Amateur Radio meets Voice over the Internet Protocol EchoLink Amateur Radio meets Voice over the Internet Protocol Andy Zwirko – K1RA http://go.to/andyz andyz@sort.net

Overview VoIP Concepts and Terminology Ham VoIP Projects 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/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

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.

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

VoIP Network Topology 209.176.50.1 68.54.3.2 K1HTV K1RA 128.10.60.73 WA3NAN-R 212.50.33.5 141.9.5.102 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 Function Commercial Homegrown Isolate Attenuate Match Key PTT COR

Commercial Interfaces

DIY Interface Schematic

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

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 Control Control Operators DTMF over Link Frequency HTTP Web Interface Direct PC Keyboard Control Operators K1RA - Andy KZ1AMY - Amy

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

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

Local EchoLink Nodes List

Local EchoLink Nodes Map

Question? Tnx & 73 ! Andy Zwirko – K1RA http://go.to/andyz andyz@sort.net