[R-390] r390a and SDR

[Alan Victor]

Hi Jose,

Can you clarify? Not sure what you mean "the floor is -100 dB." Do you mean
-100 dBm or -100 dB relative to WHAT? If the noise figure of the receiver
is known up to the point of the IF output port and the S/N ratio for the
SDR software is specified for proper decode or display, you should be able
to determine a noise floor value. That is typically specified as xxx dBm.

Thanks, Alan W4AMV

On Thu, Apr 18, 2019 at 3:56 PM jm <josemic at gmail.com> wrote:

> Hi fellows!
>
> Taking advantage of the IF external connection of the receiver, I have been
> using it with my SDR dongle. It is a Funcube pro+ and the  sdr software is
> Gqrx running under linux. I have to thank my son the program settings and
> his willingness to help me with the obscure world of linux.   The
> combination of both new and old technology runs smoothly.
>
> Obviously, the program is tuned to 455 kcs and the bandwith used in the 390
> is its maximum capability,  16 kcs.
>
> I am impressed by the technical level of the people in the list and hope
> not to be an annoying beginner that makes silly questions.
>
> In spite of the above, here are my questions:
>
> 1. I was surprised about the floor level in the sdr sofware. The floor is
> -100 db which is very low, in my opinion, according to what I have read
> about the 390. I don't aspire to have a receiver whith a 'galactic level'
> as Mr. Rippel says, but this is far from expected. Does that level
> correspond to the r390 or is it the sdr receiver level (funcube)?
>
> 2. I read somewhere that it is possible to feed the sdr receiver through
> some point of the 390 with the result of obtaining a much widest bandwidht.
> I remember that could be extended to 1 mhz. The current 16khz is
> appropriate for amateurs chunks of bands but in broadcasting the reception
> is limited to only one station.
>
> Many thanks as always and happy Easter!
>
> Jose
> EA8DCP
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