PicoScope 7 Software
Available on Windows, Mac and Linux
2205 spectrum analy harmonic view incorrect
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richy
2205 spectrum analy harmonic view incorrect
My 2205 has this peculiar behaviour of not showing the correct harmonics. One varies the input level and the f2,3,5 (ref 1Khz) all shoot up/down as if the input to the A/D converter is showing harmonics related to amplitude. No it's anti-aliasing- The input is well below warning exclamation. Whats the reason: poor decoupling on 2205 ?
Other instruments don't have this varying harmonic representation with input level. So in the field it's impossible to get the true picture.
Help !
Other instruments don't have this varying harmonic representation with input level. So in the field it's impossible to get the true picture.
Help !
Re: 2205 spectrum analy harmonic view incorrect
Hi,
I can't duplicate your problem here. Varying the input amplitude up/down causes the whole display to go up/down but all harmonics stay in the same proportion as they should. What settings are you using? What do you expect to see?
Regards,
Peterf.
I can't duplicate your problem here. Varying the input amplitude up/down causes the whole display to go up/down but all harmonics stay in the same proportion as they should. What settings are you using? What do you expect to see?
Regards,
Peterf.
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richy
Re: 2205 spectrum analy harmonic view incorrect
Peter, I've taken a couple of FFT's using the inbuilt sine generator with direct connection. I cannot post pics on this site so I will send them to the company main.
Re: 2205 spectrum analy harmonic view incorrect
Hi Richy,
I can see what the problem is now. You are looking for harmonics which are at a level 50dB lower than the fundamental signal. Since the 2205 input, and the AWG are both 8 bit, the maximum resolution possible is about 48dB.
Please read the following explanation:-
http://www.picotech.com/applications/resolution.html
To do what you want, I feel you will need a 12 bit scope like the 4224.
Regards,
PeterF.
I can see what the problem is now. You are looking for harmonics which are at a level 50dB lower than the fundamental signal. Since the 2205 input, and the AWG are both 8 bit, the maximum resolution possible is about 48dB.
Please read the following explanation:-
http://www.picotech.com/applications/resolution.html
To do what you want, I feel you will need a 12 bit scope like the 4224.
Regards,
PeterF.