Inside Echolink

1
Inside Echolink

• Amateur Radio
• meets
• Voice over the Internet Protocol

Ron P. Milione W2TAP w2tap_at_arrl.net
ron.p.milione.ctr_at_us.army.mil
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
• W2LV - 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
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 http//www.echolink.o
  rg.
• 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/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.

6
Encode / DecodeCompress / Decompress

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

10
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/

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 (http//www.echolink.org/logins.a
  sp)
• 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
212.50.33.5
WA2CDL
141.9.5.102
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
24
Interfaces

• Types
• Commercial
• Homegrown
• Function
• 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
  487981 LIMARC, GlenOaks, NY (1) ON
• 40.7470463 -73.7115199
• 146.850MHz (-) 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
  487981 LIMARC, SELDEN, NY (1) ON
• 40.8664873 -73.0356625
• 147.3750MHz ( offset) Duplex
• Supports 4 simultaneous users
• Access is Open 24/7
• IRLP ID 4478

29
Control Operation

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

30
Node DTMF CommandsGiven 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_at_arrl.net ron.p.milione.ctr
_at_us.army.mil