
SvxLink as an FM Controller
SVXLINK is not just another “thing” that people can use, but is a significant package of softwares for the deployment of a Full Duplex Repeater, a Simplex node, an EchoLink entry point for either of these, a Broadcast Voice Mail Service, a Propagation Monitor Service, and a semi-phased Remote Receiver and Transmitter in an area of limit coverage, by a main Repeater on the same software.
It is already available in the UK, but so far the take-up is quite small.
On the contrary, identical set-ups in Germany has over 220 Repeaters and Simplex Nodes, in Poland has 140, in Sweden 82 clients , in Italy 36, and in France 124, although the French network is behind on the version in use.
The creator of the software Tobias Blömberg SM0SVX began the project in 2003, releasing the first non-beta version in 2013, so it has been around a while. The current version is 24-02.1.
There are other versions, but the packages in debian are out of date, and lack the resources now available.
SvxLinkCapabilities
The primary use of SvxLink is as a software controller for a radio installation.
- This can be as a Repeater Controller. It can control the operation of the transmitter and work with various configurations, and work with the receiver to forward the audio through a USB Soundcard or a suitable interface.
- A Simplex Node is also a repeater by definition, so SvxLink can also control the operations here too.
- In both circumstances the installations will work significantly better with an internet connection.
The secondary use of SvxLink is as a software controller for a ‘Reflector’, providing the means to link multiple stations together, to enhance coverage or connectivity.
- This link in the first instance is passive, where the system recognises a number of repeaters or nodes that are linked. Each Repeater or Node is a ‘stand-alone’ device, with coverage only within its own domain.
- In the second instance the link can become ‘Dynamic’ where action is taken by the system operator and the users, to develop a wider coverage.
The Tertiary use of SvxLink is as a software controller for a sub-repeater installation.
- In a case where an existing repeater has areas of reduced reception, then the final part of the package can be installed with either an additional receiver or an additional transceiver pair. This package for remotetrx need to be able to converse with the ‘Master’ Repeater, so that the repeater can determine which of the receivers is best, and is voted-in for the time of a particular transmission.
- Whilst a second Transmitter can be enabled, the System Operators need to make provisions as the transmissions will hardly be quasi-synchronous, and there will be some areas of coverage that will receive both the repeater and the sub-repeater simultaneously, causing audio issues.
- In this latter example it would be perhaps preferable to install a simplex node on a different frequency or band and connect it to the repeater via the reflector instead.
Because this is a software package, this might throw up issues with the less computer literate, but rest assured it is a simple installation, requiring only a little practical knowledge.
The Raspberry Pi, the Orange Pi and the Banana Pi are of tremendous use, and many will be reasonably conversant with their use within the Amateur Radio field. However in practical terms, any computer running Linux will be quite capable, provided the user was competent to make certain changes .
The software is installed best from a script that I have made available for all.
- The source – svxlink.org – is well worth a visit, however may make the visitor more wary, as it is not for the feint of heart.
- The script makes an installation far less daunting with few interactions with the terminal interface, and more in the way of menus to follow.
- Like most installations, a good read of the instructions (the README.md in this case) will likely prepare the installer for what will occur.
- There is no image. Images need configuration after download. This installation builds to the specification of the installer in progression.
- If the installer is familiar with the desktop dashboard, then they will be unsurprised that this will be the result.
- For the System Operator, the dashboard also gives immediate access to the parameters needed to make corrections to the configuration.
- For the audience of a Repeater, they will also have access to the visual aspect of the repeater, provided that the System Operator give adequate provision of a port at the router on the network.
The coverage of the network is only as good as the participants can provide. The more participants, the better the coverage of the network.
One might ask, why do we need another network?
- The current systems such as All-Star are quite technical, not to say that SvxLink isn’t technical. However should an installer wish to attempt a build he has only to supply me, the svxreflector supervisor with the connection password and callsign of the node, then access requires nothing more. No Node Numbers, No other registration.
So how does this network work?
- In order to be effective, there needs to be a system that can recognise DTMF.
- In order to involve several different regions in a National Project, this needs planning.
- Fortunately this has already been done in the Digital Mobile Radio world where so-called Talk Groups have been devised from the internationally recognised Mobile Country Code. SO we have a system of Talk Groups here too.
- This is a view of the Dashboard for my Simplex Node in Northumberland, at the Talk Group page. This node is also an EchoLink node, a module within the SvxLink software package.
- Each System Operator can select talk groups to monitor, to enhance the capability of their unit, but they are not unlimited. Talk Groups that are unlisted, can also be employed, if two users agree to meet there.
How do the talk groups work?
- In the example above you will see a series of boxes highlighted TG Default, TG Monitor, TG Active.
- From the example a user initiates a connect by DTMF with an RF transmission then pressing the DTMF codes 91235#.
- 91 advises the unit that a Talk Group Follows, and the # is the end character.
- The local unit activates Talk Group 235, and announces this by voice.
- Their next transmission will dynamically connect the unit to the svxreflector.
- The svxreflector initiates a connect call to all connected repeaters and nodes that have 235 in the TG Monitor List, and their voice can be heard across all the Nodes.
- As in the world of DMR, if a contact is made, then a QSY can be initiated to another Talk Group, so that only two nodes remain connected, leaving the rest of the network can be left free.
- A QSY is simply a DTMF call 91- Next Talk Group #, that anyone can follow by DTMF 93#
- Repeaters in different regions can have a regional Talk Group assigned.
- There is no limit to the extent the network can go. At this time there is a link to the Swedish Network and into Germany. There is a live link also to Hubnet on Talk Group 23526.
Other features that can be activated on Svxlink.
- Parrot – This is a facility available for a user to test their own audio. By Transmitting 1# by DTMF, the Parrot module is activated and will repeat back all transmissions, until a second # is sent or the module achieves time-out due to inactivity.
- EchoLink – This is the Linux version of EchoLink, that is activated by DTMF 2#. An EchoLink node is called by the sending of the number followed by #. The EchoLink Voice test for example is 9999# where one can again test the transmitted audio. The exit from the module and connected node is by DTMF ##
- Propagation Monitor – This is an additional module requiring additional email addressed to receive messages from DXRobot and DX Maps. Called by DTMF 10# if installed.
- Metar Infomation – This module if installed can transmit the current weather from a selected airport or one of a number airports configured, just for local interest. Activated by 5#
- QSO Recorder – If installed this is activated by 81# and terminated by 80#
- All Talk Group information is preceded by 9. A list of Available code is available.
- A System Operator can set up Macros that are called by DTMF, for example D1#, but behind the scenes, this transmission generates a longer sequence within the program to call a talk group or other function. For example D1# may be sending 9123561# that takes longer and open to errors and dropped PTT whilst pushing buttons.
- This table shows the codes each followed by a #, the first of which is to deactivate the network for the occasion of a club net for example.
The newest Repeaters on the svxportal-uk.ddns.net:81 network are GB3BD a 70 cm Repeater in Banbury, and GB3MH at Turners Hill in East Sussex near Gatwick Airport.
This link shows the svxportal dashboard that displays the live activity on the svxreflector on the server.
The public display of the Repeater Dashboard is a matter for each System Operator.
SvxLink - Instructions to build a Repeater or a Node
For full instruction I would ask you to go to https://github.com/f5vmr/svxlinkbuilder where you find everything that you will need, referencing the equipment required. Follow the README.md file, to the letter, and you won’t go wrong, provided that you understand the instructions and you understand your radio equipment, as you should of course. Alternatively go to g4nab.co.uk/svxlink for an even more rapid installation plan using a ready made image. that just needs a little configuration.
Provided the radio set up is correct, then you can have a working system in around 20 minutes.
Previous installations took upwards of around an hour, as the software had to be compiled. As this is no longer necessary the time factor is no longer a consideration.
The Swedish Network : https://svxportal.sm2ampr.net/
The Italy Network : http://195.62.162.116/
The Poland Network : https://fm-poland.pl/dashboard/
The French Network (Old version software) http://rrf4.f5nlg.ovh:82/
The German Network: https://fm-funknetz.de/dashboard/