Internet Radio Linking Project
Encyclopedia
The Internet Radio Linking Project, also called IRLP, is a project that links amateur radio
stations around the world by using Voice over IP
(VoIP). Each gateway consists of a dedicated computer running custom software that is connected to both a radio and the Internet
. This arrangement forms what is known as an IRLP Node. Since all end users communicate using a radio as opposed to using a computer directly, IRLP has adopted the motto "Keeping the Radio in Amateur Radio".
Amateur radio (or ham) operators within radio range of a local node are able to use DTMF
tone generators to initiate a node-to-node connection with any other available node in the world. Each node has a unique 4 digit node number in the range of 1000-8999. A real-time searchable list of all nodes worldwide (including their current status) is available anytime by viewing the IRLP Network at a Glance. As of June 2009, there are over 3,180 nodes across 7 continents.
IRLP connections are of two types: node to node, and node to reflector. Stations wishing to communicate with 3 or more nodes at the same time may accomplish this by connecting to what is called an IRLP Reflector. Reflectors are a type conferencing system. Most reflectors on the network have 10 channels (0-9) with channel 0 being the main channel. Each reflector has a unique 4 digit node number in the range of 9000-9999. The first 3 digits consist of the reflector number, while the fourth digit represents the channel number. As of April 2007, there are 20 operational reflectors (including Echo Reflector 9990, which digitally records and plays back transmissions for testing purposes). Since most reflectors have 10 channels, there are approximately 200 unique reflector channels available for use.
, Canada
, Cameron attended the University of British Columbia
where he joined the UBC Amateur Radio Society. He built his first repeater and computer-based repeater controller in the 1990s.
Cameron installed the first three IRLP nodes in November of 1997. They used the Windows
operating system
(OS) with VocalTec
's iPhone installed. There were problems with the software, mainly in the fact that iPhone is not very stable nor is it controllable. After running iPhone for close to 6 months on active connections to Vernon, British Columbia
, Canada and Saint John, New Brunswick
, Canada, Cameron decided to rebuild the nodes and essentially start over. This is when the Linux
OS and the Speak Freely software were first tested.
On November 12, 1998, the VE7RHS node was first installed in Gage Towers, UBC, Vancouver, British Columbia, Canada using Linux. A few days later, the VE7RVN node came online from the residence of Michael Paul Illingby, VE7TFD in Vernon, British Columbia, Canada. Since this point, no further problems were experienced. This planted the seed for the IRLP network to grow. New nodes slowly launched across Canada, followed by the United States and worldwide.
Node numbers were originally set at 3 digits in length. Due to the extensive growth of the IRLP network, an extra digit needed to be added in 2002. Existing node numbers after this change received a trailing zero. For example, if your node number was 123, it was now 1230. Most existing reflectors were also converted from single channels to 10 channels. This new type of reflector was known as a super-reflector. After all the reflectors were converted the "super-" was dropped.
is the operating system
(OS) of choice for IRLP, as it allows the best in reliability, programmability, efficiency, and functionality. Most older IRLP nodes use the Red Hat
7.3 or Red Hat 9 distribution, as they were very stable releases and ran very smoothly on any Pentium
or better computer. In 2005, a custom version of Fedora
Core 3 was introduced, followed by Fedora Core 5 in 2006. As of March 2007, IRLP no longer supports Red Hat and started shipping with the CentOS
4.4 distribution. This release provides greatly improved operation with more support for audio cards.
The IRLP board is a very simple circuit, the most difficult part being the DTMF decoder. The DTMF decoder consists of a MT8870 (or similar) DTMF decoder IC and HCF4081 (or similar) and-gate IC. Two chips are needed because the MT8870 has latched outputs, and the IRLP software looks for short pulses at the parallel port pins 10,12,13,15 in order to acknowledge a DTMF digit. MT8870 pin 15 provides a pulse when any valid DTMF digit is decoded, so this signal is used on one input of each gate on the HCF4081. The other gate input is from MT8870 pins 11,12,13,14. The output of the HCF4081 (pins 3,4,10,11) connect to the parallel port and provide the pulsed input that IRLP needs.
The IRLP software cannot decode the D digit (the bottom right key on a 16-button DTMF dial). This is a system limitation of IRLP. DTMF digit D is logic level 0 on all 4 bits from the MT8870. Thus, the parallel port pins would all be at 0 volts, which IRLP regards as no DTMF digit present. The IRLP PC does not see the MT8870's strobe pin, which would enable digit D detection.
The IRLP board has no audio transformers or bypass capacitors whatsoever. It is merely a DTMF decoder circuit with a simple COS and PTT circuit installed. Version 3 boards also have simple FET switches for AUX1,2,3.
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
stations around the world by using Voice over IP
Voice over IP
Voice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...
(VoIP). Each gateway consists of a dedicated computer running custom software that is connected to both a radio and the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
. This arrangement forms what is known as an IRLP Node. Since all end users communicate using a radio as opposed to using a computer directly, IRLP has adopted the motto "Keeping the Radio in Amateur Radio".
Amateur radio (or ham) operators within radio range of a local node are able to use DTMF
Dual-tone multi-frequency
Dual-tone multi-frequency signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF that is used in push-button telephones for tone dialing is...
tone generators to initiate a node-to-node connection with any other available node in the world. Each node has a unique 4 digit node number in the range of 1000-8999. A real-time searchable list of all nodes worldwide (including their current status) is available anytime by viewing the IRLP Network at a Glance. As of June 2009, there are over 3,180 nodes across 7 continents.
IRLP connections are of two types: node to node, and node to reflector. Stations wishing to communicate with 3 or more nodes at the same time may accomplish this by connecting to what is called an IRLP Reflector. Reflectors are a type conferencing system. Most reflectors on the network have 10 channels (0-9) with channel 0 being the main channel. Each reflector has a unique 4 digit node number in the range of 9000-9999. The first 3 digits consist of the reflector number, while the fourth digit represents the channel number. As of April 2007, there are 20 operational reflectors (including Echo Reflector 9990, which digitally records and plays back transmissions for testing purposes). Since most reflectors have 10 channels, there are approximately 200 unique reflector channels available for use.
History
IRLP was invented by David "Dave" Cameron, VE7LTD. Born and raised in West Vancouver, British ColumbiaWest Vancouver, British Columbia
West Vancouver is a district municipality in the province of British Columbia, Canada. A member municipality of Metro Vancouver, the governing body of the Greater Vancouver Regional District, the municipality is northwest of the city of Vancouver on the northern side of English Bay and the...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, Cameron attended the University of British Columbia
University of British Columbia
The University of British Columbia is a public research university. UBC’s two main campuses are situated in Vancouver and in Kelowna in the Okanagan Valley...
where he joined the UBC Amateur Radio Society. He built his first repeater and computer-based repeater controller in the 1990s.
Cameron installed the first three IRLP nodes in November of 1997. They used the Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
(OS) with VocalTec
VocalTec
VocalTec Communications Inc. , is an Israeli telecom equipment provider. The company was founded in 1989 by Alon Cohen and Lior Haramaty, who invented and patented the first Voice over IP audio transceiver...
's iPhone installed. There were problems with the software, mainly in the fact that iPhone is not very stable nor is it controllable. After running iPhone for close to 6 months on active connections to Vernon, British Columbia
Vernon, British Columbia
Vernon is a city in the south-central region of British Columbia, Canada. Named after Forbes George Vernon, a former MLA of British Columbia who helped found the famed Coldstream Ranch, the City of Vernon was incorporated on December 30, 1892. The City of Vernon has a population of 35,944 , while...
, Canada and Saint John, New Brunswick
Saint John, New Brunswick
City of Saint John , or commonly Saint John, is the largest city in the province of New Brunswick, and the first incorporated city in Canada. The city is situated along the north shore of the Bay of Fundy at the mouth of the Saint John River. In 2006 the city proper had a population of 74,043...
, Canada, Cameron decided to rebuild the nodes and essentially start over. This is when the Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
OS and the Speak Freely software were first tested.
On November 12, 1998, the VE7RHS node was first installed in Gage Towers, UBC, Vancouver, British Columbia, Canada using Linux. A few days later, the VE7RVN node came online from the residence of Michael Paul Illingby, VE7TFD in Vernon, British Columbia, Canada. Since this point, no further problems were experienced. This planted the seed for the IRLP network to grow. New nodes slowly launched across Canada, followed by the United States and worldwide.
Node numbers were originally set at 3 digits in length. Due to the extensive growth of the IRLP network, an extra digit needed to be added in 2002. Existing node numbers after this change received a trailing zero. For example, if your node number was 123, it was now 1230. Most existing reflectors were also converted from single channels to 10 channels. This new type of reflector was known as a super-reflector. After all the reflectors were converted the "super-" was dropped.
Computer
- A dedicated IBM compatible computer, Pentium class (Intel, AMD etc.), running a processor clocked at least 200 MHz
- At least 128 MB of RAM
- A dedicated hard drive of at least 2 GB
- Basic (legacy) parallel port running LPT1 (0x378/9)
- Soundcard - most PCI cards work as do many motherboard based chipsets
- Ethernet Adapter (Network Card) connected to the Internet
Operating system
LinuxLinux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
is the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
(OS) of choice for IRLP, as it allows the best in reliability, programmability, efficiency, and functionality. Most older IRLP nodes use the Red Hat
Red Hat Linux
Red Hat Linux, assembled by the company Red Hat, was a popular Linux based operating system until its discontinuation in 2004.Red Hat Linux 1.0 was released on November 3, 1994...
7.3 or Red Hat 9 distribution, as they were very stable releases and ran very smoothly on any Pentium
Pentium
The original Pentium microprocessor was introduced on March 22, 1993. Its microarchitecture, deemed P5, was Intel's fifth-generation and first superscalar x86 microarchitecture. As a direct extension of the 80486 architecture, it included dual integer pipelines, a faster FPU, wider data bus,...
or better computer. In 2005, a custom version of Fedora
Fedora (operating system)
Fedora is a RPM-based, general purpose collection of software, including an operating system based on the Linux kernel, developed by the community-supported Fedora Project and sponsored by Red Hat...
Core 3 was introduced, followed by Fedora Core 5 in 2006. As of March 2007, IRLP no longer supports Red Hat and started shipping with the CentOS
CentOS
CentOS is a free operating system based on Red Hat Enterprise Linux . It exists to provide a free enterprise class computing platform and strives to maintain 100% binary compatibility with its upstream distribution...
4.4 distribution. This release provides greatly improved operation with more support for audio cards.
IRLP hardware
An IRLP board is required to interface to the radio. Currently version 3.0 IRLP boards are available fully assembled and tested. Each board comes complete with all the cables between the board and computer parallel port (with sub-hoods) and terminates in a male DB-9 connector for interface into the radio. A cable terminated in a female DB-9 plugs into the IRLP board and interfaces to a radio/repeater/controller. Two mono or stereo 1/8" audio plugs connect to the computer's sound card. The audio circuitry is the owner's responsibility.The IRLP board is a very simple circuit, the most difficult part being the DTMF decoder. The DTMF decoder consists of a MT8870 (or similar) DTMF decoder IC and HCF4081 (or similar) and-gate IC. Two chips are needed because the MT8870 has latched outputs, and the IRLP software looks for short pulses at the parallel port pins 10,12,13,15 in order to acknowledge a DTMF digit. MT8870 pin 15 provides a pulse when any valid DTMF digit is decoded, so this signal is used on one input of each gate on the HCF4081. The other gate input is from MT8870 pins 11,12,13,14. The output of the HCF4081 (pins 3,4,10,11) connect to the parallel port and provide the pulsed input that IRLP needs.
The IRLP software cannot decode the D digit (the bottom right key on a 16-button DTMF dial). This is a system limitation of IRLP. DTMF digit D is logic level 0 on all 4 bits from the MT8870. Thus, the parallel port pins would all be at 0 volts, which IRLP regards as no DTMF digit present. The IRLP PC does not see the MT8870's strobe pin, which would enable digit D detection.
The IRLP board has no audio transformers or bypass capacitors whatsoever. It is merely a DTMF decoder circuit with a simple COS and PTT circuit installed. Version 3 boards also have simple FET switches for AUX1,2,3.
Parallel port pin assignments
3 PTT
4 Aux pin 1 (active high at parallel port)
5 Aux pin 2 (active high at parallel port)
6 Aux pin 3 (active high at parallel port)
10 DTMF 4
11 COS
12 DTMF 3
13 DTMF 2
15 DTMF 1
18 Ground
19 Ground
20 Ground
21 Ground
22 Ground
23 Ground
24 Ground
25 Ground
(Also ground DB25 shell)
RF hardware
A link radio or repeater is needed to interface to the IRLP board. The radio's COS (carrier operated squelch) and PTT lines must be available to the IRLP board. Additionally, courtesy tones, hang time, and node IDs must not be transmitted over the VoIP link. This can easily be accomplished using CTCSS on the repeater transmitter that follows the COS of the receiver.See also
- EcholinkEcholinkEchoLink is a free computer-based Amateur Radio system that allows radio amateurs to communicate with other amateur radio operators using Voice over IP technology on the Internet for at least part of the path between them...
- eQSOEQSOeQSO is a client–server software program designed by amateur radio enthusiasts for linking amateur radio frequency gateways and repeaters via the internet by using a Voice over IP protocol...
- Wide-Coverage Internet Repeater Enhancement SystemWide-Coverage Internet Repeater Enhancement SystemWide-coverage Internet Repeater Enhancement System is a standard created by Yaesu designed to link compatible amateur radio repeaters over Voice over IP, allowing any home stations using those repeaters to communicate with each other over VoIP....
- The IRLP yahoogroup