[600MRG] a discrepancy between W2 and FW2

[Tom W8JI]

Don't put too much in those S/N reports.

It looks like, assuming that is stable ground wave or direct wave 
propagation and the noise levels are stable, the F-120 is about half the 
effective bandwidth or a bit less than half of the W2 signal bandwidth.

First, the reported S/N it is a snapshot of time. Neither the noise or 
signals are constant levels over time. At any instant of time S/N can 
change significantly.

Second, it is the wide bandwidth noise compared to the narrow 
detection-bandwidth signal level. It isn't the actual signal-to-noise. 
The way it is calculated in digital modes typically inflates the 
apparent S/N by at least 15dB over what it really is.

For example, I can copy the CW ID of stations on WSPR that are reporting 
-15dB or worse on WSPR from across the room if I have the monitor 
speaker on. This is because my ears are trained to pay attention to the 
single frequency tone of maybe 100Hz or less BW and the noise BW is 
3kHz. That's log 10 (3000/100)  = 15dB right there.

Don't put too much meaning in those S/N reports. They really don't mean 
all that much if we ignore the variables.

73 Tom

On 4/8/2023 10:42 PM, Neil Klagge wrote:
> Using the same power, FW2 gives different report than wspr2
>
> 4 spots:
>
> Timestamp 	Call 	MHz 	SNR 	Drift 	Grid 	Pwr 	Reporter 	RGrid 	km 	az 
> Mode
>  2023-04-09 02:36 	 W0YSE 	 0.475729 	 -12 	 0 	 DN41ah 	 0.005 
>  KA7OEI-1 	 DN31uo 	 43 	 320 	 W-2
>  2023-04-09 02:32 	 W0YSE 	 0.475693 	 -16 	 0 	 DN41ah 	 0.005 
>  KA7OEI-1 	 DN31uo 	 43 	 320 	 F-120
>  2023-04-09 02:16 	 W0YSE 	 0.475744 	 -12 	 4 	 DN41ah 	 0.005 
>  KA7OEI-1 	 DN31uo 	 43 	 320 	 W-2
>  2023-04-09 02:12 	 W0YSE 	 0.475646 	 -15 	 0 	 DN41ah 	 0.005 
>  KA7OEI-1 	 DN31uo 	 43 	 320 	 F-120
>
>
> running wspr2 for rest of the night.
>
> 73 and GN all
>>> **´¨)
>>> ¸.•´¸.•*´¨) ¸.•*¨)
>>> (¸.•´ (¸.•`   Neil *, wØyse, DN41ah, North Ogden, Utah 84414
>
> My ham radio website: http://w0yse.webs.com/ <http://w0yse.webs.com/>
>
> My Faith website: http://neilsfaith.webs.com/ 
> <http://neilsfaith.webs.com/>
>
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