---
layout: page
title:  "Building an APRS network with garage door openers"
description: "My adventures bridging packets between On/Off-Keying and FM-based networks"
date:   2021-05-17 15:00:00 
written: 2021-05-17
tags: project radio aprs
excerpt: >-
    [words go here]
redirect_from: 
 - /post/eb0kf6d9/
 - /eb0kf6d9/
---

Lately, I have been experimenting with [AX.25](https://en.wikipedia.org/wiki/AX.25) and the [Automatic Packet Reporting System](https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System) built on top of it. Through these experiments, I have learned a lot, and built quite a few fun projects. 

APRS has a bit of a data-rate-limiting issue. Most (almost all) packets sent across the network are sent "UDP-style", and since they *may* or *may not* actually reach their target, stations re-broadcast the same packet data 5 or so times for each packet sent. Now, imagine 100 stations all trying to send data on the same radio frequency, at a fairly small interval. Not much can actually get through. This was my first piece of motivation for this project.

Secondly, APRS transmitters are *expensive*. Common boards like the [PicoAPRS](https://int.wimo.com/en/picoaprs) and [ARP Labs LightAPRS](https://www.qrp-labs.com/lightaprs.html) cost $100 to ~$300 CAD.


Solving the first problem, as you might with a standard computer network, *why not build a subnet for local data?* For the second, there have to be cheaper radio transceivers and computers in existence right?