Am 18. Jan 2013, um 23:46:39 schrieb Joe Leikhim:

I have just sent off an e-mail to David Howe of NIST Metrology requesting clarification.

I was shocked when I first saw this and posted it a couple places to get feedback.

Domenico's excellent response further demonstrated that explanation is required.

Dear Joe,

Tthe -177dBm/Hz value pertains to Phase noise (PM), which is in case of stationary (like thermal white) noise half of the total noise power ( -174 dBm/Hz - 3dB down.) (the other half is amplitude noise, which is not considered in the paper there).

Changing kTB (total thermal noise power) mathematically requires either changing B (but this is fixed to 1 Hz by the resulting unit) or T (halving the temperature, but this is not stated in the paper, nor would it make practical sense), or k (significantly changing a fundamental physical constant takes more than a single NIST paper and would have more profound effects than requiring recalibration of all NF meters :).

The other topic of the paper is that Noise Figures as usually used in the low signal case to characterize the thermal noise properties of the amplifiers may not be a good figure of merrit in the the strong signal case, the phase noise caused by intermodulation between the carrier and the noise may actually dominate there.

Best 73s,

Mario