200 MHz. It sounds like the latter won't get covered but the former
will do just fine. Right?
How does the PropScope compare to ViewPort Ultimate, which has virtual oscilloscope
functions for the Propeller chip?
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humanoido
*Stamp SEED Supercomputer *Basic Stamp Supercomputer *TriCore Stamp Supercomputer
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Always good when I end up answering a question when I run of on some tangent [noparse]:)[/noparse]
Yes, the PropScope is ideal for measuring all sorts of analog signals. Of course it also lets you measure digital and output configurable analog waveforms. To properly analyze a 200MHz signal you'll need much more expensive equipment- probably an order of magnitude more than PropScope...
I wrote ViewPort to help me easily write programs for the Propeller. The latest version helps you:
- EDIT code with a professional grade code-editor (including bookmarks, code folding, macros, regular expression search...)
- DEBUG code with conventional tools like breakpoint, pause, step through code, watch list, memory map, interpreter
- RUN programs while monitoring and changing variables using graphical instruments- like an oscilloscope, logic analyzer and more...
There's a nice review of ViewPort from "Robot" magazine in my signature...
Hanno
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Co-author of the official Propeller Guide- available at Amazon
Developer of ViewPort, the premier visual debugger for the Propeller (read the review here, thread here),
12Blocks, the block-based programming environment (thread here)
and PropScope, the multi-function USB oscilloscope/function generator/logic analyzer
humanoido
MHz is the frequency of a given signal/waveform. A 25MHz sine wave will go through a full sine wave cycle 25 million times a second.
MSa/s is the number of samples of the signal/waveform you make in a second. At 25MSa/s you would be reading where the signal is at 25 million times a second.
So, using our example rates above, in the time it takes for the sine wave to go through a full cycles, you've only taken one sample. Your sample would be somewhere along the sine wave curve. Your next sample would be during the NEXT sine wave cycle, and likely at or near the same point along the sine wave as your previous sample. You'd only see a line instead of a sine wave.
In order to represent a 25Mhz sine wave via sampling, you'd need to sample several times during a single cycle of the sine wave.
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