5 guides
APRS & Packet
From digipeater paths and IGates down to AX.25 framing, Mic-E, and the APRS-IS filter language.
APRS Without the Confusion
What APRS actually is, why your path setting matters more than your radio, and how to set up a tracker, an IGate, or messaging without annoying the entire region. Start here, then go deeper.
APRS Packet Anatomy: AX.25, TNC2, and Data Types
What is actually on the air. The AX.25 UI frame field by field, address encoding and the has-been-repeated bit, the TNC2 monitor format, and the full data type identifier table.
Decoding APRS Position Reports
The compressed base-91 format and Mic-E, decoded by hand. Exact byte offsets, the destination-address encoding table, and the arithmetic that turns printable ASCII back into coordinates.
APRS-IS: Servers, Filters, and Gateways
The internet side of APRS in full: the login handshake, q constructs and how they record provenance, the complete server-side filter language, and the rules an IGate must follow.
APRS Weather Stations: Packet Formats and Feeding the Network
The APRS weather report format field by field, the s-means-two-things trap, positionless versus positioned reports, and how to get a modern IP weather station onto APRS and CWOP.