Your phone as an IGate
An IGate passes APRS traffic between a radio and the internet. As of 1.8.0, APRS Connect can be one, using whichever radio you already have connected, for as long as you leave it running. It is part of APRS Connect Pro, and it needs a radio channel, because there is nothing to gate without one.
Two switches, two very different jobs
Radio to APRS-IS takes what your radio hears and puts it on the internet. Nothing is transmitted. The only thing leaving the phone is data over your internet connection. This is the half that makes a quiet area visible on aprs.fi and in everyone else's app, and it is the half to turn on first.
By default it gates everything your radio hears that did not already come from the internet. An Only heard directly option narrows that to packets with no digipeater in the path, which is the right setting when you sit under a busy digipeater whose whole footprint some other gate is already carrying.
APRS-IS to radio is the half with a transmitter on the end of it. It takes messages arriving from the internet and puts them on the air under your callsign, automatically. That is a real responsibility, and it is why this switch starts off.
It transmits only for stations it can reach
A message from the internet is transmitted only when the station it is addressed to has been heard directly, on your radio, in the last 30 minutes. A packet that reached you through a digipeater proves the digipeater can hear that station. It says nothing about whether your radio can. Keying up on that basis spends airtime other people need and delivers nothing.
Position reports are off by default, and when they are on they go out only for callsigns you list by name. A group working an area with no coverage is a known list of a dozen people, so you name them. N0CALL-* covers every SSID of one operator, and that is the only wildcard accepted.
Some rules cannot be changed by any setting. RFONLY and NOGATE are honoured in both directions. Anything already carrying TCPIP is not put back on the internet. General queries are never gated. There is a per-minute cap, and an identical packet is never transmitted twice inside a minute.
A receive-only gate is honest about it
Every packet gated to the internet carries a marker saying whether the gate can carry a reply back. APRS Connect works that out per packet, not per setting: with transmit switched on it still says qAO for a station it only heard through a digipeater, because it could not reach them. The claim it makes is always one it can keep.
What you see
The IGate screen shows three counts, to APRS-IS, to radio, and how many stations are inside the heard window, plus the last packets it passed in each direction. In the packet log a gated packet gains a →IS or →RF mark, and a Gated chip narrows the log to what the gate handled.
Your callsign is on everything it puts on the air. Unattended automatic transmission is regulated differently in different countries, so check what applies where you are before switching the transmit half on.
The full reference, including the position roster and how the gate behaves with more than one radio, is in the IGate documentation.
