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== Ham Radio Protocols ==
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Your comprehensive guide to radio frequencies, protocols, and the tools to explore them.
 
=== GMRS (General Mobile Radio Service) ===
 
Frequency allocation: 462-467 MHz, 22 channels total. Channels 1-7 and 15-22 allow up to 50W, channels 8-14 limited to 5W.
 
Repeater pairs: Channels 15-22 use +5 MHz offset (input 467.550-467.725, output 462.550-762.725).
 
Licensing: $35 FCC registration, no examination required, 10-year term covers immediate family.
 
CTCSS/DCS: Privacy codes prevent interference but don’t provide security - all transmissions remain receivable.
 
=== Amateur Radio Fundamentals ===
 
2 meters (144-148 MHz): Most popular VHF band. Repeater outputs 144-145 MHz, inputs 145-146 MHz with +600 kHz offset. Simplex operation on 146.52 MHz (national calling frequency).
 
70 centimeters (420-450 MHz): UHF band with +5 MHz offset for repeaters. Regional variations exist - West Coast often uses -5 MHz.
 
6 meters (50-54 MHz): “Magic band” with sporadic E propagation enabling 500+ mile contacts during openings.
 
License progression: Technician (VHF/UHF privileges, limited HF), General (most HF bands), Amateur Extra (full privileges including exclusive subbands).
 
Exam structure: 35 multiple choice questions, 74% passing score. No Morse code requirement since 2007.
 
=== Mesh Networking ===
 
Meshtastic: LoRa modulation on 915 MHz (US), 868 MHz (EU), 433 MHz (Asia). Spreading factors SF7-SF12, higher SF = longer range but slower data rate. AES-256 encryption with rotating keys.
 
Hardware: ESP32-based nodes, typical 1-10km range depending on terrain and antenna height.
 
Protocols: Position sharing, text messaging, sensor data relay through multi-hop mesh.
 
AREDN (Amateur Radio Emergency Data Network): High-speed mesh on 2.4/5.8 GHz using modified OpenWrt firmware. IP networking over amateur frequencies enables video, VoIP, file sharing.
 
Equipment: Ubiquiti devices flashed with AREDN firmware. Bandwidth up to 150 Mbps depending on modulation and channel width.
 
=== ATAK Integration ===
 
TAK (Team Awareness Kit): Military-derived situational awareness platform using Cursor-on-Target (CoT) messages in XML format.
 
Data sources: GPS positions, imagery, chat, file sharing.
 
Radio integration: APRS position feeds, voice coordination on amateur frequencies.
 
Mesh compatibility: Operates over any IP network including AREDN mesh nodes.
 
Plugin architecture: Supports various radios through TAK server or direct integration. Amateur radio provides backup when primary data links fail.
 
=== Software Defined Radio ===
 
HackRF One: 1 MHz - 6 GHz coverage, half-duplex operation. Sample rate up to 20 MSPS, 8-bit resolution.
 
Software: GNU Radio, SDR#, GQRX, Universal Radio Hacker.
 
Applications: Spectrum analysis, signal reverse engineering, protocol development, interference hunting.
 
RTL-SDR: $20-30 dongles covering 24-1700 MHz (with gaps). RTL2832U + R820T2 common chipset combination.
 
Uses: ADS-B aircraft tracking, ACARS decoding, trunked radio monitoring, ISM band analysis.
 
=== Flipper Zero Capabilities ===
 
Sub-GHz radio: 300-928 MHz coverage using CC1101 transceiver. ASK, FSK, GFSK, MSK modulations with configurable parameters.
 
Applications: Garage door analysis, weather station monitoring, ISM device research.
 
Storage: Raw recordings and protocol analysis for reverse engineering.
 
Additional radios: 125 kHz RFID, 13.56 MHz NFC, infrared transceiver.
 
GPIO interface: External radio modules and sensors. Open source firmware with active development community.
 
=== ADS-B Surveillance ===
 
Frequency: 1090 MHz, Mode S transponders broadcasting position, velocity, identification, status.
 
Range: Line-of-sight, typically 100-250 miles with elevated antenna.
 
Decoding: dump1090 software with RTL-SDR hardware.
 
Integration: Feeds to FlightRadar24, ADSBexchange for global tracking network.
 
Military/sensitive aircraft: Often operate with transponders disabled or on different frequencies.
 
MLAT: Multilateration using time-difference-of-arrival from multiple receivers enables tracking without GPS broadcasts.
 
=== Programming Procedures ===
 
TH-D3 offset programming: Menu → Frequency → Offset Direction (+ or -) → Offset Frequency → Enter value → Store.
 
Memory channels: Menu → Memory → Channel number → Store current frequency/settings.
 
CTCSS: Menu → Signaling → CTCSS → Tone frequency selection.
 
Repeater directories: RepeaterBook.com, RadioLabs.com for frequency coordination.
 
Band plans: ARRL band plan documents specify recommended uses for frequency segments.
 
See also: [[Frequencies]] [[Electronics Lab]] [[Prep Mesh]] [[ATAK]]
 
{{Navbox Ham Radio}}

Revision as of 23:26, 7 December 2025

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