Bruce Griffiths wrote:
Magnus Danielson wrote:
On 09/29/2012 02:45 PM, Bruce Griffiths wrote:
For those that have Timelab the link to the E1938A PN measurement
data is:
https://dl.dropbox.com/u/59708595/E1938A.tim
Thank you. I will measure mine so that we can compare them.
Cross-correlation with a pair of BVAs should do it.
Cheers,
Magnus
I'm still a little suspicious of the result, although measuring a
second E1938A removed from a Z3815A produced similar results.
I'll measure one of them again with an isolation transformer to
eliminate an LF earth loop to see if the earth loop was an issue.
Using a single reference (PN floor < -170dBc/Hz) should suffice for this.
I didnt have RF isolation transformers available at the time.
I have since found that using a single point LF ground (rather than
floating the entire interferometer) reduces the interferometer PN
floor substantially.
Bruce
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Measuring the E1938A with a single point LF ground produces
substantially the same result.
A PN measurement using a different technique (classical mixer and low BW
PLL) may be useful.
Bruce
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