Network Access using AX.25 over VHF Amateur Radio

AX.25 is a protocol based on the X.25 protocol and uses amateur radio call signs for addresses. It is efficient for low bandwidth, lossy environments, such as VHF/UHF radio. This makes it ideal for access to the packet BBS network from anywhere in Santa Clara County. The use of VHF radio means RF coverage throughout the county is good enough for most locations to reach at least two of the packet BBS systems.

AX.25 over VHF Amateur Radio can be used to access the following SCCo ARES/RACES service:

• Packet BBS Service
  • User Access: Users can connect to the packet BBSs using one of the VHF radio channels allocated for user access.
  • BBS Forwarding: Other packet BBSs can connect to the SCCo BBS network using AX.25 on a radio channel allocated for BBS Forwarding..

User Access

• No advanced arrangements are necessary to connect to the SCCo ARES/RACES packet BBS service via VHF radio
• Construct a packet station (see below)
• Consult the Packet Frequencies and BBS Listings page to determine which BBS you should use and the access frequencies for that BBS
• Consult the Packet BBS Service page for complete information about using the service

BBS Forwarding

• Consult the Packet Frequencies and BBS Listings page to determine the BBS forwarding frequencies to use
• Make a test connection to verify reachability
• Contact one of the SCCo BBS sysops directly to set up forwarding

• AX.25 over VHF Station Configuration Diagram (PDF)
• Consider the following when building an AX.25 (packet) over VHF radio station:
  • City/Agency EOC/DOC Equipment
  • Antenna
  • Lightning Arrestor
  • Radio
  • TNC
  • USB-to-Serial Adapter
  • Computer
  • Printer
  • Software
  • Power
  • Make sure your station helps to reduce/eliminate the "hidden node" problem

Application Notes

Technical Reference

Training

User Group

Technical Support