Re: Measuring the noise floor

From: qrk (SpamTrap_at_reson.com)
Date: 03/03/05 

Date: Wed, 02 Mar 2005 18:36:20 -0800

On Wed, 02 Mar 2005 20:49:29 GMT, PaulCsouls
<paulcsouls@worldnet.att.net> wrote:

>
>Thanks. I didn't know about the low noise setting, I'll have to check
>the manual again. The resolution bandwith with the 3588 was 17k. The
>4195A only lets me set 10k and 30k in that range. Though I would
>expect to see a descrepancy between the data from the 3588 and 4195A,
>the lack of change between the on and off conditions worries me about
>the condition of the 4195A. The preamp is probably what I need. I'll
>look into renting one of those when the 4195A come back from cal.
>
>Thank you
>
>Paul C
>
To get to the low noise mode, press the Receive Attenuation button.
You will have a selection of
IF RNG Normal
IF RNG Low Distortion (only in spectrum mode)
IF RNG Hi Sensitivity

Low distortion and high sensitivity mode will give you a better noise
floor. I'm a bit baffled by your bandwidth setting limitations. The
4195 allows you to use bandwidth settings down to 3 Hz. Might take a
few days to make the measurement at 3 Hz depending on your setup.

What is your basic setup? Freq range, mode, circuit impedance, ...
If your doing noise floor measurements, you want to use the spectral
density mode (dBuV/Hz, dBm/Hz, uV/rtHz) which reports noise in a 1 Hz
bandwidth.

Mark