With no signal connected to the RF input of the analyzer, let us press the green PRESET
button to put the instrument back to its factory default state.
You can see here the factory default for the N9342C is a center frequency of 3.5 GHz and
a Span of 7 GHz - so we are sweeping the entire frequency range here.
You can see here the Reference Level (that is the top line of the graticule) is 0 dBm.
We have got a LOG scale on the Y-axis of 10 dB per division,
there is 20 dB of attenuation, the resolution bandwidth is 3 MHz,
and the video bandwidth is 3 MHz. Let us select a center frequency of say 2.4
GHz and let us zoom in a bit. I will press the SPAN button and select a
Span of say 100 kHz. Now a couple of things happen when we do that.
First of all the Span changes of course so we are now only sweeping over a 100 kHz range,
but you will notice that the analyzer also selects a narrower resolution bandwidth in
this case 1 kHz and the sweep speed has increased as well, we are now sweeping at 5 ms.
The most significant thing you will notice is that the noise floor of the trace here
has reduced significantly. If you are not familiar with Boltzmann’s
law and why narrowing the resolution bandwidth also has the effect of reducing the noise
floor, refer to Application Note 150 which you can download from Agilent's website.
So if I press the MARKER button, you can the noise floor is now around -90 dBm.
There are a couple of things we can do again to improve that sensitivity still further.
First I am going to press the AMPLITUDE button, and adjust the Reference Level,
to bring the trace further up onto the screen. I am then going to set the Attenuation to
0 dB. You will see we have gained about another
10 dB of sensitivity there. If I reduce the resolution bandwidth further
by pressing the BANDWIDTH button, and then RESOLUTION BANDWIDTH,
set it to Manual, and we will reduce that to its narrowest which
is 10 Hz. Now the sweep time is going to go up to about
8 seconds it will take longer to sweep the trace.
But you can now see the marker - we have got an amplitude value of about -133, -132 dBm.
And finally, if you have got the internal preamplifier option on your analyzer I can
press the AMPLITUDE button, and turn the preamplifier on,
and I am going to need to bring the trace back onto the screen again,
so I will press REFERENCE LEVEL, and we will just bring that up onto the screen
here. You will see we have got a sensitivity now
of almost -150 dBm. Now, because this instrument is so sensitive,
we may actually be picking up stray signals from around the room through the open Type-N
input connector on the top here. Let us terminate that with a 50 ohm load.
I will press SPAN, and zoom in a bit more,
and I will press TRACE, and MORE,
and let us turn on AVERAGING. And you will now see the really amazing sensitivity
of Agilent's Handheld Spectrum Analyzers. You can see here the marker is now reading
-156, -157 dBm. If you would like further information on these
products including; demonstration guides,
operating manuals, or application notes,
please visit: www.agilent.com/find/hsa