There may be a way to use the NaoVNA as a spectrum analyzer, but I don't
think you can get an absolute measurement of the signal strengths like you
can with the TinySA. You can get relative measurements, comparing the
strengths of two signals. But I would not trust it to indicate a desired
value like "+6 dBm" with accuracy.
73, Zack W9SZ
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On Mon, Dec 2, 2024 at 9:40 AM Jim Lux via groups.io <jimlux=
earthlink.net@groups.io> wrote:
Clever idea - the RBW is a few kHz, and it’s not particularly sensitive
(i.e. somewhere between -10 and 0 dBm is S21 of 0). Noise floor is around
-80 dB (on S21 log mag), so you’d need -60 dBm into the receiver to see
anything.
I’m not sure a TV or FM station would have that much power in a 5 kHz BW.
TV is spread over 5-6 MHz. Say an EIRP of 1 MW at 100 MHz 10 km away = +90
dBm -32.44 - 40 - 20 = about 0dBm, and the RBW is about -30dB of the signal
BW. So you would see that. But 10 km is pretty close (which is why nobody
in Pasadena needs a TV antenna - a paper clip in the antenna connector is
plenty). And 100 MHz is the middle of the FM band, where EIRPs aren’t 1 MW,
like they are for TV.
I note that when I was running two NanoVNAs back to back with a SMA T (to
try making full 4 parameter measurements at one time), you could see the
other NanoVNA sweep across the receiver occasionally (a big spike in
apparent S21), if they were both sweeping.
On Dec 2, 2024, at 06:11, jskinner58@... wrote:
I realize this hardware is not made for this and results will be poor
but I want to give it a shot anyway. New user of the H4 version. Looking
to get some idea of signal strength of some local FM and TV stations. I
tried setting the start and stop freq for the FM band and looking at logmag
of S21 and got nothing - just an almost flat line near the bottom of the
screen. Thinking I am missing a few settings. I have searched and read
some but haven't found a complete list of settings needed. If I need to do
this as some smaller freq bands I could do that.
