In addition to the more traditional analog and digital voice modulation, you can modulate the VHF radio with a multitude of digital formats so that data can be exchanged directly between two radios. Read on to see how Hams are using digital data on VHF and how you can too.
VHF Data Modes
In addition to the more traditional analog and digital voice modulation, you can modulate the VHF radio with a multitude of digital formats so that data can be exchanged directly between two radios. Read on to see how Hams are using digital data on VHF and how you can too.
Packet Data Modes – AX.25 and APRS / WinLink
Packet Modulations
Automated Packet Reporting System (APRS)
WinLink
The Winlink System and Network uses the packet protocol to transmit formatted messages (very similar to email) over ham frequencies. The Winlink system also interconnects radios to the internet and uses Central Message Servers to handle message traffic.
Other Data Modes
There are many other data modes that are used in ham radio, and some are very well suited to VHF operations. You will find digital modes on both SSB and FM ranges of the VHF bands – some modes are well suited for weak-signal work and other modes take advantage of the clear FM audio to maximize data transfer speeds.
Other modulation schemes and the concept of FEC
APRS.fi
Many local APRS stations also contain an “internet gateway” – many of the position packets are sent to central servers and can be relayed to adjacent APRS stations that are not in direct contact with the station that you are in contact with. These central servers offer the ability to present a map of the received position packets. If you look at APRS.FI, you can see your local area to see what the current APRS position reports are active.
Raspberry Pi Digital Station
You can use a cheap Raspberry Pi computer to make your own Digital Station and use it to communicate via digital data modes with others in your area (via VHF/UHF radio), and also to view and report APRS packets.
Next: T600 – Introduction to Foxhunting and Radiolocation
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