TIARA Technology
Technology Implemented by App_Rpt / Asterisk
OVERVIEW HISTORY MAILING LISTS LINKS CONTACT US
OVERVIEW
Technology Implemented by App_Rpt / Asterisk
OVERVIEW HISTORY MAILING LISTS LINKS CONTACT US
OVERVIEW
TIARA is a two-way radio control system that provides the following:
The radio hardware that connects to a port on an interface device may either be a full-duplex repeater system, or a simplex transceiver (with or without frequency flexibility). There are fairly standard signals that interconnect the radio hardware with the interface (such as transmit and receive audio, Push-to-talk, etc.). Some radios bring these signals to a convenient connector, and some have to be .operated on. to gain access to the appropriate signals. In either case, the interface devices have enough tolerance built into them to compensate for large amounts of variance in standards (if any) and methodologies between different radios.
Radio systems in the TIARA technology are referred to as .nodes.. A node may be a Full-Duplex Repeater system, a Simplex Repeater system, a Remote Base system, or a Reflector (no radio hardware) system. Any number of these in any combination may be implemented on a single computer system, as long as there are sufficient radio interfaces provided for all of them, and the computer is powerful enough to support them.
Each node is assigned a number. The organization of the numeration of these nodes is up to the system implementor. Currently, for Amateur Radio use, allstarlink.org (or pttlink.org for Commercial, Public Service, GMRS, etc) is provided as a public convenience for the purpose of coherent node number assignment. Any node may be part of any network, or none at all. It's all up to the configuration designed by the system implementor. In other words, you don't have to have any affiliation to any club or organization to use the TIARA technology.
A node may be thought of as a communications endpoint (destination). Each is associated with a particular purpose, generally connected to a radio system (that is in or covers a particular area). Repeater and Hub nodes may be interconnected to other nodes multiply in any way desired, and Remote-Base nodes may only have one connection from another node at a time. For full duplex Repeater operation, TIARA implements an excellent and rich-featured repeater controller, whose features and performance meets or exceeds other existing technologies, most of which are expensive commercial products. Despite the advantage of the other things it does, it is sometimes used as just a stand-alone repeater controller (without Internet linking, etc).
Hub operation is precisely that of Repeater operation, with the exception that there is no actual radio interface connected to the software for the node. It uses a .dummy. channel driver and the software believes there is a radio connected with no traffic on it ever. Hubs are placed at locations where high bandwidth is available, as not to overuse lower-bandwidth facilities as may be typically found in most places where one might put a radio system (such as DSL, Cable Modem, etc). Any repeater node can accept multiple connections from other nodes, but there wont necessarily be sufficient Internet bandwidth available at that location, so well-placed hubs may be used to solve the bandwidth problem.
Simplex repeater operation is performed by interfacing with a simplex radio transceiver, generally permanently set to one particular frequency. This operation has most of the same features as full-duplex operation, but you cant be heard when the transmitter is transmitting to you, and phone calls (autopatch, etc) must be done with VOX operation (which leaves a whole lot to be desired).
Remote Base operation is also an interconnection with a simplex radio transceiver. This mode, however is designed to work basically as a controlled .slave. node, controlled by another node (normally a Repeater or GUI client). Most remote bases allow for selection of operating parameters, such as frequency, tone, output power, and sometimes mode (like FM, USB, LSB, AM). A Remote Base is a standard transceiver (base station) at a remote location controlled by you via a control link. That is precisely what this mode provides.
In all modes, DTMF control codes are available to perform various functions, such as control linking, autopatch, status query, system control functions, etc. In Repeater modes, DTMF commands may be entered via the main receiver for the node. In all modes, commands may be entered through the link connection from another node (using remote command mode), including GUI connections and phone control connections. In every case, the DTMF codes are fully configurable by the system implementor.
Autopatch and Reverse Autopatch (access to telephone from a Repeater system) functionality is available if desired. It uses the phone switching capabilities of Asterisk when doing so (calls may be placed using conventional or VOIP means).
Direct control (and ability to interactively communicate using voice on the air) via the telephone (an inbound call) is also available. Such connections can, if desired, have different DTMF codes as a regular user on the system (some extra system control codes might be included that would not be desirable to have access to on the air).
PC users, via a GUI program (IAXRPT) may connect to TIARA nodes. Their connection is treated as a standard connection to any node, with the exception that its not announced as an actively connected node. Username/Password security (via IAX2) is provided to prevent unauthorized access.
Another main feature of TIARA is its general design philosophy. Unlike other PC-based radio linking systems currently available, it is designed to be part of the infrastructure of the radio network. In other words, like many stand-alone radio system controllers (repeater controllers, etc.), the radio systems are implemented using TIARA as a main backbone structure of the system, not an add-on or afterthought.
Of course, that's not to say that TIARA can not be interfaced with an existing radio control system. It can, and it has been done with great success. There are many ways to accomplish this, and all are at least somewhat of a compromise. Its use will not be available at 100% efficiency, but dealing with small inconveniences caused by having the 2 different systems work together and not get in each other's way is well worth it.
There are a couple of interface hardware options available. The URI (USB Radio Interface) is a device that connects a single radio system to the PC host via the USB (2.0). It is an excellent quality interface, and is as reliable as a USB device can get. It contains the ability to drive 2 audio outputs to the radio system and have 1 audio input from the radio system, plus drive the PTT (transmit) signal to the transmitter, and have inputs from the COR (Signal Present Indicator) and/or CTCSS decoder from the receiver, plus a couple of general purpose digital I/O pins. It is possible, and in fact recommended, when possible, to simply interface directly with a radio's discriminator for receive, and modulator for transmit. There is DSP software within the program (chan_usbradio with the xpmr library) that does all the standard 2-way radio audio processing within the PC. This allows for the PC to be VERY versatile and to offer many operational modes that would not be possible any other way. The URI can operate in full-duplex or simplex mode, and for someone just starting with the TIARA technology, its inexpensive price (along with its full feature set) makes it very attractive.
The Quad PCI Radio Interface card is also available. This interfaces between (up to) 4 radio systems and the PC via a PCI bus slot. It contains hardware to decode and encode CTCSS or DCS on each channel and works in full-duplex or simplex. It has an audio input and output, an optional separate output for transmit CTCSS, PTT (transmit) signal and COR (Signal Present Indicator) and/or CTCSS decoder signal from the receiver, and 2 digital I/O pins (which may optionally be used for 9600 bps serial data). All of the filtering, audio processing, etc. is done in hardware on the PCI card. It just simply feeds processed audio in and out of the PC.
For the most critical applications (where you want something to be left unattended for very long periods of time and just work), the Quad PCI card is highly recommended. Currently, the USB bus implementation in most PC's is just not 100% reliable or stable over long periods of time. We have had a number of these systems left alone on mountain tops and they just work.
The PC needed (and appropriate) varies a great deal with what type of interface technology you are using and in what environment your radio system is intended to be deployed.
For a mountain-top (or other location not readily accessible), we recommend using an embedded PC (like the SolarPC SR209) that runs directly off of 12 volts DC that has a PCI slot available, and is rack-mountable. This device contains a VIA 1GHz processor that is capable of processing for 4 systems served from the Quad PCI Radio Interface card. This system is completely fan-less and moving-part-less, and therefore has the maximum reliability a PC has to offer.
For locally accessible applications, a standard PC with a hard drive, etc. can certainly be appropriate (and less costly then an embedded system) if desired, and since it's a local application, use of a USB device is highly recommended.
It all really depends on what you're trying to accomplish and your budgetary constraints. From a system-wide standpoint (not just considering the system controller) a wide number of options are available.
The PC must be running Linux (like Fedora or Centos, for example) and Asterisk PBX. Additionally, the latest versions of app_rpt and chan_usbradio/xpmr must be downloaded and installed. For full installation instructions click here.
There are also complete pre-built downloadable system install packages available. Limey Linux is used on the VIA embedded platform, and package using EasyVoxBox and Centos is available for standard PC's. Both of these contain the full Linux operating system, Asterisk (properly configured) and all the TIARA Technology radio software.
After installing the appropriate package, all you have to do is make some configuration file changes, hook up your radio hardware, and you will have a functional radio system.