Echolink

EchoLink is an Internet application that is used by radio amateurs to crosslink preferably relay. This is not a stand-alone mode.

EchoLink was originally developed by Jonathan Taylor ( K1RFD ). The same software for Microsoft Windows is available for free and can be downloaded by licensed radio amateurs from the EchoLink Web site. EchoLink is a registered trademark of Synergenics, LLC. The original program EchoLink working with Wine under Linux.

Overview

In EchoLink existing amateur repeaters are linked via voice -over- IP over the Internet, but also the connection via radio frequencies is possible to direct for some time. ( The combination of radio equipment of a public communications networks used to be forbidden in Germany by law. ) The control commands are transmitted over the radio interface by DTMF. Similarly, the direct contact between the hams through the Internet ( without the signal is transmitted over an amateur radio frequency ) is also possible, although not originally intended primarily.

For voice transmission, the GSM codec is used. The VoIP software takes over not only the (de-) coding of the language, but simultaneously controls the connected radio. A built- in software, the squelch detecting whether someone is speaking, and a DTMF decoder is used for remote control via the radio interface for example, for connection set-up.

With the EchoLink system, it is possible (assuming a EchoLink -enabled relay radio station in range ) via a handy mobile radio station in the 2- m or 70 cm band or a PC with the EchoLink program to connect to a radio amateur, which can otherwise only be achieved under favorable conditions or with great effort. Besides, it is also possible via the PC and a headset -microphone combination to take without the intervention of a radio callsign directly from owner to owner callsign alone each connection in order to refrain from the purchase of a radio altogether. Meanwhile, there are even apps for the iPhone or Android devices, which allow EchoLink on these devices. Furthermore, there are so -called conference rooms where meet a variety of participants and can communicate with each other. For setting up a EchoLink relay is required (in addition to being admitted to the amateur service ):

• Initially a PC with fast internet access as possible. He takes over the encoding and decoding of speech signals.

You'll also need

• A sound card,
• An amateur radio transceiver

As well as

• A special interface card. It switches the connected transceiver alternately in the transmit or receive mode and evaluates the DTMF dial tones of the connection- seeking radio stations. Often this purpose are also simpler sound card interface used, which is just a PC and wireless device electrically because the DTMF tones can be decoded via the PC sound card.

Is EchoLink due to the coupling of amateur radio with relative large shortwave antennas, handy devices and antennas with the now ubiquitous Internet especially for mobile ham radio, amateur radio operators with lack of antenna options ( travel, vacation, hotels, town homes ... ) attractive.

The EchoLink network counts as of June 2010, more than 520,000 registered users (all licensed radio amateurs) in 162 countries - with about 4200 stations that are online at any time.

The screen

The picture shows a EchoLink software as it appears on the computer when connected.

Directly below the command line is stated that currently 5196 stations are active. Among the stations to the left are listed, registered in the personal so-called " alarm list " of the receiving station. These are O.A. friends, group members

The connection takes place in telephony. The microphone is in turn passed around in the round. At the same time can also be written. Bottom right are exchanged texts.

Criticism

As with the introduction of any new technology (not mode ) in the amateur radio service also attended EchoLink for lively debates. Arguments as EchoLink is due to the intervening Internet not a "real " radio operation more and rang the end of the amateur radio an were called. Meanwhile, the discussion has, however, calmed down a bit.

EchoLink is criticized because its implementation is not disclosed and specifications of the protocols used are not available. Some amateur radio operators argue that the amateur radio is an experimental radio service, and the software should be used only if protocols and specifications of EchoLink be freely accessible, or should each develop their own software without having to pay any licensing fees. The necessary software is available from the EchoLink project only for Microsoft Windows. This limits the access to this technology unnecessarily.

But EchoLink is no modulation, but describes the combination of VoIP frontend, the software and the Internet infrastructure. The specifications of the protocols in question are disclosed. Only by reverse engineering it was alternative projects such as SvxLink, CQiNet and EchoMac software for the Apple Macintosh whose source code is freely available, it is possible to create a too EchoLink compatible software for different operating systems and applications.

Frequencies

There are the following for EchoLink simplex frequencies: