1. Amateur Radio meets Voice over the Internet Protocol
Inside Echolink
Amateur Radio
meets
Voice over the Internet Protocol
Ron P. Milione – W2TAP

2. Overview VoIP Concepts and Terminology Ham VoIP Projects
Analog, Digital, Samples, Buffers
Packets, Client/Server, TCP/IP
Ham VoIP Projects
Access, Modes, Connecting, Audio Quality
Topology, Users, Is this ‘Ham Radio’?
EchoLink Software Graphical User Interface
Setup, Radio, Computer
Modes, Configuration
Radio Interfaces
W2LV - Live Node Demo
Good Practices
Common Problems

3. What is VoIP? Convert Voice to Digital 1’ 0’s (A/D)
Compress Digital Data (Encode)
Buffer digital sample data into packets
Send packet buffers via Internet Protocol
Receive and assemble packet buffers
Uncompress Digital Data (Decode)
Convert Digital 1’s 0’s to Voice (D/A)

4. What is THIS Echolink?
EchoLink uses VoIP (Voice Over Internet Protocol) to allow licensed Amateur Radio Operators to communicate with other Amateurs via the Internet.
It is primarily a Windows based application and is offered free of charge at
There is also a new EchoLinux and EchoMac available.
It was developed by Jonathan Taylor (K1RFD) in 2002 (He received Hamvention 2003 Special Achievement Award).

5. A/D – D/A Terms and Concepts
Analog <> Digital
Continuous <> Discrete
Air Pressure <> Volts
Sampling Rate
Freq. (KHz) 8, 11, 22, 44
Unit time (secs)
Sampling Bits
Quantization (#) 2^8, 2^16
Dynamic range (dB) 50, 98
Nyquist Theorem
Sample Rate >= 2 x Freq.

6. Encode / Decode Compress / Decompress
Codec Types
GSM (E/L 8kbps)
uLaw
aLaw
ADPCM
Function
Don’t send dead air
Combined similar values
Save space and time

7. What Modes Are Available?
EchoLink can be operated strictly between two computers connected to the Internet using the PC soundcard with Speakers and a Microphone.
EchoLink can be interfaced to a standard FM transceiver as a “simplex link” from your home QTH.
EchoLink can be interfaced to a VHF or UHF repeater for more coverage.

8. Internet and IP Hosts Routers Dotted Decimal Addresses
Transport (TCP/UDP)
Source & Destination Ports
Data / Buffers
Checksum

9. Connecting via VoIP Two methods / implementations
Client / Server (Middleman)
Client is Authenticated (Callsign / Password)
Client Requests Users List ( Callsign, IP Addr.)
Client Makes Connection to User
No Central Server (Client to Client)
Client Must manually obtain remote IP Addr.

10. Amateur Radio VoIP Projects
EchoLink –
IRLP –
CQiNet –
WIRES II –
eQSO –

11. Echolink Overview Link Radio Amateurs via the Internet
PC-PC Users, PC-RF Gateways, RF-RF
Simple Password Access to Server
“By Hand” Callsign check for Password Validation
GSM Vocoder 8kbps/user
Lower Voice Quality (Dial-up or Broadband ISP)
Multiple Connections per Node Possible
Bandwidth Limited (Broadband Required for Conf)
Node Information (
4715+ Active Nodes Worldwide
1050 Users, 1464 Links, 1113 Repeaters, 192 Confs.

12. VoIP Network Topology 209.176.50.1 68.54.3.2 W2TAP W2LV 128.10.60.73
WA2CDL
W4AJX

13. PC to PC

14. Sys Op Mode

15. Simplex Link

16. Repeater Link

17. PC Users, Links, Repeaters

18. EchoLink - The Software
Windows
Mac
Linux
Sysop
User

19. And now -- The Software…
Here is the main Screen, listing the Stations currently on the Link, by Country, Call Zone etc.
The Bottom of the Screen shows the current Transmit and Receive Audio levels in a colored bar graphic.

20. Basic Setup
The first thing to do after installing the software is to configure your Station Setup.
The first time you use Echolink, you will have to wait to be validated, before you are connected to the EchoLink server.

21. Audio Setup
This includes your Audio details, for the PC Speakers and Microphone.

22. Connection Setup
This Screen allows you to configure the various Internet connections you are willing to accept.

23. The Two Pc Audio Screens
This is the Output
This is the Input

24. Interfaces Types Function Commercial Homegrown Isolate Attenuate Match
Key PTT
COR

25. Commercial Interfaces

26. DIY Interface Schematic

27. W2VL
Echolink node #487981
Call Node Location/Connection Status W2VL-R LIMARC, GlenOaks, NY (1) ON
MHz (-) Offset Duplex
Supports 4+ simultaneous users
Access is Open 24/7
IRLP ID: 4438

28. W2KPQ
Echolink node #503075
Call Node Location/Connection Status W2KPQ-R LIMARC, SELDEN, NY (1) ON
MHz (+ offset) Duplex
Supports 4+ simultaneous users
Access is Open 24/7
IRLP ID: 4478

29. Control Operation 3 Levels of Control Control Operators
DTMF over Link Frequency
HTTP Web Interface
Direct PC Keyboard
Control Operators
LIMARC
WA2CDL - Andy

30. Node DTMF Commands Given as an example
Status – 08
Connect – 4, 5, 6 digit node number
Echo Test Server = 9999
short cuts, ex: *90 = WA2CDL-R
Disconnect - #
Reconnect – 09
Help File -*411

31. Good Operating Practices
Identify Yourself
When connecting
When sending DTMF
Pause, Wait, Listen
Use DTMF Status Command 08
Rag chewers beware
3 minute timeout

32. Common Problems Connection Timeout Disconnects Audio issues Broken
Garbled
Drop outs

33. W2VL REPEATER

34. W2KPQ REPEATER

35. Local EchoLink Nodes List

36. Local EchoLink Nodes Map

37. Question? Tnx & 73 ! Ron Milione Ph.D. w2tap@arrl.net