Documentation
Onboarding
Getting Started
Power & Battery
Hardware & Components
Build & Assembly
Radio & RF Design
Frequencies & Regulations
Firmware & Software
USB & Connectivity
GPS & Navigation
Morse & Communication
Modes & Operation
Field Operations & Rescue
Building Effectively
Build Variants
Project & Reference
Docs Morse & Communication Simplex Communication

Simplex Communication

Edit on GitHub

Simplex operation, the mode the beacon uses: one frequency, one direction at a time, and the rules that keep simplex usable.

Simplex Communication

The beacon is a simplex device: it transmits on a frequency and receivers listen on the same one, never at the same time. This page is what simplex means and how to operate it.

Simplex versus duplex

ModeFrequenciesDirection
SimplexOneOne way at a time
Duplex (repeater)Two (input and output)Simultaneous

The beacon’s design is pure simplex: it transmits its bursts on its channel, and any receiver on that channel hears them (see Receiver Compatibility).

The simplex rules

  1. One at a time: in simplex, only one station transmits at a moment. The beacon respects this by bursting briefly and waiting (see Firmware TX Scheduler).
  2. Listen before you speak: the universal habit (see Radio Etiquette Basics).
  3. The tail: wait a second after the other station stops; radio squelch tails are real.

The beacon’s simplex behavior

The beacon never listens and transmits simultaneously, and it has no collision avoidance: it transmits on schedule, briefly, and repeats. In a shared simplex channel this is the correct strategy for a device that cannot hear (the one-way design documented in Rescue Communication Basics).

The group simplex net

For a group, simplex on one channel is the simplest coordination: everyone hears everything, and the Group Communication Plan staggers the beacons so the bursts do not collide.