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Commonwealth legislation
This Act has been repealed and is no longer in force. It is retained for historical reference.
These guidelines set technical rules for Multipoint Distribution Service (MDS) licence holders in regional Australia to assess and prevent radio interference. Licensees must run detailed, calculation-based assessments using terrain, transmitter and antenna data and compare field strengths to strict limits; regulators can then impose conditions (power, direction, location) if interference risks are found.
They protect other MDS users, microwave fixed links and key radio astronomy sites (Parkes, Tidbinbilla), preserving services and efficient spectrum sharing.
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Direct links to the current provisions in Radiocommunications (Multipoint Distribution Station Licences - Regional Licences) Guidelines No. 1 of 1995.
PURPOSE OF ASSESSMENT OF INTERFERENCE FROM MDS TRANSMITTER TO MDS RECEIVER
The assessments A.1, A.2 and A.3 below specify how to assess the potential for interference from an MDS transmitter to co-channel or adjacent channel MDS receivers for the purposes of Guidelines 14(a), (b) and (c).
A.1.1. This assessment (A.1) is intended to lead, where necessary, to the imposition of a licence condition aimed at ensuring that the field strength from an MDS transmitter does not exceed 32 dBuV/m in any other co‑channel licensee's MDS licence area.
A.1.2. The following information is needed to decide if an interference assessment must be carried out:
- MDS transmitter location
- MDS transmitter channel
- MDS licence area boundaries
[NOTE. Details of the MDS licence area boundaries are contained in Schedule 1 to the Radiocommunications (Allocation of Multipoint Distribution Station Licences - Regional Licences) Determination No. 1 of 1995.]
A.1.3. An assessment of the potential for interference from an MDS transmitter to another MDS licence area is necessary if the MDS transmitter is to be located within a distance 'D' of another MDS licence area. The distance 'D' is determined from the height of the transmitting antenna of the MDS transmitter above average ground level and is indicated in the following table.
| Height of Transmitting Antenna above Average Ground Level, Ht*(m) | D(km) |
|---|---|
| Ht 37.5 | 65 |
| 37.5 Ht 75 | 75 |
| 75 Ht 150 | 90 |
| 150 Ht 300 | 110 |
| 300 Ht 600 | 135 |
| 600 Ht 1200 | 175 |
* Ht: the height of the MDS transmitting antenna above the average level of the ground between distances of 3 and 15 km from the transmitter in the direction of the nearest point on the boundary of another MDS licence area (see CCIR Rec 370-5).
[NOTE. Distances for MDS transmitters with heights of transmitting antennas greater than 1200 m above average ground level will be provided by the Customer Services Group of the SMA, if required.]
[NOTE. CCIR Recommendations are available from the Standards Australia International Sales Group, Strathfield NSW.]
A.1.4. If an interference assessment is necessary, the assessment will comprise the following Steps 2, 3 and 4.
A.1.5. The following information is needed to complete this calculation:
- MDS transmitter location, site height and antenna height
- terrain profiles between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter
Information provided by the SMA
- MDS licence area boundaries
- nominal MDS receiver antenna height = 10m
[NOTE. Details of the MDS licence area boundaries are contained in Schedule 1 to the Radiocommunications (Allocation of Multipoint Distribution Station Licences - Regional Licences) Determination No. 1 of 1995.]
A.1.6. Using the method detailed at Schedule 2, calculate the terrain loss between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter.
[NOTE. If the protection criteria of Assessment A.1.10 are satisfied when a terrain loss value of Lt = 0 dB is used in the equation at Assessment A.1.8. then calculation of an actual value for Lt is not required.]
A.1.7. The following information is needed for this calculation:
A.1.9. The following information is needed for this assessment:
A.2.1. This assessment (A.2) is intended to lead, where necessary, to the imposition of a licence condition aimed at ensuring that the field strength from an MDS transmitter does not exceed 76 dBuV/m in any other MDS licence area where transmitters are licensed to operate on adjacent MDS channels.
A.3.1. This assessment (A.3) specifies how to assess the potential for interference from an MDS transmitter to a notional adjacent channel MDS receiver lying within a defined area (called an assessment area) around an adjacent channel MDS transmitter operating in the same licence area.
A.3.2 The assessment is intended to lead to the imposition, where necessary, of a licence condition aimed at ensuring that the field strength from an MDS transmitter will not exceed 76 dBuV/m in the assessment area around any adjacent channel transmitter operating in the same licence area.
This Assessment D specifies how to assess the potential for interference from an MDS Group B transmitter to an earth station receiver in the space research service.
A detailed discussion of the interference mechanisms between MDS and earth stations can be found in Section 2 Part B of the Coordination Handbook.
The SMA considers that earth station receivers in the space research service are not likely to receive interference from Group A MDS transmitters. Accordingly, no assessment of the interference potential to earth station receivers from Group A MDS transmitters need be carried out.
Step 1: Identifying if an Interference Assessment is Necessary
D.1. The following information is needed to decide if an interference assessment must be carried out:
Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.
PURPOSE OF ASSESSMENT OF INTERFERENCE FROM MDS TRANSMITTER TO MDS RECEIVER
The assessments A.1, A.2 and A.3 below specify how to assess the potential for interference from an MDS transmitter to co-channel or adjacent channel MDS receivers for the purposes of Guidelines 14(a), (b) and (c).
A.1.1. This assessment (A.1) is intended to lead, where necessary, to the imposition of a licence condition aimed at ensuring that the field strength from an MDS transmitter does not exceed 32 dBuV/m in any other co‑channel licensee's MDS licence area.
A.1.2. The following information is needed to decide if an interference assessment must be carried out:
- MDS transmitter location
- MDS transmitter channel
- MDS licence area boundaries
[NOTE. Details of the MDS licence area boundaries are contained in Schedule 1 to the Radiocommunications (Allocation of Multipoint Distribution Station Licences - Regional Licences) Determination No. 1 of 1995.]
A.1.3. An assessment of the potential for interference from an MDS transmitter to another MDS licence area is necessary if the MDS transmitter is to be located within a distance 'D' of another MDS licence area. The distance 'D' is determined from the height of the transmitting antenna of the MDS transmitter above average ground level and is indicated in the following table.
| Height of Transmitting Antenna above Average Ground Level, Ht*(m) | D(km) |
|---|---|
| Ht 37.5 | 65 |
| 37.5 Ht 75 | 75 |
| 75 Ht 150 | 90 |
| 150 Ht 300 | 110 |
| 300 Ht 600 | 135 |
| 600 Ht 1200 | 175 |
* Ht: the height of the MDS transmitting antenna above the average level of the ground between distances of 3 and 15 km from the transmitter in the direction of the nearest point on the boundary of another MDS licence area (see CCIR Rec 370-5).
[NOTE. Distances for MDS transmitters with heights of transmitting antennas greater than 1200 m above average ground level will be provided by the Customer Services Group of the SMA, if required.]
[NOTE. CCIR Recommendations are available from the Standards Australia International Sales Group, Strathfield NSW.]
A.1.4. If an interference assessment is necessary, the assessment will comprise the following Steps 2, 3 and 4.
A.1.5. The following information is needed to complete this calculation:
- MDS transmitter location, site height and antenna height
- terrain profiles between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter
Information provided by the SMA
- MDS licence area boundaries
- nominal MDS receiver antenna height = 10m
[NOTE. Details of the MDS licence area boundaries are contained in Schedule 1 to the Radiocommunications (Allocation of Multipoint Distribution Station Licences - Regional Licences) Determination No. 1 of 1995.]
A.1.6. Using the method detailed at Schedule 2, calculate the terrain loss between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter.
[NOTE. If the protection criteria of Assessment A.1.10 are satisfied when a terrain loss value of Lt = 0 dB is used in the equation at Assessment A.1.8. then calculation of an actual value for Lt is not required.]
A.1.7. The following information is needed for this calculation:
- MDS transmitter power and antenna gain in the direction of the point on the boundary of each other licence area, identified at Step 1, that is nearest to the MDS transmitter
- terrain loss (as calculated at Step 2)
- none
A.1.8. The unwanted field strength is then calculated at the point on the boundary of each other MDS licence area identified at Step 1, that is nearest to the MDS transmitter. The following equation is used for this calculation:
Eu = 44.77 - 20log(d) + Pt + Gt – Lt
where:
Eu = unwanted field strength at the point (dBuV/m)
d = distance between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter (km)
Pt = MDS transmitter power (dBm)
Gt = gain of the MDS transmitter antenna in the direction of the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter (dBi)
Lt = terrain loss as calculated at Step 2 (dB)
A.1.9. The following information is needed for this assessment:
- unwanted field strength (as calculated at Step 3)
- maximum permissible unwanted field strength in a co‑channel MDS licence area (see below).
A.1.10. An MDS transmitter will meet the protection requirements for co-channel MDS licence areas if:
Eu Em
where:
Eu = unwanted field strength at the point on the boundary of each other licence area identified at Step 1, that is nearest the MDS transmitter (as calculated at Step 3) (dBuV/m)
Em = 32 dBuV/m, the maximum permissible unwanted field strength in a co-channel MDS licence area
[NOTE. The results of Assessment A.1 may lead to the imposition or variation of licence conditions (see Guideline 14(a)).]
A.2.1. This assessment (A.2) is intended to lead, where necessary, to the imposition of a licence condition aimed at ensuring that the field strength from an MDS transmitter does not exceed 76 dBuV/m in any other MDS licence area where transmitters are licensed to operate on adjacent MDS channels.
A.2.2. The following information is needed to decide if an interference assessment must be carried out:
- MDS transmitter location
- MDS transmitter channel
- MDS licence area boundaries
[NOTE. Details of the MDS licence area boundaries are contained in Schedule 1 to the Radiocommunications (Allocation of Multipoint Distribution Station Licences - Regional Licences) Determination No. 1 of 1995.]
A.2.3. An assessment of the potential for interference from an MDS transmitter to another MDS licence area is necessary if the MDS transmitter is to be located within a distance 'D' of another licence area in which an MDS service is on an adjacent channel. The distance 'D' is determined from the EIRP of the MDS transmitter and is indicated in the following table:
| EIRP*(dBm) | D(km) |
|---|---|
| 50 | 10 |
| 53 | 15 |
| 60 | 30 |
| 63 | 40 |
| 70 | 90 |
*EIRP: the EIRP of the MDS transmitter
A.2.4. The following information is needed to complete this calculation:
- MDS transmitter location, site height and antenna height
- terrain profiles between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter
- MDS licence area boundaries
- nominal MDS receiver antenna height = 10m
[NOTE. Details of the MDS licence area boundaries are contained in Schedule 1 to the Radiocommunications (Allocation of Multipoint Distribution Station Licences - Regional Licences) Determination No. 1 of 1995.]
A.2.5. Using the method detailed at Schedule 2, calculate the terrain loss between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest the MDS transmitter.
A.2.6. The following information is needed for this calculation:
- MDS transmitter power and antenna gain in the direction of the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter.
- terrain loss (as calculated at Step 2)
- none
A.2.7. The unwanted field strength is then calculated at the point on the boundary of each other MDS licence area identified at Step 1, that is nearest to the MDS transmitter. The following equation is used for this calculation:
Eu = 44.77 - 20log(d) + Pt + Gt – Lt
where:
Eu = unwanted field strength at the point(dBuV/m)
d = distance between the MDS transmitter and the point on the boundary of each other licence area identified at Step 1, that is nearest the MDS transmitter (km)
Pt = MDS transmitter power (dBm)
Gt = gain of the MDS transmitter antenna in the direction of the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter (dBi)
Lt = terrain loss (as calculated at Step 2) (dB)
A.2.8. The following information is needed for this assessment:
- unwanted field strength (as calculated at Step 3)
- maximum permissible unwanted field strength in each other licence area in which licensees are on adjacent channels identified at Step 1 (see below)
A.2.9. An MDS transmitter will meet the protection requirements for adjacent channels in another licence area if:
Eu Em
where:
Eu = unwanted field strength at the point on the boundary of each other licence area identified at Step 1, that is nearest to the MDS transmitter (as calculated at Step 3) (dBuV/m)
Em = 76 dBuV/m, the maximum permissible unwanted field strength in other licence areas in which services are on adjacent channels
[NOTE. The results of Assessment A.2 may lead to the imposition or variation of licence conditions (see Guideline 14(b)).]
A.3.1. This assessment (A.3) specifies how to assess the potential for interference from an MDS transmitter to a notional adjacent channel MDS receiver lying within a defined area (called an assessment area) around an adjacent channel MDS transmitter operating in the same licence area.
A.3.2 The assessment is intended to lead to the imposition, where necessary, of a licence condition aimed at ensuring that the field strength from an MDS transmitter will not exceed 76 dBuV/m in the assessment area around any adjacent channel transmitter operating in the same licence area.
A.3.3. The following information is needed to identify if an interference assessment must be carried out:
- MDS transmitter location
- MDS transmitter channel
[NOTE. The location and channel of the MDS transmitter are required because the notional MDS receiver for which this assessment (A.3.) may be required is deemed to be lying within the assessment area around that MDS transmitter. The assessment area is bounded by a circle of radius R kilometres from the MDS transmitter. The radius R is derived from the transmitter height and EIRP, and is calculated in accordance with Schedule 3. See also A.3.9. below.]
- location of existing adjacent channel MDS transmitters within the same licence area
[NOTE. Information on the location of licensed MDS transmitters is held by the Spectrum Management Agency.]
A.3.4. It is not necessary to carry out the adjacent channel interference assessment in this section in relation to a transmitter and another MDS transmitter in the same licence area, if the MDS transmitters are ‘co-sited’.
[NOTE. Transmitters are taken to be co-sited with each other if they can be encompassed within a circle having a radius of 500 metres (see Guideline 3(2).]
A.3.5. An assessment of the potential for interference must be carried out if:
(a) the MDS transmitters are not co-sited (see Guideline 3(2)); and
(b) an MDS transmitter is to be located within a distance 'D' of an adjacent channel MDS transmitter operating in the same MDS licence area.
A.3.6. The distance 'D' referred to in A.3.5.(b) above is determined from the EIRP of the MDS transmitter and is indicated in the table below.
| EIRP*(dBm) | D(km) |
|---|---|
| 50 | 155 |
| 53 | 160 |
| 60 | 175 |
| 63 | 185 |
| 70 | 235 |
This is an opening excerpt, not the complete document.