APRS.FI intercepting ALL N1RIJ messages

[Jonathan Moore]

I love the ability to tx/rx messages via the iOS app in my iPhone 12! However I have discovered today that if I send messages from my RF devices that use the internet at some point in the process (i.e. WXBOT) the replies ONLY return to the iOS app and do not make it back to the RF device. Also, the RF device doesn't seem to get an "ack" so it keeps resending the packets. I could not find any hints/tricks/or workarounds. It is handy my iPhone sees the replies but I really need the radios to get the messages when the iOS app is not connected to the internet. Thoughts? 73's Jonathan/N1RIJ

[Quentin Smith]

That's primarily a function of how the digipeaters in your area are configured. Each digipeater has a filter of which packets, if any, it is willing to repeat from the Internet to RF. I suggest looking at aprs.fi to see what node is receiving your RF packets and contact that node's operator to inquire about their digipeater configuration. e.g. the digipeater I operate is configured with a filter of "m/40", which means messages addressed to a station that was last seen within 40 km are repeated over RF.

That said, you shouldn't be using the same SSID on multiple devices at once - so you shouldn't be seeing the replies on your phone if your RF device sends a request. It's possible that is confusing something, especially if the two devices are not reporting the same location.

73,

--Quentin

AB1IZ

On Mon, Nov 30, 2020 at 11:31 PM Jonathan Moore <emsja...@gmail.com> wrote:

I love the ability to tx/rx messages via the iOS app in my iPhone 12! However I have discovered today that if I send messages from my RF devices that use the internet at some point in the process (i.e. WXBOT) the replies ONLY return to the iOS app and do not make it back to the RF device. Also, the RF device doesn't seem to get an "ack" so it keeps resending the packets. I could not find any hints/tricks/or workarounds. It is handy my iPhone sees the replies but I really need the radios to get the messages when the iOS app is not connected to the internet. Thoughts? 73's Jonathan/N1RIJ

--
You received this message because you are subscribed to the Google Groups "aprs.fi" group.
To unsubscribe from this group and stop receiving emails from it, send an email to aprsfi+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/ec5a5060-447f-41e2-ad62-f8b1944cdb2fn%40googlegroups.com.

[Heikki Hannikainen]

On Mon, 30 Nov 2020, Jonathan Moore wrote:

> I love the ability to tx/rx messages via the iOS app in my iPhone 12!

I'm glad you like it! I'm myself a bit surprised how smooth the
SMS/iMessage/whatsapp/facebook-style chat approach works for APRS.

> However I have discovered today that if I send messages from my RF
> devices that use the internet at some point in the process (i.e. WXBOT)
> the replies ONLY return to the iOS app and do not make it back to the RF
> device. Also, the RF device doesn't seem to get an "ack" so it keeps
> resending the packets.

Hi,

This is probably due to a transmit-capable igate not being present in your
area, within range from your RF device (perhaps via a digipeater to extend
the range). Many igates are RX-only, i.e. they receive packets from RF
and pass it on to the APRS-IS network on the Internet. A TX igate is
needed to transmit messaging packets from the APRS-IS to RF so that they
can be received by the RF device. To improve the situation you can
probably set one up yourself, or possibly initiate such a project with a
local club.

On the APRS network messages are not routed to a single recipient device,
but rather to *all* recipients listening for a specific callsign. So the
presence of the aprs.fi app listening for these packets does not affect
that RF device in any way.

APRS messaging capable devices typically receive messages targeted to any
SSID of the callsign they're configured with, so that the sender of a
message does not need to know exactly which SSID you're on right now (car?
mobile? desktop client?) when sending an initial message. But they will
only send an ACK if the message is targeted to the exact correct SSID.
This is according to Bob Bruninga's specification, and I think it makes
sense. This is why the app is showing the messages even if they're sent to
the SSID of your RF device.

- Hessu

[Heikki Hannikainen]

On Tue, 1 Dec 2020, Quentin Smith wrote:

> That's primarily a function of how the digipeaters in your area are
> configured. Each digipeater has a filter of which packets, if any, it is
> willing to repeat from the Internet to RF.

I'd like to clarify the terminology a bit, to reduce confusion in the
longer term:

* a digipeater is a station which receives packets from RF and retransmits
them on RF; a digipeater is by default not connected to the Internet at
all

* an iGate is a gateway station which has a radio receiver or transceiver
and is connected to the APRS-IS network on the INternet

A station *may* be both an igate and a digipeater at the same time. But
there are a lot of hilltop and mast-mounted digipeaters with no Internet,
with just a radio and a TNC.

> I suggest looking at aprs.fi to see what node is receiving your RF
> packets and contact that node's operator to inquire about their
> digipeater configuration.

iGate configuration.

> e.g. the digipeater I operate is configured with a filter of "m/40",
> which means messages addressed to a station that was last seen within 40
> km are repeated over RF.

If an iGate software is working according to the specification, it does
not require a range filter such as "m/40". It will, by default, transmit
message packets to RF if a the recipient has been heard recently.

If you're setting a server-side filter of "m/40" the APRS-IS server will
send you *all* packets within 40 kilometers from your position; not just
message packets.

If you don't set any filter, the APRS-IS server will send you the
*message* packets for stations which you have heard recently (within 3
hours if I remember right; the APRS-IS server keeps track of the callsigns
you've igated to it).

> That said, you shouldn't be using the same SSID
> on multiple devices at once - so you shouldn't be seeing the replies on
> your phone if your RF device sends a request.

Right - you should use a unique SSID on each device. But it is expected
that you'll see the replies on the phone, as the devices will show all
messages sent to a callsign regardless of the SSID. They just won't send
out ACKs if the SSID is not used by that device.

- Hessu

[Jonathan Moore]

Excellent feedback. I will pursue all. All my SSID numbers are unique per each device. The SSID for the aprs.fi app ( iphone ) is -4 but still receives N1RIJ- messages regardless of SSID. Will dig further, thank you! JWM

Sent from Jonathan's iPhone

On Dec 1, 2020, at 3:37 PM, Quentin Smith <qsm...@gmail.com> wrote:



You received this message because you are subscribed to a topic in the Google Groups "aprs.fi" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/aprsfi/gbrfxwfaAhE/unsubscribe.
To unsubscribe from this group and all its topics, send an email to aprsfi+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/CAE4MTM_oK_yZ-9ccftPahO5fst5AN%3DoNuRTQQh7qJa67dtt94w%40mail.gmail.com.