Oct 7, 2020

APRS Digipeater iGate

Alinco DR-135T, Argent Data Systems T3-135 TNC

The APRS-SDR receive-only iGate project was fun to build, and great for seeing what's happening, real time, in the state. But one thing it doesn't do well is help non-iGate APRS users. This is where a simplex APRS iGate repeater can really help, by sending data as well as receive data. 

The APRS iGate repeater requires two things. First, a transceiver to receive and repeat data to and from local stations via RF. The second is an APRS-IS internet gateway connection. With the iGate, local stations can also receive wide-area data originating from the APRS-IS gateway, data outside the reach of their RF radios.



For example, take this poor guy who's arm fell off. They are out in the middle of nowhere, beyond the reach of getting help. But because his friend has an HT with APRS, and there is a nearby APRS iGate repeater, the ambulance guys can see right where they are, even though the stations are too far apart to receive each other's RF signals directly. Thanks to the simplex APRS iGate repeater, help is on the way. What a lucky break for this guy!



Components

  • Alinco DR-135T 144 MHz transceiver
  • Argent Data Systems T3-135 internal TNC for the DR-135, 1200 bps AFSK
  • Raspberry Pi 4B 4GB
  • Armor case heat sink for the Pi
  • 32 GB SD card
  • LMR-400 flex coax
  • Diamond X-50 antenna

Software

  • Raspberry Pi OS
  • Direwolf
  • Xastir mapping

Busy downloading, configuring, doing other stuff... I'll get back soon.

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