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The Internet Radio Linking Project

Paul Cassel (VE3SY) on July 24, 2001
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The Internet Radio Linking Project
Another Canadian Invention Sweeps the World

Thanks to an innovative Canadian, we now have a new and powerful recruitment tool for the younger generation interested in technologies like the Internet, Linux and Ham Radio. By enabling the new IRLP technology to our standard FM repeaters we provide instant on-demand-linking with one or more repeaters world-wide. And if you're concerned about cost, this entire project is definitely within a Ham Approved -cheap- budget of under CA$200 including hardware and software.

IRLP is the brainchild of David Cameron, VE7LTD of Vancouver BC. IRLP is the abbreviation used for the Internet Radio Linking Project which David developed over the past several years. Back in 1998 Dave became frustrated with the unreliable operation of the Windows based Voice over IP software. All Windows based amateur linking software used VOX and were not secure from non-amateur access. The IRLP network uses a digital switching concept and produces an instant and secure link between licensed repeaters all around the world.

Eight months after Dave started his design work in 1998, the IRLP network was born and is now on Version 2.0 of hardware/software. As of this printing, IRLP will be serving well over 150 nodes and growing in leaps and bounds. When we ordered our interface hardware here in Kitchener this past February there were 63 active nodes with 26 other new node orders shipped with our package.

How It Works

David's custom IRLP software -takes the audio from the receiver which is fed into the sound card - where it is converted into ADPCM digital data the same format used by the phone companies for Long Distance service. The Linux PC then converts this digital information into digital packets each assigned with IP addresses for the destination node. These packets now flow through the internet to the destination Linux PC where the packets are decoded then sent to the sound card and out to the transmitter microphone of the link radio which then transmits the audio out over the local repeater. The transmitter is keyed as soon as these TCP/IP (Internet Protocol) packets start to arrive. As soon as the data stops the link radio automatically un-keys and process reverses.

0x08 graphic

The underlying audio processing technology in IRLP is a freeware application called Speak Freely. Speak Freely produces Voice-Over-IP (VoIP) audio streaming and is very similar to other VoIP software packages such as Microsoft NetMeeting and the VocalTec iPhone with one major difference - It runs under Linux not Windows. Linux was David's operating system of choice for the IRLP system as it allows the best in reliability, programability, efficiency, and functionality. Since our repeaters don't need anything even close to MP3 audio quality, IRLP is using a low-bitrate VoIP to communicate. Most nodes use an encoding system that requires only 32KB/s of bandwidth, however some nodes with extremely limited bandwidth, use a GSM encoding method which only requires 17KB/s albeit at the cost of audio quality.

The control of the radio is performed using a small custom logic board build by Dave VE7LTD which is connected to the computers parallel port. This board samples the received audio for Touch Tone audio, detects when the link receiver is active, and feeds the TX PTT line to the link radio. All of the command I/O between the PC and the IRLP board is handled by a connection to the PC's parallel port.

The whole system is DTMF (touch-tone) controllable. The control codes lie imbedded in a separate program that reads the DTMF tones from the decoder located on the interface controller board and activates various parts of the software. DTMF codes are used to enable/disable linking, open/close links and set identifiers. Every site has the ability to connect direct to any other site(s), either using direct connections or reflector sites.

To host an IRLP node you require; a) a full time high speed Internet connection - DSL or Cable works well - b) a dedicated Linux computer - a 486 DX100 or better is required, c) the IRLP custom software/hardware and d), a link radio or direct connection to a repeater. Each node on the IRLP network is assigned an ID code and a central server keeps track of the IP addresses in use by all nodes. (IP= the routing code used by all packets of data flowing on the internet)

The Kitchener Ontario IRLP Node

I had read about Dave's work on his web site and based on the low cost of entry US$120 I ordered the IRLP package which arrived within 10 days.

Paul VE3SY interfacing the IRLP board between the GE Phoenix link radio and the LINUX computer The audio levels are important and were set using the old Cushman CE50 service monitor.

The first thing I had to do was sacrifice my Windows 98 based P133 machine in favour of the Linux operating system for which I had no previous experience. Following the very detailed installation instructions posted on the IRLP web site, the installation went very smooth however I did encounter a weird inbound Telnet problem that was quickly resolved thanks to assistance from Dave VE7LTD and our resident K-W Linux guru Dave VA3DGS.

Now that I had the Linux box talking both ways to the internet I had to install the IRLP hardware and a Windows based Plug-n-Play SoundBlaster card. Since many hardware manufacturers do not yet "support" this most powerful operating system, this is where my fun began. The sound card wanted to use the same machine resources used by the Ethernet NIC card causing interesting issues such as trashing my BIOS settings and leaving the machine almost brain dead. After a day I was able to locate a DOS utility which I put on a DOS boot disk and booted the now Linux box in DOS and changed the conflicts. The machine then booted flawlessly under Linux and recognized the sound card immediately. I was now ready to go on the air however Dave VE7LTD, the IRLP project leader was off sick and unable to send me node access codes.

The next morning "AJ", VE3ABZ checked in and indicated he had codes from the London club and keyed in the four digit code to bring up VE3SUE in London. Typical of many repeaters these days, no one was on the air so AJ then brought up the Denver reflector - a Reflector is a Linux based PC sitting on some serious bandwidth that allows multiple audio streaming out to many repeaters. Now connected to the reflector we were able to talk with amazing clarity to stations in California, Pennsylvania and Yellowknife in the NWT. The audio was awesome and anyone listening would swear the Yellowknife station was in Kitchener not the North West Territories in minus 35 degree weather.

Using the IRLP Network

To connect to another node (repeater) you simply dial a 4 digit on-code. Within a few seconds that node will ID in plain voice with it's callsign and location. If the node is currently connected to another or to a reflector, you will receive a recording telling you which connection the other node (repeater) is currently engaged with. As of press time there were over 150 IRLP nodes QRV around the world with over 8 repeaters in Australia linked full time.

Before placing a call you can always check the status of any node in real time by going to http://status.irlp.net and look at the node you wish to connect with. This page updates in real-time and refreshes every minute so it is always current.

Just as with any linking system, IRLP is subject to some minor audio delays which are mostly radio related. These delays are caused by the amount of time it takes for numerous radios to decode the Tone Squelch information so the first thing to remember is to slow down and be patient. (to dispel internet delay myths, the audio delay over the internet is the same as you experience when using a digital cell phone)

When completed with a QSO announce your call and dial the 4 digit OFF code at which time a voice ID indicating the link is dropping will play. Since many repeaters are not heavily used, there are always a number of nodes left connected to the Denver CO Reflector allowing you to place a CQ, or ORZ type call with an excellent chance to speak with someone somewhere in the world.

IRLP Reflectors

A reflector is a server that allows multiple nodes (repeaters) to be linked together at the same time. As of press time there were 5 reflectors located in Toronto, Saskatoon, Denver Colorado, Yellowknife and Sydney Australia. The most common world-wide reflector is in Denver CO. Most reflectors are hosted by public service minded companies who have lots of bandwidth to support the requirement of a reflector. The amount of bandwidth required for a reflector is directly related to the number of connected nodes. During one Sunday evening net with 25 nodes connected the bandwidth being used on the Denver reflector was just about 1mb. This reflector usually has a number of Canadian, US, Australian and Caribbean repeaters connected so any conversation that occurs on one is heard on all connected stations.

The Sunday evening net (alternates between 01:00Z Monday and 16:00 Sunday every other week) is a great place to listen for check-ins from around the world. For those outside of IRLP coverage repeaters, a streaming audio feed is usually available on the internet. Point your browser to www.kwarc.org/irlp/listen.html for info.

CANWARN net controllers in Southern Ontario are linking themselves via IRLP using the new Ontario Reflector hosted by Group Telecom in their Toronto Central Office. This allows the CANWARN controllers to rapidly exchange severe weather information between themselves and the Environment Canada Toronto Severe Weather Desk without interfering with the local CANWARN nets. (CANWARN is the Canadian SkyWarn system)


Active nodes around the World

The following chart lists repeaters that are active around the world.


VE6RJZ

Canmore

AB

VE6MPR

Banff

AB

VE6WRT

Calgary

AB

VA6IRL

Lethbridge

AB

VE6SBR

Edmonton

AB

VE6TE

Red Deer

AB

VE6ZV

Calgary

AB

VE6TRC

Ft. McMurray

AB

VE6RPT

Calgary

AB

KB8JXX

Anchorage

AK

W7FDF

Tucson

AZ

N7CK

San Manuel

AZ

VE7MFS

Coquitlam

BC

VE7VIC

Victoria

BC

VE7RNA

Chemainus

BC

VE7BHI

Port Alberni

BC

VE7TSI

Kamloops

BC

VE7REE

Penticton

BC

VA7OKN

Vernon

BC

VA7RDX

Vanderhoof

BC

VE7URG

Vancouver

BC

VE7RGF

Grand Forks

BC

VE7FFF

Prince George

BC

VE7RVN

Vernon

BC

VE7RHS

Vancouver

BC

WA6SUP

Sacramento

CA

WB6EGR

Burbank

CA

KU6V

Fremont

CA

KD6GDB

Santa Monica

CA

K6UB

Saratoga

CA

WD6AWP

Huntington Beach

CA

KE6PCV

Los Angeles

CA

WA6RQD

Oceanside

CA

K6JSI

San Diego

CA

VE6RGP

San Diego

CA

WA4HND

Grand Junction

CO

REF2

Denver Reflector

CO

NOPSR

Denver

CO

WA3KOK

Washington

DC

K4KSA

Tampa Bay

FL

KD4BBM

Miami

FL

KD4Z

Orlando

FL

W4DOC

Atlanta

GA

N4NEQ

Atlanta

GA

KH6GMP

Kailua Kona

HI

AH6GR

Maui

HI

AH6JA

Hilo

HI

AH6CP

Honolulu

HI

K7OJI

Fruitland

ID

W9DXN

Dixon

IL

K9WZ

Plymouth

IN

VE4UMR

Winnipeg

MB

VE4SRR

Swan River

MB

W1IMD

Portland

ME

WB8NXP

Bloomfield Hills

MI

N8DNX

Stutsmanville

MI

KC8NCE

Grand Haven

MI

KB3HF

St. Peters

MO

AC7DE

Helena

MT

VE9MCH

Fredricton

NB

KF6SWL

Omaha

NE

VO1BWP

Corner Brook

NF

VO1HHR

Grand Falls

NF

VO1KEN

St. Johns

NF

KA2JZO

Brown Mills

NJ

VE1WRC

Amherst

NS

VE1NSG

Halifax

NS

VK2RMR

Mt. Riverview

NSW

VK2RCZ

Sydney

NSW

REF5

Sydney

NSW

VK2RMP

Wollongong

NSW

VK2RBM

Sydney

NSW

VK8RTE

Darwin

NT

REF4

Yellowknife

NT

VE8NWT

Yellowknife

NT

VE8YK

Yellowknife

NT

AB7TJ

Minden

NV

W7AOR

Las Vegas

NV

NV7RM

Reno

NV

K1IMD

E. Long Island

NY

K1IMD

NY

WR2ROC

Rochester

NY

W8HDU

Lima

OH

VE3KAR

Kingston

ON

VE3ULR

Toronto

ON

VA3RVU

Brampton

ON

VA3MME

Omemee

ON

VE3ORX

Orangeville

ON

VA3CWS

Richmond Hill

ON

VA3LU

Thunder Bay

ON

VE3RBM

Kitchener

ON

VE3MUS

Huntsville

ON

VE3RAK

Toronto

ON

VE3OD

Halton Hills

ON

VE3SUE

London

ON

VE3PGC

Cornwall

ON

VE3DPL

Norwich / Delhi

ON

VE3ADT

Toronto (Milton)

ON

REF1

Toronto Reflector

ONT

AH6LE

Mt. Angel

OR

KA3KCJ

Downingtown

PA

KA3VMA

Drexel Hill

PA

N3IO

Philadelphia

PA

N3APP

Erie

PA

KF3DY

Wellsboro

PA

VA2RLP

Baie-Comeau

QC

VE2TPE

Baie-Comeau

QC

VE2RJS

Montreal

QC

VE2BRR

Montreal

QC

VK4RKP

Ipswich

QLD

N4GLB

Upstate

SC

VE5MLR

Meadow Lake

SK

VE5RAD

North Battleford

SK

VE5CC

Saskatoon

SK

VE5WM

Regina

SK

VE5IOU

Prince Albert

SK

REF3

Sask Reflector

SK

VE5SKN

Saskatoon

SK

GB3US

Sheffield

SY

G4NJI

Rotherham

SY

WB5TUF

Houston

TX

WB6ARE

Cedar Park

TX

G4CUI

Sheffield

UK

WX7Y

Castle Dale

UT

KA7STK

St. George

UT

KD7EFG

Murray

UT

K7SDC

Castle Dale

UT

VK3TNB

Melbourne

Vic

VK3RGL

Melbourne

Vic

J73CS

Roseau, Dominica

W Indies

J73D

Roseau, Dominica

W Indies.

VK6RFM

Fremantle

W.A.

VK6RNC

Perth

W.A.

N7BFS

Spokane

WA

W1CDO

MOBILE

XX

VY1RHJ

Haines Junction

YT

VY1RW

Whitehorse

YT


As for DX stations you can look for two nodes in The Commonwealth of Dominica (not the Dominican republic) where it's not unusual to hear Bernadine, the Mayor of the capital city Roseau on the air promoting the Island. As well you may hear J79 stations on from St. Lucia accessing the Roseau repeater across the Caribbean. As well, there is lots of activity from the 8 active nodes in the land down under which reminds you of the movie Back To The Future as most QSOs with VK land are taking place tomorrow.

Summary
Where else can you witness an open world-wide VoIP wireless network using a free and open protocol like IRLP? This exciting new technology will be a tremendous catalyst to bring new young blood into our hobby. As we all know there has been a real challenge for us to draw kids into our hobby as they could previously talk on their poor quality iPhone connections over the Internet. Now with a basic HT they can enjoy far superior audio and be talking with their friends across town and around the world.

Since we brought our node on here in Kitchener our membership has taken a real boost. Many former members see the excitement back in the hobby and many new members are joining to be part of the IRLP system. The VE3RBM repeater has gone from possibly 2 QSOs per week to our busiest repeater and is dedicated to IRLP use. It is highly recommended that an IRLP node not be added to a high traffic repeater unless the reflector feature is locked out which is easily done.

Are You Interested?

If this article has piqued your interest and you seek additional information please browse the official IRLP web site at www.irlp.net and feel free to contact the IRLP designer Dave, VE7LTD at dcameron@irlp.net or the author at paul@ve3sy.com .

References:

http://www.irlp.net Internet Radio Linking Project web site

http://www.kwarc.org/irlp/listen.html Streaming Audio feed of IRLP

  • - 30 -

Author: Paul Cassel VE3SY
Box 29 RR2
PETERSBURG, Ontario
N0B 2H0

Canada

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