I found the attached pdf from old thread on hot/Cold Load & N8975A and one of the paragraph mention that :
'22. PHOT should show the noise source excess noise. You can substitute any source of noise (unknown or known) to measure its excess noise in dB (relative to kTB). So long as the noise source you used during the calibration process was at the same temperature as the unknown noise source, the excess noise measured is now measured against a calibrated reference. '
I am trying to measure ENR of my noise source (unknown noise source) using N8975A My question as follows:
1) So i can actually cal N8975A with the standard Agilent noise source at rm temp and by looking at the Phot it actually measure ENR of my unknown noise source?
2) what if the unknown noise source is place at a hot plate of 80 degree C (323.15k), and the calibration using the known noise source was done and rm temp 303k, Can i measure the ENR of the unknown source correctly? do i have to do any calculation to remove the temp different between calibration n actual measurement?
Thanks
Best Regards
Jas
'22. PHOT should show the noise source excess noise. You can substitute any source of noise (unknown or known) to measure its excess noise in dB (relative to kTB). So long as the noise source you used during the calibration process was at the same temperature as the unknown noise source, the excess noise measured is now measured against a calibrated reference. '
I am trying to measure ENR of my noise source (unknown noise source) using N8975A My question as follows:
1) So i can actually cal N8975A with the standard Agilent noise source at rm temp and by looking at the Phot it actually measure ENR of my unknown noise source?
2) what if the unknown noise source is place at a hot plate of 80 degree C (323.15k), and the calibration using the known noise source was done and rm temp 303k, Can i measure the ENR of the unknown source correctly? do i have to do any calculation to remove the temp different between calibration n actual measurement?
Thanks
Best Regards
Jas
Please use the attached document to make a Manual Mode measurement of the noise source.
1) +So I can actually cal N8975A with the standard Agilent noise source at rm temp and by looking at the Phot it actually measure ENR of my unknown noise source?+
Using Manual Mode will allow you to measure the Phot and the Pcold values of a noise source. The ENR will be Phot(dB) – Pcold (dB). In the attached document the Phot was 13.896 dB. Pcold was 0.143 dB, 13.896 – 0.143 = ENR of 13.753 dB.
2) +What if the unknown noise source is place at a hot plate of 80 degree C (323.15k), and the calibration using the known noise source was done and rm temp 303k, Can I measure the ENR of the unknown source correctly? Do I have to do any calculation to remove the temp different between calibration n actual measurement?+
The ENR of the noise source will increase by 10log [ Tplate/Treference ]. Tplate = 323.15°K and Treference = 303°K = 0.279 dB increase in ENR because of increased temperature. Please keep in mind that the topic of discussion here is the ENR of a noise source. Another key parameter in the overall uncertainty of a measurement is the ENR uncertainty. An NFA does not measure this parameter. In order to make this measurement the N2002A, Noise Source Test Set with a gold standard noise source would be required.
Regards -