AM-FM conversions in regional licence areas

Things we consider

Coverage differences

When converting from AM to FM, we consider several factors to ensure the new service provides sufficient coverage and service continuity. These include:

coverage of the AM service
predicted coverage of the proposed FM replacement service
coverage from existing services within and around the service/licence area
interference from other services into the service/licence area
population analysis
other relevant interference mechanisms, including IF beat
other relevant factors, as appropriate, to maintain service continuity.

Signal characteristics

AM and FM radio use different technologies which affect how their signals travel. This difference means that AM and FM services need different site parameters – such as transmitter location, power and antenna design – to operate effectively. While networks of both can be planned to deliver similar coverage outcomes, the network topology is most likely to differ.

Each technology also has its own:

strengths and limitations of sound quality
resistance to electrical noise
signal reach.

Adequate coverage levels

Coverage is assessed in different electrical noise environments, referred to as noise-limited coverage. The minimum field strengths for adequate reception in these environments are below:

Table 1: Adequate coverage levels for stereo reception
Environment	For FM planning	For AM planning
Rural	>54 dBµV/m	>0.5 mV/m
Suburban	>66 dBµV/m	>2.5 mV/m
Urban	>74 dBµV/m	>10 mV/m

This information is from Table 3A.1 for AM and Table 3B.2 for FM services in the following document.

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Technical Planning Parameters and Methods for Terrestrial Broadcasting (TPPMs)

Coverage assessments include interference from other broadcasting services. Under such conditions, higher field strengths may be necessary to maintain service quality. This can result in the effective coverage area being interference-limited. These factors are considered to ensure coverage expectations are representative of mutual interference conditions.

Rural coverage reception

AM and FM signals should be received at levels well below what is considered adequate for planning purposes. However, areas at or above the threshold may still experience poor reception due to interference from other radiocommunications or electrical noise.

This is particularly the case for AM. These factors don’t alter our planning criteria but are an important consideration.

Determining coverage levels

Coverage levels describe how well a radio signal reaches a given area. This can then determine if the coverage is adequate. Coverage levels can be determined by:

Measured analysis: using field strength surveys or receiver data to assess actual signal performance – both at that moment and over time.
Predicted analysis: using software modelling tools that simulate propagation based on different parameters, which accounts for differences in location and time.

Coverage levels may also consider interference impacts, which affect signal quality and reliability.

Population estimation methods

Population estimates are used to assess coverage and to identify the potential for population loss because of an AM-FM conversion. Several methods exist, including proportional geographic allocation and centroid-based approaches. These tend to be inaccurate in sparsely populated or large geographic areas.

To improve accuracy, we have developed a grid-based approach (3 arc-seconds), that weights ABS Census Data population by address information. This approach tries to provide a more representative view of the population, especially in rural and unevenly populated areas.

Current conversion program

In 2016, we commenced a program to convert AM services to FM in solus (single licensee) regional radio licence areas.

In September 2022, we expanded our conversion program to include competitive regional radio licence areas.

In July 2025, we planned our first town-based upgrade that involves making FM transmission available in a populous town area while maintaining AM transmission in the less populated locations of a licence area.

We have adopted a set of planning principles to help guide conversions.

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Principles for planning AM to FM conversions in regional licence areas

The principles apply to:

commercial radio conversions in the remaining regional solus licence areas
regional competitive licence areas.

They help to identify eligibility for inclusion in the conversion program for industry and to assist our prioritisation of conversion requests.

We expect industry participants to apply these planning principles when:

identifying which commercial services to convert
engaging consultant engineers to identify frequencies for conversion.

LAP variation complete

List of locations with completed LAP variations
State	Markets
Tasmania	Burnie Devonport Queenstown Scottsdale
New South Wales	Armidale Bathurst Bega Cooma Deniliquin Goulburn Grafton Mudgee Nowra Tamworth Taree
Victoria	Wangaratta Warrnambool
Northern Territory	Katherine
South Australia	Murray Bridge Port Lincoln Riverland Spencer Gulf North Mt Gambier
Western Australia	Karratha Port Hedland Remote WA (Exmouth, Paraburdoo and Tom Price) Mandurah

The progress and timing of AM to FM conversions depends on various factors and cannot always be predicted.

For more information on how we prioritise requests, please refer to the broadcast planning and LAP variation guidelines and conversion principles.