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Jubayer JalilParticipantJubayer Jalil July 24, 2018 at 7:45 pm
I want to measure output noise at 7 kHz for my circuit using USB-SA44B. The circuit’s output noise density (theoritically calculated) is 125 nV/Hz^-1/2. Measurment RBW will be 1 Hz. For DC block, I am using 3.3 uF capacitor within PCB. But I cant get output! Even though noise floor for this range is -130 dbm (=71 nV).
Can you please provide me the solution?
Thanks in advance.
Justin CrooksModeratorJustin Crooks July 25, 2018 at 10:06 am
Setup for this type of measurement would be something like:
RBW 100 Hz, VBW 10 Hz, detector settings power, average. Center frequency 7 KHz, span 10 kHz. Reference level -50 dBm.
A 3.3 uF DC block should be reasonably flat down to 3 kHz or so.
Let me know if this works for you.
Justin CrooksModeratorJustin Crooks July 25, 2018 at 10:44 am
The other thing to note is your circuit should have a 50 ohm output impedance. If it does not, the SA44B will load it down and the noise reading will be much lower.
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