[aprssig] UI question

Jason KG4WSV kg4wsv at gmail.com
Sun Apr 11 20:40:09 EDT 2010

On Sun, Apr 11, 2010 at 7:08 PM, Gary <n6lrv at cox.net> wrote:
> Can anyone direct me to a website or online document that explains what UI
> is

UI is unnumbered information in AX.25 protocol speak.  It signifies
that a packet is a datagram, a connectionless packet, like a UDP
packet in the IP protocol (as opposed to a packet that's part of a
connected data stream, like TCP).

In general UI frames _can_ be directed to a specific station, but in
APRS we typically use them as broadcasts.

> as well as what UIDIGI, UICHECK, and UIFLOOD are?

I think these are configuration options relating to how UI frames are
handled that originated with a particular brand of TNC, maybe


More information about the aprssig mailing list