atten_map_fast#

pycraf.pathprof.atten_map_fast(freq, temperature, pressure, h_tg, h_rg, timepercent, hprof_data, polarization=0, version=16, base_water_density=<Quantity 7.5 g / m3>)[source]#

Calculate attenuation maps using a fast method.

Parameters:
freqQuantity

Frequency of radiation [GHz]

temperatureQuantity

Temperature (K)

pressureQuantity

Pressure (hPa)

h_tg, h_rgQuantity

Transmitter/receiver heights over ground [m]

timepercentQuantity

Time percentage [%] (maximal 50%)

hprof_datadict, dict-like

Dictionary with height profiles and auxillary maps of dimension (my, mx) as calculated with height_map_data.

polarizationint, optional

Polarization (default: 0) Allowed values are: 0 - horizontal, 1 - vertical

versionint, optional

ITU-R Rec. P.452 version. Allowed values are: 14, 16

base_water_densityQuantity, optional

For atmospheric attenuation, the water vapor content plays a role. In Rec. ITU-R P.452, Eq. (9a), the water content is variable (depending on the fraction of the path over the water). However, the base level is set to \(7.5~\mathrm{g}/\mathrm{m}^3\). For extraordinarily dry places, which are often used for radio astronomy, this value can be too high. (Default: 7.5 g / m^3)

Returns:
resultsdict

Results of the path attenuation calculation. Each entry in the dictionary is a 2D ndarray containing the associated value for the map of dimension (my, mx). The following entries are contained:

  • L_b0p - Free-space loss including focussing effects

    (for p% of time) [dB]

  • L_bd - Basic transmission loss associated with diffraction

    not exceeded for p% time [dB]; L_bd = L_b0p + L_dp

  • L_bs - Tropospheric scatter loss [dB]

  • L_ba - Ducting/layer reflection loss [dB]

  • L_b - Complete path propagation loss [dB]

  • L_b_corr - As L_b but with clutter correction [dB]

  • eps_pt - Elevation angle of paths w.r.t. Tx [deg]

  • eps_pr - Elevation angle of paths w.r.t. Rx [deg]

  • d_lt - Distance to horizon w.r.t. Tx [km]

  • d_lr - Distance to horizon w.r.t. Rx [km]

  • path_type - Path type (0 - LoS, 1 - Trans-horizon)

Notes

  • The diffraction-loss algorithm was changed between ITU-R P.452 version 14 and 15. The former used a Deygout method, the new one is based on a Bullington calculation with correction terms.

  • In future versions, more entries may be added to the results dictionary.