On 7/10/13 12:29 PM, Didier Juges wrote:
Jim said:
"It's like a HP 8663B (not the modern Agilent E8663).. very low noise,"
The Agilent E8663 has similar SSB phase noise spec as the older HP 8662A
(-144dBc/Hz @ 10 kHz with option UNY, versus -143 for the 8662). You seem
to imply they are different. Can you elaborate?
Of course, the Agilent has many more features and 0.001Hz resolution, and
the 8662 only goes to 990MHz (I think, I should know, I have two thanks to
JohnM...), but are they that much different in pure phase noise or ADEV?
Didier
It's not the phase noise that raised the problems for us. It's that when
you program them for a sweep, it goes in steps that aren't phase
continuous AND the behavior when you feed a signal into the FM input
isn't the same. The HP 8663B was, at the core, a really good phase
locked VCO, so when a sweep is programmed, the output is phase
continuous as it sweeps. This is a huge problem when you are testing a
very narrow band tracking loop (our deep space transponders have a loop
bandwidth of a few Hz)
I can't remember the details on the FM input, but it too has some
behavior that we depended on.
We take the output of the 8663B and run it into a x7 to make the 7150
MHz uplink and/or the 8450 MHz downlink frequencies.
Part of the reason we do a x7 is so that any leakage from the
synthesizer isn't in band for our receiver under test. A typical input
level for test is -150 to -160 dBm, so leakage at the wrong frequency
can easily be more than the desired signal.
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