Cap Pannell, KE6AFE, explains the UIFLOOD command in Packet TNCs, and when it should be used.

More Packet and APRS info is available via the links on the right side of this article.

UIFLOOD - What's That?

UIFlood is a command (a setting) in Kantronics TNCs (and some software), used for digipeating.

Back in the old days of APRS, the high altitude digipeaters would set their TNC's UIFlood to WIDE and that would digipeat the WIDEn-N paths like WIDE2-2. Those digipeaters would use a "N overlay" on their digi symbol on the APRS map. But those old "N overlay" digis are too old and obsolete now, not helping until their settings are brought up to date.

Nowadays, that WIDEn-N digipeating is done by the UITrace setting in the digi's TNC (not the UIFlood setting). Using UITrace also causes the digi's callsign to be added into the path history, so you can see the callsigns of all the digipeaters which did their job.

This better new system also leaves the UIFlood command available to digipeat a LAN alias, like a State abbreviation, in those high digipeaters. In Nevada UIFlood is now set to NV in the high digipeaters so users can set NVn-N digipaths like NV2-2. In California high digipeaters UIFlood is set to NCA or SCA for Northern California or Southern California. This way, a user setting a path of NCAn-N like NCA2-2 will only be digipeated by high Northern California digipeaters. These digipeaters will have a "S overlay" on their symbol on the APRS map. The "S" shows that digi can use those SSn-N "State" abbreviations aliases (like NCA2-2 or SCA2-2 or NV2-2) as well as WIDE2-2 or WIDE2-1 or WIDE1-1.

Modern "fill-in" or "event" digis do not use UIFlood (nor UITrace). They have a "1 overlay" on their symbol on the APRS map and only digipeat WIDE1-1 paths. They do not digipeat the SSn-N paths like NCA2-2 or SCA2-2 or NV2-2.

Today's helpful digipeaters are only the "S overlay" digis and "1 overlay" digis. North American stations should NOT allow or enable continued use of RELAY or WIDE or TRACE or TRACEn-N aliases.

I hope we can update the settings in the rest of our old obsolete digis in California before the weather turns wet and cold, making hilltop access less pleasant. Nevada has already finished the updates in _all_ of their digis!

73, Cap KE6AFE