PLRI (Parallel Logic Radio Interface) is a set of circuits of interest to radio amateurs Amateur Radio (hams). These circuits are fully compatible with IRLP ( Internet Radio Linking Project). IRLP is trademarked by Dave Cameron.
The circuit shown below is the Deluxe PLRI interface, and is used to connect a radio to a PC using a parallel port and sound card. This circuit is fully compatible with the Version 3 IRLP board, and can be used in place of an IRLP board. This circuit allows negative or positive COS from the radio, and also supports negative or positive PTT keying. This circuit can be home built for roughly $20 US.
This circuit can be used with several software packages, such as Asterisk, Allstar, app_rpt, IRLP, RtpDir, TheLinkBox, Echolink or as a repeater controller board under any of the supported Linux software packages.