Editing Terminal node controller (section)

== Current status ==
{{Unreferenced section|date=September 2016}}


Since the late 1990s, most AX.25 usage has shifted to a different one-to-many communication paradigm with the [[Automatic Packet Reporting System]] (APRS).

The TNCs of the 1980s and 1990s were complete solutions that only needed a radio and an optional [[Computer terminal|dumb terminal]]. As home computers made their way into [[Amateur radio|ham]] "shacks," there was a movement toward simpler, cheaper [[KISS (TNC)|"KISS"]] (Keep It Simple, Stupid) devices. These have a modem and minimal processing of the AX.25 protocol. Most of the processing is moved to the personal computer.

The next logical step in the evolution is to eliminate the specialized hardware and move all of the processing to a computer.   A "[[Sound card|soundcard]]" is used for audio to and from the radio.  Everything else is done in software.<ref>{{Cite web |title=Dire Wolf Software TNC |url=https://github.com/wb2osz/direwolf-presentation |date=10 May 2021 |website=[[GitHub]]}}</ref>

Some of the earlier attempts performed poorly, giving this approach a bad reputation.  Modern software TNCs, using [[Digital signal processing|digital signal processing (DSP)]] techniques, can successfully decode poor quality signals that the older equipment can't.<ref>{{Cite web |title=WA8LMF TNC Test CD Results a.k.a. Battle of the TNCs |url=https://github.com/wb2osz/direwolf/blob/dev/doc/WA8LMF-TNC-Test-CD-Results.pdf |website=[[GitHub]]}}</ref>

Some handheld and mobile VHF radios currently on the market incorporate TNC abilities within the radio itself in support of the APRS protocol.

Many TNCs are still in use, especially in unattended stations where reliability is important.  The importance of location to the APRS system has fueled development of a new generation of small low-power TNCs often integrated with a GPS module for use in mobile tracking stations. Not all AX.25 activity is APRS: Some AX.25 data networks exist, including the EastNet Packet Network mostly in the Northeastern United States<ref>{{Cite web |title=EastNet Packet Radio Group Welcome. |url=https://www.qsl.net/ww2bsa/eastnetpackethome.htm |access-date=2024-09-01 |website=www.qsl.net}}</ref> and TARPN Network mostly in North Carolina.<ref>{{Cite web |title=TARPN Network Page |url=https://tarpn.net/t/network.html |access-date=2024-09-01 |website=tarpn.net}}</ref> 

APRS [[Repeater#Data handling|digipeating]] protocols require specific naming conventions, and older TNCs may not have the required support to be used as a digipeater.  However, almost any TNC can be pressed into service for Home or Tracker use.  TNCs that were clones of the popular [[Tucson Amateur Packet Radio|TAPR]] [[TNC-2]] may be upgradeable via the UIDIGI firmware project.