echolink amateur radio meets voice over the internet protocol andy zwirko – k1ra andyz@sort.net

EchoLink

Amateur Radio meets

Voice over the Internet Protocol

Andy Zwirko – K1RAhttp://go.to/andyzandyz@sort.net

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

K1RA-L 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)

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

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

VoIP Network Topology

68.54.3.2

128.10.60.73

209.176.50.1

212.50.33.5 141.9.5.102

K1RA

WA3NAN-R

K1HTV

NA3J/0

PC to PC

Sys Op Mode

Simplex Link

Repeater Link

PC Users, Links, Repeaters

EchoLink - The Software

Windows

Mac

Linux

Sysop

User

Interfaces

Types Commercial Homegrown

Function Isolate Attenuate Match Key PTT COR

Commercial Interfaces

DIY Interface Schematic

K1RA-LEcholink 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

Node Hardware

Radio Equipment

•ICOM IC207H

•20 Watts

•5/8ths vertical @25ft

•12v 20A P.S.

Computer Equipment

•Pentium II – 350MHz

•192 MB RAM

•6 GB Hard Disk

•10baseT NIC

•Linksys D614+ FW

•2000VA UPS

Control Operation

3 Levels of ControlDTMF over Link FrequencyHTTP Web InterfaceDirect PC Keyboard

Control OperatorsK1RA - AndyKZ1AMY - Amy

Node DTMF Commands

Status – 08

Connect – 4, 5, 6 digit node numberEcho Test Server = 9999short cuts, ex: *90 = WA3NAN-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

Local EchoLink Nodes List

Local EchoLink Nodes Map

Question?

Tnx & 73 !

Andy Zwirko – K1RAhttp://go.to/andyzandyz@sort.net