[Elecraft] P3 as a phase noise measurement tool

[Al Lorona]

According to Al, N1AL, "The effective bandwidth of the P3 is approximately one pixel on the display, which is SPAN/468.  So, for example, if the span is 47 kHz, the effective bandwidth is about 100 Hz."

To "convert" or "correct" to a 1 Hz bandwidth, use the formula:

BW_correction_factor = 10 * log(P3_effective_BW)

For instance, to "convert" a 100 Hz effective P3 bandwidth to 1 Hz, the factor would be 20 dB. So, if you measured a noise level of -80 dBm on the P3 whose effective bandwidth were 100 Hz, that would really be -100 dBm in a 1 Hz bandwidth.

Al  W6LX/4




On Tuesday, June 7, 2022, 11:06:05 AM EDT, Dave (NK7Z) <dave at nk7z.net> wrote: 





Hi,

I am contemplating practicing some phase noise measurements using a P3. 
If I correctly understand the measurement, (which I may not), I should 
express the result, using db down from peak, so many Hz away from peak, 
using a 1 Hz width.

First question; is the above correct?

Second question; (amusing Q1 is correct), what is the pixel width of the 
P3, and can I just divide that width by total frequency spread shown on 
the P3, and assume that number I get is correct for width per pixel in Hz?

Third question, (assuming Q2 is correct), once I get a number from 
question 2, can I then just divide that result by X, where X is selected 
to bring the width of measurement to 1 Hz?

Thanks in advance for any help in this...

-- 
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to alorona at sbcglobal.net