Current Developments in Internet Linking

This page has received hits since November 28 2002

Looking to see who's on IRLP, EchoLink, iLINK or WIRES?  Click here!

Internet linking of radio systems is a fast moving part of Amateur Radio.  In the 2 years since I became involved at the start of 2001, there have been many changes.  Internet linking also represents a whole new area for amateur experimentation.

Current Projects

There are a couple of projects which are under active development.  Due to the newness of Internet radio linking and human nature, as well as regulatory concerns, what follows may not appeal to all.  However, please read these pages with an open mind.

The projects I'm working on are as follows:

• Enhanced IRLP control scripts.
• Cross-linking of different systems - This takes into account the cultural and security requirements of each system.

Cross-linking IRLP and EchoLink

The cross-linking project has its own page.  Explore the issues involved in cross-linking these two systems and some suggested solutions for dealing with the issues raised.  View some sample code as well.

IRLP-EchoLink Cross Linking.

Enhanced IRLP control scripts.

IRLP is a sophisticated and secure solution for linking distant repeaters and simplex sites together.  One of IRLP's strengths is that it is highly customisable.  However, even with the extreme flexibility that IRLP offers the node owner, there are some enhancements that involve the core, globally distributed scripts.  It is this core functionality that I have concentrated on.  The scripts I've developed add the following functionality to an IRLP node:

• Restores the ability to select connections without a timeout on the fly via DTMF.  This is implemented via a node owner defined prefix.
• Allows the node owner to select the codec used for a specific connection.  This is ideal for testing or special circumstances.  Codec bit rates vary from 2.4kbps (LPC-10) to 64kbps (raw uncompressed uLAW audio).
• A separate reflector prefix can be defined by the node owner, so users can be allowed node-node connections, but not reflector connections without sysop assistance.
• Remote DTMF command functionality via custom_regen.  Allows DTMF commands entered at a remotely connected node to control scripts.
• Listen only connections - Ideal for connecting to broadcasts without fear of local users causing interference.  This feature was also released separately to the IRLP community.

The scripts are under active development and are regularly updated to include new features or incorporate significant changes made to the official core scripts.

You can download the latest version here

To install the scripts, you need to enable the NOUPDATE feature of IRLP.  Edit /home/irlp/custom/environment and make sure the line

NOUPDATE=YES

is in the file.  It will either be set to NOUPDATE=NO or not exist at all.  While you're editing the environment file, you may as well setup the parameters to configure the new features of the system.  Without any changes, the scripts will behave identically to the standard IRLP distribution.  The variables to add are listed below.  The below is a guide, edit your environment file to suit your needs. The below are my settings (note I'm not allowing the CELP CODEC or using a reflector prefix).

# Extra variables for VK3JED enhanced features
export LPCTPREFIX=1 ## Prefix to select LPC-10 CODEC
export LPCPREFIX=2 ## Prefix to select LPC CODEC
export SGSMPREFIX=3 ## Prefix to select Simple + GSM CODEC
export CELPPREFIX=4 ## Prefix to select CELP CODEC (Speak Freely 7.5 only)
export GSMPREFIX=5 ## Prefix to select GSM CODEC
export ADPCMPREFIX=6 ## Prefix to select ADPCM CODEC
export RAWPREFIX=7 ## Prefix to select uncompressed audio
export NOTIMEOUTPREFIX=0 ## Prefix to disable idle timeouts
export RAW_AUDIO_ENABLE=YES ## Set to YES to allow incoming calls to select uncompressed audio
export LISTENONLYPREFIX=8 ## Prefix to select listen only connect mode
#export ALLOW_CELP_CODEC ## Allow use of CELP codec (requires Speak Freely 7.5 and a fast system)
#export REFLECTORPREFIX=12345 ## Prefix for connecting to reflectors (overrides DTMFPREFIX)

After making these changes, save the environment file and as root run:

/home/irlp/custom/rc.irlp

To install the files, log in as repeater and create a directory called /home/irlp/noupdate/scripts.  Copy the downloaded file into this directory and then extract the files using:

tar -zxvf vk3jed-irlp-x.y.z.tar.gz

Finally, force an update of the IRLP files:

update files

Now the scripts are installed and you can use the new features of the system.

Future developments:

• Speak Freely 7.5 is highly desireable, as its CODECs are much better (i.e. debugged), and it also supports the CELP CODEC.
• A system to select whether CODEC overrides have the idle timers enabled or disabled is planned.