Radiocommunications Advisory Guidelines (Protection of Molonglo Observatory Synthesis Telescope) 1998 (Cth)

Commonwealth of Australia

Radiocommunications Act 1992

Radiocommunications Advisory Guidelines

(Protection of Molonglo Observatory Synthesis Telescope) 1998

THE AUSTRALIAN COMMUNICATIONS AUTHORITY makes the following guidelines under subsection 262 of the Radiocommunications Act 1992

Dated 4 February 1998.

A J Shaw   Chairman

R Horton       Deputy Chairman

Australian Communications Authority

BACKGROUND

The Molonglo Observatory Synthesis Telescope (‘MOST’) is a radio telescope located approximately 30 km to the East of Canberra that monitors radio signals from weak celestial radio sources in a frequency band centred on 843 MHz.

The frequency band 825-845 MHz is subject to spectrum licensing and all transmitters to be operated in this band may potentially affect the MOST.

These advisory guidelines set out the compatibility requirement that would provide the MOST with a reasonable level of interference protection from transmitters operating in this band.  A suggested approach to assessing the compatibility is also provided.

Spectrum licences in the relevant bands will require that operation of transmitters under the licence must not interfere with the MOST.  This requirement to protect the MOST will cease at the end of 2008.

PART 1¾GENERAL INFORMATION

Title

1.1   These guidelines are called the Radiocommunications Advisory Guidelines (Protection of Molonglo Observatory Synthesis Telescope) 1998.

Commencement

1.2   These guidelines commence on 4 February 1998.

Interpretation

1.3   In these guidelines:

“compatibility requirement” means the requirement set out in Part 2;

“coordination threshold distance” means the maximum distance from the MOST receiver within which a transmitter operated under spectrum licence needs to be coordinated;

   “EIRP” means equivalent isotropically radiated power;

   “the MOST” means the radio telescope operated by the University of Sydney located about 30 km east of Canberra, ACT at latitude 35° 22’ 30” S, longitude 149° 25’ 35” E.  The telescope has a receive frequency of 843 MHz with a 3 dB bandwidth of +/- 1.5 MHz.

[Note: Australian Map Grid coordinates - Zone: 55, Easting: 720420, Northing: 6082653.].

Purpose of these guidelines

1.4   The purpose of these advisory guidelines is to set out the compatibility requirement and provide a basis upon which spectrum licensees in the 825-845 MHz band may coordinate the operation of their transmitters so as to prevent interference being caused to the MOST.  If such interference is caused to the MOST the ACA will have regard to whether or not the spectrum licensee has coordinated the transmitters in a manner that meets the compatibility requirement set out in these guidelines, during interference settlement.

1.5   The compatibility requirement is intended to reflect the ACA’s policy of providing adequate interference protection to the MOST.  This does not alter the fact that the ACA will deal with each interference scenario on a case by case basis according to its own circumstances.

1.6   The compatibility requirement set out in these guidelines is based on the results of tests[1] conducted to determine the interference susceptibility of the MOST.  These tests were undertaken jointly by the Spectrum Management Agency, the Department of Communications and the Arts and the University of Sydney.  The compatibility requirement and the methodology presented in these guidelines have been developed in consultation with industry.  Spectrum licensees should take all reasonable steps to ensure that, whatever coordination methods are used, the compatibility requirement set out in these guidelines is met in respect of any transmitters to be operated under a spectrum licence.

[1] Reference: Spectrum Planning Report SPP 5/96, “Interference Susceptibility of the Molonglo Observatory Synthesis Telescope.

1.7   The compatibility requirements for the MOST are set out in Part 2.

            PART 2¾COMPATIBILITY REQUIREMENT

2.1   The compatibility requirement for spectrum licensees to protect the MOST is as follows:

Ptx - L = Prx

Prx = Prx₀ - G(f) - G(f)

where:
Ptx is the EIRP of the proposed transmitter in the direction of the MOST (dBm);
L is the transmission loss (dB) (definition ref: ITU-R Rec. P.341-4 );
G(f) is the relative gain of the MOST as a function of the bearing to the
         transmitter (dB) found from Table 2;
G(f) is the relative gain of the MOST as a function of frequency (dB) found from
         Table 3;
Prx is the received power at the MOST; and
Prx₀ (the worst-case protection level) = -174 dBm.

2.2   The average power received by the MOST within its 3 dB bandwidth (3 MHz) should not exceed the compatibility requirement for more than 10 % of the time as a result of variations in propagation conditions (ref:  ITU-R Rec. RA.1031-1).

2.3   The coordination methodology set out in Parts 3 to 6 inclusive may be used to determine whether a transmitter proposed for operation under a spectrum licence (‘the proposed transmitter’) will meet the compatibility requirement.

PART 3¾FINDING OUT IF DETAILED COORDINATION IS NECESSARY

Distance to the MOST

3.1   Calculate the distance between the proposed transmitter and the MOST.

3.2   If the proposed transmitter is within 10 km of the MOST and is intended to operate within the frequency range 825-845 MHz the spectrum licensee should not operate the transmitter unless steps are taken as set out in Part 6.

3.3   If the proposed transmitter is more than 10 km from the MOST and is intended to operate in the frequency range 825-845 MHz, the procedure described in clauses 3.4 to 3.11 inclusive may be used to determine if the compatibility requirement can be met.  For mobile transmitters intended to operate in the frequency range 825-840 MHz, and exempt from device registration as provided for in the spectrum licence, the compatibility requirement does not apply.

Coordination threshold distance

3.4   Table 1[2] may be used to evaluate whether a detailed coordination assessment  is necessary by determining the ‘coordination threshold distance’ for a proposed transmitter.

[2] Note that due to the range of EIRP values shown in the table, the table spans two pages.  These two pages can be joined horizontally to form one complete table.

3.5   Before using Table 1, spectrum licensees should take note of the underlying principles used in developing the table as set out in clauses 4.1 to 4.2 and make a judgement as to whether these assumptions are appropriate for their proposed transmitter(s).  If the assumptions are not appropriate, or the range of values of effective antenna height or EIRP is not sufficient, then Table 1 should not be used and a detailed coordination assessment will be necessary as described in Part 5.

3.6   The methodology for using Table 1 to find the coordination threshold distance is set out in Part 4.  Determining the coordination threshold distance from Table 1 is a two stage process.  The first stage determines an initial distance and the second stage refines the required protection level, thereby allowing a reduced distance to be determined from the table in many cases.  The second stage is unnecessary if the distance between the proposed transmitter and the MOST is greater than the initial distance determined from the table.

3.7   The initial coordination threshold distance should be found from Table 1 as described in clause 4.3.

3.8   If the proposed transmitter is outside this coordination threshold distance then no coordination with the MOST is required and the transmitter may be operated (providing other relevant conditions of the spectrum licence are met).

3.9   If the proposed transmitter is closer to the MOST than the initial coordination threshold distance then the coordination threshold distance should be refined, if possible, as described in clauses 4.4 to 4.6.

3.10   If the proposed transmitter is closer to the MOST than the revised coordination threshold distance then the spectrum licensee should conduct a detailed coordination assessment as set out in Part 5.

3.11   If the proposed transmitter is outside the revised coordination threshold distance then no coordination with the MOST is required and the transmitter may be operated (providing other relevant conditions of the spectrum licence are met).

PART 4¾USING THE COORDINATION THRESHOLD DISTANCE TABLE (TABLE 1)

Validity of Table 1 for the path between the proposed transmitter and the MOST

4.1   Table 1 was produced using the spherical Earth propagation model to calculate the coordination threshold distances listed in the table.  Parameters used in the calculations included an effective Earth radius (k) of 5.5 and a receiver (the MOST) antenna height of 10 m.  The transmitter antenna height used in each calculation was the effective antenna height listed in the same row of the table as the calculated distance.

4.2   Generally, the spherical Earth propagation model used in calculating the coordination threshold table will give less loss than the actual propagation path.  However, care should be taken if the path is either unobstructed or obstructed by a single knife edge, as these propagation paths can result in less loss than the spherical Earth propagation model.  In such cases the coordination threshold distance table should not be used.

Initial coordination threshold distance

4.3   Looking first at the upper part of Table 1 (upwards from and including the row titled “EIRP”):  For a given EIRP and effective antenna height[3], a distance can be read from the table.  This distance is the initial coordination threshold distance.

[3]

Refining the coordination threshold distance

4.4   For a proposed transmitter closer to the MOST than the initial distance determined by using the upper part of Table 1, a further stage can be undertaken to determine whether the compatibility requirement can be reduced.  By considering the directionality and frequency response of the MOST the compatibility requirement can be reduced thereby reducing the coordination threshold distance.

4.5   The total reduction in the compatibility requirement can be determined as follows:

(a)   determine the bearing of the proposed transmitter from the MOST.  Then look up the relative gain figure corresponding to this bearing in Table 2;

(b)   using Table 3 find the frequency range relevant to the proposed transmitter’s frequency bandwidth and then look up the corresponding frequency response figure;

(c)   the total reduction in the compatibility requirement is the sum[4] of the two figures determined in sub clauses (a) and (b).

[4] The absolute value of the sum should be used in Table 1.

4.6   The left hand column in the lower part of Table 1 lists the amount by which the compatibility requirement has been reduced.  Find the appropriate figure in the left hand column corresponding to the reduction in the compatibility requirement calculated in clause 4.5.  If the appropriate figure is not listed, the next lowest figure should be used.  (eg if the compatibility requirement is reduced by 29 dB, find 27 dB in the left column).  The lowest value of EIRP that is equal to or greater than that of the proposed transmitter should then be located in the row corresponding to this reduction in the compatibility requirement.  Once the appropriate EIRP is found in a particular column, this column can then be used in the upper part of the table to find the new coordination threshold distance for the appropriate effective antenna height.

PART 5¾ DETAILED COORDINATION ASSESSMENT

Detailed coordination

5.1   For a proposed transmitter to be sited closer to the MOST than the distance determined from the coordination threshold distance table, detailed coordination studies will be needed to determine if the transmitter can operate without interference to the MOST.

5.2   The methodology to be applied in conducting the detailed coordination has not been specified due to the range of possible system applications and potential interference scenarios.  It is the responsibility of spectrum licensees to ensure that the studies are conducted with due care using supportable and valid methodologies such as those presented in ITU-R recommendations, ACA guidelines, or ACA radiocommunications assignment and licensing instructions (RALIs).

5.3   The objective in undertaking a detailed coordination study is to determine whether the signal level at the MOST from the proposed transmitter is below the level specified by the compatibility requirement.  This level will range from -174 dBm to -104 dBm depending upon the proposed frequency and the bearing on which the signal

arrives at the MOST.  The appropriate compatibility requirement can be calculated by adding the reduction in the compatibility requirement determined in clause 4.4 to -174 dBm.  The signal levels from proposed transmitters should not exceed this compatibility requirement for more than 10% of the time as a result of variations in propagation conditions.  (ref: ITU-R Rec. RA.1031-1).

5.4   Detailed coordination studies can take into account the actual terrain between the MOST and the proposed transmitter(s).  Knowing the nature of the terrain may allow a different propagation model to be used in calculating the propagation loss between the proposed transmitter and the MOST.  If greater propagation loss results from using a different propagation model the coordination distances will be reduced.  However, as noted in clause 4.2 some propagation paths may result in less loss than the spherical Earth propagation model that was used in calculating the coordination threshold distance table.

PART 6¾COORDINATION OF TRANSMITTERS CLOSE TO THE MOST

6.1   Transmitters operating in the band 825-845 MHz and within 10 km of the MOST could cause interference by overloading the low noise amplifiers resulting in a blocking effect.  The susceptibility of the MOST to this type of interference has not been characterised. 

6.2   Spectrum licensees proposing to operate transmitters within this range should approach the Sydney University’s Department of Astrophysics with a view to undertaking test transmissions to determine if such operation is feasible.

Stage 1:  Determine initial distance from EIRP and effective antenna height.
Effective Antenna Height (m)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)
1200	271	285	290	229	313	318	327	341	347	355	369	375	383
600	193	207	212	170	234	240	248	262	268	276	290	296	304
300	139	152	158	130	180	185	193	207	213	221	235	240	249
150	101	114	120	101	141	146	154	168	173	182	195	201	209
75	74	87	92	81	113	118	126	139	145	153	166	172	180
37.5	54	66	71	65	92	97	105	118	123	131	144	150	158
10	27	38	42	44	61	66	73	86	91	99	112	117	125
3	10	17	21	28	37	41	48	60	65	72	85	90	97
1.5	*	*	11	19	24	28	35	46	50	57	70	74	82
* Transmitters operating in any part of the 825-845 MHz band within 10 km of the MOST should undertake detailed coordination with the MOST.
Prop Loss (dB)	144	149	151	154	159	161	164	169	171	174	179	181	184
EIRP (watts)	0.000001	0.000003	0.000005	0.00001	0.00003	0.00005	0.0001	0.0003	0.0005	0.001	0.003	0.005	0.01
Compatibility Requirement	Stage 2: Reduced compatibility requirement allows reduced distances for the same EIRP and effective antenna height.  From the row below with the appropriate reduction in protection find the proposed EIRP and then read the new distance above from that column.
Reduced by (dB)	EIRP (watts)
3	0.000002	0.000006	0.00001	0.00002	0.00006	0.0001	0.0002	0.0006	0.001	0.002	0.006	0.01	0.02
6	0.000004	0.000012	0.00002	0.00004	0.00012	0.0002	0.0004	0.0012	0.002	0.004	0.012	0.02	0.04
9	0.000008	0.000024	0.00004	0.00008	0.00024	0.0004	0.0008	0.0024	0.004	0.008	0.024	0.04	0.08
12	0.000016	0.000048	0.00008	0.00016	0.00048	0.0008	0.0016	0.0048	0.008	0.016	0.048	0.08	0.16
15	0.000032	0.000095	0.00016	0.00032	0.00095	0.0016	0.0032	0.0095	0.016	0.032	0.095	0.16	0.32
18	0.000064	0.000190	0.00032	0.00064	0.00190	0.0032	0.0064	0.0190	0.032	0.064	0.190	0.32	0.64
21	0.000130	0.000380	0.00063	0.00130	0.00380	0.0063	0.0130	0.0380	0.063	0.130	0.380	0.63	1.30
24	0.000260	0.000760	0.00130	0.00260	0.00760	0.0130	0.0260	0.0760	0.130	0.260	0.760	1.30	2.60
27	0.000510	0.001600	0.00260	0.00510	0.01600	0.0260	0.0510	0.1600	0.260	0.510	1.600	2.60	5.10
30	0.001000	0.003000	0.00500	0.01000	0.03000	0.0500	0.1000	0.3000	0.500	1.000	3.000	5.00	10.00
33	0.002000	0.006000	0.01000	0.02000	0.06000	0.1000	0.2000	0.6000	1.000	2.000	6.000	10.00	20.00
36	0.004000	0.012000	0.02000	0.04000	0.12000	0.2000	0.4000	1.2000	2.000	4.000	12.000	20.00	40.00
39	0.008000	0.024000	0.04000	0.08000	0.24000	0.4000	0.8000	2.4000	4.000	8.000	24.000	40.00	80.00
42	0.016000	0.048000	0.08000	0.16000	0.48000	0.8000	1.6000	4.8000	8.000	16.000	48.000	80.00	159.00
45	0.032000	0.095000	0.16000	0.32000	0.95000	1.6000	3.2000	9.5000	16.000	32.000	95.000	159.00	317.00
48	0.064000	0.190000	0.32000	0.64000	1.90000	3.2000	6.4000	19.0000	32.000	64.000	190.000	316.00	631.00
51	0.130000	0.380000	0.63000	1.30000	3.80000	6.3000	13.0000	38.0000	63.000	126.000	378.000	630.00	1260.00
54	0.260000	0.760000	1.30000	2.60000	7.60000	13.0000	26.0000	76.0000	126.000	252.000	754.000	1260.00	2520.00
57	0.510000	1.600000	2.60000	5.10000	16.00000	26.0000	51.0000	151.0000	251.000	502.000	1510.000	2510.00	5020.00
60	1.000000	3.000000	5.00000	10.00000	30.00000	50.0000	100.0000	300.0000	500.000	1000.000	3000.000	5000.00	10000.00
63	2.000000	6.000000	10.00000	20.00000	60.00000	100.0000	200.0000	599.0000	998.000	2000.000	5990.000	9980.00	20000.00
66	4.000000	12.000000	20.00000	40.00000	120.00000	200.0000	399.0000	1200.0000	2000.000	3990.000	12000.000	20000.00	39900.00
70	10.000000	30.000000	50.00000	100.00000	300.00000	500.0000	1000.0000	3000.0000	5000.000	10000.000	30100.000	50000.00	100000.00

Notes:      1. Calculated distances are based on the spherical Earth diffraction loss model (loss not exceeded for 10 % of the time).

2. Protected receive level Prx=-174 dBm.

3. If a value of EIRP, effective antenna height or protection reduction is not listed then the next highest value should be used.  Alternatively, the results obtained from using both the higher               and lower values could be interpolated

Stage 1:  Determine initial distance from EIRP and effective antenna height.
Effective Antenna Height (m)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)	Distance (km)
1200	397	403	412	426	432	440	454	460	469	483	489	497
600	318	324	332	346	352	361	375	380	389	403	409	417
300	263	268	277	291	296	305	319	324	333	347	352	361
150	223	228	237	251	256	265	279	284	293	307	312	321
75	194	199	207	221	227	235	249	254	263	277	282	291
37.5	171	177	185	199	204	213	226	232	240	254	260	268
10	138	144	152	165	171	179	193	198	207	220	226	234
3	111	116	124	137	142	151	164	169	178	191	197	205
1.5	95	100	108	121	126	134	148	153	161	175	180	189
Prop Loss (dB)	189	191	194	199	201	204	209	211	214	219	221	224
EIRP (watts)	0.03	0.05	0.1	0.3	0.5	1	3	5	10	30	50	100
Compatibility Requirement	Stage 2: Reduced compatibility requirement allows reduced distances for the same EIRP and effective antenna height.  From the row below with the appropriate reduction in protection find the proposed EIRP and then read the new distance above from that column.
Reduced by (dB)	EIRP(watts)
3	0.06	0.1	0.2	0.6	1	2	6	10	20	60	100	200
6	0.12	0.2	0.4	1.2	2	4	12	20	40	120	200	399
9	0.24	0.4	0.8	2.4	4	8	24	40	80	239	398	795
12	0.48	0.8	1.6	4.8	8	16	48	80	159	476	793	1590
15	0.95	1.6	3.2	9.5	16	32	95	159	317	949	1590	3170
18	1.90	3.2	6.4	19.0	32	64	190	316	631	1900	3160	6310
21	3.80	6.3	13.0	38.0	63	126	378	630	1260	3780	6300	12600
24	7.60	13.0	26.0	76.0	126	252	754	1260	2520	7540	12600	25200
27	16.00	26.0	51.0	151.0	251	502	1510	2510	5020	15100	25100	50200
30	30.00	50.0	100.0	300.0	500	1000	3000	5000	10000	30100	50000	100000
33	60.00	100.0	200.0	599.0	998	2000	5990	9980	20000	59900	99800	200000
36	120.00	200.0	399.0	1200.0	2000	3990	12000	20000	39900	120000	200000	399000
39	239.00	398.0	795.0	2390.0	3980	7950	23900	39800	79500	239000	398000	795000
42	476.00	793.0	1590.0	4760.0	7930	15900	47600	79300	159000	476000	793000	1590000
45	949.00	1590.0	3170.0	9490.0	15900	31700	94900	159000	317000	949000	1590000	3170000
48	1900.00	3160.0	6310.0	19000.0	31600	63100	190000	316000	631000	1900000	3160000	6310000
51	3780.00	6300.0	12600.0	37800.0	63000	126000	378000	630000	1260000	3780000	6300000	12600000
54	7540.00	12600.0	25200.0	75400.0	126000	252000	754000	1260000	2520000	7540000	12600000	25200000
57	15100.00	25100.0	50200.0	151000.0	251000	502000	1510000	2510000	5020000	15100000	25100000	50200000
60	30100.00	50000.0	100000.0	300000.0	501000	1000000	3010000	5000000	10000000	30100000	50000000	100000000
63	59900.00	99800.0	200000.0	599000.0	998000	2000000	5990000	9980000	20000000	59900000	99800000	200000000
66	120000.00	200000.0	399000.0	1200000.0	2000000	3990000	12000000	20000000	39900000	120000000	200000000	399000000
70	300000.00	501000.0	1000000.0	3010000.0	5000000	10000000	30100000	50000000	100000000	301000000	500000000	1000000000

Notes:      1. Calculated distances are based on the spherical Earth diffraction loss model (loss not exceeded for 10 % of the time).

2. Protected receive level Prx=-174 dBm.

3. If a value of EIRP, effective antenna height or protection reduction is not listed then the next highest value should be used.  Alternatively, the results obtained from using both the higher               and lower values could be interpolated

Bearing Range			Relative Gain    G(phi) (dB)
358	-	2	0.0
3	-	7	0.0
8	-	12	-6.3
13	-	17	-8.7
18	-	22	-10.3
23	-	27	-11.4
28	-	32	-12.3
33	-	37	-13.1
38	-	42	-13.7
43	-	47	-14.3
48	-	52	-14.8
53	-	57	-15.2
58	-	62	-15.6
63	-	67	-16.0
68	-	72	-14.3
73	-	77	-11.6
78	-	82	-3.0
83	-	87	-11.3
88	-	92	-14.0
93	-	97	-11.3
98	-	102	-3.0
103	-	107	-11.6
108	-	112	-14.3
113	-	117	-16.0
118	-	122	-15.6
123	-	127	-15.2
128	-	132	-14.8
133	-	137	-14.3
138	-	142	-13.7
143	-	147	-13.1
148	-	152	-12.3
153	-	157	-11.4
158	-	162	-10.3
163	-	167	-8.7
168	-	172	-6.3
173	-	177	0.0
178	-	182	0.0
183	-	187	0.0
188	-	192	-6.3
193	-	197	-8.7
198	-	202	-10.3
203	-	207	-11.4
208	-	212	-12.3
213	-	217	-13.1
218	-	222	-13.7
223	-	227	-14.3
228	-	232	-14.8
233	-	237	-15.2
238	-	242	-15.6
243	-	247	-16.0
248	-	252	-14.3
253	-	257	-11.6
258	-	262	-3.0
263	-	267	-11.3
268	-	272	-14.0
273	-	277	-11.3
278	-	282	-3.0
283	-	287	-11.6
288	-	292	-14.3
293	-	297	-16.0
298	-	302	-15.6
303	-	307	-15.2
308	-	312	-14.8
313	-	317	-14.3
318	-	322	-13.7
323	-	327	-13.1
328	-	332	-12.3
333	-	337	-11.4
338	-	342	-10.3
343	-	347	-8.7
348	-	352	-6.3
353	-	357	0.0

Note:  Round all bearings to a whole number before using table.

Frequency range			Relative gain due to frequency response      G(f)  (dB)
<	840.0	-54.6
840.0	<=	840.1	-48.7
840.1	<=	840.2	-43.2
840.2	<=	840.3	-38.1
840.3	<=	840.4	-33.3
840.4	<=	840.5	-29.0
840.5	<=	840.6	-25.3
840.6	<=	840.7	-21.8
840.7	<=	840.8	-18.5
840.8	<=	840.9	-15.4
840.9	<=	841.0	-12.5
841.0	<=	841.1	-10.8
841.1	<=	841.2	-9.3
841.2	<=	841.3	-7.9
841.3	<=	841.4	-6.5
841.4	<=	841.5	-5.3
841.5	<=	841.6	-4.2
841.6	<=	841.7	-3.2
841.7	<=	841.8	-2.3
841.8	<=	841.9	-1.5
841.9	<=	842.0	-0.8
842.0	<=	842.1	-0.5
842.1	<=	842.2	-0.2
842.2	<=	842.3	0.0
842.3	<=	842.4	0.0
842.4	<=	842.5	0.0
842.5	<=	842.6	0.0
842.6	<=	842.7	0.0
842.7	<=	842.8	0.0
842.8	<=	842.9	0.0
842.9	<=	843.0	0.0
843.0	<=	843.1	0.0
843.1	<=	843.2	0.0
843.2	<=	843.3	0.0
843.3	<=	843.4	0.0
843.4	<=	843.5	0.0
843.5	<=	843.6	-0.1
843.6	<=	843.7	-0.3
843.7	<=	843.8	-0.7
843.8	<=	843.9	-1.0
843.9	<=	844.0	-1.4
844.0	<=	844.1	-1.8
844.1	<=	844.2	-2.6
844.2	<=	844.3	-3.5
844.3	<=	844.4	-4.6
844.4	<=	844.5	-5.8
844.5	<=	844.6	-7.2
844.6	<=	844.7	-8.8
844.7	<=	844.8	-10.5
844.8	<=	844.9	-12.3
844.9	<=	845.0	-14.4
>	845.0	-16.5

 The effective antenna height of the transmitting antenna may be determined with any valid methodology.  The ITU-R defines the effective antenna height as the height of the transmitting antenna over the average level of
the ground between distances of 3 and 15 km from the transmitter in the direction of the receiver (ref: ITU-R Rec. P.370-7).  An alternative methodology developed by the ACA could also be used.  This alternative method is used in spectrum licensing for evaluating the geographic device boundary for spectrum licensed transmitters.