[aprssig] IGate (Identification? (RO or RT)?

Steve Dimse steve at dimse.com
Sat Jul 16 05:00:52 CDT 2016


> On Jul 16, 2016, at 12:01 AM, Robert Bruninga via aprssig <aprssig at tapr.org> wrote:
> 
> Is there a way to see who is one way, and who is 2 way?
> I dont think so.
> 
There is if the IGates send the beacon that looks like this:

<IGATE,MSG_CNT=1501,LOC_CNT=55

A one-way gate will have a msg_cnt of zero (or haven't IGated a message since the last restart). If the counter increments then it is trying to IGate messages to RF. Of course, it still may be getting RF from a scanner, not have the PTT line connected, etc, but the software is trying at least.

You can even use this as an imprecise test of whether they are IGating a message to you. Check the count, send a (few) message(s) to your call via the internet that should be IGated, then check the next count. If it doesn't increase then it definitely is not IGating your call, if it increases by at least the number of messages you sent then it may be IGating to you (or someone else is using that IGate in the same interval - so the more messages the lower the chance someone else incremented the counter).

> Looking at the raw packets, I see 6 IGates that hear my 2-2 packets (yes, I coiuld drop to 1 hop), but if the local 1 hop IGaqtes are 1 way only, then I just shot byself in the foot and dont know it.
> 
I'm guessing you are getting this from the path of the raw packets. Keep in mind that there are dup removals along the way, so there may be many IGates that do not win the battle to the buzzer but are still IGating. Repeat after me....
"The APRS-IS cannot be used for deriving any reliable propagation information."
"The APRS-IS cannot be used for deriving any reliable propagation information."
"The APRS-IS cannot be used for deriving any reliable propagation information."
....

> So now the question is, can we ADD IT somehow. 

Send the IGATE beacon and look for non-zero cnt. If you want to eliminate the possibility of a two-way IGate that hasn't IGated yet start the counter at 1 if set for two way operation.

Steve K4HG






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