On Tue,9/1/2015 2:52 PM, Rick Stealey wrote:
> Jim,
>
> I'm duplicating your slide 8 test with my K3 going into a flex 6300.
> 25 watts
> At 80 db down I'm seeing a little over 400 cycles, and a pedestal.
> This is K3 with the original synthesizer.
Studying this measurement, I have several thoughts. First, the
resolution bandwidth appears to be about 30-40 Hz at -70 dBc, compared
to 60 Hz for the K3 with P3SVGA. That's very good. Also, those peaks
that show up in the range of 260-310 Hz either side of the carrier are
visible in the waterfall and are moving in the waterfall, so I suspect
they are some sort of modulation. Note that they are not visible earlier
in the waterfall.
> Do you know, when you say you see X dbc what effective bandwidth that
> is? i.e. how to translate that into signal power in a 1 hz bandwidth
> like ARRL does?
No, I don't know, because we don't know the effective bandwidth of our
measurement systems.
> Because with the FFT spectrum analyzers there is no fixed bandwidth
> filter sweeping across the spectrum.
Right. We've been working with both swept measurement systems like TDS
(Time Delay Spectrometry) and dual channel FFT since 1980. I had a TDS
system in 1982. Cost me $12K.
> ex: at 1 khz offset (14051= 5 divisions) phase noise is ~-95 dbc. but
> what would that be in a 1 hz bw?
No good answer, for the reason noted above. But this measurement shows
that this test setup is very good for measurement occupied bandwidth as
long as you stay out of non-linearity (that is, either too close to the
top or bottom of the A/D).
By all means save this measurement and compare it with what you see with
the new synth board.
73, Jim K9YC
>
> Rick K2XT
>
>
>
>
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