aprs.me/docs/contexts/devices.md

Devices Context

Overview

Identifies APRS equipment from packet data, maintaining a local registry of known devices.

Schema: Aprsme.Devices (lib/aprsme/devices.ex)

Stores known APRS device information in the devices table:

Field	Type	Notes
identifier	string	Unique device identifier
class	string	Device class (e.g., "tracker", "handheld")
model	string	Model name
vendor	string	Manufacturer name
os	string	Operating system
contact	string	Vendor/author contact
features	{:array, :string}	Feature tags

No FK constraint: device_identifier on the packets table is a free-text string, not a DB-level reference.

DeviceIdentification (lib/aprsme/device_identification.ex)

Static Identification

Matches known MIC-E symbol patterns (regex-based) to identify ~20 common device types from packet data.

Remote Registry

Fetches device database from aprs-deviceid.aprsfoundation.org:

• maybe_refresh_devices/0 — Weekly refresh cycle
• fetch_and_upsert_devices/0 — HTTP fetch wrapped in CircuitBreaker, upserts results into devices table
• lookup_device_by_identifier/1 — Wildcard-matching lookup, delegates to DeviceCache

Caching

• DeviceCache GenServer caches device data, refreshed daily
• Backed by Aprsme.Cache abstraction

DeviceParser (lib/aprsme/device_parser.ex)

Extracts device identifiers from incoming packets by probing:

1. data_extended.device_identifier field
2. destination field
3. data_extended.symbol_table_id + symbol_code combination

Called during packet ingestion pipeline in PacketConsumer.

Resilience

• CircuitBreaker wraps remote HTTP fetch, preventing cascading failures
• Cache ensures device lookups work even when remote source is unavailable
• Static patterns provide fallback identification without network calls