CL_ev_visibilityEph

Description

• This function is deprecated.

  Replacement function: CL_ev_stationVisibility

• Computes the periods of time (start and end times) when a satellite is visible from a given set of ground stations.

  The satellite is visible from a ground station when its elevation is over a given threshold (stations_masks).

  The satellite trajectory is interpolated using order 8 Lagrange interpolation (using t_eph and pos_eph).

  The results are computed in the simulation period defined by sim_period.

  The intervals returned in visi_dates define the visibility periods start and end times of the satellite by at least one ground station. It means that the visibility intervals for ground stations considered independently are concatenated.

• Notes:

  - Visibility intervals with length less than visi_min are not computed. This parameter is also used for the detection of visibility intervals. So that choosing a small value for visi_min will increase the computation time.

  - The times t_eph should be well chosen so that intepolation errors are small enough.

Parameters

t_eph:

Time at which the satellite positions are defined; Must be in increasing order and all different. [days] (1xNeph)

pos_eph:

Satellite's cartesian coordinates relative to the frame where the ground stations are defined (i.e. rotating frame). (3xNeph)

stations:

Ground stations elliptical (geodetic) coordinates [long;lat;alt]. [rad,rad,m] (3xNsta)

stations_masks:

Station minimum elevations (above which there can be visibility). [rad] (1xNsta or 1x1)

sim_period:

(optional) Simulation time interval ([t_sim_start; t_sim_end]). Default is [t_eph(1); t_eph($)]. (2x1)

visi_min:

(optional) Minimum visibility duration. Default is 60 seconds. [sec] (1x1)

prec:

(optional) Computation accuracy on start/end visibility times. Default is 1 sec. [sec] (1x1)

er :

(optional) Planet equatorial radius. Default is %CL_eqRad. [m] (1x1)

obla :

(optional) Planet oblateness. Default is %CL_obla. (1x1)

visi_dates:

Visibility start and end times: [t_visi_start; t_visi_end]. (2xN)

Authors

• CNES - DCT/SB

See also

• CL_ev_visibilityExtr

Examples

T = 1; // days t_eph = linspace(0,T,100); pos_eph = [cos(2*%pi*t_eph/T); zeros(t_eph); sin(2*%pi*t_eph/T); ] * 7.e6; // ground stations definition sta1 = [0;0;0]; // equator sta2 = [0;%pi/2;0]; // North pole stations = [sta1,sta2]; stations_masks = [CL_deg2rad(10), CL_deg2rad(0)]; // visibility computation [visi_dates] = CL_ev_visibilityEph(t_eph,pos_eph,stations, .. stations_masks); [visi_dates] = CL_ev_visibilityEph(t_eph,pos_eph,stations, .. stations_masks, obla=0);