[R-390] r390a and SDR

[Martin Sole]

It belongs to the sdr most likely, and can be made to show whatever you 
like by adjustment of some sdr controls, depending on the software and 
driver. Quite often you can adjust the gain of the sdr device which 
esentially moves the "grass" that which shows as random noise in the 
spectrum display. This is purely a relative figure, unless calibrated, 
and most likely bears no relationship to the performance of the receiver 
to which it is attached as a detector at the receivers IF. Much will 
also depend on the gain in the receiver between the antenna port and the 
IF output.

I don't know the R390 that well but I doubt the noise level present at 
the IF output is much lower than -100dBm possibly it is even higher than 
that. I expect there is significant amplification between the antenna 
connector and the IF output.

Martin, HS0ZED


On 22/04/2019 18:08, jm wrote:
> Hi Alan,
>
> The noise floor that I can see in the sdr software (-100 dbm) belongs to
> the sdr device or to the r390a receiver?
>
> Your explanation is about a noise floor of -100 dbm. This level  could be
> considered as low if  the comments of Chuck Rippel are taken into account
> (up to -143 db in exceptional cases).
>
> Is my receiver performance below its possibilities?
>
> Thanks
>
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