Ham Radio
Ham Radio Protocols
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 462.550-462.725). ‘’‘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.
Digital Protocols
‘’‘Packet radio:’’’ AX.25 protocol standard, typically 1200 baud on 2m (145.01-145.09 MHz). ‘’‘APRS:’’’ 144.39 MHz North America primary frequency. Transmits position, weather, messages using unconnected protocol. ‘’‘Winlink:’’’ Email over radio using Pactor, VARA, or packet modes. RMS (Radio Message Server) gateways connect to internet.
‘’‘DMR (Digital Mobile Radio):’’’ Time-division multiple access, two talk paths per 12.5 kHz channel. Talk groups enable worldwide communication. ‘’‘D-STAR:’’’ Digital voice with 6.25 kHz bandwidth, internet linking via reflectors. ‘’‘System Fusion:’’’ Yaesu’s digital mode with analog fallback capability.
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. ‘’‘Encryption:’’’ AES-256 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. ‘’‘Protocols:’’’ 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. ‘’‘Frequency coordination:’’’ Amateur radio provides backup when primary data links fail. Voice channels coordinate movement and logistics.
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). ‘’‘Chipsets:’’’ RTL2832U + R820T2 common 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. ‘’‘Modulations:’’’ ASK, FSK, GFSK, MSK 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. ‘’‘Firmware:’’’ Open source with active development community.
ADS-B Surveillance
‘’‘Frequency:’’’ 1090 MHz, Mode S transponders. ‘’‘Message types:’’’ 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.