Inside Inside EcholinkEcholinkAmateur Radio

meets

Voice over the Internet Protocol

Ron P. Milione – W2TAPw2tap@arrl.net

ron.p.milione.ctr@us.army.mil

OverviewVoIP 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/ATerms 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 / DecodeCompress / 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

HostsRouters

Dotted Decimal AddressesTransport (TCP/UDP)Source & Destination PortsData / BuffersChecksum

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 OverviewLink 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

68.54.3.2

128.10.60.73

209.176.50.1

212.50.33.5 141.9.5.102

W2LV

WA2CDL

W2TAP

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.

This is the Output

This is the Input

The Two Pc Audio Screens

Interfaces

Types Commercial Homegrown

Function Isolate Attenuate Match Key PTT COR

Commercial Interfaces

DIY Interface Schematic

W2VLEcholink 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

W2KPQEcholink 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 ControlDTMF over Link FrequencyHTTP Web InterfaceDirect PC Keyboard

Control OperatorsLIMARCWA2CDL - Andy

Node DTMF CommandsGiven as an example

Status – 08

Connect – 4, 5, 6 digit node numberEcho Test Server = 9999short cuts, ex: *90 = WA2CDL-R

Disconnect - #

Reconnect – 09

Help File -*411

Good Operating Practices

Identify YourselfWhen connectingWhen sending DTMF

Pause, Wait, ListenUse DTMF Status Command 08

Rag chewers beware3 minute timeout

Common Problems

Connection Timeout

Disconnects

Audio issuesBrokenGarbledDrop 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