[amsat-bb] ISS APRS with an HT

Thu Mar 26 22:40:24 UTC 2020

In the past day, I have been working with W4GCW and KJ4EJR (author of
APRSIS32 and APRSISCE who lives in my County)

There is no way not to filter based on callsign and his software is
compliant to the APRS-IS specification. Therefore, there is no way to
prevent the iGate of my messages. W4GCW says he does not listen on the ISS
frequency and rather the standard APRS frequency. Below is a response from
KJ4EJR when I asked him if it’s possible to filter out my packets.

“per the IGate specs at http://www.aprs-is.net/IGateDetails.aspx

Gate all packets heard on RF to the Internet *EXCEPT* if any of the
following are true:

   1. (AX.25 RF) The packet does not have a control field of 0x03 or a PID
   of 0xf0.
   2. The TNC has PASSALL turned on.
   3. 3rd-party packets (data type } ) with TCPIP or TCPXX in the 3rd party
   header.
   3rd-party packets without TCPXX or TCPIP mnust have the RF header and
   the 3rd party data type stripped before passing to APRS-IS.
   4. generic queries (data type ? ).
   5. packets with TCPIP, TCPXX, NOGATE, or RFONLY in the header (last 2
   are optional).

You will notice that there is NOT any option for blacklisting or otherwise
not forwarding RF-received packets to the APRS-IS for spec-compliant IGate
operation.“

On Wed, Mar 25, 2020 at 9:33 PM Brian Wilkins KO4AQF <bwilkins at gmail.com>
wrote:

> That makes sense to me and I will contact him. He is my neighbor. What I
> am not clear on is why all of a sudden it stopped working when it was
> working prior to the ISS APRS shutdown. It may also explain why when I see
> you (K4KDR) and send messages via the ISS (or what I am told is being
> digipeated because my radio gets a message that the ISS received it) you
> never see them. I have been trying off and on for a couple months now to
> reach you. I have successfully reached N1RCN on multiple occasions.
>
>
> On Wed, Mar 25, 2020 at 8:59 PM Scott via AMSAT-BB <amsat-bb at amsat.org>
> wrote:
>
>> Hi Brian & everyone.
>>
>> Websites like ARISS.net monitor the APRS traffic and display a list of
>> packets that match certain criteria.  In the case of a site that wants to
>> display packets digipeated via the ISS, they're looking for "RS0ISS*",
>> which is appended to the digipeat path of a packet that is relayed thru
>> the
>> ISS.
>>
>> When it works correctly, you transmit a packet that is digipeated by the
>> ISS and the digipeat from the ISS is heard by an iGate that puts it onto
>> the internet for sites like ARISS.net to display.
>>
>> However, generally speaking, the APRS network is designed to toss out
>> "duplicate" packets.  And as you might imagine, it's
>> first-come-first-served.
>>
>> If you'll notice on the following link to a screen shot:
>>
>> https://www.qsl.net/k/k4kdr//images/KO4AQF-digipeats.png
>>
>> ... the vast majority of your packets are being heard DIRECTLY by in iGate
>> run by W4GCW.  So, a good portion of the time, when you get digipeated via
>> the ISS, the APRS network considers that a duplicate and it's discarded.
>> YOU (and others) might hear it off the air, but it'll never show up online
>> anywhere.
>>
>> In the same image you can contrast those locally heard packets with
>> packets
>> that were digipeated & uploaded by iGate's KE4AZZ-3 & KC5ILO-12... of
>> course that's how it's supposed to work.
>>
>> You might want to reach out to W4GCW to see if he'll filter out your call
>> sign on his iGate to give your digipeated packets a chance to be heard by
>> an iGate and get forwarded onto the greater APRS network as DIGIPEATS
>> (instead of being discarded as duplicates).
>>
>> -Scott,  K4KDR
>>
>> ==========================
>>
>> On Wed, Mar 25, 2020 at 7:30 PM Brian Wilkins KO4AQF via AMSAT-BB <
>> amsat-bb at amsat.org> wrote:
>>
>> > I had no issue until it went offline and then came back. I believe one
>> of
>> > the iGates near me may have went offline since the ISS APRS pause as
>> ISS is
>> > confirming my messages however nothing is showing up on ariss.net and I
>> > can
>> > exchange messages with others. I am considering building my own APRS RX
>> > iGate from an RTLSDR and Raspberry Pi just to digipeat my own packers
>> back
>> > to APRS.fi website
>> >
>> > On Wed, Mar 25, 2020 at 7:22 PM John Brier via AMSAT-BB <
>> > amsat-bb at amsat.org>
>> > wrote:
>> >
>> > > I got through it on March 21st on a 12 degree pass using a TH-D72 and
>> an
>> > > Arrow:
>> > >
>> > > https://twitter.com/SpaceComms1/status/1241598936814694400?s=19
>> > >
>> > > It was hard, as I believe it is a little deaf or not decoding
>> > consistently
>> > > based on past reports. Some have said it seems to be easier with
>> Kenwood
>> > > radios.
>> > >
>> > > They are sending up a new Kenwood radio system soon that supports
>> > > digipeater ops so don't dismiss this mode entirely!
>> > >
>> > > 73' John Brier KG4AKV
>> > >
>> > > On Wed, Mar 25, 2020, 19:02 Steve Kristoff via AMSAT-BB <
>> > > amsat-bb at amsat.org>
>> > > wrote:
>> > >
>> > > >
>> > > >  Has anyone been able to digipeat APRS through the ISS with a 5
>> watt HT
>> > > > and an Arrow antenna lately? If so, what are your secrets for
>> success?
>> > > > If 5 watts and an Arrow doesn't work please let me know that, too,
>> so I
>> > > > can pursue a different aspect of our hobby.
>> > > > thanks!
>> > > > Steve AI9IN
>> > > > Grid EM79ji
>> > > > Oldenburg IN 47036
>> > > >
>> > > > _______________________________________________
>> >
>> >
>> >
>> _______________________________________________
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> --
> Brian Wilkins
> KO4AQF
>
-- 
Brian Wilkins
KO4AQF