Code-based usage

SatLink is structured with three main classes Satellite, Reception and GroundStation. For the most functions, the user needs to instance an object of each class and relate these objects with a set-type function. Please check the example files.

For example, to calculate one link availability, execute the following steps:

Import the modules:

from GrStat import GroundStation, Reception
from sat import Satellite

Instanciate the objects of each class:

station = GroundStation(site_lat, site_long)
sat = Satellite(sat_long, freq, eirp_max, hsat, b_transponder, b_util, _, _, mod, rolloff, fec)
receptor = Reception(ant_size, ant_eff, coupling_loss, polarization_loss, lnb_gain, lnb_noise_temp, cable_loss, desfoc_max)

Use the set functions:

sat.set_grstation(station)
sat.set_reception(receptor)

Use the link availability function with default values:

availability = sat.get_availability()
print(availability)

Examples

Code-based examples can be found in Satlink main folder as single_point_example.py, multi_point_example.py, example_single_point_ant_size.py and example_multi_point_ant_size.py. These examples use the majority of class functions and emulate the GUI calculations.

Classes

Satellite

Satellite is the code's main class. It has the majority of functions. Its parameters are:

Parameters

sat_long: geostationary satellite longitude in degrees
freq: frequency in GHz
eirp_max: transponder maximun E.I.R.P. in dBW
h_sat: satellite height in Km
b_transp: transponder bandwidth in MHz
b_util: actual used transponder bandwidth
back_off: decrease in transmitted power to avoid non-linear amplification
modulation: please check Modulation_dB.csv in models folder to see the available modulations
fec: please check Modulation_dB.csv in models folder to see the available options
roll_off: factor of spectral efficiency, ROF (Roll-Off Factor)

Functions

Satellite class functions are:

to set the GroundStation object of the link the user wants to compute
```
.set_grstation(grstation: GroundStation)
```
to set the Reception object of the link the user wants to compute
```
.set_reception(reception: Reception)
```
to return the elevation angle between satellite and ground station (degrees)
```
.get_elevation() # need set_grstation()
```
to return the azimuth angle between satellite and ground station (degrees)
```
.get_azimuth() # need set_grstation()
```
to return the distance between satellite and ground station (km)
```
.get_distance() # need set_grstation()
```
to return the threshold for a given modulation and FEC
```
.get_reception_treshold()
```
to return multiple attenuation values: a_fs, depointing_loss, a_g, a_c, a_r, a_s, a_t, a_tot
```
.get_link_attenuation(p=0.001, method='approx') # need set_grstation() and set_reception()
```
- a_fs: free-space attenuation (dB)
- depointing_loss: depointing for a given max. align mismatch (dB)
- a_g: gaseous attenuation (dB)
- a_c: cloud attenuation (dB)
- a_r: rain attenuation (dB)
- a_s: scintillation or tropospheric attenuation (dB)
- a_t: total atmospheric attenuation (dB)
- a_tot: total attenuation (free-space + atmospheric) (dB)

to return total attenuation values: a_t, a_tot and depoint_loss
```
.get_total_attenuation(p= None) # need set_grstation() and set_reception()
```
- a_t: total atmospheric attenuation (dB)
- a_tot: total attenuation (free-space + atmospheric) (dB)
- depoint_loss: depointing for a given max. align mismatch (dB)

to return the power flux density at the reception (W/m²)

.get_get_power_flux_density(p=None) # need set_grstation() and set_reception()

to return the antenna noise temperature under rain conditions (K)

.get_antenna_noise_rain(p=None) # need set_grstation() and set_reception()

to return reception's total noise temperature (K)

.get_total_noise_temp(p=None) # need set_grstation() and set_reception()

to return the link's figure of merit (G/T) (dB/K)

.get_figure_of_merit(p=None) # need set_grstation() and set_reception()

to return the carrier over noise per bandwidth unit (dB-Hz)

.get_c_over_n0(p=None) # need set_grstation() and set_reception()

to return the signal over noise (dB)

.get_snr(p=None) # need set_grstation() and set_reception()

to return the link availability (%/year) for a SNR + a given margin (dB) with a relaxation (dB) over the target value
```
.get_availability(margin=0, relaxation=0.1) # need set_grstation() and set_reception()
```
- margin: summed value over the modulation threshold to be considered. If margin = 0, the calculation target equals the modulation threshold.
- relaxation: (+-) relaxation over the error between the target value and actual SNR in availability calculation

Reception

Parameters

ant_size: antenna diameter in meters
ant_eff: antenna efficiency (between 0 and 1)
coupling_loss: coupling losses in dB
polarization_loss: polarization loss in dB
lnb_gain: LNB gain in dB
lnb_noise_temp: LNB noise temperature in Kelvin
cable_loss: cable loss in dB
max_depoint: maximum depointing angle between transmission and reception (degrees)

Functions

Reception class functions are:

to return the calculated antenna gain (dB)
```
.get_antenna_gain()
```
to return the antenna 3dB beamwidth (degrees)
```
.get_beamwidth():
```
to return the calculated maximum depoint loss based on the maximum depointing angle (dB)
```
.get_depoint_loss()
```
to return the ground temperature received in the antenna (Kelvin)
```
.get_ground_temp(self):
```
to return the sky brightness temperature received in the antenna (Kelvin)
```
.get_brightness_temp():
```
to return the total antenna noise temperature (Kelvin)
```
.get_antenna_noise_temp(self):
```

GroundStation

Parameters

site_lat: site latitude in decimal degrees
site_long: site longitude in decimal degrees

Functions

Reception class functions are:

to return the earth radius from lat, long (km)
```
.get_earth_radius(self)
```
to return a nearest value from a point of a table. It is used in get_R001, get_h0 and get_hR. Its an auxiliary function and should be moved to another class in the future.
```
getnearpos(self, array, value)
```
to return the R001 (rain exceedance in 0.01% of year) value from ITU 837-7
```
get_R001(self)
```
to return h0 (isometric height) from ITU 839-4
```
get_h0(self)
```
to return hR (annual rain height) from ITU 839-4
```
get_hR(self)
```