Radio Mobile - RF propagation simulation software
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Network prop.. Parameters



Net name

The name of the net.

A net name can be up to 30 characters long.

Minimum and maximum frequency

For a frequency hopping net, these entries correspond to the lower and upper limits of the hopping set.

The program computes the mean frequency as the entry for the propagation model.

Surface refractivity

The terrain surface refractivity is a measure of the air refractivity above/near the ground. In general, the average refractivity would decrease with altitude, being a maximum at sea level.

Area specific data is in the table below. In the absence of any specific data, the default value should be used.

  Area Surface Refractivity (N-units)
  Equatorial (Congo) 360
  Continental Subtropical (Sudan) 320
  Maritime Subtropical (West Coast of Africa) 370
  Desert (Sahara) 280
  Continental Temperate (use for avg. atmospheric conditions) 301
  Maritime Temperate, over land (United Kingdom and Continental West Coasts) 320
  Maritime Temperate, over sea 350
Ground conductivity

Area specific data is in the table below. In the absence of any specific data, the default value should be used.

  Area Conductivity of Ground (Siemens/m)
  Average Ground 0.005
  Poor Ground 0.001
  Good Ground 0.020
  Fresh Water 0.010
  Sea Water 5.0
Relative ground permittivity

These properties determine together the nature of the radio wave reflection on the ground in a Line-Of-Sight radio link. In general, the more conductive the terrain is, the greater is the risk to have important attenuation or fluctuations of the radio signal. The worst case is the “picket fence” type. In the absence of any specific data, default values should be used.

  Area Dielectric Constant of Ground
  Average Ground 15
  Poor Ground 4
  Good Ground 25
  Fresh Water 81
  Sea Water 81

Polarization

Either horizontal or vertical (in accordance with the system in use).

Mode of variability

The Mode of Variability settings modify the statistical margin value shown in Radio Link that is added to the link's path loss.

As an example, for a local VHF packet data link select spot coverage. While varying the % of situations, the following statistial margins result for a particular link:

70% = 5.9 dB
80% = 9.6 dB
90% = 14.8 dB
95% = 19.3 dB
99% = 28.0 dB

The Spot mode is for a one-try message. The Accidental mode is for interference evaluation. The Mobile mode is for units that are moving while communicating. The Broadcast mode is for stationary units.

The effect of percentage of time, locations, and situations depends on the mode selected.

  • Spot
  • Accidental
  • Mobile
  • Broadcast

Climate

This option is used to select the type of climate mostly encountered in the selected deployment area.

These options set some of the calculation parameters in the ITS algorithm used in the program. The atmospheric conditions like climate and weather vary in the different areas of the world, and affect both the refractive index of free air and play an important role in determining the strength and fading properties of radio signals. For instance, the refractive index gradient of air near the surface of the earth determines the way a radio ray is bent or refracted as it passes through the atmosphere.

  Description Climate
    Continental Subtropical
    Maritime Sub-Tropical
    Desert
  Large landmasses in the Temperate Zone Continental Temperate
    Maritime Temperate Over Land
    Maritime Temperate Over Sea

Additional loss

here additional compensation can be set for Forest or Urban environment.
In the case that Land Cover is enabled this option will not be displayed. Also the values will be determined from the settings in Land Cover.

 

'Land Cover useage enabled'

 

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