[OKDXA] Radios and noise

[John Geiger]

What band was this on?

On Fri, Jan 27, 2017 at 3:37 PM, Rick <K9KK at atlinkwifi.com> wrote:

> 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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