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RALI LM8: Land Mobile Service

RALI LM8 provides the rules and advice for assigning and coordinating frequency. It applies to single and 2-frequency land mobile systems that use analogue and digital modulation methods.

The Radiocommunications Assignment and Licensing Instruction (RALI) LM8 applies to:

  • analogue and digital modulated systems in the VHF Mid Band (70-87.5 MHz), VHF High Band (148-174 MHz) and 400 MHz band using 6.25 kHz, 12.5 kHz and 25 kHz channel bandwidths
  • high power (LMRS) and low power (LPMRS) systems, and both single frequency and two frequency systems
  • 800 MHz trunked systems using 25 kHz channels

This RALI:

  • helps us and accredited persons who assign frequency consider all relevant factors to make decisions based on merit
  • guides people who plan land mobile systems

To ask about an issue the RALI does not cover, email

History of reviews and changes to RALI LM8


As part of the ACMA’s Frequency coordination requirements review work program 2021–22, we undertook to review the 400 MHz land mobile services (LMS) coordination procedures. In particular, we proposed to review the frequency distance constraints (FDC) tables so that they might better accommodate digital services, as well as future-proofing these procedures by considering to adopt a more universally recognised propagation model for calculating the FDC rules.

We have now completed an initial review of the FDC coordination requirements for 400 MHz LMS services, by recalculating the requirements using the proposed ITU-R P.1546-6 (Method for point-to-area predictions for terrestrial services in the frequency rang 30 MHz to 4 000 MHz) propagation model. Preliminary results indicate that adopting this model would create some opportunities to reduce the FDC distance and, as a result, allow scope for more efficient allocation of services in congested areas.

However, these opportunities are mostly limited to the assignment of simplex services, which are both low in number (with respect to duplex services) and declining in number. Duplex services, which are far more heavily subscribed, would not benefit from any material efficiency gains if we adopted the proposed changes. Consequently, the benefits to actual frequency assignments that would arise from altering the propagation model at this stage seem minimal. We have therefore decided not to amend 400 MHz LMS services FDC requirements at this stage. However, we will continue to observe licensing trends and potentially implement the proposed amendments at a later date if a clear benefit of doing so becomes apparent.


We consulted industry in May in IFC 12/2020 on a proposal to add new channel arrangements for 806–809/851–854 MHz. The proposed changes align with those detailed for key date 5 in support of Milestone 3, as outlined in our decision paper, The ACMA’s long-term strategy for the 803-960 MHz band.


We consulted industry in September on a proposal that included:

  • a new coordination model. This supported systems with equivalent isotropic radiated power of 1.6watts or less
  • consolidating existing requirement for bi-directional amplifiers
  • updating coordination requirements with television channel 6, referencing spectrum embargo 32


We updated RALI LM8 in July 2016. The changes followed the identification of spectrum in the 400MHz band as ‘harmonised government spectrum’.


Public consultation in 2014 resulted in updates to LM8 in June 2015. Changes included:

  • clarifying arrangements for supplementary base stations, height power restrictions and intermodulation calculations
  • making frequency-distance constraints symmetrical and based on worst-case values
  • for low powered systems, addressing concerns about small separation distances when channel bandwidths overlap
  • adjusting first adjacent channel separation for 12.5 and 25kHz high-powered 2-frequency systems to be 0km
  • making reference levels for 25/12.5kHz systems the same
  • for 6.25 kHz systems, adjusting reference levels by 3dB in recognition of smaller bandwidth
  • calculating separation distances by determining a reference propagation loss at the co-channel separation distance
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