Inside Echolink by n13g88

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									        Inside
       Echolink
        Amateur Radio
             meets
Voice over the Internet Protocol
        Ron P. Milione – W2TAP
             w2tap@arrl.net
      ron.p.milione.ctr@us.army.mil
                 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
        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)
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.org.

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).
                    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.
           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
         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.
              Internet and IP
Hosts
Routers

Dotted
Decimal
Addresses
Transport
(TCP/UDP)
Source &
Destination
Ports
Data /
Buffers
Checksum
    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
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/
    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.asp)
  4715+ Active Nodes Worldwide

  1050 Users, 1464 Links, 1113 Repeaters, 192 Confs.
VoIP Network Topology


                            209.176.50.1




         68.54.3.2
         W2TAP


                                           128.10.60.73       W2LV




WA2CDL        212.50.33.5                       141.9.5.102    W4AJX
PC to PC
Sys Op Mode
Simplex Link
Repeater Link
PC Users, Links, Repeaters
  EchoLink - The Software

Windows
Mac
Linux

Sysop
User
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.
                    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.
               Audio Setup

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

           This Screen allows
           you to configure the
           various Internet
           connections you are
           willing to accept.
 The Two Pc Audio
     Screens

                    This is the Output




This is the Input
                Interfaces

Types
   Commercial
   Homegrown
Function
   Isolate
   Attenuate
   Match
   Key PTT
   COR
Commercial Interfaces
DIY Interface Schematic
            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
          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
    Control Operation
3 Levels of Control
 DTMF over Link Frequency
 HTTP Web Interface

 Direct PC Keyboard

Control Operators
 LIMARC
 WA2CDL - Andy
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
Good Operating Practices
 Identify Yourself
  When connecting
  When sending DTMF

 Pause, Wait, Listen
    Use DTMF Status Command 08
 Rag chewers beware
    3 minute timeout
    Common Problems
Connection Timeout
Disconnects
Audio issues
 Broken
 Garbled

 Drop outs
W2VL REPEATER
W2KPQ REPEATER
Local EchoLink Nodes List
Local EchoLink Nodes Map
 Question?

 Tnx & 73 !

      Ron Milione Ph.D.
       w2tap@arrl.net
ron.p.milione.ctr@us.army.mil

								
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