Radiocommunications Advisory Guidelines (Managing Interference from Spectrum Licensed Transmitters - 2.5 GHz Band) 2023

The instrument’s core organisational concept is a mapping of protection guidance to services and frequency sub‑bands, anchored to the Register as the mechanism that confers priority for protection. The definitions section (s5) establishes the frequency boundaries for the 2.5 GHz lower band (2500-2570 MHz), mid‑band gap (2570-2620 MHz) and upper band (2620-2690 MHz), and it defines fixed transmitter and fixed receiver by reference to being located at a fixed point and not designed for use while in motion (s5). The instrument uses the term in‑band to mean the frequencies authorised by a spectrum or apparatus licence and out‑of‑band to mean any other frequency (s5). It incorporates by reference a range of external technical and administrative instruments and ITU‑R Recommendations, and in so doing, signals a layered approach: the Guidelines set policy and high‑level coordination distances and point readers to more detailed technical methods in other documents.

A recurring structural device is the phrase “included in the Register before the registration of a fixed transmitter operating under a 2.5 GHz spectrum licence” (for example ss9(1), 11(1), 13(2), 15(2), 17(2)). The Register, maintained under the Act, is therefore the temporal and evidentiary trigger for protection under these Guidelines. Practically, a receiver that appears in the Register earlier than a transmitter’s registration is the protected entity; the converse is implied but not always spelled out in technical detail in the instrument. The instrument also distinguishes between categories of receivers: spectrum‑licensed receivers (for example, ENG in the mid‑band gap), apparatus‑licensed fixed services (point‑to‑point stations), space services (EESS, MSS, RSS, SRS), radio astronomy receivers (including AUS87 specified receivers and those in 2690-2700 MHz), aeronautical radionavigation service (ARS), and radiolocation service (RLS). Each category is associated with different guidance, typical coordination distances, and reference documents (ss7, 9, 11, 13, 15, 17).

“Protection requirements” feature in multiple places. For spectrum‑licensed fixed receivers in the mid‑band gap and 2.3 GHz band, the instrument refers readers to the “compatibility requirement” and “notional receiver performance levels” set out in separate Radiocommunications Advisory Guidelines (for example the Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap 2023, and the Managing Interference to Spectrum Licensed Receivers - 2.3 GHz Band 2013 or any replacement) (s9(1)-(3)). For apparatus‑licensed point‑to‑point stations, protection requirements are in RALI FX 3 and the instrument expects spectrum licensees to provide the same level of out‑band and in‑band protection as apparatus licence holders (s11(1)-(2)). For space and passive services, the instrument records that operating in accordance with all licence conditions means a 2.5 GHz spectrum transmitter is not taken to cause interference to EESS, MSS and RSS (s13(1)), while specific ITU‑R protection criteria are pointed to for SRS (s13(2)) and radio astronomy protection in 2690-2700 MHz is directed to ITU‑R RA.769‑2 (s15(4)).

The instrument repeatedly distinguishes between advisory technical guidance, typical coordination distances and strict protection obligations. Words such as “typically necessary”, “should have regard to”, “are to comply with” and “protection is to be afforded” appear throughout. That vocabulary matters for legal effect: the instrument is framed as guidance that ACMA may use in interference determinations (s7(5)), and many coordination requirements are couched as typical rather than absolute. The instrument also preserves private ordering, explicitly permitting parties to negotiate alternate protection arrangements (s7(6)). Finally, the instrument specifies how parts of the frequency band are to be read: subsection 5(5) makes clear that, unless specified, a part of the spectrum includes frequencies greater than but not including the lower numerical boundary, up to and including the higher frequency numerical boundary. That numbering rule has practical consequences for edge cases at band boundaries.

The instrument affects multiple classes of market participants and regulators. Primary addressees are licensees of 2.5 GHz spectrum licences. Those licensees must plan, register and operate transmitters in a way that gives effect to the protection requirements and guidance set out in this instrument and the external documents it references. Specifically, those licensees will be expected to consider compatibility requirements and notional receiver performance levels for spectrum‑licensed fixed receivers in the mid‑band gap and 2.3 GHz band (s9(1)-(4)). They must also coordinate with apparatus‑licensed fixed service operators, particularly point‑to‑point stations whose protection is set out in RALI FX 3 (s11(1)-(2)). Spectrum licensees in areas adjacent to the ARQZWA are required to coordinate proposed stations following RALI MS 32 (s15(6)).

Operators of apparatus licences and class licences whose receivers operate in and adjacent to the 2.5 GHz band are directly affected as well. This includes operators of ENG links in the 2.5 GHz mid‑band gap, point‑to‑point fixed links, fixed earth stations, SRS space receive and earth receive stations, EESS satellite receivers, MSS and RSS space‑to‑Earth receivers in 2483.5-2500 MHz and 2690-2700 MHz, radio astronomy facilities (including AUS87 specified receivers and the Paul Wild and Parkes observatories mentioned as examples in the notes), aeronautical radionavigation service receivers (often sited at major airports), meteorological radars used for radiolocation service, and radiodetermination receivers used by the Department of Defence (ss7, 11, 12, 13, 14, 15, 16, 17). These operators' protection depends on their inclusion in the Register and their insertion date relative to the registration of nearby 2.5 GHz fixed transmitters.

Regulatory and administrative actors are also affected. The Australian Communications and Media Authority (ACMA) is the decision maker who may take these Guidelines into account when determining whether interference is occurring (s7(5)). ACMA is also the body that maintains the Register and issues apparatus and spectrum licences, and it publishes the RALI instruments referenced (s5 notes, s6). Parties that provide technical services such as RF propagation modelling, compatibility studies and coordination facilitation will face demand as licensees must model path loss and perform coordination, consistent with the guidance to consider ITU‑R propagation methods such as P.1144 and other published models (s7(4)).

Who pays and who bears the operational costs is set out implicitly by the instrument’s framing: spectrum licensees will incur the direct costs of planning, modelling, coordination and possibly station relocation or configuration changes to meet protection requirements. Operators of protected receivers will bear the cost of being listed in the Register and providing technical details that facilitate coordination. Parties wishing to negotiate protection arrangements outside the instrument will bear the legal and transaction costs of those negotiations (s7(6)). ACMA bears the administrative cost of maintaining the Register and applying the instrument in interference determinations. Finally, there are potential indirect effects on consumers, broadcasters, news organisations that use ENG links, meteorological services, defence operations and scientific research projects that depend on radio astronomy and satellite reception; these services may experience constraints on deployment options or incur additional coordination costs because of the protections outlined here.

The instrument sets out a mixture of duties on spectrum licensees and corresponding protections for certain receivers. Those duties are generally phrased as guidance that licensees should follow, with specific technical obligations referenced in other instruments. Key duties and rights include:

• Duty to observe protection criteria for spectrum‑licensed fixed receivers in the 2.5 GHz mid‑band gap and the 2.3 GHz band. For mid‑band gap receivers included in the Register before a fixed transmitter’s registration, protection requirements and minimum receiver performance are to be applied through the compatibility requirement and notional receiver performance levels specified in the separate Radiocommunications Advisory Guidelines Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap 2023 (s9(1)-(2)). For 2.3 GHz receivers, the corresponding criteria are in the 2013 guidelines or a later replacement instrument (s9(3)-(4)).

• Duty to coordinate with certain fixed receivers at specified typical distances. The instrument indicates coordination is typically necessary for outdoor fixed transmitters within 1.5 kilometres of mid‑band gap receivers, and within 500 metres of 2.3 GHz receivers, recognising that Register listings and antenna details are available to inform coordination (s9(2), s9(4)).

• Duty to provide equivalent out‑of‑band and in‑band protection to apparatus‑licensed point‑to‑point stations as those stations receive under RALI FX 3 (s11(1)-(2)). In practice, spectrum licensees must plan their deployments to meet the same protection levels that apparatus licensees expect under RALI FX 3.

• Duty to consider ITU‑R propagation models and recommendations, and to use appropriate modelling methods for path loss estimates and coordination studies (s7(4)). The instrument explicitly points to ITU‑R Recommendation P.1144 as a guide and notes other published propagation models may be suitable (s7(4) notes).

• Duty to comply with specific protection criteria for radio astronomy and space services where identified. For radio astronomy receivers in 2690-2700 MHz, licensees are to comply with the protection criteria set out in ITU‑R RA.769‑2 (s15(4)). For SRS space receive and earth receive stations registered before a fixed transmitter, ITU‑R SA.609 provides the protection criteria (s13(2)).

• Duty to coordinate with ARS and RLS receivers and Department of Defence radars in 2700-2900 MHz. Protection is to be afforded to ARS fixed receivers registered earlier than a fixed transmitter (s17(2)-(3)). Coordination is typically needed within 10 kilometres for ARS stations with station class ‘AL’ and within 20 kilometres for RLS stations with station class ‘LR’ (s17(3), s17(7)). For Department of Defence radiodetermination services, compliance with an out‑of‑band emission limit equivalent to not exceeding a power flux density of ‑125 dBm/MHz/m2 at the radar antenna height at the radar site is specified (s17(4)).

• Right not to be treated as causing interference if operating within licence conditions for adjacent band EESS, MSS and RSS receivers. The instrument states a transmitter operating under a 2.5 GHz spectrum licence is not taken to cause interference to adjacent band receivers used for EESS, MSS and RSS provided it operates in accordance with all licence conditions, including core conditions (s13(1)). That statement is a defensive right for licensees who comply with their licence terms.

• Right to negotiate alternative arrangements. The instrument expressly notes that it does not prevent persons negotiating and implementing other protection requirements with each other (s7(6)). That preserves commercial freedom to agree bespoke solutions that deviate from the guidance.

• ACMA’s administrative discretion. The instrument does not itself create offence provisions, but ACMA may take it into account in interference determinations under the Act (s7(5)). That gives the instrument administrative weight: parties should expect ACMA to reference it when deciding whether interference is occurring.

Practical implications of these duties and rights include the need for spectrum licensees to check the Register before registering stations, to model and document compliance with the referenced technical criteria, to engage in notification and coordination procedures set out in the RALI instruments (notably RALI MS 31, MS 32 and MS 35), and to design deployments to meet the applicable notional receiver performance or out‑of‑band emission limits. For operators of protected receivers, the practical right of protection depends on timely and accurate Register entries and the temporal priority of those entries compared to any nearby 2.5 GHz transmitter registrations.

The instrument is framed as advisory guidance made under section 262 of the Act (s3). It does not itself create new criminal or civil penalties, nor does it specify administrative sanctions. Instead, the instrument plays an evidentiary and policy role in administrative enforcement. The critical enforcement clause is that the Australian Communications and Media Authority may take the instrument into account when determining whether a radiocommunications transmitter operated under a 2.5 GHz spectrum licence is causing interference to apparatus‑licensed or class‑licensed receivers in the circumstances set out in the instrument (s7(5)). Therefore, non‑compliance with the guidance may influence ACMA’s finding on interference under the Act, which in turn may trigger the Act’s enforcement mechanisms.

Because the instrument does not itself set out penalty provisions, enforcement proceeds under the Radiocommunications Act 1992. The Act contains the substantive powers and sanctions for dealing with interference, unauthorised transmissions, breaches of licence conditions and related matters. This instrument provides standards and references ACMA can use in the exercise of those powers, for example when deciding whether a transmitter is causing harmful interference or whether corrective action is required. The instrument’s role in that process is to provide a reference framework: licence holders who depart from its guidance may be at greater risk of an adverse administrative finding if they cannot otherwise show compliance with licence conditions or demonstrate an agreed alternative protection arrangement.

Several parts of the instrument set out technical thresholds that have the potential to be determinative in enforcement contexts. For example, protection for Department of Defence radars is achieved if out‑of‑band emissions from a 2.5 GHz spectrum station do not exceed a maximum power flux density of ‑125 dBm/MHz/m2 at the antenna height at the radar site (s17(4)). Compliance with such a clearly specified technical threshold can be measured and therefore can be directly used in an interference determination. Other guidance is less prescriptive, for example statements that coordination is “typically necessary” within certain distances for various receivers (ss9(2)-(4), 15(5), 17(3), 17(7)). Those “typical” distances create expectations but leave room for site‑specific technical evidence in enforcement processes.

The instrument also interacts with administrative instruments such as RALI FX 3 and RALI MS 31/32/35 which contain coordination procedures and notification regimes. Those RALI instruments are administrative guidance published by ACMA and are used operationally by licensees and ACMA officials. Failure to follow the procedures in RALI instruments can be relied upon in administrative determinations, even if the Guidelines themselves do not specify a penalty.

In summary, the Guidelines do not impose new statutory penalties but function as a body of technical and administrative expectations that ACMA will reference when exercising its enforcement powers under the Act. Parties should therefore treat the Guidelines as carrying material administrative weight in interference disputes and licence compliance matters.

This instrument is situated within the Radiocommunications Act 1992 framework and explicitly interacts with several other legal instruments and technical documents. The instrument is made under section 262 of the Act (s3) and refers to Act concepts throughout, including definitions for ACMA, spectrum licence, apparatus licence and the Register (s5 and Note). It also defers to the spectrum plan for meaning of many service definitions and allocations (s5(2)) and relies on the Register as the evidentiary mechanism by which protection is determined (repeated references throughout, e.g. ss9(1), 11(1), 13(2), 15(2), 17(2)).

The instrument expressly cross‑references other legislative instruments, administrative instruments and international recommendations. Subsection 6 states that references to other legislative instruments mean those instruments as in force from time to time, and references to other writings or instruments mean those documents as current (s6). This means the Guidelines operate dynamically with the current versions of the RALI instruments, the Radiocommunications (Interpretation) Determination, the spectrum plan and the ITU‑R Recommendations cited. The instrument’s notes emphasise availability of those documents on ACMA and ITU websites (s5 notes; various notes in ss7, 11, 13, 15, 17) and make clear that the Radio Regulations are not domestic regulations under the Act (s5 Note 1).

Several specific interactions stand out:

• Spectrum plan. The instrument relies on allocations and Australian footnote references in the spectrum plan, for example AUS87 for radio astronomy receivers and the allocation of 2690-2700 MHz to EESS and SRS passive use (s12, s14). Service protection depends on those spectrum plan allocations and footnotes. For primary and secondary services references, the instrument points to sections 5, 7 and 12 of the spectrum plan (s14 Note).

• RALI instruments and administrative guidance. The instrument integrates ACMA’s RALI instruments into its guidance architecture. Protection for point‑to‑point apparatus licensed stations is in RALI FX 3 (s11(1)). Notification procedures for radio astronomy receivers are in RALI MS 31 (s15(2)). Coordination with the ARQZWA is guided by RALI MS 32 (s15(6)). Defence coordination is aided by RALI MS 35 (s5 notes; s17(5)). Because s6 treats references dynamically, changes to those RALI instruments will affect how the Guidelines operate.

• ITU‑R Recommendations and Radio Regulations. The instrument directs readers to several ITU‑R Recommendations for propagation modelling, compatibility and protection criteria, including P.1144 for propagation methods (s7(4)), F.1777 for ENG characteristics (s8 Note), SA.609 for SRS space receive protection (s13(2)), RA.769‑2 for radio astronomy protection in 2690-2700 MHz (s15(4)), and M.1464, M.1461, M.1849 for radars and meteorological radars in 2700-2900 MHz (s17(1)). The instrument does not make those Recommendations binding domestic law, but it requires licensees to have regard to them and ACMA may use them when assessing interference.

• Register and timing. The Register is a statutory resource under the Act. The Guidelines’ repeated dependence on the Register as the trigger for protection ties the instrument to the Act’s licensing and registration procedures and creates a clear procedural interaction: placing a receiver on the Register ahead of a transmitter gives the receiver the protection described in these Guidelines.

• Private contracting and negotiation. The instrument expressly allows parties to negotiate other protection arrangements (s7(6)), preserving the operation of contract law and commercial agreements outside the administrative framework. That means parties may lawfully agree to higher or lower protection than the Guidelines recommend, subject to any constraints in licences or ACMA determinations.

• Acts Interpretation and Legislation Acts. The notes direct readers to the Acts Interpretation Act 1901 for references to Commonwealth Acts and to the Legislation Act 2003 for application of the Acts Interpretation Act to legislative instruments (s6 Note 1). This is a reminder that statutory interpretation rules apply to the instrument and its references.

In short, the Guidelines operate as a node connecting the Radiocommunications Act’s licensing and Register apparatus, ACMA’s administrative RALI instruments, the spectrum plan, and international technical Recommendations. They are advisory but designed to be used by ACMA in exercising statutory powers. Parties should therefore consider both the Guidelines and the suite of cross‑referenced documents when assessing legal obligations and technical compliance.

The instrument is the 2023 iteration of guidance on managing interference from spectrum licensed transmitters in the 2.5 GHz band and, in one specific mechanical act, repeals the 2012 Radiocommunications Advisory Guidelines (Managing Interference from Transmitters - 2.5 GHz Band) [F2012L02550] (s4). The instrument’s commencement clause provides it takes effect at the start of the day after registration on the Federal Register of Legislation (s2). There are no internal amendment clauses within the text that prespecify transitional arrangements or staged implementation steps; the instrument achieves update by repeal of the 2012 instrument and by referencing a set of current documents.

Because the instrument incorporates other instruments and recommendations by reference and s6 makes references apply “as in force from time to time”, the Guidelines are designed to operate with a moving set of technical and administrative documents. For example, protection criteria for 2.3 GHz band spectrum‑licensed receivers are to be found in the Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.3 GHz Band) 2013 or “if a later instrument replaces those guidelines - the later instrument” (s9(3)(c)-(d)). Similarly, the Radiocommunications (Interpretation) Determination 2015 is the source of definitions for some terms unless replaced, and the instrument defers to any replacement (s5(3)-(4)). That structural approach means that, even in the absence of amendments to this instrument itself, changes to the referenced instruments will alter the operational effect of the Guidelines.

The instrument also cites RALI instruments by title with notes that they are available from ACMA’s website (s5 notes). Those RALI instruments are administrative and can be updated by ACMA. Because the Guidelines instruct readers to consult RALI FX 3, MS 31, MS 32 and MS 35 without embedding their provisions, amendments to those RALI instruments will be consequential. Subsection 6(1)(a) formalises the cross‑instrument dynamism by making explicit that references to other legislative instruments are references to those instruments “as in force from time to time” (s6).

There are no additional amendment entries or historical notes included in the text provided beyond the express repeal of the 2012 instrument. The text does not record transitional protection arrangements for transmitters or receivers that were in the process of registration at the time of repeal and commencement. Practitioners should therefore consult the Federal Register of Legislation entry for the instrument to confirm the registration date and check the Register itself for any transitional administrative notes or ACMA guidance that may accompany the instrument’s publication.

Finally, because the instrument’s protective effect depends heavily on Register inclusion dates, any administrative change in Register procedures, or an ACMA policy change affecting how registrations are processed, will have an immediate operational effect without the need to amend these Guidelines. That is a structural feature of an instrument that defers to the Register as the priority‑establishing mechanism.

The instrument itself contains no record of litigation and does not cite judicial decisions. It is an administrative guideline designed to be used by ACMA and industry and therefore its immediate legal footprint is in administrative decision making rather than in judicial pronouncement. Because the instrument is advisory and ACMA may “take it into account” (s7(5)), disputes about interference determinations or ACMA’s application of the Guidelines could in principle give rise to merits review or judicial review proceedings under the administrative law framework and to enforcement action under the Radiocommunications Act. The instrument does not specify a path of review or litigation; those procedures are governed by the Act, the Administrative Decisions (Judicial Review) Act 1977 and other procedural statutes and common law remedies relevant to administrative action. No judicial interpretation or authority is embedded in the instrument text.

From the perspective of litigation risk factors that are identifiable within the instrument itself, several features may invite contested administrative decisions:

• Temporal priority via the Register. Many protection rules hinge on whether a receiver was included in the Register before the registration of a fixed transmitter. That temporal dependency can create disputes about registration dates, the sufficiency of Register entries, and what constitutes an “included” receiver. These are factual matters that may be litigated if ACMA uses the Register to deny protection or requires remedial action.

• “Typical” distances vs site‑specific evidence. The Guidelines repeatedly use phrases such as “typically necessary” in identifying coordination distances and expectations (e.g. 1.5 kilometres for mid‑band gap outdoor fixed transmitters, 500 metres for 2.3 GHz fixed transmitters, 10 kilometres for ARS class ‘AL’, 20 kilometres for RLS class ‘LR’, and historical guidance of 100 kilometres for radio astronomy in 2690-2700 MHz) (ss9, 15, 17). Because those distances are framed as typical, affected parties may contest ACMA’s application of those figures to particular sites if technical evidence shows a different interference profile.

• Reliance on external technical documents. The Guidelines reference multiple ITU‑R Recommendations and RALI instruments for technical criteria. Disputes may arise over which edition or which specific modelling approach applies, particularly given s6’s “as in force from time to time” approach. Parties may litigate whether ACMA properly applied a particular Recommendation or model in reaching an interference finding.

• Specific technical thresholds. The instrument specifies some measurable thresholds, such as the Department of Defence PFD limit of ‑125 dBm/MHz/m2 at the radar antenna height (s17(4)). Where these numerical thresholds are relied upon by ACMA in enforcement, there is less room for argument about interpretive ambiguity and more scope for technical challenge about measurement methods and uncertainty.

Because the instrument itself contains no litigation history, practitioners should monitor ACMA determinations and any judicial challenges that arise from interference disputes that invoke these Guidelines for evolving case law. Until such cases are available, the legal weight and judicial gloss on the Guidelines will remain a matter of administrative practice and any future court decisions.

There are a number of traps and practical pitfalls that arise from the instrument’s drafting and its reliance on external documents and the Register. These are concrete, source‑grounded issues to watch when advising clients or planning deployments.

• Protection depends on Register timing. Many protections are only available to receivers that are “included in the Register before the registration of a fixed transmitter operating under a 2.5 GHz spectrum licence” (for example ss9(1), 11(1), 13(2), 15(2), 17(2)). If a receiver operator fails to enter appropriate station details in the Register in a timely way, it may lose the benefit of the protections described. Conversely, a spectrum licensee that registers a transmitter before a receiver is placed on the Register may face fewer administrative obligations in relation to that receiver. The instrument does not set out transitional remedies for late registration.

• “Typical” distances are not absolute rules. Coordination distances are often expressed as “typically necessary” rather than as mandatory exclusion zones (see ss9(2)-(4), 15(5), 17(3), 17(7)). That language creates uncertainty about whether coordination is required in a given set of circumstances and leaves room for site specific technical evidence to depart from the typical case. Parties should not assume that an absence of a mandatory numeric distance means free operation; rather, they should collect technical evidence and prepare to justify choices to ACMA.

• Edge frequency rules. Subsection 5(5) makes the lower frequency number in a band excluded and the higher included. Practitioners must be careful at band edges. For example, a device operating exactly at the lower numerical boundary of a band may in legal terms fall outside that band. This counting rule can change whether a device is in‑band or out‑of‑band, with consequences for which licence conditions apply.

• Reliance on external instruments and versions. The Guidelines refer to multiple RALI instruments and ITU‑R Recommendations without reproducing their content (s5 notes; s7(4); s11; s13; s15; s17). Because s6 treats references dynamically, the version of those documents current at the time of an ACMA determination will apply. That can create uncertainty if parties rely on older versions in planning. Practitioners must verify which edition ACMA will use in any given determination and keep an eye on updates to the RALI suite.

• Differing language across protections. Some protections are phrased narrowly and as mandatory, for example the Department of Defence PFD limit in s17(4). Other protections, such as those for AUS87 radio astronomy receivers, are phrased as encouragements to liaise and to follow RALI MS 31 notification arrangements rather than as absolute constraints (s15(1)-(2)). Parties may misread the instrument if they assume uniform legal force across all paragraphs.

• Non‑binding but administratively consequential. The Guidelines are advisory and do not create offences; nonetheless ACMA may rely on them in interference determinations (s7(5)). A common miscalculation is to treat the instrument as optional in a way that ignores the administrative consequences of non‑compliance. Licensees should treat the Guidelines as carrying practical weight in enforcement and licensing processes.

• Radio astronomy proximity and ARQZWA exclusions. The instrument notes the ARQZWA protects a site in remote central Western Australia and that an area within 70 kilometres of the site has been excluded from the geographic area of 2.5 GHz band spectrum licences (s14(2) note). Parties planning deployments near the ARQZWA boundary must check geographic exclusions and not assume licence geography overlaps where the ARQZWA applies.

• Conflicts with negotiated arrangements. The Guidelines preserve the parties’ ability to negotiate other protection requirements (s7(6)). However, failing to record negotiated deviations or to register changes properly may result in inconsistent expectations or disputes that ACMA may have to resolve. Practitioners should ensure negotiated arrangements are documented and, where relevant, notified to ACMA or reflected in the Register.

• Measurement and modelling assumptions. The Guidelines recommend that the most recent ITU‑R propagation models be considered (s7(4)). Different models give different results, and measurement methods can materially affect whether coordination is required. Disputes can arise because of differing modelling assumptions. Parties should document modelling inputs and be prepared to defend them.

• Non‑exclusive treatment of the Radio Regulations. The instrument notes the Radio Regulations are not domestic regulations made under the Act (s5 Note 1). Reliance on the Radio Regulations as authoritative in domestic contexts requires careful translation into Australian regulatory practice and cannot be assumed to be directly enforceable.

In all of these areas, the common theme is that administrative and technical detail matters. The instrument establishes an ecosystem of cross‑referenced documents, Register entries and site‑specific technical analysis. Overlooking any of these elements can create exposure in interference disputes or when ACMA assesses licence compliance.

Compliance with the Guidelines requires a structured compliance programme that connects Register management, technical modelling, coordination procedures, documentation and engagement with ACMA and affected parties. Below is a practical, stepwise compliance checklist and the rationale tied to specific provisions of the instrument.

1. Check the Register before planning and registering transmitters. The Guidelines predicate many protections on whether a protected receiver was included in the Register before a transmitter’s registration (see repeated phrasing in ss9(1), 11(1), 13(2), 15(2), 17(2)). Before submitting a station registration for a new fixed transmitter under a 2.5 GHz spectrum licence, retrieve and record Register entries for nearby spectrum‑licensed and apparatus‑licensed receivers, including station classes, antenna details and inclusion dates. Keep screenshots or PDFs of the Register extracts to evidence due diligence.

2. Identify the receivers and services potentially affected. Map nearby services by frequency and class: ENG and mid‑band gap spectrum‑licensed receivers in 2570-2620 MHz (s7(2)(a)); 2.3 GHz band receivers (s7(2)(b)); apparatus‑licensed fixed services operating in and adjacent to the 2.5 GHz band (s7(2)(b), s11); space services in 2483.5-2500 MHz and 2690-2700 MHz (s12); radio astronomy receivers, including AUS87 specified receivers and those in 2690-2700 MHz (s14-15); ARS and RLS and Department of Defence radars in 2700-2900 MHz (s16-17). For each relevant receiver, note whether it is included in the Register and the date of inclusion.

3. For spectrum‑licensed fixed receivers in the mid‑band gap and 2.3 GHz band, consult the separate Radiocommunications Advisory Guidelines referenced for compatibility requirements and notional receiver performance levels (s9(1)-(3)). Ensure system design meets those notional receiver performance levels or document why an alternative design is technically equivalent. Where mid‑band gap receivers are registered, anticipate that coordination is typically necessary for outdoor fixed transmitters within 1.5 kilometres and for 2.3 GHz receivers within 500 metres (s9(2), s9(4)).

4. For apparatus‑licensed point‑to‑point stations, follow RALI FX 3 coordination procedures. The Guidelines require that planning for 2.5 GHz transmitters should provide at least the same level of out‑of‑band and in‑band protection as apparatus‑licensed fixed transmitters assigned under RALI FX 3 (s11(1)-(2)). Obtain and follow the current RALI FX 3 procedures and document compliance.

5. For space and passive services, confirm whether operation in accordance with licence conditions affords protection. The Guidelines state a 2.5 GHz transmitter is not taken to cause interference to adjacent band EESS, MSS and RSS receivers if it complies with all licence conditions (s13(1)). For SRS space receive stations included earlier in the Register, apply ITU‑R SA.609 for protection criteria (s13(2)). For radio astronomy in 2690-2700 MHz, comply with ITU‑R RA.769‑2 (s15(4)). Obtain the relevant Recommendation and document how your design satisfies its protection criteria.

6. For radio astronomy and AUS87 receivers, engage early. The Guidelines encourage direct liaison between 2.5 GHz licensees and AUS87 receiver operators and suggest following RALI MS 31 notification arrangements (s15(1)-(2)). Where you operate near the ARQZWA, coordinate under RALI MS 32 (s15(6)). Keep records of all liaison and notifications.

7. For ARS, RLS and Defence receivers in 2700-2900 MHz, run radar coordination studies. The Guidelines direct licensees to consider ITU‑R Recommendations M.1464, M.1461 and M.1849 for coordination and protection criteria (s17(1)). For ARS fixed receivers of class ‘AL’, anticipate coordination typically required for transmitters within 10 kilometres; for RLS class ‘LR’, expect 20 kilometres (s17(3), s17(7)). For Department of Defence receivers, ensure that out‑of‑band emissions do not exceed a PFD of ‑125 dBm/MHz/m2 at the radar antenna height at the radar site (s17(4)). Where measurement or mitigation is required, document the measurement methodology and results.

8. Use appropriate propagation models and modelling assumptions. The Guidelines advise considering ITU‑R Recommendation P.1144 for selection of propagation methods and the most recent version of ITU‑R propagation models when modelling propagation in the 2.5 GHz band (s7(4)). Make modelling inputs explicit, record the choice of model and version, and retain outputs and assumptions as part of compliance evidence.

9. Document coordination and agreements. The instrument allows parties to negotiate alternative protection requirements (s7(6)). Any negotiated arrangements should be recorded in writing, include technical parameters, and be retained so that, if an ACMA interference determination arises, you can show the agreed approach. Where notification procedures in RALI MS 31 are followed, retain proof of notification and responses.

10. Design stations to meet in‑band and out‑of‑band limits. Ensure transmitter configurations (power, antenna height, orientation, filters) are set to meet the notional protection levels, RALI expectations and any PFD limits specified. Where equipment cannot meet the required protections, consider site relocation, directional antennas, lower power, or coordination agreements with affected receivers.

11. Maintain ongoing monitoring and Register updates. Because protection depends on the Register and because RALI and ITU‑R instruments may be updated, maintain a compliance calendar for checking for updates to RALI instruments, the spectrum plan and ITU‑R Recommendations. Update system designs and coordination as necessary.

12. Prepare for potential ACMA assessment. Since ACMA may take the Guidelines into account in determining interference (s7(5)), prepare compliance packages describing Register checks, modelling, coordination attempts, measurement evidence, and any negotiated arrangements. These packages will be important if ACMA conducts an interference investigation.

Costs and practical burdens of compliance are concrete. Spectrum licensees should expect to fund RF propagation modelling, technical compatibility studies, design adjustments to antenna height and power, administrative costs for Register checking and notifications, and personnel time for coordination with other operators and ACMA. Space and defence coordination may require specialist measurement equipment and engineering expertise to demonstrate compliance with tight PFD thresholds. For small operators or ENG users, the burden may be lower if they rely on spectrum licence technical frameworks and if major fixed base stations are sited away from sensitive receivers. Where large numbers of receivers are registered, or where sensitive receivers such as radio astronomy or defence radars are present, the costs and operational constraints on station siting and capacity will be higher.

In short, to comply, licensees must integrate Register due diligence, up‑to‑date modelling using ITU‑R methods, adherence to RALI procedures, documented coordination, and evidence of technical compliance with any specified thresholds. Those steps and their documentation are the practical means by which licensees will demonstrate conformity with the instrument and prepare for any ACMA interference determination.