EchoLink

1
EchoLink

• Amateur Radio meets
• Voice over the Internet Protocol

Andy Zwirko K1RA http//go.to/andyz andyz_at_sort.n
et
2
Overview

• VoIP Concepts and Terminology
• 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 0s (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 1s 0s to Voice (D/A)

4
A/D D/ATerms and Concepts

• Analog ltgt Digital
• Continuous ltgt Discrete
• Air Pressure ltgt Volts
• Sampling Rate
• Freq. (KHz) 8, 11, 22, 44
• Unit time (secs)
• Sampling Bits
• Quantization () 28, 216
• Dynamic range (dB) 50, 98
• Nyquist Theorem
• Sample Rate gt 2 x Freq.

5
Encode / DecodeCompress / Decompress

• Codec Types
• GSM (E/L 8kbps)
• uLaw
• aLaw
• ADPCM
• Function
• Dont 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.
• Client Makes Connection to User

8
Amateur Radio VoIP Projects

• EchoLink http//www.echolink.org/
• IRLP http//www.irlp.net/
• CQiNet http//cqinet.sourceforge.net/
• WIRES II http//www.vxstd.com
• eQSO http//www.eqso.net/

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 (http//www.echolink.org/logins.a
  sp)
• 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
212.50.33.5
WA3NAN-R
141.9.5.102
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
• Commercial
• Homegrown
• Function
• Isolate
• Attenuate
• Match
• Key PTT
• COR

18
Commercial Interfaces
19
DIY Interface Schematic
20
K1RA-L

• Echolink node 199756
• Warrenton, VA FM18cr - 550ft ASL
• 144.440 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 vertical _at_25ft
• 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
• 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 andyz_at_sort.n
et