Radio and Signals: Receive-first radio, SDR, packet concepts, antenna basics, signal strength, and lawful maker experiments.
Topic group
Radio and Signals
Receive-first radio, SDR, packet concepts, antenna basics, signal strength, and lawful maker experiments.
Topic goal to ladder route
A topic names the maker goal. A ladder is the route from what you already understand to the next useful proof.
Name the part of the build you cannot explain yet.
Start with Packet Radio with a Baofeng: Receive-First APRS Basics, then choose the next related route.
Draw a receive-first packet-radio path and explain what a decoded packet proves without assuming transmit permission.
Packet Radio with a Baofeng: Receive-First APRS Basics
Understand packet radio and APRS with a Baofeng-class handheld by mapping the radio, audio path, decoder, packet fields, and license boundary before any transmit work.
Outcome: Draw a receive-first packet-radio path and explain what a decoded packet proves without assuming transmit permission.
Antenna Length Math for Makers
Estimate wavelength, quarter-wave, and half-wave starter lengths from frequency before changing antennas, cutting wire, or trusting a build video.
Outcome: Convert frequency into wavelength fractions, compare meters/feet/inches, apply a velocity factor, and explain why the result is only a starter estimate.
RSSI Mapping for Direction Finding
Use receive-only signal-strength readings to sketch a direction clue, compare angles, and explain uncertainty before making any field claim.
Outcome: Record angle/RSSI pairs, plot a strongest lobe, and explain what the reading suggests without claiming exact source location.
SDR Flight Tracking: ADS-B First Pass
Use an RTL-SDR-style receiver to understand public ADS-B aircraft broadcasts: frequency, antenna, receiver, decoder, fields, map display, and the receive-only boundary.
Outcome: Name the ADS-B frequency, antenna role, receiver role, decoded fields, and map output without confusing receive-only learning with official tracking or transmitting.
Stepper Antenna Sweep for Direction Finding
Connect trigonometry, a rotating fixture, and receive-only RSSI readings so a maker can sweep an antenna in known steps and write an honest bearing clue.
Outcome: Build a repeatable sweep plan: angle steps, antenna orientation, RSSI sample, strongest lobe, repeated run, and uncertainty note.
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