[Skimmertalk] Difference of RP10 14 16

Björn Ekelund bjorn at ekelund.nu
Mon Jul 22 03:05:58 EDT 2019 

I make similar observations.

Because the RP FT8 recevier is completely without compromise and runs a
straight 24/32 bit signal processing chain without AGC it is super
sensitive.
No traditional transceiver has this architecture since it is also quite
vulnerable.

Does the K3's built in preamp not help?

Björn SM7IUN


Den lör 20 juli 2019 kl 02:46 skrev Lee Sawkins <ve7cc at shaw.ca>:

> Sorry, I should have said start.sh does not work with the FT8 application.
>
> FWIW, I had put a 20 dB pre-amp on my RP-14 when it was not decoding
> anything.  It still did not decode anything.  After I changed to chan = "2"
> it started decoding signals.  I then found my K3, using the WSJT FT8
> decoder, could not hear many of the signals that the RP plus pre-amp was
> decoding.  I then put a splitter after the pre-amp and fed both the RP and
> the K3 with the amplified signals.  Then the K3 came to life and started
> hearing as well as the RP.  The pre-amp improves the s/n of the K3 by about
> 6 dB on 6 meters.  They are now reporting signals with very similar s/n.  I
> find that I can hear even more signals on 6 that I can't work with my
> barefoot K3!
>
> Lee VE7CC
>
>
> ----- Original Message -----
> From: Bob Wilson, N6TV <n6tv at arrl.net>
> To: SkimmerTalk Reflector <skimmertalk at contesting.com>
> Sent: Fri, 19 Jul 2019 16:39:19 -0600 (MDT)
> Subject: Re: [Skimmertalk] Difference of RP10 14 16
>
> Modifying start.sh works fine for sdr_receiver_hpsdr but not
> sdr_transceiver_ft8.  Only one of those applications runs at a time.
>
> 73,
> Bob, N6TV
>
>
> On Fri, Jul 19, 2019 at 3:28 PM Lee Sawkins <ve7cc at shaw.ca> wrote:
>
> > For Pavel's FT8 decoder I can confirm that chan = "2" allows me to use my
> > 6 meter antenna for my 6 meter spots and chan = "1" is used for all other
> > frequencies with my multi band vertical
> >
> > Modifying start.sh does not work.
> >
> > Lee
> > ----- Original Message -----
> > From: Björn Ekelund <bjorn at ekelund.nu>
> > To: Bob Wilson, N6TV <n6tv at arrl.net>
> > Cc: SkimmerTalk Reflector <skimmertalk at contesting.com>
> > Sent: Fri, 19 Jul 2019 13:03:36 -0600 (MDT)
> > Subject: Re: [Skimmertalk] Difference of RP10 14 16
> >
> > Bob,
> >
> > I believe my concept for cycling control scripts for Pavel's FT8 decoder
> > actually allows you to use
> > different antenna inputs for different bands. Without modifying start.sh.
> >
> > Each line in the files write-c2-files-*.cfg specifies which antenna input
> > is used for the sample collection.
> > I have not mentioned this in my write up since i have not tried it
> myself.
> >
> > ...
> >   { freq  =  7.075500; chan = 1; },
> > ...
> >
> > 73,
> >
> > Björn
> >
> > Den tors 18 juli 2019 kl 09:27 skrev Bob Wilson, N6TV <n6tv at arrl.net>:
> >
> > > Are you using a pre-amp?  Does it cover 6m?  My CliftonLabs does not.
> > >
> > > The SM7IUN scripts rotate the bands for day/twilight/night, but not the
> > > antenna assignments.  It sounds like you have a workaround for that.
> If
> > > you make the last receiver of the eight in all three .cfg files always
> be
> > > 6m, then it should work and always use antenna port 2 if using the
> > start.sh
> > > described in your post.
> > >
> > > 73,
> > > Bob, N6TV
> > >
> > > On Thu, Jul 18, 2019, 12:10 AM Lee Sawkins <ve7cc at shaw.ca> wrote:
> > >
> > >> Bob
> > >>
> > >> Splitting the signal before the pre-amp is a bad idea.  It costs you
> at
> > >> least 3.5 dB of s/n on all signals.
> > >>
> > >> I am using an RP-14 for 8 bands of FT8 skimming.
> > >>
> > >> As per your instructions I set 6 meters to Antenna "2" and the other 7
> > >> bands to "1" in "sdr_receiver_hpsdr/start.sh" "1 1 1 1 1 1 1 2 &"
> > >>
> > >> All bands except 6 meters have spotted FT8 stations.  There has been
> > >> activity on 6.
> > >>
> > >> After not receiving any 6 meter spots I took another very careful look
> > at
> > >> the setup info at https://sm7iun.ekelund.nu/red-pitaya/ft8-skimmer
> > >>
> > >> "You may also want to modify the band selection for the three daylight
> > >> periods. This is done by commenting/uncommenting the corresponding
> > lines.
> > >> If you do this, make sure you activate exactly eight bands and also
> > keep an
> > >> eye on the commas for correct syntax. The number after "chan ="  is
> the
> > >> input used for that frequency. The receiver thus supports the use of
> two
> > >> different antennas."
> > >>
> > >> My understanding from this is that you can select which antennas you
> > >> want, either "1" or "2" for each band for each time period.  I am
> using
> > an
> > >> RP-14 with 8 bands selected.  I have now selected "chan = "2" for
> only 6
> > >> meters for all 3 time periods.  The other bands all use antenna = "1".
> > >> Unfortunately 6 is dead right now.  Tomorrow I will hopefully see
> > whether
> > >> this works for 6.
> > >>
> > >> There is no mention of using "sdr_receiver_hpsdr/start.sh" for antenna
> > >> selection in the write up.
> > >>
> > >> Lee
> > >>
> > >> ----- Original Message -----
> > >> From: Bob Wilson, N6TV <n6tv at arrl.net>
> > >> To: SkimmerTalk Reflector <skimmertalk at contesting.com>
> > >> Sent: Wed, 17 Jul 2019 11:08:42 -0600 (MDT)
> > >> Subject: Re: [Skimmertalk] Difference of RP10 14 16
> > >>
> > >> On Tue, Jul 16, 2019 at 4:07 PM Lee Sawkins <ve7cc at shaw.ca> wrote:
> > >>
> > >> > It's a trade off for me. Sensitivity on high bands with a 20 dB
> > pre-amp
> > >> or
> > >> > a few busted calls on lower bands.
> > >> >
> > >>
> > >> Well, since the RP has two antenna inputs, one can assign the low band
> > >> slices to antenna input 1 (no preamp), and the high band slices to
> > input 2
> > >> (with preamp).  If using one common antenna, use a splitter:
> > >>
> > >>                                                    +------------>
> Input1
> > >> (Low Bands)
> > >> Antenna -> Front End Protector -> Passive Splitter +
> > >>                                                    +-> Pre-amp ->
> Input2
> > >> (High Bands)
> > >>
> > >> A passive attenuator in the low band input could also achieve the same
> > >> result.
> > >>
> > >> Antenna assignments for all 16 receiver slices are defined in
> > >> *sdr_receiver_hpsdr/start.sh*, and are independent, but not dynamic,
> so
> > >> this works best with no .ini file rotation in Aggregator.
> > >>
> > >> 73,
> > >> Bob, N6TV
> > >>
> > >> _______________________________________________
> > > Skimmertalk mailing list
> > > Skimmertalk at contesting.com
> > > http://lists.contesting.com/mailman/listinfo/skimmertalk
> > >
> >
> >
>
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