The application to OfCom gave consideration to many factors, some of which are given in
brief below.
The gateway would be controlled so that only amateur stations that were predetermined would be able to use it. In terms of the VoIP port, the software allows comprehensive control of every participant (see Interference & Security below). Clearly, it is less easy to completely prevent a non-participant on the radio side from being relayed via the gateway. However, it is hoped that by the nature of the controlled net to be used for the tests, plus instant manual intervention by the licensee if required, such unwanted audio would be avoided. In any case, the only recipients of the relayed audio on the Internet side would be the permitted participants rather than some indeterminate destination.
The two principal groups that have participated are:
1. Raynet HF group
2. GEM
The first group is a sub-section of the UK Radio Amateur Emergency Network that is especially interested in developing HF bands for emergency communications. This project would be an adjunct to their present activities; convening regular nets, exploring propagation matters and experimenting with new modes.
The second group is made up of amateurs from all over the world who are interested in using the ability of the Internet to provide instantaneous communications between any points on the globe. Operations are based around the conference facility of Echolink that effectively allows many hundreds of individual stations to connect together.
The fact that support into a major disaster zone can then be provided from unaffected parts of the world has great potential. However, it would generally be the case that the disaster zone itself would lose Internet access and amateur radio-frequency links would be necessary to the nearest point of connection to Echolink. Therefore, the value of an HF gateway as proposed here becomes clear.
For example, the Andaman Islands tsunami disaster was greatly assisted by amateur 40m operation, the path distances being too great to employ UHF/VHF. Imagine how much more effective the amateur assistance could have been if an HF gateway was available to allow communications directly from the disaster zone to support agency headquarters in a distant land.
It is the ambition of GEM to develop HF gateways in many countries of the world, while also providing, at the ‘other end’ of the Internet link, Echolink terminals at the headquarters of the search & rescue or aid agencies. In this way, direct monitoring or even interaction using the amateur radio facility would potentially replace the extremely expensive portable satellite telephones that these agencies are currently required to use.
It is obvious that an HF gateway requires very clear identification in order to avoid confusion. Such identification would need to be of a form that could be easily understood by non-amateur users as well as those for whom English is not their first language.
As the proposal is to fully attend the gateway at all times, regular announcements would be made. However, the VoIP software of Echolink can be placed in a Sysop mode designed for this type of gateway. Voice or CW announcements can be automatically generated either directly from the software (in an American accent!) or by triggering WAV files that can be pre-recorded by the licensee.
So almost any form of identification can be made on both the radio and Internet ports of the gateway, by correct setting of the Echolink program. For example, the identification can be set to trigger on every Internet connection and disconnection (including announcement of the connecting station's callsign) and at selectable intervals during or after the gateway is active. These features are currently in use on the VHF and UHF Echolink-to-RF repeaters already licensed in the UK (currently about 40 GB3xx-R repeaters).
It should firstly be noted that several 29MHz gateways are in use in the UK. Therefore, it would not be unusual for non-UK amateurs to use these gateways, speaking over the Internet from their home country but effectively being transmitted from a station in the UK and working any other amateurs in range of the RF link. It is therefore assumed that the potential licensing issues surrounding this operation have already been considered. In effect, such stations are identifying themselves by giving their normal home callsigns but are being radiated from within a different country.
It would be beneficial for all GEM members, for example, to participate in testing this proposed gateway. However, the majority of this group are non-UK amateurs and some are VHF-only licensees in their own country. Therefore, some guidance (presumably that which has already been provided to the 29MHz gateway licensees) is required regarding whether there must be restrictions on access, perhaps based on CEPT agreements.
The Echolink program allows for all activity across the gateway to be recorded as audio files on the local computer. This would be used at all times to provide a record of gateway activity as well as for useful examination during test debriefing.
As already mentioned above, it is hoped to eliminate deliberate interference through strictly controlled access to the VoIP port of the gateway, coupled with controlled net operation and manual intervention of the link on the RF side.
Echolink has been specifically proposed for the Internet side of the gateway for several reasons. Firstly, only licensed radio amateurs are able to use Echolink. On first downloading the software, it is disabled until the network managers have received a copy of the licence of the individual. I have personally never experienced any form of malicious interference in all the years that I have been active on Echolink.
Secondly, Echolink has powerful facilities that completely control the ability to access the gateway and, additionally, whether connected stations are enabled to transmit or only monitor. This means that the VoIP side of the gateway has its ‘house fully in order’ before any connection to the gateway is made.
In a simple form, an HF gateway can be used by a radio amateur to monitor their transmitted signal at a distance. For example, a net controller would be able to monitor their HF transmissions as received by a distant gateway then peeled back to their headphones via VoIP. This would not only allow them to identify any transmission defects, but also gauge propagation variations. They could also potentially hear weak outstations via the distant receiver that they could not discern via their own station directly, a sort of widely-spaced diversity antenna!
HF gateways create the possibility of a transceiver geographically near to the zone of interest while the user can be located anywhere on the globe, courtesy of the instantaneous shrinking of the world permitted by VoIP linking. Furthermore, once in the electronic domain, the received audio can be safely and securely streamed to a website where multiple consumers can monitor without any danger of return intrusion and without loading the available bandwidth of the Echolink network itself. This was, for example, carried out by IRESC during the Katrina hurricane: SATERN (Salvation Army communicators) in Europe were desperately trying to monitor the USA 40m net for news and information but, at such a distance, copy was poor and badly affected by powerful European stations. IRESC accessed the N8AD HF gateway close to the disaster area and streamed the audio to the web, where a very large audience were able to consume the emergency net traffic, interference-free.