Linking Ham Radio Via the Internet
allows Amateur Radio stations to communicate
with one another over the Internet, using voice-over-IP (VoIP) technology.
The program allows worldwide connections to be made between stations,
from computer to station, or from computer to computer.
The Internet Linking Project (IRLP). IRLP is the most mature of the various VoIP programs for Hams. It is very successful, reliable, and secure. IRLP runs exclusively on the Linux operating system and is tightly controlled by it's authors. Perhaps in the interest of security IRLP does not allow Internet only connections, users must access the IRLP network via a link repeater.
EchoIRLP is a group who's goal is sharing technical information regarding IRLP and EchoLink network inter-operability.
WD4NMQ's home page. Jeff is the author of a EchoLink client for the Linux operating system called EchoLinux. He was one of the first people to dissect the original iLink protocol that formed the basis of EchoLink. His research has resulted in Linux server code to access the iLink and EchoLink directory servers. A couple of people have now written scripts to generate real time Web pages from the directory servers based on the information Jeff gathered.
EchoMac is a program for MacOS X to access the Echolink system. EchoMac is based on EchoLinux with a new GUI written by N9YTY.
An alternate GUI for EchoLinux written in Perl/Tk written by Andrew G8FSL.
GJ7JHF's "Amateur Radio Voice-Links via the Internet" web site. GJ7JHF provides an excellent overview of all of the various packages as well as good background information on Internet linking in general.
Speakfreely is a open source program that is the admitted basis for IRLP and probably iLink and EchoLink as well. Since the first version of Speakfreely was released in 1991 it is safe to say it's a mature program. Windows and Unix versions are available and interoperate. Speakfreely is able to talk to iLink and EchoLink nodes with slight modifications.
Real-Time Transport Protocol (RTP) Working group. RTP is the protocol most often used for streaming over the Internet. A modified form of RTP is the basis of the EchoLink protocol.
GSM 06.10 lossy speech compression is the compression algorithm used by EchoLink. This site has excellent information about GSM and other speech compression codecs as well as the free source code that is used by Speak Freely and EchoLinux.
A survey on connecting Ham radio and the Internet. Hams are an opinionated bunch, not everyone thinks it's a good idea. Read the comments yourself and you decide.