Commonwealth of Australia

 

 

Australian Communications Authority

 

 

Radiocommunications Act 1992

 

 

Radiocommunications Advisory Guidelines (Managing Out-of-band Interference in Receivers Operating in Spectrum Licensed Space¾3.4 GHz Band) 2000

 

 

The AUSTRALIAN COMMUNICATIONS AUTHORITY makes the following guidelines under section 262 of the Radiocommunications Act 1992.

 

 

Dated        17  July  2000

 

 

 

 

R Horton

Acting Chair

 

 

 

 

G W Luther

Senior Executive Manager

Radiocommunications

 

Australian Communications Authority

__________________________

 

CONTENTS

 

Clause

PART 1 - INTRODUCTION

1.1                     Title

1.2                     Commencement

1.3                     Purpose of these Guidelines

1.4                     Interpretation

1.5                     Background

1.6                     Managing In-band interference

1.7                     Managing Out-of-band interference

 

PART 2 - USE OF THE COMPATIBILITY REQUIREMENT

2.1                     When the compatibility requirement is used

 

PART 3 - RECEIVERS TO WHICH THE COMPATIBILITY REQUIREMENT APPLIES

3.1                     When the compatibility requirement is applied

3.2                     First-in-time registration and interference settlement

3.3                     Receiver performance levels

3.4                     Receivers operated or authorised to operate by the spectrum licensee

3.5                     Types of receivers

3.6                     Receiver deployment

 

PART 4 - MINIMUM RECEIVER PERFORMANCE AND COMPATIBILITY REQUIREMENT

4.1                     Minimum level of receiver performance

4.2                     Compatibility requirement

4.3                     Receiver selectivity

4.4                     Receiver intermodulation immunity

4.5                     Receiver blocking

4.6                     Receiver spurious response immunity

 

SCHEDULE 1      Receiver minimum level of performance

SCHEDULE 2      Compatibility requirement

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PART 1 - INTRODUCTION

Title

     1.1       These Guidelines are called the Radiocommunications Advisory Guidelines (Managing Out-of-band Interference in Receivers Operating in Spectrum Licensed Space—3.4 GHz Band) 2000.

 

 

Commencement

     1.2       These Guidelines commence on 17 July 2000.

 

 

Purpose of these Guidelines

     1.3       These guidelines provide a compatibility requirement to be complied with by transmitters for the management of out-of-band interference in certain receivers that are operated in spectrum licensed space in the 3.4 GHz band.  The compatibility requirement is intended to be used as the basis for both the development of coordination procedures and settlement of interference for devices operating under frequency-adjacent licences.

 

 

Interpretation

     1.4 (1)  In these Guidelines, unless the contrary intention appears:

 

Act means the Radiocommunications Act 1992.

 

blocking means a measure of the ability of a receiver to receive a wanted signal, in the presence of a high level unmodulated signal, that:

(a)   is at the frequency offsets set out in Schedule 1 (but excluding the characteristic frequencies relating to spurious response immunity); and

(b)   increases the non-linearity of the receiver’s pre-amplifier;

without the receiver’s grade of service falling below the compatibility requirement.

 

compatibility requirement means a receiver grade of service based on the conditions for wanted and unwanted signal levels at the receiver’s input, as set out in Schedule 2.

 

in-band means:

(a)     for a transmitter operated under a spectrum licence, the frequencies within the frequency band to which the licence relates; and

(b)     for a receiver operating in the space of a spectrum licence, the frequencies within the frequency band to which the licence relates; and

(c)     for a transmitter or receiver operating under an apparatus licence, the frequencies between the lower frequency limit and the upper frequency limit of its spectrum access.

 

[Note: For an apparatus licence, the lower frequency limit and the upper frequency limit of its spectrum access are published by the ACA on the Register of Radiocommunications Licences CDROM.  The bandwidth contained by those limits often appears on the licence as the ‘chargeable bandwidth’.]

 

in-band interference, for a receiver, means those levels of emissions from a transmitter that are permitted under the conditions of the licence under which it operates and:

(a)     if the receiver is operated in the space of a spectrum licence, the emissions at frequencies within the frequency band of the spectrum licence; or

(b)     if the receiver is operated under an apparatus licence, the emissions at frequencies between the lower frequency limit and the upper frequency limit of the spectrum access of the apparatus licence.

 

[Note: When interpreting ‘in-band interference’ it is important to keep in mind that ‘those levels of emissions from a transmitter that are permitted under the conditions of the licence’ relate to in-band as well as out-of-band emissions.] 

 

incumbent, for a device, means a device:

(a)     that operates under an apparatus licence; and

(b)     that had part of the band comprising the frequencies between the lower frequency limit and the upper frequency limit of its spectrum access, and its location, within the re-allocation of the 3.4 GHz band when that band was re-allocated.

 

intermodulation immunity, for a receiver, means a measure of the ability of the receiver to receive a wanted signal without the receiver’s grade of service falling below the compatibility requirement due to the presence of two or more unwanted signals with a specific amplitude and frequency relationship to the wanted signal frequency.

 

Marketing Plan means the Radiocommunications Spectrum Marketing Plan (3.4 GHz Bands) 2000.

 

out-of-band interference means interference:

(a)     relating to selectivity, blocking, intermodulation immunity and spurious response immunity; and

(b)     if the receiver is operated in the space of a spectrum licence, caused by emissions at frequencies outside the frequency band of the spectrum licence; or

(c)     if the receiver is operated under an apparatus licence, caused by emissions at frequencies outside the band that is between the lower frequency limit and the upper frequency limit of the spectrum access of the apparatus licence.

 

[Note:  This definition of out-of-band interference should not be confused with ‘out-of-band emission’, a term used in apparatus licensing to refer to emissions at frequencies outside a channel.]

 

RALI LM8 means the Radiocommunications Assignment and Licensing Instruction No. LM8 issued by the ACA, as in force from time to time, copies of which are available from the ACA.

 

selectivity means a measure of the ability of a receiver to discriminate between wanted and unwanted signals according to the IF and RF response set out in Schedule 1.

 

spurious response immunity means a measure of the ability of a receiver to receive a wanted signal at its operating frequency, in the presence of an unwanted signal at characteristic frequencies at which the receiver responds that are greater than 3 MHz from the receiver’s operating frequency, without the receiver’s grade of service falling below the compatibility requirement.

 

section 145 determination means the Radiocommunications (Unacceptable Levels of Interference¾3.4 GHz Band) Determination 2000.

 

3.4 GHz band means the following frequency bands:

(a)     3425MHz – 3475 MHz (the 3.4 GHz Lower Band);

(b)     3475 MHz – 3492.5 MHz (the 3.4 GHz Upper Band A);

(c)     3542.5 MHz – 3575 MHz (the 3.4 GHz Upper Band B).

[Notes:          1.  The following terms, used in these advisory guidelines, are defined in the Radiocommunications Act 1992 and have the meanings given to them by that Act:

core condition                                             Register

frequency band                                           interference

ACA                                                             spectrum licence

transmitter.

2.  The following terms, used in these advisory guidelines, are defined in the section 145 determination and have the meanings given to them by that determination:

device boundary                                         emission centre frequency

effective occupied bandwidth                  groups of receivers

effective antenna height                            effective occupied band]   

 

 

Background

1.5 (1)  The conditions of spectrum licences (and in a related manner, the conditions of apparatus licences) are designed to keep significant levels of emission within the geographic and frequency space of the licence and in doing so tend to manage in-band interference.  For spectrum licences, the main conditions managing in-band interference are:

(a)     the core condition about emission limits outside the area; and

(b)     the device boundary criterion; and

(c)     the core condition about emission limits outside the band.

 

If protection from in-band interference is required at levels that are above the intrinsic levels provided by these conditions then receivers operated under spectrum licences (or under apparatus licences issued after[1] the date of the Marketing Plan) must be operated in ways which provide that additional protection.

 

(2)        Emissions causing in-band interference do not normally[2] need to be reduced.  The management of in-band interference is left to the operator of the receiver, who would need to consider:

(a)     the likelihood of transmission from popular sites; and

(b)     the levels of emission in the direction of the receiver that are allowed by relevant licence conditions.

The operator of the receiver would need to take precautions to protect the receiver from the possibility of these emissions for the full term of the relevant licence.

 

(3)        Out-of-band interference is managed differently (see clause 1.7).  Out-of-band interference refers to a number of non-linear types of interference that may occur across the frequency boundaries of licences.  For example, receiver intermodulation may occur when a receiver is in the presence of two or more unwanted signals at frequencies outside the bandwidth of the receiver.

 

(4)        The likelihood of out-of-band interference depends on the proximity, in terms of both frequency and distance, of transmitters and receivers and, therefore, requires special consideration at communal sites.  Out-of-band interference:

(a)     may be caused by transmitters operating at frequencies that are many MHz from the operating frequency of a receiver; and

(b)     is related to the quality of the receiver as well as the levels of transmitter emissions.

 

(5)     The emission limits of spectrum licences are not designed to manage out-of-band interference.  It is not practical to manage out-of-band interference (for example, receiver intermodulation) with transmitter emission limits because that type of interference increases much faster than changes in the level of the signal causing it and, therefore, any limits would have to be very low.  Low limits throughout the entire geographic area of a licence (the frequency band limits of a spectrum licence exist throughout the entire area of the licence) would be unreasonable when mostly only communal sites require that level of protection and then only in certain situations.  Out-of-band interference is more efficiently managed through coordination procedures based on a defined compatibility requirement.  This approach maximises spectrum utility and flexibility and provides equitable spectrum access for devices operating near frequency boundaries.

 

Managing in-band interference

1.6 (1)  Although these Guidelines are directed towards the protection of receivers operated within the space of spectrum licences, it is helpful to present the general policy for management of interference to receivers in any situation.

 

(2)        In-band interference is considered to be acceptable if the interfering transmitter complies with all the conditions of the licence under which it operates.  This policy applies equally to apparatus and spectrum licences, and is designed to provide certainty for licensees by allowing them to continue to operate radiocommunication systems in accordance with the emission limits of a licence for the full term of the licence.  In the case of spectrum licences, this certainty also extends to emission limits relating to the device boundary criterion.  For apparatus licensing, the re-use distance provides a similar guarantee.  It is only when emissions create out-of-band interference that additional management is required.  This is the purpose of these Guidelines.

 

(3)        In-band interference caused by apparatus licensed transmitters licensed before the date of the Marketing Plan to receivers operating in the space of spectrum licences, is managed by the conditions of the apparatus licence.  Spectrum licensees must accept that interference:

(a)     if the transmitter is non-incumbent, for the licence term; or

(b)     if the transmitter is incumbent, for the relevant re-allocation period. 

Before a Marketing Plan is made, the frequencies of apparatus licences are usually assigned without regard to future spectrum licences.

 

(4)        In-band interference caused by apparatus licensed transmitters licensed after the date of the Marketing Plan to receivers operating in the space of spectrum licences is usually managed by assigning frequencies to apparatus licences using coordination procedures identical to the device boundary criterion in the relevant s.145 Determination.  This process ensures that the receivers do not experience higher levels of in-band interference than they would if the adjacent spectrum was managed under spectrum licensing.

 

(5)        In-band interference caused by spectrum licensed transmitters to non-incumbent and incumbent apparatus licensed receivers licensed before the date of the Marketing Plan is managed in accordance with the compatibility requirements described in the Radiocommunications Advisory Guidelines (Managing Interference to Apparatus Licensed Receivers—3.4 GHz Band) 2000.  These compatibility requirements apply:

(a)     if the receiver is non-incumbent, for the licence term; or

(b)     if the receiver is incumbent, for the relevant re-allocation period. 

For these purposes, receivers that communicate with incumbent transmitters are to be treated as incumbent.

 

(6)        In-band interference caused by spectrum licensed transmitters to apparatus licensed receivers licensed after the date of the Marketing Plan is managed by the conditions of the spectrum licence.  Those receivers must accept that interference from the time when the transmitter is first registered.

 

Managing out-of-band interference

            1.7 (1)  Out-of-band interference is managed through a coordination procedure using devices that are selected on a first registered basis to meet a compatibility requirement, as follows:

(a)     the operator of a transmitter need only take account of receivers already registered when the transmitter is registered; and

(b)     the operator of a receiver need only take account of transmitters already registered when the receiver is registered.

 

(2)        A receiver will not be afforded protection unless its details are in the Register.

 

 

PART 2 - USE OF THE COMPATIBILITY REQUIREMENT

 

When the compatibility requirement is used

2.1 (1)  The compatibility requirement is used to manage out-of-band interference occurring in receivers operating in the space of a spectrum licence that is frequency-adjacent to either apparatus licences or other spectrum licences.  These situations may commonly occur:

(a)     across the frequency boundaries 3425, 3442.5, 3475, 3492.5, 3542.5 and 3575 MHz, when caused by transmitters operated under apparatus licences; and

(b)     across the frequency boundary 3475 MHz, when caused by transmitters operated under spectrum licences having effective occupied bands containing frequencies above 3475 MHz.

 

(2)        The ACA intends to take the compatibility requirement into account when settling interference disputes between apparatus and spectrum licensees under Part 4.3 of the Act.  Therefore, the compatibility requirement is intended to be used as a basis for the development of coordination procedures used to assign transmitter frequencies.

 

(3)        The compatibility requirement may also be used to guide the settlement of interference between frequency-adjacent spectrum licensees.

 

 

PART 3 - RECEIVERS TO WHICH THE COMPATIBILITY REQUIREMENT APPLIES

 

When the compatibility requirement applies

3.1       The compatibility requirement does not apply to all receivers operating in spectrum licensed space.  It will only apply if the receiver:

(a)     is registered before any of the transmitters causing the interference (first-in-time registration); and

(b)     has a level of performance equal to or better than the level specified in Schedule 1; and

(c)     is operated or authorised to operate by the licensee; and

(d)     is of a type specified in clause 3.5; and  

(e)     is deployed as set out in clause 3.6, having regard to the band in which it is operated, the effective antenna height and the beamwidth of the antenna.

 

First-in-time registration and interference settlement

3.2 (1)  The ACA intends to support the use of coordination procedures based on first-in-time registration by varying the details of the most recently registered device to remove interference—unless the other devices are not operating in accordance with their licence conditions.  In some instances it may be more appropriate both technically and economically for the first service to have changes made at the expense of the later service operator, provided these arrangements do not degrade the service performance requirements of the first service. 

 

(2)        If the operating conditions of a transmitter or receiver are later varied so as to increase the likelihood of interference, the effective date of registration for interference settlement purposes is:

(a)     the date at which the variation was made; or

(b)     if the operator reverts to the original registration details—the original registration date.

 

(3)        The likelihood of interference to a varied transmitter or receiver increases whenever:

(a)     for a transmitter operated under a spectrum licence:

(i)      the device boundary expands; or

(ii)    the effective occupied band expands outside the original frequency band; or

(b)     for a receiver operated in the space of a spectrum licence:

(i)      the antenna gain for any azimuth increases; or

(ii)    the receiver’s deployment changes so that the compatibility requirement is applied when previously it was not applied; or

(iii)    the location is changed; or

(iv)  the effective occupied band of the transmitter communicating with the receiver expands outside the original frequency band; or

(c)     for a transmitter operated under an apparatus licence:

(i)     the radiated power for any azimuth increases; or

(ii)   the location is changed; or

(iii)  the antenna height is changed; or

(iv) the lower frequency limit of its spectrum access decreases or the upper frequency limit of its spectrum access increases.

(d)     for a receiver operated under an apparatus licence:

(i)  the antenna gain for any azimuth increases; or

(ii) the location is changed; or

(iii) the lower frequency limit of its spectrum access decreases or the upper frequency limit of its spectrum access increases.

 

(4)        The early registration of devices at the network design stage is encouraged by the ACA as an aid for licensees who wish to check the coordination work of adjacent licensees. 

 

Receiver performance levels

            3.3 (1)  The degree of out-of-band interference to a receiver depends to an extent on the interference susceptibility of the receiver.  Emission levels from transmitters should not have to be reduced when poor performance of the receiver is to blame.  Therefore, when establishing a compatibility requirement for receivers, it is necessary to also establish a minimum receiver performance.  The receiver minimum performance level is set out in Schedule 1.

 

(2)        Transmitter emission levels will be judged against the receiver minimum performance.  Note that, under spectrum licensing, a licensee may choose to operate a receiver of any performance level.  The protection given by the compatibility requirement is not available to receivers with a performance level below the minimum level.  However, if transmitter emission levels are excessive in relation to the minimum receiver performance then action would normally be required to reduce them to the necessary level.

 

(3)        The ACA proposes that, because the desired outcome is equity in the use of adjacent spectrum, the minimum receiver performance level should be similar throughout the entire 3.4 GHz spectrum licensed bands.

 

Receivers operated or authorised to operate by the spectrum licensee

3.4 (1)  The compatibility requirement applies only to a receiver operated by the licensee (or a receiver authorised to operate by the licensee):

(a)     in the geographic area and frequency band of the relevant spectrum licence; or

(b)     as described in subclause (3).

 

(2)        A receiver is operating in the frequency band of a spectrum licence when the effective occupied bandwidth of the transmitter communicating with the receiver is within the frequency band limits of the licence.  Broadly speaking, this occurs when the receiver’s IF bandwidth stays within the spectrum licence limits.  In practice, the IF bandwidth of a receiver may be slightly broader than the effective occupied bandwidth and this must be taken into account by the operator of the receiver.

 

(3)        Where a transmitter is registered under a spectrum sharing agreement and its effective occupied bandwidth overlaps the frequency bands of two or more licences, the receiver is taken to be operating within the space of a spectrum licence having a frequency band equivalent to the combined frequency bands of the shared licences.

 

Types of receivers

            3.5 (1)  The compatibility requirement does not apply to mobile[3] devices operating under any type of licence because the mobility of the devices prevents the use of a practical coordination procedure for managing out-of-band interference.

 

(2)        Except for a group of fixed receivers located near a central point[4], the compatibility requirement does not apply to receivers that are registered in a simplified manner using the concept of group of receivers.

 

Receiver deployment

3.6 (1)  When a transmitter is certified as complying with the relevant section 145 determination and is registered, it means that it satisfies certain conditions about the deployment of transmitters (deployment constraints).  Receiver compatibility requirements are assigned in a manner complementary to the transmitter deployment constraints, to provide immediate spectrum access for the most common equipment configuration without loss of spectrum utility from out-of-band interference.  This is one aspect of the operational certainty offered by Australian spectrum licences.  It is not acceptable for a successful bidder either to risk the ability to negotiate, or to pay the additional cost of negotiation, with an adjacent licensee about the management of out-of-band interference.  Deployment constraints remove a substantial amount of negotiation costs that would otherwise be necessary.

 

(2)        While a licensee is allowed to operate any type of receiver at any location, the provision of a compatibility requirement depends on the beamwidth of the antenna, the band in which it operates and its effective antenna height.  If a compatibility requirement does not apply to a receiver, a licensee would normally take account of the risk of interference in some other manner, for example, by some agreement with the manager of a communal site or by using guard space within the spectrum licence space. 

 

(3)        The compatibility requirement is provided to receivers:

(a)     that communicate with a transmitter that has its effective occupied band totally within the 3.4 GHz Lower band; and

(b)     that use an antenna with a beamwidth greater than 5 degrees; and

(c)     that operate at high sites, that is, above an effective antenna height for any segment 1, he₁(f_n) greater than 20 metres^[5].

This is because wide beamwidth transmitters are usually kept below an effective antenna height for any segment 1, he₁(f_n) of 10 metres in that band.

 

(4)        The compatibility requirement is provided to receivers:

(a)     that communicate with a transmitter that has its effective occupied band totally within the 3.4 GHz Upper band A or 3.4 GHz Upper band B; and

(b)     that use an antenna with a beamwidth greater than 5 degrees; and

(c)     that operate at low sites, that is, below an effective antenna height for any segment 1, he₁(f_n) of 10 metres.

 

(5)        The compatibility requirement is not provided to receivers:

(a)     that communicate with a transmitter that has its effective occupied band partly within the 3.4 GHz Lower band and 3.4 GHz Upper band A; and

(b)     that use an antenna with a beamwidth greater than 5 degrees.

 

(6)        The compatibility requirement is provided to receivers using an antenna with a beamwidth less than or equal to 5 degrees irrespective of their effective antenna height and the band in which they operate.

 

(7)        The deployment constraints for the compatibility requirement provide operational certainty for hub receivers at high sites in the 3.4 GHz Lower Band.  However, it is possible for transmitters that operate at high sites in this band to be registered if internal or shared guard space is provided.  In these cases, the guard band should provide the necessary frequency separation for the management of out-of-band interference, if necessary, through the use of filters.

 

 

PART 4- MINIMUM RECEIVER PERFORMANCE AND COMPATIBILITY REQUIREMENT

 

Minimum level of receiver performance

4.1 (1)  A minimum level of receiver performance is set out in Schedule 1.

 

(2)        The minimum level of receiver performance relates to:

(a) selectivity;

(b) intermodulation immunity;

(c) blocking; and

(d) spurious response immunity.

 

Compatibility requirement

4.2       The compatibility requirement is set out in Schedule 2.

 

Receiver selectivity

4.3 (1)  The selectivity of a receiver affects its susceptibility both to in-band and out-of-band interference.  

 

(2)        In the case of out-of-band interference, by specifying an IF and RF bandwidth shape, the power falling within it may be calculated from a knowledge of the power spectral density of an off-channel unwanted signal.  The interference is assumed to be noise-like within the IF and generally created through reciprocal mixing with the local oscillator of the receiver.

 

Receiver intermodulation immunity

4.4 (1)  Models for out-of-band interference related to receiver intermodulation immunity are available (see RALI LM8) and are based on the RF selectivity of a receiver and a conversion ratio.  The interference power may be calculated from knowledge of these parameters and compared with the compatibility requirement. 

 

(2)        Models for the conversion ratios for various intermodulation types are based on the non-linear characteristics of a semiconductor and are usually a very good approximation to actual receiver performance.  Two-signal third order, two-signal fifth order and three-signal third order intermodulation interference scenarios are normally checked in a co-ordination study.

 

Receiver blocking

4.5 (1)  Out-of-band interference caused through receiver blocking usually results from a change in the operating point of the RF-amplifier or mixer stages when overloaded. 

 

(2)        This type of interference is not the same as that involving receiver selectivity, although both effects can sometimes occur simultaneously for small frequency offsets.

 

(3)        The interference power is not easily modelled and a minimum blocking performance is specified in Schedule 1.

 

Receiver spurious response immunity

4.6 (1)  Spurious response immunity is largely a function of the selectivity of the RF stages and local oscillator spectral purity.

 

(2)        The power for this type of interference is not easily modelled and a minimum spurious response immunity ratio is specified in Schedule 1.

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SCHEDULE 1

 

Receiver minimum level of performance

 

1.  Table 1 sets out the minimum IF selectivity for a receiver. The frequency offsets are specified for the upper and lower limits of the effective occupied bandwidth of the transmitter communicating with the receiver.

 

Frequency Offset (MHz)	Loss (dB)
0	0
0.32	3
0.45	10
0.62	20
0.84	30
0.97	40
1.25	50

                 Table 1. Receiver IF filter Characteristics

 

2.  The minimum RF selectivity for a receiver (between the antenna and receiver input) is:

(a) 2 + 60*Log₁₀ [1 + (FreqOffset/13)^1.6] dB for FreqOffset £ 64 MHz; and

(b) 70 dB for FreqOffset > 64 MHz;

where FreqOffset is the separation in frequency from the upper or lower limits of the frequency band of the spectrum licence in whose space the receiver operates. 

[Note:  The symbol * represents the operation of multiplication.]

 

For a receiver operating under agreement in the shared space of more than one licence, FreqOffset is specified for the minimum lower and maximum upper limits of the shared licences.

 

3.  Table 2 sets out the minimum conversion ratios for the three main intermodulation types.

Intermodulation Type	Conversion Ratio (dB)
Two-signal Third-order (2A±B)	11
Two-signal Fifth-order (3A±2B)	28
Three-signal Third-order (A±B±C)	5

                 Table 2. Receiver Intermodulation Conversion Ratios

 

 

SCHEDULE 1 (continued)

 

4.  (1)        The minimum level of performance for a receiver in relation to interfering signals from transmitters with frequency offsets based on the upper and lower limits of the effective occupied bandwidth of the transmitter communicating with the receiver is:

 

(a) a blocking level of greater than or equal to 80 dB for frequency offsets greater than 2.5 MHz from the wanted signal; and

(b) a spurious response immunity performance of greater than or equal to 65 dB.

 

(2)             All levels are referenced to the antenna connector of the equipment.

 

(3)             The minimum level of performance of an antenna system for a receiver is a gain of 10dBi in all directions and a feeder and combiner loss of 2 dB.

 

___________________

 

SCHEDULE 2

 

Compatibility requirement

 

The compatibility requirement is:

 

·      an output quality equivalent to a wanted to unwanted signal level ratio that is not less than 15 dB for more than 1% of the time in any 1 hour period;

 

·      with the wanted signal never less than -111 dBm; and

 

·      when measured as mean power within a 30 kHz rectangular bandwidth that is within the frequency band of the spectrum licence.

 

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