[Skimmertalk] Difference of RP10 14 16

[Bob Wilson, N6TV]

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
>
>
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