[OKDXA] Radios and noise

[Rick]

Yes, Roger.  I believe you are correct on all counts.
I */_think I have also heard _/*the term "NOISE POWER" used in this 
context ???
Hey, just had an interesting contact(s).
I worked New Caledonia*LONG* path and New Zealand *SHORT* path.
I did NOT even hear New Caledonia short path ???
Since they are neighbors that is very strange.
My guess is that the New Caledonia station was aiming long path ???
OR~~~~~who knows ?????
73 Rick
K9KK


On 1/27/2017 3:16 PM, Roger Simpson wrote:
> Gentlemen:
>
> Thanks for your replies regarding S Meter Readings on CW vs. SSB. I 
> never thought of this before but I guess you are saying that assuming 
> the signal level for every 10Hz slot from 7,100,000 Hz up to 7,101,000 
> Hz was exactly -60 Dbm then the way receivers are designed then if 
> your total bandwidth is say 2.4Khz then you are going to hear more 
> noise out of the speaker than you would if you have a 500Hz bandwidth 
> -- given that the background noise on the band is the "same" in any 
> given 10Hz slot.
>
> I guess I was a little slow to the draw but I did not realize that the 
> S meter was reporting on the aggregate signal that is in the bandwidth 
> -- not just the strongest signal.  I guess another way to say this is 
> that the S-meter reading relates to how loud the noise is that is 
> heard on the speaker -- assuming that the audio level "volume control" 
> is not changed as you change modes / filters.
>
> I guess I've been living in a cave over here. I just did an experiment 
> on CW where everything stays exactly the same except I switch from a 
> 250Hz filter, to a 500Hz filter, and then a 1200Hz filter. Lo and 
> behold the S-meter changes. So the S-meter doesn't really have a 
> DIRECT correlation to the noise level going on in the band. So I can't 
> just say I've got a high noise level [or a low noise level] on 40m 
> right now because my S meter says some given reading.
>
> Implicit in this is that if W5XYZ says "the noise level on 40m CW 
> right now is S9" and W5ABC says "over here at my QTH the noise level 
> on 40CW is S6" it could be that they are both seeing the same thing. 
> We don't know unless we know what the bandwidth is that they are 
> using. Also, of course, who is to say that rig manufacturer X and rig 
> manufacturer Y have comparable S meter readings even if the mode and 
> bandwidth are the same. Also various stations have different antennas. 
> An antenna with a 40meter 3 element yagi at 100 feet might given a 
> different "noise level S meter reading" than a 40m dipole at 40 feet.
>
> I guess it is the margin between the signal to noise in terms of DBs 
> that is important -- not some particular noise level S meter reading.
>
> 73  Roger  K5RKS
>
>
>
>>>
>>
>
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