2205A, noise level in Spectrum mode

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vit_s
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Joined: Thu Mar 11, 2021 6:21 pm

2205A, noise level in Spectrum mode

Post by vit_s »

Hello,

I would like to check is this OK for 2205A to have noise floor at about -115 dbV?

Probe is shortened, 50 mV, AC, 1:1. MacOS, 6.14.36, MacBook Pro (15-inch, 2016), Macbook Pro 2013 (any of them, the same).

Thanks!
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vit_s
Newbie
Posts: 0
Joined: Thu Mar 11, 2021 6:21 pm

Re: 2205A, noise level in Spectrum mode

Post by vit_s »

A friend of mine has also 2205A which is about 4 y.o. I saw by myself it has less than -150 db noises. Does this one have different ADC chip?

Gerry
PICO STAFF
PICO STAFF
Posts: 936
Joined: Mon Aug 11, 2014 11:14 am

Re: 2205A, noise level in Spectrum mode

Post by Gerry »

Hi vit_s,

You can't check the noise floor in Spectrum Mode because we apply an adjustment to the values displayed, in order to correct the peaks of signals for maximum accuracy. This correction changes the noise floor depending upon how many bins you select for the frequency plot (for more information go here: topic25101.html?&p=86081&hilit=Process+gain#p86081). You would need a Power Spectrum in which an adjustment is made for the average power level in a bin, which leaves the noise floor unchanged when you change the number of bins. We don't plot a Power Spectrum (only a Linear Spectrum),

So you will need to make any noise measurements, in Scope mode, by terminating the input with a 50 ohm terminator (e.g. this one: https://www.picotech.com/accessories/bn ... inator-bnc), to minimize any induced interference, and then perform an AC RMS measurement. However, It is essential that you perform this on a quiet ring Main (i.e. no spurious noise being picked up through the supply or ground plane) and away from other equipment that might be generating EMI.

When you do all of that you should find that the noise level is, at least, as low as we specify on our product web page, here: https://www.picotech.com/oscilloscope/2 ... ifications (under Dynamic Performance).

Regards,

Gerry
Gerry
Technical Specialist

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