Echolink

from Wikipedia, the free encyclopedia

EchoLink is an Internet application used by radio amateurs to network relays , preferably . It is not an independent operating mode .

EchoLink was originally developed by Jonathan Taylor (K1RFD). The software of the same name for Microsoft Windows is offered free of charge and can be downloaded from the Echolink website by licensed radio amateurs. Echolink is a registered trademark of Synergenics, LLC. The original Echolink program also runs on Linux with Wine .

overview

Example of a connection setup between two relay stations using Echolink
Fig. 1 EchoLink transmission of audio data from PC to PC, optionally via interfaces (not shown) to the FM radio

With EchoLink, existing amateur radio relays are networked via Voice-over-IP over the Internet , but the connection via radio devices on direct frequencies has also been possible for some time. (The connection of radio equipment with public communication networks was previously prohibited by law in Germany.) The control commands are transmitted via the radio interface by DTMF . Direct contact between radio amateurs via the Internet (without the signal being transmitted via an amateur radio frequency) is also possible, even if not originally intended.

The GSM codec is used for voice transmission . The VoIP software not only takes over the (de) coding of the language, but also controls the connected radio at the same time. A squelch built into the software recognizes whether someone is speaking and a DTMF decoder is used for remote control via the radio interface, for example to establish a connection.

With the Echolink system, it is possible to connect to a radio amateur via a handy mobile radio station in the 2 m or 70 cm band (an EchoLink-capable relay radio station is within range) or a PC with the EchoLink program that can otherwise only be achieved under favorable conditions or with great effort. In addition, it is also possible, without switching on a radio, to establish a connection directly from call sign owner to call sign owner via the PC and a headphone-microphone combination, in order to completely dispense with the purchase of a radio. There are now even apps for the iPhone or Android devices that enable Echolink operation on these devices. There are also so-called conference rooms in which a large number of participants can meet and communicate with one another.

To set up an EchoLink relay you need (in addition to an authorization to participate in the amateur radio service ):

  • first a PC with the fastest possible internet access. It takes over the encoding and decoding of the speech signals.

Besides, you need

such as

  • a special interface card. It switches the connected transceiver alternately to transmit or receive mode and evaluates the DTMF dialing tones of the radio stations seeking connection. Often simpler sound card interfaces are used, which only galvanically separate the PC and radio , since the DTMF tones can be decoded via the PC's sound card.

EchoLink is particularly attractive for mobile radio amateurs, for radio amateurs with a lack of antenna options (business trip, vacation, hotels, city apartments ...) because of the coupling of amateur radio with comparatively large shortwave antennas, handy devices and antennas with the now ubiquitous Internet.

As of June 2010, the EchoLink network already had more than 520,000 registered users (all licensed radio amateurs) in 162 countries - with around 4200 stations that are online at all times.

criticism

As with the introduction of any new technology (not operating mode) in the amateur radio service, Echolink also caused lively debates. Arguments such as that EchoLink is no longer a "real" radio operation due to the intervening Internet and that it heralds the end of amateur radio were given. In the meantime, however, the discussion has calmed down somewhat.

EchoLink has come under fire because its implementation is not disclosed and specifications of the protocols used are not available. Some radio amateurs argue that amateur radio is an experimental radio service and that the software may only be used if the protocols and specifications of Echolink are freely accessible, or everyone is allowed to develop their own software without having to pay any license costs. The necessary software from the EchoLink project is also only offered for Microsoft Windows. This limits access to this technique.

Echolink is not a type of modulation, but describes the combination of the VoIP front end, the software and the Internet infrastructure. The specifications of the relevant protocols are disclosed. Only through reverse engineering was it possible for alternative projects such as SvxLink, CQiNet and EchoMac Software for the Apple Macintosh , whose source code is freely available, to create software compatible with EchoLink for different operating systems and applications.

Frequencies

According to the current band plan, the following simplex frequencies are available for EchoLink:

2 meter tape region
145.2375 MHz Germany - replacement for 144.9625 MHz
145.2875 MHz Germany - replacement for 144.9750 MHz
145.3375 MHz Germany
70 centimeter tape region
430.025 MHz Germany
430.050 MHz Germany
432.800 MHz Germany
432.825 MHz Germany
432.850 MHz Germany
432.875 MHz Germany

See also

Web links

Individual evidence

  1. ↑ Echolink main page (English)
  2. ↑ SvxLink - Linux software for Echolink relay stations and users
  3. ↑ CQiNet - Linux software for Echolink operation
  4. ↑ EchoMac - Echolink software for Apple Macintosh
  5. ↑ Changes for operators of Echolink Simplex Gateways. DARC e. V. , August 12, 2014, archived from the original on June 7, 2015 ; Retrieved October 4, 2014 .