The authorised operation of low powered devices in the radiofrequency band 433.05 to 434.79 MHz is supported through the former ACA's Radiocommunications class licence for low interference potential devices (LIPDs). Specifically, item 17 of the schedule to that class licence provides for the operation of all transmitters in this band up to a maximum equivalent isotropically radiated power (EIRP) of 25 mW. This is one of many relatively small bands established throughout the radiofrequency spectrum at operating frequencies ranging from a few kilohertz to many tens of gigahertz that support the licensed use of a wide range of LIPDs which provide benefit to the Australian community.
This summary explains the planning considerations that led to the introduction of this provision in the class licence.
Need for the LIPD allocation
The former ACA had statutory responsibilities under the Radiocommunications Act that essentially relate to maximising the public benefit in the use of a national resource. In exercising this spectrum management function on behalf of all of the Australian people, the former ACA tried to accommodate the needs of all groups of users. Where there are competing demands for access to particular parts of the spectrum, the former ACA tried to take a balanced approach in weighing up these demands. In making these sorts of decisions, the former ACA typically considered:
- domestic and international spectrum allocations
- likely demand
- public benefit
- international regulatory arrangements and
- interference potential and effects on incumbents.
The band 433.05 MHz to 434.79 MHz is shared by amateur radio, low-powered applications and the radiolocation service. The radiolocation service is the only primary service in this band. Other services operating in this band must not cause harmful interference to the primary service, and are not afforded protection should they receive harmful interference from that primary service. These allocation arrangements can be viewed in the Australian radiofrequency spectrum plan.
Amateur applications in the 433.05 MHz to 434.79 MHz band (1.74 MHz bandwidth) include FM repeaters and FM simplex services. Amateur services operate on a secondary basis over the wider band 420 to 450 MHz (30 MHz bandwidth) and in a number of other bands throughout the radiofrequency spectrum. That is, the segment allocated for LIPDs overlaps just 6% of the 30 MHz bandwidth used by amateurs in this band.
Arrangements to support low powered devices in the 434 MHz band were introduced to the LIPDs class licence in June 1997 to support a growing demand for such applications sourced mainly from Europe, which is part of International Telecommunication Union (ITU) Region 1. In many countries in that Region, the band 433.05 to 434.79 MHz has a long-standing designation for industrial, scientific and medical (ISM) applications (note that Australia is part of ITU Region 3 the band 433.05 to 434.79 MHz is not a designated ISM band in Australia). ISM applications use radiofrequency energy for their function but are not radiocommunications devices, for example, microwave ovens.
There has been a significant international trend by manufacturers to develop communications devices to operate at low power and on an uncoordinated basis in ISM bands. Radiocommunications devices operating in designated ISM bands do so on the internationally established basis that they must accept any interference they may receive from ISM applications (see international footnotes 150, 139 and 280 of the Spectrum plan). Products have been developed for ISM bands that are common world-wide and in other bands adopted in major regions for ISM. As a consequence of the European adoption of the 434 MHz band for ISM, manufacturers have developed a range of low powered radiocommunications products for that band.
From a review of international regulatory arrangements it was clear that European countries, and the United States of America to a lesser extent, supported the operation of low powered devices in the band 433.05 to 434.79 MHz. Whilst Australia is in ITU Region 3 geographically, we are continually approached by customers, importers, manufacturers, retailers, etc to support products that are designed in other countries and not necessarily in accordance with Region 3 spectrum arrangements. In Australia by 1996/97 there was a strong demand to operate European based low powered applications designed to operate in the 434 MHz band, and that demand has continued to increase.
The former ACA decided that it was in the public interest to facilitate the operation of these devices in Australia. The former ACA believed that this public benefit significantly outweighs the relatively small loss suffered by the amateur users. A factor in that decision was a concern that, being prevalent in many other countries, the devices would be imported into Australia anyway as happened in the case of the 900 MHz band which is used widely in Region 2 for these sorts of devices.
Feasibility for continued amateur operations
The band chosen for LIPD operation was aimed to achieve commonality with international developments. The associated power cap of 25 mW was set at a level that balanced the identified needs against the overall utility of the band for uncoordinated LIPD operations - a few countries allow up to 500 mW transmitters in this band for such operations. The class licence specifies the essential technical conditions and does not specify the type of application for this band. The regulatory approach chosen is deliberately intended to minimise the need for unique Australian products and so maximise the public benefit.
Having made the basic decision to develop a class licence, studies were done to assess the potential for continued operation of amateur services in the segment. It is recognised that interference from LIPDs is possible in some circumstances and is probably more likely in heavily populated areas, but there is still a lot of potential for amateurs to continue to use the segment if they wish.
Officers from the former ACA liaised with the Wireless Institute of Australia on this issue. One aspect that has been discussed is what interference mitigation steps might be taken. The former ACA encouraged the amateur community to review the technical viability of its repeater network in its current configuration (in Europe, the repeater configuration is different to Australia's and is less susceptible to interference from the LIPDs). The former ACA expected that, given the very nature of the amateur hobby itself, and the associated technical skills held by amateur enthusiasts, they would be much better placed than most users to identify which repeaters may be more susceptible to interference and to take protective measures.
The former ACA believed that development of the class licence to support LIPDs is clearly in the public interest. Further, the former ACA believed that the conditions of the class licence are appropriate and should not be changed or further restricted in the types of applications allowed.
The overall loss to the amateur community is relatively small. The former ACA encouraged the amateur community to make realistic assessments of the likely levels of interference. If the levels of interference or operational constraints are judged to be too high, the former ACA encouraged amateurs to consider ways to modify the repeaters to build in better immunity.