PicoScope 7 Software
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picoscope 2204a ; not sure what I'm doing wrong
picoscope 2204a ; not sure what I'm doing wrong
Dear forum. I'm trying to characterize an unknown noise on a signal of about 2.3 volt, with my picoscope 2204a. I'm rather a newbie on this matter.
The setup: a pressure sensor generates a current between 4 and 20mA, which I measure by letting the current flow through a 150 Ohm resistor and measuring the voltage over the R with an ADC connected to an ESP processor. I noticed that the measurement is not stable, there is a "noise" on it of about +- 8mV.
Trying to look at this signal with the 2204a, I'm having the following issues:
- DC: I get the impression that accuracy is not enough (need the +-5v range for my 2.3v DC offset signal, so 8 bits on 10V range); need to use AC I guess for this? However, on AC the signal is not symmetrical around 0. Not sure if this is a problem? Or can I use DC after all?
- I played with the time base: but changing the time base, also the AC signal min/max changes: this is something I completely don't understand: how can time base setting change the signal levels that I see?
The setup: a pressure sensor generates a current between 4 and 20mA, which I measure by letting the current flow through a 150 Ohm resistor and measuring the voltage over the R with an ADC connected to an ESP processor. I noticed that the measurement is not stable, there is a "noise" on it of about +- 8mV.
Trying to look at this signal with the 2204a, I'm having the following issues:
- DC: I get the impression that accuracy is not enough (need the +-5v range for my 2.3v DC offset signal, so 8 bits on 10V range); need to use AC I guess for this? However, on AC the signal is not symmetrical around 0. Not sure if this is a problem? Or can I use DC after all?
- I played with the time base: but changing the time base, also the AC signal min/max changes: this is something I completely don't understand: how can time base setting change the signal levels that I see?
Re: picoscope 2204a ; not sure what I'm doing wrong
For a +2.3V signal in DC coupling you will indeed need to use the +/-5V range with that model scope, and resolution will indeed be a bit poor for small voltage variations. The 8 bit resolution gives you 256 steps between +5 and -5V, meaning about a 0.04V step size.
You should be able to use AC coupling and a lower voltage range to get a closer look at small variations, and I'm not sure why you are having issues with that. Perhaps we can spot what's going on if you show us the results you are getting, and the settings you are using.
You should be able to use AC coupling and a lower voltage range to get a closer look at small variations, and I'm not sure why you are having issues with that. Perhaps we can spot what's going on if you show us the results you are getting, and the settings you are using.