The conversion technical framework has been designed to meet the minimum requirements of a spectrum licence capable of supporting the operation of the existing Multi-point Distribution Stations (MDS) in the band. A simplified system model was used to determine the framework limits. The model was based on a survey of the existing MDS transmitters and the original planning for MDS services in the capital cities. This together with a literal interpretation of the requirements specified in the Act was used to develop the framework values rather than trying to adapt existing technical frameworks from other spectrum licences. This is particularly evident in the out-of-area limit that was specified as a received power level at the boundary rather than as a radiated EIRP as found in other licences.
The Conditions included by the ACMA include a number that deem any device operated under the licence to be an MDS transmitter for the purposes of interference tests using the Radiocommunications (Multipoint Distribution Station Licences – Regional Licences) Guidelines No.1 of 1995 (the MDS Guidelines). This existing document included a number of Co-channel, adjacent channel MDS interference requirements between services and interference requirements for other services.
System model
The simplified system model consisted of a 1 kW (60 dBm) central transmitter using an omni directional antenna operating to a 50 km service area with a clear line of sight propagation. The propagation model appropriate under these conditions is the Free Space Propagation model. This propagation model allowed calculation of a good worst case approximation of the level of signal at the boundary.
Emissions were deemed to fall under the MDS emission mask set out in the MDS guidelines. The emission mask was however simplified noting the potential use of a digital television modulation scheme and analog stereo sound. The receiver model was based on the use of directional antenna.
Core conditions: Out-of-area emissions
The out-of-area limit was calculated using the simplified MDS model as below:
| Maximum Transmitter EIRP: | 60.0 dBm (1 kW) |
|---|---|
| Free Space Loss @ 2350 MHz and 50 km: | 133.9 dB |
| Level at the boundary | -73.9 dBm |
| Rounded up | -73 dBm |
In discussions with accredited assigners after conversion the following clarifications were made:
- This is the power in the 7 MHz channel; and
- Should the level be measured, a standard 10 m measurement height would be used.
Core conditions: Out-of-band emissions
The out-of-band limit was based on the MDS emission mask in part 2 section 5 of the MDS Guidelines applied to a 1 kW vision carrier level. Note that these values were intended to capture a worst case value for existing analog MDS transmitters. Unlike other spectrum licence out-of-band limits the limits to replicate the MDS mask sloping elements were introduced.
The break point values were calculated as set out below:
| On the lower edge of the licence frequency band | 60.0 dBm - 50 dB = 10 dBm |
|---|---|
| Lower edge – 1 MHz | 60.0 dBm - 55 dBm = 5 dBm |
| Lower edge – 5 MHz | 60.0 dBm - 60 dBm = 0 dBm |
| Beyond 5 MHz | 0 dBm |
| On the upper edge of the licence frequency band | 60.0 dBm - 50 dB = 10 dBm |
| Upper edge + 1 MHz | 60.0 dBm - 60 dB = 0 dBm |
| Beyond 1 MHz | 0 dBm |
The sloping elements were implemented as set out below:
Maximum Radiated Power for core condition 4(a)
10 dBm at 0 Hz offset decreasing linearly to 5 dBm at 1 MHz offset
Maximum Radiated Power for core condition 4(b)
5 dBm at 1 MHz offset decreasing linearly to 0 dBm at 5 MHz offset
Maximum Radiated Power for core condition 4(d)
10 dBm at 0 Hz offset decreasing linearly to 0 dBm at 1 MHz offset
Conditions included by the ACMA
A number of specific conditions were added to the licence to reflect those of the existing MDS apparatus licences required to minimise interference to other services.
Additional emission limits
Additional controls on emissions from high powered MDS transmitters were required to protect Space Services in the band 2290-2300 MHz using sensitive cooled MASER based receivers. These requirements were brought across from the existing MDS Guidelines part 2, section 7. The requirements were particularly important for the protection of receivers operating at the Tidbinbilla Deep Space Tracking Station, and the Parkes Observatory. These requirements are not limited to areas around these sites as the coordination areas are large and the requirements generally achievable by MDS transmitters.
Interference management and co-siting
The standard interference self management text used in other licences was incorporated in the licence. The co-siting requirement was extended to 500 m based on the MDS Guidelines definition of co-siting set out in part 1 section 2.
Section 145 determination of unacceptable interference
The Radiocommunications (Unacceptable Levels of Interference—2302-2400 MHz Band) Determination 2000, the Radiocommunications Act 1992 section 145 Determination for the conversion, is a simplified document declaring that for registration all conditions of the licence must be met. A transmitter that did not meet the conditions of the licence is deemed to cause unacceptable interference.
Advisory guidelines
The conversion framework calls upon the Guidelines drafted for the original apparatus licensing of MDS services in regional areas, the Radiocommunications (Multipoint Distribution Station Licenses – Regional Licences) Guidelines No. 1 of 1995.