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

Andrew P. andrewemt at hotmail.com
Mon Dec 2 15:04:03 CST 2013

Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: "Andrew Pavlin" <AndrewEMT at hotmail.com>
Date: Mon, 2 Dec 2013 21:04:32 
To: Lynn W. Deffenbaugh (Mr)<ldeffenb at homeside.to>
Reply-To: AndrewEMT at hotmail.com
Subject: Re: [aprssig] are write-only APRS-IS clients valid?

OK, so this means that YAAC is compliant, but with not enough controls. The missing controls being:

1. the categorization of an RF-heard station as recent enough and close enough to be a I-gate-to-RF target (settings are hard-coded in YAAC instead of adjustable). Since YAAC allows any interface to be configured receive-only (both RF and Internet), that provides the legal constraints for jurisdictions requiring attended transmitting;

2. The ability to have transmit-enabled ports on RF and Internet without I-gating between the ports (YAAC currently assumes that if the ports can transmit then I-gating should occur in the transmit-enabled direction(s)). YAAC is smarter and more configurable about RF-digipeating (including cross-band digipeating).

And I have been informed of "low bandwidth" client ports on APRS-IS servers that I should consider supporting as well.

So, off to code some more......

Andrew Pavlin, KA2DDO
author of the ever-evolving YAAC
------Original Message------
From: Lynn W. Deffenbaugh (Mr)
To: aprssig at tapr.org
Sent: Dec 2, 2013 3:10 PM
Subject: Re: [aprssig] are write-only APRS-IS clients valid?

On 12/2/2013 2:27 PM, Andrew P. wrote:
> b) I didn't know of any way to tell an APRS-IS server to not send any packets back to me (and, from what Pete is saying, that appears to be deliberately impossible).

You can always ignore the packets coming back from the APRS-IS server.  
Basically that's what APRSISCE/32 does if the operator disables -IS to 
RF gating.  Of course, the operator can also put APRSISCE/32 into 
Receive-Only mode (provided for countries like the UK that only allow 
attended transmit unless you have special licensing), or disable 
transmit on the RF port(s) (similar to just disconnecting the PTT 
between the TNC and radio).

IMHO, an IGate shouldn't just blindly pass all packets received from the 
APRS-IS server to the local RF anyway.  The IGate operator should be in 
control of the "recently" and "local" parameters which govern which (if 
any) messages should be gated from -IS to RF.  The APRS-IS server, I 
believe, defaults to 3 hours for recent and local just means that the 
connected client has received a packet from the message-addressed station.

And if the IGate operator wants to use a filter that receives data just 
for his/her own viewing, those packets should definitely not be gated to RF.

The APRS-IS server attempts to deliver packets on a filtered port that 
the IGate might be interested in.  The server is not implying that such 
packets must be gated to the RF by an IGate.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

PS.  APRSISCE/32 defaults to a full bi-directional IGate whenever both 
the APRS-IS and at least one RF port is configured.  The operator has to 
change the defaults to force a Receive-Only IGate.

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