[time-nuts] New Question on HP3048A Phase Noise Test Set
mfeher at eozinc.com
Thu Jan 17 09:24:08 EST 2008
It depends on what you want to know. If you mix 10 MHz with 10.0001 MHz to
create 100 Hz, you will have + 100 Hz and -100 HZ. The spectrum analyzer
will more than likely only show the + 100 Hz. That does not mean there is no
energy at -100 Hz, in fact most of the DSP I/Q processing depends on it. I
do not have a 3048A so cannot replicate your measurement, but, I bet the
3048A is measuring the energy in both sidebands and that is why you are
reading twice the voltage. The only way to guarantee that you have a true
single sideband spur is by filtering. And, even then you have to make sure
that any amplifiers following the filtered signal is well below compression
or you will experience spectral re-growth of the unwanted sideband. Regards
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Martyn Smith
Sent: Thursday, January 17, 2008 9:03 AM
To: time-nuts at febo.com
Subject: [time-nuts] New Question on HP3048A Phase Noise Test Set
Thanks for your input.
Sorry I still don't understand.
Could you explain further.
The spur I inject is single sided (I mix 10 MHz with 10.000100 MHz to
produce 100 Hz)
So who is right? The spectrum analyser or the HP3048A.
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