[600MRG] RSSI Versa's Noise reports

[Brian Pease]

These negative s/n numbers for digital modes are the signal to noise 
ratio, in dB, of the received signal in the SSB noise bandwidth of a 
typical receiver, 2.5 or 2.7kHz.  This give a more or less standard way 
to report s/n.

Since most modes are much narrower BW, they may actually have a positive 
s/n in dB if measured and reported in a noise BW closer to the signal BW.


On 10/5/2016 6:14 PM, Alan Cooper wrote:
>   
>
>   
>
> I like Rudy's dose of common sense of averaging many readings. In the
> commercial field of
>
> telecommunications I run into a fair number of highly educated "engineer's"
> who will tell one
>
> that on a certain street corner at the intersection of chaos and discipline,
> the RSSI will always be
>
> a negative blah blah db without exception or variation. When I hear that I
> always think to myself
>
> here we go again!  It however makes a valid point that most all of the guys
> on this 600MRG reflector
>
> have a better practical understanding of propagation than they do! Not all
> of those engineers mind
>
> you (there are some who are really sharp and are way under appreciated for
> the skills they have).
>
>   
>
> There is one thing I am not getting a good grasp of in these discussions
> however that I hope someone
>
> can help me with..
>
> What are the points of reference that these S/N logarithmic readings revolve
> around?
>
> In the telecommunications field the noise floor (with some manmade noise
> thrown in) is considered
>
> To be between -125db down to -140db with normal loss of a call in progress
> happening near -117db
>
> To -120db. A RSSI of a -45 to a -70db is considered to be a very HOT signal
> level range. This of course
>
> takes place at freq.'s that range from 700 MHz up to 1.9 GHz.
>
>   
>
> the reports here on the 600MRG of -30db then as compared to all of that (if
> one could remove the noise factor)
>
> is a very good signal level so I feel that my points of reference are all
> messed up in terms of 475Khz RSSI measurements.
>
> Can anyone please shed some light on this?
>
>   
>
> Thanks
>
>   
>
> Alan Cooper
>
> w7aln at netzero.com
>
> Bandon, Oregon
>
>   
>
>   
>
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>
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