[aprssig] are write-only APRS-IS clients valid?

Steve Dimse steve at dimse.com
Sun Dec 1 22:37:23 CST 2013

On Dec 1, 2013, at 10:51 PM, Tom Hayward <esarfl at gmail.com> wrote:

> On Sun, Dec 1, 2013 at 7:35 PM, Andrew P. <andrewemt at hotmail.com> wrote:
>> Greetings, all.
>> I've had what seems to be an odd request for a feature expansion to my APRS
>> client YAAC, and I want to make sure it's sane before I implement it.
>> I've had more than one user ask how to configure my client to be a
>> write-only client to APRS-IS, that is, relaying RF-received packets to
>> APRS-IS, but refusing to accept any traffic back for possible relay back to
>> RF. I've seen a lot of receive-only IGates on the map, but how does one tell
>> the APRS-IS servers that a given Igate does not accept traffic for relay to
>> RF? Having a write-only GUI client seems to be a little strange (as in, why
>> not use aprx or some similar daemon-style client instead of a GUI client
>> like YAAC?).
> This breaks two-way messaging. The APRS-IS assumes that the igate that
> gated a position packet for a station can also relay a message to that
> station.

The APRS-IS assumes no such thing. In fact, when the APRS-IS was created there were only receive only IGates. It operated for a year before I developed the two-way feature. Even then I went out of my way to be sure rx only IGates were welcome. An rx only IGate is better than no IGate in almost all cases. The only possible negative effect rx-only IGates can have is to discourage people who would otherwise operate two way IGates but are unaware the IGate putting local traffic on the APRS-IS. 

On the other hand, if there are too many two way IGates in a local area they can have a negative effect on RF channel load. 

> In RX-only igates, this assumption is false and the
> message/ack may not reach its recipient.

If an area is ONLY served by an rx-only IGate, then of course internet originated traffic will not appear on RF - both messages to the local RF stations as well as ACKs for their messages to internet stations. But that is in no way related to any assumption by the APRS-IS.

If nothing else, all ARISS IGates should be receive only.

Steve K4HG

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