Committee on Radio Astronomy Frequencies

Estimate of maximum acceptable e.i.r.p. of transmitting device without interfering to a radio astronomy station

This routine calculates the maximum acceptable e.i.r.p. of terrestrial transmitters that must be respected to protect the Radio Astronomy Service using the propagation model given in Recommendation ITU-R P.452 while to estimate the atmospheric attenuation Recommendation ITU-R P.676 is used. This routine can also be used to estimate the separation distance between the transmitter and the radio astronomy station for an aggregate of transmitting devices. In this routine, calculations are done for different minimum distance values until the maximum tolerable e.i.r.p. is reached.

The calculation uses the geographic summation methodology. Since a generic solution is anticipated: no terrain model is included.

The protection criteria for Radio Astronomy are given in Recommendation ITU-R RA.769. The tolerable date loss to radio astronomy observations and percentage-of-time criteria resulting from degradation by interference for frequency bands allocated to the radio astronomy on a primary basis is given in Recommendation ITU-R RA.1513.

maximum permissible spectral power density: (in dB(Wm-2Hz-1))
frequency (above ~0.7 GHz): (MHz)
reference bandwidth for transmitter: (MHz)
height radio astronomy antenna: (in meters)
path angular distance: (in degrees)
density of active users transmitting towards the victim station: (km-2)
height transmitting station: (in meters)
sea-level surface refractivity:
percentage of time lost due to variable propagation: (this value should be 10% or less)
minimum separation distance (>= 0.0001 km): (in km)
air pressure: (in hPa)
temperature: (in oC)
water vapour density: (in g/cm3)
maximum radius of rings: (in km)
ring width: (in km - the accuracy of the results depends strongly on this number)
number of mobile systems:

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Last modified: September 21, 2004