SerpiParticipantSerpi August 5, 2021 at 6:41 am
I need the BB60C NF value, does I directly use the DANL vs NF formula (DANL (dBm/Hz) = -174 (dBm/Hz) + NF – 2.51 (dB).
That provide :
9Khz to 500 KHz : DANL = -140 dBm/Hz => NF = 36.51 dB
500KHz to 10MHz : DANL = -154 dBm/Hz => NF = 22.51 dB
10MHz to 6 GHz : DANL = -158 + 1.1 dG/GHz => NF (1GHz) = 19.61dB
These value seems to be too high for a receiver, but why not.
Correct or not ?
Justin CrooksModeratorJustin Crooks August 5, 2021 at 9:50 am
If you select average, power units, there is no 2.51 dB correction. This only applies to log averaging. Our DANL spec is worst case. NF is usually calculated off of typical DANL. You can use the noise marker with a reference level of -50 dBm, input terminated, at the frequencies of interest. Then add 174 to calculate noise figure of your actual unit.
SerpiParticipantSerpi September 30, 2021 at 6:29 am
Thanks for your answer.
Just to be sure, for the NF measurment, what is the setup ?
For 500MHz central frequency, I use 10 MHz bandwidth, the reference level to -50dBm.
I just put a marker noise at 501 MHz and read the value ?
I do not have to set the trace in average mode ?
Cause the 501MHz value I found is only 9.2 dB NF instead of the 16.55 dB calculate from your DANL worst case spec.
I always have margin between the datasheet of my systems and the reality, but here it is quite crazy.
Justin CrooksModeratorJustin Crooks September 30, 2021 at 11:58 am
The noise marker, using power, average settings, will give you a good noise measurement. The trace does not have to be in average mode, but it may help stabilize the reading a bit more.
You will find most frequencies have a noise figure quite a bit better than our specification. As a spectrum analyzer, we are required to meet the DANL specification at all operating frequencies for the life of the instrument, so padding these numbers a bit is prudent.
You must be logged in to reply to this topic.