COMSPT

• Near Vertical Incidence Skywave (NVIS)
• NVIS Antenna Theory and Design (pdf)
• NVIS Theory & Practice (pdf)

DIGITAL

• Asterisk Radio Networks * Interoperability Solutions – RF Gateways, Digital Telephone, HSMM
• Digital Analog Radio Network – DARN to mend by weaving thread across a gap
• Green Bay Professional Packet Radio – Projects
• Icom D*STAR 1200MHz/10GHz Digital Linking System
• Icom IDAS – Icom Digital Advanced System – NXDN Digital
• Kenwood NEXEDGE^tm – NXDN Digital
• P25 – What is it?

PROPAGATIONS

• HF Systems – North America Ionospheric Map
• Space Weather NOW
• VHF/UHF Tropospheric Ducting Forecast

REPEATERS

• RepeaterGear.com
• K1IW Amateur Repeater - Websearch
• Repeater Builder ‘s Technical Information Page

RF GATEWAYS (RoIP/VoIP)

• Allstar Link Network – a network of repeater and remote base stations accessible to each other via Voice over IP
• Asterisk^TM – Asterisk is a complete PBX in software with radio connectivity.
• app_rpt – The integration of 2-way radio systems and reasonable telephony.
• EchoLink
• eQSO - Linking the World by Radio.
• Internet Radio Linking Project * IRLP
• Southeastern Asterisk Radio Network – A diverse network of RF Gateways and Telephone Resources.
• Speak Freely – For those times when secure pc-to-pc coms is needed.
• WIRES-II * Wide-coverage Internet Radio Enhancement System