Recommendation ITU-R P.1853¶

This Recommendation provides methods to synthesize rain attenuation and scintillation for terrestrial and Earth-space paths and total attenuation and tropospheric scintillation for Earth-space paths.

Title	PDF	Latest approved in
Recommendation ITU-R P.1853	[PDF]	2019-08
Time series synthesis of tropospheric impairments
Current recommendation version (In force)		Date
Recommendation ITU-R P.1853-2	[PDF]	08/2019
Recommendations implemented in ITU-Rpy		Date
Recommendation ITU-R P.1853-1	[PDF]	02/2012
Recommendation ITU-R P.1853-0	[PDF]	10/2009
Recommendations not implemented in ITU-Rpy		Date
Recommendation ITU-R P.1853-2	[PDF]	08/2019

Introduction¶

The planning and design of terrestrial and Earth-space radiocommunication systems requires the ability to synthesize the time dynamics of the propagation channel. For example, this information may be required to design various fade mitigation techniques such as, inter alia, adaptive coding and modulation, and transmit power control.

The methodology presented in this Recommendation provides a technique to synthesize rain attenuation and scintillation time series for terrestrial and Earth-space paths and total attenuation and tropospheric scintillation for Earth-space paths that approximate the rain attenuation statistics at a particular location.

Module description¶

itur.models.itu1853.change_version(new_version)[source]¶

Change the version of the ITU-R P.1853 recommendation currently being used.

Parameters:

new_version (int) –

Number of the version to use. Valid values are:

1: Activates recommendation ITU-R P.1853-1 (02/12) (Current version)

0: Activates recommendation ITU-R P.1853-0 (10/09) (Superseded)

itur.models.itu1853.get_version()[source]¶

Obtain the version of the ITU-R P.1853 recommendation currently being used.

Returns:	version – Version currently being used.
Return type:	int

itur.models.itu1853.set_seed(seed)[source]¶

Set the seed used to generate random numbers.

Parameters:	seed (int) – Seed used to generate random numbers

itur.models.itu1853.rain_attenuation_synthesis(lat, lon, f, el, hs, Ns, Ts=1, tau=45, n=None)[source]¶

A method to generate a synthetic time series of rain attenuation values.

Parameters:	lat (number, sequence, or numpy.ndarray) – Latitudes of the receiver points lon (number, sequence, or numpy.ndarray) – Longitudes of the receiver points f (number or Quantity) – Frequency (GHz) el (sequence, or number) – Elevation angle (degrees) hs (number, sequence, or numpy.ndarray, optional) – Heigh above mean sea level of the earth station (km). If local data for the earth station height above mean sea level is not available, an estimate is obtained from the maps of topographic altitude given in Recommendation ITU-R P.1511. Ns (int) – Number of samples Ts (int) – Time step between consecutive samples (seconds) tau (number, optional) – Polarization tilt angle relative to the horizontal (degrees) (tau = 45 deg for circular polarization). Default value is 45 n (list, np.array, optional) – Additive White Gaussian Noise used as input for the
Returns:	rain_att – Synthesized rain attenuation time series (dB)
Return type:	numpy.ndarray

References

[1] Characteristics of precipitation for propagation modelling https://www.itu.int/rec/R-REC-P.1853/en

itur.models.itu1853.scintillation_attenuation_synthesis(Ns, f_c=0.1, Ts=1)[source]¶

A method to generate a synthetic time series of scintillation attenuation values.

Parameters:	Ns (int) – Number of samples f_c (float) – Cut-off frequency for the low pass filter Ts (int) – Time step between consecutive samples (seconds)
Returns:	sci_att – Synthesized scintilation attenuation time series (dB)
Return type:	numpy.ndarray

References

[1] Characteristics of precipitation for propagation modelling https://www.itu.int/rec/R-REC-P.1853/en

itur.models.itu1853.integrated_water_vapour_synthesis(lat, lon, Ns, Ts=1, n=None)[source]¶

The time series synthesis method generates a time series that reproduces the spectral characteristics and the distribution of water vapour content.

Parameters:	lat (number, sequence, or numpy.ndarray) – Latitudes of the receiver points lon (number, sequence, or numpy.ndarray) – Longitudes of the receiver points Ns (int) – Number of samples Ts (int) – Time step between consecutive samples (seconds) n (list, np.array, optional) – Additive White Gaussian Noise used as input for the
Returns:	L – Synthesized water vapour content time series (kg/m2)
Return type:	numpy.ndarray

References

[1] Characteristics of precipitation for propagation modelling https://www.itu.int/rec/R-REC-P.1853/en

itur.models.itu1853.cloud_liquid_water_synthesis(lat, lon, Ns, Ts=1, n=None)[source]¶

The time series synthesis method generates a time series that reproduces the spectral characteristics, rate of change and duration statistics of cloud liquid content events.

Parameters:	lat (number, sequence, or numpy.ndarray) – Latitudes of the receiver points lon (number, sequence, or numpy.ndarray) – Longitudes of the receiver points Ns (int) – Number of samples Ts (int) – Time step between consecutive samples (seconds) n (list, np.array, optional) – Additive White Gaussian Noise used as input for the
Returns:	V – Synthesized cloud liquid water time series (mm)
Return type:	numpy.ndarray

References

[1] Characteristics of precipitation for propagation modelling https://www.itu.int/rec/R-REC-P.1853/en

itur.models.itu1853.total_attenuation_synthesis(lat, lon, f, el, p, D, Ns, Ts=1, hs=None, tau=45, eta=0.65, rho=None, H=None, P=None, hL=1000, return_contributions=False)[source]¶

The time series synthesis method generates a time series that reproduces the spectral characteristics, rate of change and duration statistics of the total atmospheric attenuation events.

The time series is obtained considering the contributions of gaseous, cloud, rain, and scintillation attenuation.

Parameters:

lat (number) – Latitudes of the receiver points
lon (number) – Longitudes of the receiver points
f (number or Quantity) – Frequency (GHz)
el (number) – Elevation angle (degrees)
p (number) – Percentage of the time the rain attenuation value is exceeded.
D (number or Quantity) – Physical diameter of the earth-station antenna (m)
Ns (int) – Number of samples
Ts (int) – Time step between consecutive samples (seconds)
tau (number, optional) – Polarization tilt angle relative to the horizontal (degrees) (tau = 45 deg for circular polarization). Default value is 45
hs (number, sequence, or numpy.ndarray, optional) – Heigh above mean sea level of the earth station (km). If local data for the earth station height above mean sea level is not available, an estimate is obtained from the maps of topographic altitude given in Recommendation ITU-R P.1511.
eta (number, optional) – Antenna efficiency. Default value 0.5 (conservative estimate)
rho (number or Quantity, optional) – Water vapor density (g/m3). If not provided, an estimate is obtained from Recommendation Recommendation ITU-R P.836.
H (number, sequence, or numpy.ndarray, optional) – Average surface relative humidity (%) at the site. If None, uses the ITU-R P.453 to estimate the wet term of the radio refractivity.
P (number, sequence, or numpy.ndarray, optional) – Average surface pressure (hPa) at the site. If None, uses the ITU-R P.453 to estimate the wet term of the radio refractivity.
hL (number, optional) – Height of the turbulent layer (m). Default value 1000 m
return_contributions (bool, optional) – Determines whether individual contributions from gases, rain, clouds and scintillation are returned in addition ot the total attenuation (True), or just the total atmospheric attenuation (False). Default is False

Returns:

A (Quantity) – Synthesized total atmospheric attenuation time series (dB)
Ag, Ac, Ar, As, A (tuple) – Synthesized Gaseous, Cloud, Rain, Scintillation contributions to total attenuation time series, and synthesized total attenuation time seires (dB).

References

[1] Characteristics of precipitation for propagation modelling https://www.itu.int/rec/R-REC-P.1853/en