Al,
THANK YOU!!!!  Also, thanks for the formula!  :)

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 6/7/22 08:18, Al Lorona wrote:
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) <d...@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...

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