[Elecraft] K3: listening to both rcvrs - Reduced receiver noise floor

[David Woolley (E.L)]

Tayloe Dan-P26412 wrote:

> single composite receiver with a lower noise floor.  If you 
> added just enough RF pre-amplification to overcome the signal 
> splitting loss to N receivers, adding more and more receivers 

Only if the pre-amplifiers are noiseless, or at least contribute 
equivalent input noise power that is much less than the equivalent power 
generated by the receiver times their gain.  In that case, you could do 
better by using the pre-amp on one receiver and dumping the excess gain 
later in the system.  That's better in noise, but you may compromise 
dynamic range more.

> in parallel will produce a composite receiver that has a 
> better and better noise floor.  This is in essence what the 
> space telescope folks do.  They gang many dishes and many 
> receivers together across a very large area to get an 
> enhancement on the signal and space noise and a suppression of 
> the effective receiver noise contribution.

In this case, there is no splitting loss, and the noise is uncorrelated 
because it is being received at different locations.




-- 
David Woolley
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