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XML format definition for EIRP and PFD masks information

1. Introduction

A mask defines an envelope of the power radiated by the space stations of the non-geostationary system or its associated earth stations. Three masks, as required in Appendix 4, are mandatory to describe the non-geostationary system and examine it under RR Article 22 and Appendix 5: a power flux-density mask for the downlink (A.14.c), an equivalent isotropically radiated power mask for the uplink (A.14.b) and inter-satellite link (A.14.a). Detailed definition of these masks, description of their generation and calculation methodology are provided in Rec. ITU-R S.(BO).1503-1.

2.1. Definition of the space station power flux-density mask

The power flux-density (PFD) mask of the non-geostationary satellite system is defined as the maximum PFD generated by any space station in the system as seen from any point at the surface of the Earth.
The mask is specified using one of the three options as referential. The first and second options specify the mask by separation angle and difference in longitude between the non-geostationary satellite and the point on the geostationary orbital arc where the separation angle is minimized.
Option 1:
      for each latitude of the non-geostationary sub-satellite point; and
      for each separation angle a between the non-geostationary space station and the geostationary orbital arc, as seen from any point on the surface of the Earth. The a angle is the minimum topocentric angle measured from this particular earth location between the non-geostationary space station and the geostationary orbital arc; or
    for each difference ΔL in longitude between the non-geostationary sub-satellite point and the point on the geostationary orbital arc where the a (or X) angle is minimized.
Option 2:
      for each latitude of the non-geostationary sub-satellite point; and
      for each separation angle X, which is the angle between a line projected from the geostationary orbital arc through the non-geostationary space station to the ground and a line from the non-GSO space station to the edge of the non-GSO beam; and
    for each difference ΔL in longitude between the non-geostationary sub-satellite point and the point on the geostationary orbital arc where the a (or X) angle is minimized.
 
The third option specifies the mask by azimuth and elevation angles used for the non-geostationary satellite.
Option 3:
      for each latitude of the non-geostationary sub-satellite point; and
      for each azimuth angle; and
    for each elevation angle.
The GSO arc avoidance defines a non-operating zone on the ground in the field of view of a non-GSO space station. The location of this non‑operating zone on the ground will move as a function of the latitude of the non-GSO sub‑satellite point.

2.2. XML format definition for the pfd mask

The information described below must appear in the XML mask data file associated with a notice.
§  non-geostationary satellite system
    ntc_id = “ntc_id value”, it is the basic numerical identifier and it must be identical to the content of the ntc_id field allocated in the related notice table defined in the SRS database.
    sat_name = “satellite system name”, it must be identical to the content of the sat_name field in the related non_geo table defined in the SRS database.
§  pfd_mask  (see RR Appendix 4, item A.14.c)
    mask_id = “mask_id value”; it is the unique numerical identifier of this mask within the complete notice for this non-geostationary satellite system, (see item A.14.c.1).
    low_freq_mhz = “low_freq_mhz value”, it is the lowest frequency, in MHz, of the frequency band for which this mask is valid (see item A.14.c.2).
    high_freq_mhz = “high_freq_mhz value”, it is the highest frequency, in MHz, of the frequency band for which this mask is valid (see item A.14.c.3).
    type = “type value”, it must be one of the following values specifying the referential used for this mask (see item A.14.c.4).
·          “alpha_deltaLongitude” for option 1; or
·          “X_deltaLongitude” for option 2 or
·          “azimuth_elevation” for option 3.
    a_name = “latitude”, it specified the use of latitudes of sub-satellite points.
    b_name = “name of angle b”, it must be one of the values: “alpha” or “X” or “azimuth” in accordance with the selected type of PFD mask.
    c_name = “name of angle c”, it must be one of the values: “deltaLongitude” or “elevation” in accordance with the selected type of PFD mask.
         by_a
    a = “a value”, it is the latitude, in decimal degrees, of the non-GSO sub-satellite point.
         by_b
    b = “b value”, it is, in accordance with the selected type of PFD mask, either:
·       the separation angle α, in decimal degrees, between the non-GSO space station and the GSO arc, as seen from any point on the surface of the Earth when type = “alpha_deltaLongitude” and b_name = “alpha”; or
·       the separation angle X, in decimal degrees, between a line projected from the GSO arc through the non-GSO space station to the ground and a line from the non-GSO space station to the edge of the non-GSO beam when  type = “X_deltaLongitude”  and b_name = ”X”; or
·       the azimuth angle, in decimal degrees, when  type = “azimuth_elevation”  and b_name = “azimuth”.
         pfd
    c = “c value” it is, in accordance with the selected referential, either:
·       the difference in longitude, in decimal degrees, between the non-GSO sub-satellite point and the point on the GSO arc where the angle α is minimized when  type = “alpha_deltaLongitude” and b_name = “alpha” and c_name = “deltaLongitude” ;  or
·       the difference in longitude, in decimal degrees, between the non-GSO sub-satellite point and the point on the GSO arc where the  angle X is minimized when  type = “x_deltaLongitude” and b_name = “X” and c_name = “deltaLongitude” ;  or
·       the elevation angle, in decimal degrees, when  type = “azimuth_elevation”  and c_name = “elevation”.
    “pfd value”, it is the value of power-flux density, in dB((W/m2)/BWref), in the reference bandwidth generated at this location on the earth surface (see item A.14.c.5).

3.1. Definition of the earth station EIRP mask

The equivalent isotropically radiated power (EIRP) mask of the associated earth station part of the non‑geostationary system is defined by the maximum EIRP as a function of the off-axis angle generated by the earth station.

3.2. XML format definition for the earth station EIRP mask

§  non-geostationary satellite system
    ntc_id = “ntc_id value”, it is the basic numerical identifier and it must be identical to the content of the ntc_id field allocated in the related notice table defined in the SRS database.
    sat_name = “satellite system name”, it must be identical to the content of the sat_name field in the related non_geo table defined in the SRS database.
§  eirp_mask_es  (see RR Appendix 4, item A.14.b)
    mask_id = “mask_id value”; it is the unique numerical identifier of this mask within the complete notice for this non-geostationary satellite system, (see item A.14.b.1).
    low_freq_mhz = “low_freq_mhz value”, it is the lowest frequency, in MHz, of the frequency band for which this mask is valid (see item A.14.b.2).
    high_freq_mhz = “high_freq_mhz value”, it is the highest frequency, in MHz, of the frequency band for which this mask is valid (see item A.14.b.3).
    min_elev = “min_elev value”, it is the minimum elevation angle, in decimal degrees, at which any associated earth station can transmit to a non-geostationary satellite (see item A.14.b.4).
    d_name = “separation angle”, the use of the off-axis angle.
         eirp
    d = “d value” it is the separation angle θ, in decimal degrees, between the non-GSO space station and the GSO space station at the non-GSO earth station.
    “eirp value”, it is the equivalent isotropically radiated power, in dB(W/BWref), in the reference bandwidth for this angle (see item A.14.b.6).

4.1. Definition of the space station EIRP mask

The equivalent isotropically radiated power (EIRP) mask of the non-geostationary space station is defined by the maximum EIRP generated as a function of the off-axis angle between the boresight of the non‑geostationary space station and the direction of the GSO space station.

4.2. XML format definition of the space station EIRP mask

§  non-geostationary satellite system
    ntc_id = “ntc_id value”, it is the basic numerical identifier and it must be identical to the content of the ntc_id field allocated in the related notice table defined in the SRS database.
    sat_name = “satellite system name”, it must be identical to the content of the sat_name field in the related non_geo table defined in the SRS database.
§  eirp_mask_ss  (see RR Appendix 4, item A.14.a)
    mask_id = “mask_id value”; it is the unique numerical identifier of this mask within the complete notice for this non-geostationary satellite system, (see item A.14.a.1).
    low_freq_mhz = “low_freq_mhz value”, it is the lowest frequency, in MHz, of the frequency band for which this mask is valid (see item A.14.a.2).
    high_freq_mhz = “high_freq_mhz value”, it is the highest frequency, in MHz, of the frequency band for which this mask is valid (see item A.14.a.3).
    d_name = “separation angle”, the use of the off-axis angle.
         eirp
    d = “d value”, it is the separation angle θ, in decimal degrees, between the boresight of the non‑GSO space station and the pointing direction of the GSO space station.
    “eirp value”, it is the equivalent isotropically radiated power, in dB(W/BWref), in the reference bandwidth for this angle (see item A.14.a.4).

5. Data arrangement

During the simulation, the EPFD Validation Software will calculate the relevant parameters, such as latitude and off‑axis angle or a angle, and then use the mask to calculate a pfd or e.i.r.p. using the following approach:
  1. The array of {Latitude, Table} is searched and the table which has the nearest latitude to the value calculated in the simulation is selected.
  2. Using the selected table, the pfd or e.i.r.p. is then calculated by interpolation using:
    1. pfd: calculated using bi-linear interpolation in either pfd(a, Dlong) or pfd(azimuth, elevation);
    2. e.i.r.p.: calculated using linear interpolation in e.i.r.p.(q).
Each table is independent i.e. at different latitudes it can use a different grid resolution and range. The mask does not need to cover the whole range: outside the supplied values the last valid value is assumed to be used.
However, it should be noted that for latitude and {azimuth, elevation, a, Dlong} regions where no actual pfd is produced, in order to avoid using nearest latitude table containing operational pfd values it is advisable to provide extremely low pfd values for these ranges to simulate no transmission scenario.
The pfd mask table is not assumed to be symmetric in {azimuth, elevation, a, Dlong} and should be given for the full range from positive to negative extremes. The e.i.r.p. masks are assumed to be symmetric around the boresight line via use of the off-axis angle as the parameter. In the case that the {azimuth, elevation, a, Dlong, off-axis angle} calculated in the simulation is outside the ranges given in the pfd or e.i.r.p. masks then the last valid value should be used.