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[aprssig] APRS Messaging

Gregg Wonderly gregg at wonderly.org
Thu Jul 29 16:52:08 UTC 2010


I've used exactly this capability of the IS in my iPad APRS application, 
APRSNow.  You can send a message and see the acknowledgement come back from the 
RF station.

Gregg Wonderly
W5GGW

Brett Friermood wrote:
> On Wed, Jul 28, 2010 at 11:56 PM, Adi Linden <adil at adis.on.ca> wrote:
>> I've read the docs you've recommended. I suppose I am interested in a lot more detail. In order
>> for a message to make it from IS to RF, does the iGate need to listen to the complete IS data
>> stream? Or is there a mechanism that allows an iGate to forward the "heard" list to upstream
>> server(s) to establish a path for messaging?
> 
> The IS is smart. It knows which stations have been heard by which
> IGates. When a message is
> sent to an RF station, the IS forwards that packet to an appropriate
> IGate which heard that station
> recently. That IGate then transmits the message packet, which is
> received by that station.
> 
> So, no. An IGate should not have to listen to the complete data stream
> because the IS forwards
> message packets to an appropriate IGate irrelevant of any filters
> blocking most of the data stream.
> 
>> I tried sending message to my two messaging capable radios. One should have been gated
>> through my iGate, the other via some other iGate while I was travelling. Neither message ever
>> made it. I'd like to understand why. Especially when it comes to my own iGate I'd like to be
>> able to configure it appropriately for messaging.
> 
> First, the particular IGate has to be configured for two way, as
> compared to one way, operation. A
> one way IGate only receives via RF and transmits to the IS. A two way
> IGate has the ability to take
> packets, usually messages, heard on the IS and transmit them over RF.
> In many places IGates do
> not function as two way, but receive only.
> 
> Second, an IGate has to hear an RF station before it can transmit to
> it. This is because the IS
> doesn't know where to send a packet until it knows which IGate(s) are
> receiving that station. I'm
> not sure of the exact timing, but an IGate also has to hear that
> station fairly recently.
> 
> After making sure your IGate is set for gating to RF, try sending a
> position packet from your
> portable. Then if you send a message through the IS to your portable,
> it should be gated to RF.
> 
> Hope that helps,
> Brett
> KC9MWG
> 
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