1. Amateur Radio meets Voice over the Internet Protocol
EchoLink
Amateur Radio meets
Voice over the Internet Protocol
Andy Zwirko – K1RA

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
K1RA-L 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. 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.

5. 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

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

7. 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.

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

9. 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 (
2700 Active Nodes Worldwide
552 Users, 1064 Links, 962 Repeaters, 122 Confs.

10. VoIP Network Topology 209.176.50.1 68.54.3.2 K1HTV K1RA 128.10.60.73
WA3NAN-R
NA3J/0

11. PC to PC

12. Sys Op Mode

13. Simplex Link

14. Repeater Link

15. PC Users, Links, Repeaters

16. EchoLink - The Software
Windows
Mac
Linux
Sysop
User

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

18. Commercial Interfaces

19. DIY Interface Schematic

20. K1RA-L Echolink node #199756 Warrenton, VA – FM18cr - ~ 550ft ASL
MHz Simplex - ~20w
Adelphia Cable ISP - 4Mbps / 512Kbps
Supports 4 simultaneous users
Software version 1.980
Access is Open 24/7

21. Node Hardware Radio Equipment ICOM IC207H 20 Watts
5/8ths
12v 20A P.S.
Computer Equipment
Pentium II – 350MHz
192 MB RAM
6 GB Hard Disk
10baseT NIC
Linksys D614+ FW
2000VA UPS

22. Control Operation 3 Levels of Control Control Operators
DTMF over Link Frequency
HTTP Web Interface
Direct PC Keyboard
Control Operators
K1RA - Andy
KZ1AMY - Amy

23. Node DTMF Commands Status – 08 Connect – 4, 5, 6 digit node number
Echo Test Server = 9999
short cuts, ex: *90 = WA3NAN-R
Disconnect - #
Reconnect – 09
Help File -*411

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

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

26. Local EchoLink Nodes List

27. Local EchoLink Nodes Map

28. Question? Tnx & 73 ! Andy Zwirko – K1RA http://go.to/andyz