DSM 2.4GHz Approval MOP058

MODEL AERONAUTICAL ASSOCIATION OF AUSTRALIA

MOP058
 
APPROVED: M.A.A.A. PRESIDENT

Date: 30/11/2006

Table of Contents
 
1.     INTRODUCTION
2.     REQUIREMENTS
3.     GUIDANCE
APPENDIX A

This Policy and/or Procedure forms part of the M.A.A.A. Manual of Procedures.  This entire document is for the use of all classes of members of the M.A.A.A. in the conduct of activities associated with the M.A.A.A. and is not be used for any other purpose, in whole or in part, without the written approval of the M.A.A.A. Executive.

Shading of text identifies changes to the previous version.

2.4 GHz EQUIPMENT POLICY

1.  INTRODUCTION

This frequency band specified for this application in Australia covers the frequency range 2.4000 GHz to 2.4835 GHz.
 
The use of the 2.4 GHz band for model aircraft is a developing technology and as such this document provides the current M.A.A.A. Policy and Guidance.  However it is to be expected that as development continues and experience is gain that it will be subject both to refinement and possibly significant changes.
 
 
2.  REQUIREMENTS

The M.A.A.A. requires that the equipment used for the control of model aircraft using frequencies in the 2.4 GHz band complies with the requirements of the Australian Communications and Media Authority (ACMA) and the relevant Class licence, Radiocommunications (Low Interference Potential Devices) Class Licence 2000.   This is available from the ACMA and is posted on their web site http://www.acma.gov.au

Only equipment that is specifically approved by the M.A.A.A. for aircraft use is permitted. A list of the M.A.A.A. permitted equipment is included in this document as Appendix A.  In addition, this equipment shall not be used outside any limitation on the approval stated in Appendix A.
 
The equipment shall be used in accordance with the manufacturer’s instructions.
 
The M.A.A.A. does not require that any additional testing is undertaken on approved equipment.  However to ensure compliance with the Class Licence and the Australian Radiocommunications Standards the equipment shall be identified as being traceable to those Standards by the application of an Australian “C Tick”. The “C-Tick” is a logo attached to the equipment that shows that the supplier takes the responsibility for compliance with, and traceability to, the Standards.
 
The pilot cannot control the actual frequency of operation as it is determined by the technology used within the equipment.  However the M.A.A.A. still requires that a keyboard, or similar system, identifies who the individual users of this band are.  It is recommended that Clubs use a similar system to the one used by them for the other approved frequency bands, whether this is a Silvertone© type keyboard system or otherwise.  This will just identify the name of the owner of transmitters actually either in use or ready for use.
 
The maximum number of transmitters to be available for use under this system at the same time is not to exceed ten.  The reason is that at some time in the future the technologies used may mean that the maximum number is limited by the actual technology.  Whilst with currently approved equipment this specific number is conservative in most environments, this limit should also ensure that there is no practical limitation on the actual number operating at any given time.

3. GUIDANCE

Whilst not part of the M.A.A.A. Requirements, the following information is provided to assist users of this class of equipment.

1. Not all equipment currently supplied for model use is suitable for model aircraft. Equipment that is suitable for model aircraft may have different standards of performance.
2. The band is a common user band.  This means that many applications can use the same frequencies including, but not limited to, computer networks, hands-free phones, data links, as well as other model applications.
3. The maximum output power allowed by the class licence means that applications in this band are restricted to local areas.
4. The Class Licence and Supporting Radiocommunications Standards require that the technology incorporates ‘collision avoidance’.  This means that the frequency that all equipment uses is determined by the technology in a way that should not allow it to interfere with other equipment operating in the immediate area.  This significantly reduces the possibility of interference including of course between the systems controlling model aircraft, but it is always possible that interference can occur particularly if models are flown toward other interference sources.
5. Because every time a system is switched on the actual frequencies in use both locally and in the general environment may be different, the possibility of interference may vary each time the equipment is used.
6. The actual technology used to achieve satisfactory performance both with model aircraft and to achieve ‘collision avoidance’ will vary between equipments.  The difference may be very significant.  The performance of different equipment designs may therefore vary considerably.
7. Equipment that is different to the one you are using, whether for models or another applications may have a much greater or lower range, due to actual output power or the gain of the antenna.  Whilst the maximum output power is specified in the class licence, fixed systems in particular, may use antennas which provide a much stronger signal in specific directions.
8. Aircraft modellers should be aware of possible sources of interference and look out for evidence of it happening.
9. Any suspicion of interference should be investigated, particularly if a pattern develops such is in a particular direction or with particular types of equipment.  It should be remembered that for the reasons stated in 5 above there may be a pattern even if the interference does not occur every time a system is operated.
10. Clubs have the right to restrict the use of 2.4GHz, particularly where sources of interference have been identified.
11. Because of the wavelength of the radiated signal from the transmitter to the receiver, there is more likely to be interference caused by metal or carbon fibre components in the airframe than with the lower frequencies used up to now.  Whilst the technology may overcome the interference to some extent the user has to be aware of the possibility of “on board” generated interference.  In the event that the airframe contains either significant amounts of carbon fibre or metal, or if the modeller suspects there might be a problem, then testing the range in various directions from the model whilst on the ground and comparing the range with the same antenna arrangement, at the same height and orientations, but outside the model is a wise precaution.
12. In the event of a modeller suspecting that there is a problem with the performance of his/her particular equipment then he/she should take it to a manufacturer approved repair station for investigation.
13. As the technology advances, and as experience of operation is gained, the advice and requirement may change.

APPENDIX A

CURRENT APPROVED SYSTEMS

(transmitter and receiver equipment combinations)

Spektrum DSM Pro

Spektrum Telementry