[time-nuts] New Question on HP3048A Phase Noise Test Set

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Jan 17 14:08:52 EST 2008

Martyn Smith wrote:
> Bruce,
> 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.
> Best Regards
> Martyn
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With coherent double sideband spurs the DSB to SSB correction is
actually 6dB (not 3dB - applies to incoherent (noise) spurs).
Perhaps the 3048 is identifying the spur as a pair of coherent DSB spurs
and making the 6dB correction.
In most cases (modulation of EFC voltage, modulation via OCXO power
supply) you will get coherent DSB spurs.

The question is if you produce equal amplitude  DSB spurs does the 3048
give the correct answer?


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