I-Gating Tutorial for YAAC
The basic concept of an I-gate (Internet gateway), is that it
digipeats APRS packets between the local RF network and the global
Internet APRS-IS backbone network, as served by the Tier 1 core
servers, the Tier 2 regional servers, and uncounted site-local
servers. This permits long-distance messaging between stations not
within normal digipeater hop range.
Note that, as always, you are required to be licensed as an
amateur radio operator in order to transmit packets to RF; as such,
the APRS-IS backbone also requires that you be licensed in order to
send packets to the backbone, because packets you send to the
backbone may be transmitted to RF by other stations connected to the
backbone. Note that the only packets forwarded from Internet to RF will be:
- APRS text messages addressed to an RF station that this I-gate was
previously forwarded to the Internet;
- the next position report from stations sending such text messages after
the text message is forwarded;
- any additional messages explicitly filtered forward from the Internet
by the filter expression on the APRS-IS port and further enabled for RF
retransmission by the supplemental Tx I-gate filter.
To function as an I-gate, your station needs the following
- a radio covering the local APRS frequency in your area;
- a TNC (or software equivalent) to send and receive APRS frames;
- a computer to run the I-Gating software; and
- a reliable always-up Internet connection that can get you to
one of the APRS-IS servers.
YAAC is capable of functioning as I-gating software, once the
following steps are carried out to set it up:
- You need to get an APRS-IS server passcode for your
government-assigned callsign, so you can send packets to the
APRS-IS. If you already have a passcode for other software, it will
also work with YAAC (the passcode is for the APRS-IS network, not
for YAAC itself). If you do not have a passcode, please e-mail
YAAC's author through his website, http://www.ka2ddo.org, sending
your name and amateur radio callsign, to apply for a passcode.
Alternatively, if you have a valid ARRL Logbook of the World certificate,
you can use that to log into SSL-enabled APRS-IS servers.
- You need to configure your RF port in YAAC, using either the
Serial_TNC port type (for hardware TNCs or integrated radio-TNCs
like the Kenwood TM-D710 or TH-D72) or the AGWPE port type (for
software TNCs running on your computer and connecting to your radio
through a sound card and some kind of PTT trigger port). The KISS-over-TCP TNC
port type and possible additional port types provided by plugins
may also be suitable for this.
- You need to configure your passcode-authenticated APRS-IS or
SSL-authenticated APRS-IS (Internet) port in YAAC,
specifying your passcode or certificate and enabling the port for Transmit.
- You need to specify your beacon symbol for an I-Gate, which
is typically one of the following codes (other codes exist, but YAAC
does not support their modes):
- I& - generic I-gate (prefer using more specific and
- T& - full-function 2-way I-gate (RF-to-Internet and
Internet-to-RF) with one-hop receive and transmit
- 2& - full-function 2-way I-gate (RF-to-Internet and
Internet-to-RF) with two-hop receive and transmit
- R& - receive-only (Rx) I-gate (RF-to-Internet only)
- I# - simultaneous full-function 2-way I-gate and digipeater
- You need to ensure I-gating is enabled in the directions you
will support, by viewing the expert-mode Configure dialog's Transmit
tab and ensuring the Allow Gating checkboxes are appropriately
enabled and the maximum hop count is properly set. Note that it is possible for YAAC to function as a
digipeater and receive-only (Rx) I-gate simultaneously by setting these
checkboxes appropriately, although two-way (Tx) I-gates are preferred
if permitted in your jurisdiction. Use of Rx-only I-gates is discouraged as it
actually reduces messaging coverage by confusing nearby Tx I-gates into thinking
the Rx-only I-gate can forward messages to RF stations so the Tx I-gate shouldn't to
avoid local RF bandwidth wasting with duplicate transmissions.
- If you wish to transmit additional traffic to RF that you are receiving from the Internet,
first ensure that the rate at which these supplemental packets are arriving at your station
will not saturate the local RF channel when added to existing RF traffic. Then specify the
most restrictive supplemental Tx I-gate filter that will include the specified traffic
(and no other extra traffic).
Monitoring and Controlling Your I-Gate's Operation
A special view is provided in YAAC to display the callsigns of all
stations whose packets were repeated from the Internet to your local
RF network. The View menu's View Tx IGated Stations choice shows
every station that was gated from Internet to RF by YAAC, displaying
the last time a message was forwarded and the last time a position
report was forwarded for the Internet station.
You can see all the stations you are receiving over RF by using the
packet source filter to trim down the stations appearing in many of the
tabular views in YAAC to only RF-originated stations. The Station/Object list
is probably the most convenient view for this filter mode.
If there is a station generating objectionable traffic that you do
not wish to have your station forward, the blacklisting feature can
be used to prevent your station from forwarding traffic (either by
digipeat or I-gate) or responding to queries from selected