[Skimmertalk] Difference of RP10 14 16

[Björn Ekelund]

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
>>
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