[600MRG] measuring noise level ?

[Frank Lotito]

Don't forget, the "noise"measured, be it dBm, uV, S-Units, etc. is also "bandwidth" dependent.  I would also submit, for complete receive systems, a noise measurement is also directional, such a sweeping across the path of the sun with a VHF, UHF, SHF or microwave antenna.  If the noise peaks, Great; if the noise does not peak your aim is off, or your total system is lacking.  Ditto when your HF yagi is aimed in certain directions.  
73 Frank K3DZ / WH2XHA
________________________________________
From: 600MRG <600mrg-bounces at w7ekb.com> on behalf of Edward R Cole <kl7uw at acsalaska.net>
Sent: Sunday, July 17, 2016 12:13 PM
To: 600mrg at w7ekb.com
Subject: Re: [600MRG] measuring noise level ?

Most likely the poster of that noise measurement intended to say -85
dBm.  Spectravue provides direct level measurements of signal and
noise on a waterfall display.  Most SDR sw do this.

All modern service equipment show signal level in dBm.  I hear almost
no one using uv anymore (unless they are audiophiles).  DBm are
direct measurement in power while uv is ac voltage which requires one
to specify the impedance if it is to relate to power.

So would you rather S-meter reading be given - ha ha!  Show me two
receivers that have s-meter properly calibrated.

73, Ed - KL7UW

At 07:26 AM 7/17/2016, sbjohnston at aol.com wrote:

>I did not say there was no reason to be aware of noise - far from
>it.  In both my amateur and my professional life the problem of
>radio noise is a very big deal.  I just don't get the point of
>sharing a figure like "-85 dB".
>
>Decibels don't mean anything unless you provide the reference level
>to which your measurement is -85 dB down from.
>
>And without considering the gain or loss of the complete antenna
>system (or the bandwidth of the receive system in which you are
>adding up the noise) I can't see how you can compare station A to
>station B in a different location.
>
>
>
>
>Steve WD8DAS
>
>sbjohnston at aol.com
>http://www.wd8das.net/
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>
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73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
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