[R-390] r390a and SDR

[jm]

Hi

I thought that the noise floor could be better than -100 db . My mistake.

Thanks and regards

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El vie., 19 abr. 2019 a las 14:56, Alan Victor (<amvictor at ncsu.edu>)
escribió:

> Hi Larry, Jose.
>
> If the R390A is set to 16 kHz BW that is a noise power 40 dB above kTB or
> -100 dBm.
> If the NF of the 390A is say 10 dB that would at least place the noise
> floor at -90 dBm. Perhaps additional
> gain would be required to improve the S/N ratio at the display.
>
> What am I missing? Is the noise floor of the pan adapter much higher?
> Hence we require a wider BW
> prior to applying signal to the adapter.
>
> Thanks, Alan
>
>
>
> On Fri, Apr 19, 2019 at 1:02 AM jm <josemic at gmail.com> wrote:
>
>> Thanks Larry. 50-60 khz would be a good improvement.
>>
>> Regards, Jose
>>
>> El vie., 19 abr. 2019 a las 9:00, jm (<josemic at gmail.com>) escribió:
>>
>> > Hi Larry
>> >
>> > Many thanks for your answer. Sorry that I'm not very familiar with the
>> > terms. I think thas it's called the noise floor. In my layman words the
>> > place where the signal begins. I have checked different sdr receivers
>> and
>> > the point (I suppose the noise floor?) where the signal appears is
>> > different. For example in the sdrplay the figure is -90 db. In the case
>> of
>> > the combination Funcube/r390 is -100db. My doubt is whether that figure
>> of
>> > -100db corresponds to the sdr receiver of to the 390.  I am not sure if
>> my
>> > explanation now is clear enough.
>> >
>> > Thanks
>> >
>> > El vie., 19 abr. 2019 a las 5:53, Larry H (<larry41gm at gmail.com>)
>> > escribió:
>> >
>> >> Hi Jose,  In reference to increasing the bandwidth, it might be
>> possible
>> >> to increase it to 50 or 60 kh, but I doubt any more than that.  In
>> order to
>> >> do that, you would need to bypass the 16 kh filter in the IF deck.  You
>> >> would also need to put a custom filter in it's place to increase the
>> gain
>> >> of the skirts, so the result would be some what flat.  The R390s were
>> >> designed to not have a panoramic bandwidth.
>> >>
>> >> Regards, Larry
>> >>
>> >> 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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