[hpsdr] Janus Lives!!

[Ahti Aintila]

On 03/07/06, Gerald Youngblood <gerald at flex-radio.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****

> RMS noise measures -159 dBm.  If you subtract 26 dB for the 500 Hz
> bandwidth, you get a noise floor of -185 dBm/rt Hz.  This is below kTB of
> -174 dBm/rt Hz.  That would equate to a negative NF (-11dB).  I would be
> interested in seeing the 500 Hz bandwidth shot after calibration with the
> radio attached.

Gerald,

You are calculating dBm,  so you should use dBm/Hz for the noise
density. Look only at the spectrum display. Then -160 dBm/10Hz becomes
to -170 dBm/Hz and that translates to 4 dB noise figure. No need for
dewars!

Am I right or do I get confused with this exceptionally low noise level?

73, Ahti OH2RZ

PS: BTW, I get only slightly higher noise level with my WaveTerminal
192X sound card.

 1151948267.0