Echolink system coverage area & radio equipment Updated (08-22-10)
These images were generated with Radio Mobile software (free).

KD5QHJ-L coverage maps: Click images to enlarge.	10km	25km - large size file (950k)	80km	50km 3D view
Equipment:
	Old IC-2100H, Replaced by Alinco 605	Duron 1.4Ghz Win2k Server.	2.4Ghz & 2m Antenna

KD5QHJ-L radio path :
	Radio path from KD5QHJ-L to Sandia Crest	Radio path from KD5QHJ-L to Downtown ABQ

For more information on Echolink, or Echolink troubleshooting, visit the Echolink home page.

The most updated version of this procedure is held on the discussion forum here: http://www.richardsmrt.com/phpBB3/viewtopic.php?f=7&t=22

Introduction:

These diagrams show that you can set up a simple system, with no need to build a radio controller, or generate custom code. All that is needed are a few sound cards to interface echolink to Freeswitch (FS). I will show the following configurations that are tested and working:

Examples:

Example 1.)
FS with Echostation. This gives you the ability to configure a simplex/repeater autopatch, enabling phones to be manually patched into any radio system. Additionally, you can use your radio (TX/RX) from any computer softphone. For example, I like to listen to/talk on simplex while sitting at my office computer, or any other computer in my home (all of which are quite a distance from the radio transmitter).

Example 2.)
FS with Echolink. You can connect to your echolink system from any computer softphone or external phone. Very similar to the discripton above, although in this "standalone" configuration, there is no radio involved. To interface echolink and FreeSWITCH to a radio, see Example 3.

Example 3.)
Fully functional FS home PBX with Echolink and Echostation. Here, all the audio passes through a custom FS conference. See below for more details.

Design Notes: All of the examples presented here could potentially be done on a single computer with two instaces of FS running. The trick here is that each instance of the software (FS, Echolink, and Echostation) have its own dedicated soundcard, or running Virtual Audio Cable 4.10 to prevent audio loops. If you can improve this design, please contact me!

Update: Virtual Audio Cable 4.10, can be used to bridge/feed audio from one program to another. This method is highly preferred over using audio cables to achieve the same thing.

This diagram shows Example 1, Example 2, and Example 3. See the explanation below:

Example 1 Procedure: In this system, Computer #1 contains two dedicated soundcards, each soundcard is dedicated to it respective software (one for freeswitch, one for echostation). The red lines represent audio cables that plug directly into the respective soundcard inputs/outputs. The computer controls the PTT of the radio via a West Mountain Radio RIGblaster. Alternately, Virtual Audio Cable can be used to eliminate one pair of audio cables and provides better sound (if you want to use VAC, see this example). The specific configuration of FreeSwitch is quite extensive to be described here, but briefly FS uses "portaudio". In portaudio, you can configure the soundcard input/output. This idea was initially inspired by club radio projects I lead with the Tech Amateur Radio Association (TARA) at NMT in Socorro, NM.

Example 2 Procedure: Computer #2 also uses two dedicated soundcards, and the audio cables criss-cross so that the echolink output is the FS input, and visa-versa. This criss-cross can easily, and more effectively be achieved using Virtual Audio Cable (see this example). After careful software volume adjustments, the audio levels result in clear audio into the system. Connect to KD5QHJ (-L or -R) to test my system.

Note: You can run EchoStation, Echolink, and FreeSwitch on the same computer. To do this, you will need two instances of FreeSwitch running, one dedicated to echolink, and the other receiving audio directly from the radio. From the examples just imagine that Computer #1 and #2 = FreeSwitch #1 and #2. The two instances can be linked to each other by a conference (see conference diagram below).

Example 3 Procedure: In this system, Computer #1 and #2 are the same as above, but I have added a third computer. Computer #3 is a dedicated FreeSwitch PBX, It runs the "Radio" conference, and the other FS servers (FS 1 and FS 2) connect to this conference so that audio from all 3 systems are shared. Computer #3 also functions as a PBX, independent of the radio system, and it is registered with a commercial VoIP sip terminator. This enables me to make and receive land-line phone calls using my standard home phones, and computer software phones (softphone, such as X-Lite). This also allows me to connect to the Radio system via my cell phone by calling my home phone number and dialing a code to connect me into the radio conference. Thus the radio can be controlled by phone, very similar to a standard autopatch system.

Here is a conceptual diagram of how two FreeSWITCH conferences can be linked to select for specific set of commands available to radios and phones.

Here, radio DTMF tones can be passed through the "Radio Conference" to be decoded by Echolink. The Radio Conference is connected to the Call-in Conference by an originate loopback command (...more to come on that later). The Call-in Conference has a unique set of DTMF features available, such as adjusting the call volume, voice sensitivity (energy), and muting. The muting/unmuting DTMF function serves as a Push-To-Talk (PTT) for phones.

Conclusions:

Conceptually, any audio source, remote or local, can be tied into this conference system. For that reason, the potential application of this system is extremely broad, including the use of this deployable system for emergency ham radio operation. However for the same reason, the flexibility of this system could lead to unwanted audio transmissions, thus the system operator is responsible for proper configuration to avoid this. I believe this system is a unique addition to amateur radio, and can be used to connect multiple modes of communication (radio, Internet, and telephone networks). Hybrid systems like this demonstrate the flexibility and potential of amateur radio Internet linking.

More details to come as I continue to test this system.