Once logged in, the layer will render several different features; a banner in the top left corner showing session information, a layer of green rectangles over the earth showing server terrain coverage (each tile is 1 degree latitude/longitude) and an orange button in the centre of the screen. The orange button appears after the view has changed and settled and will only appear once the view has focused and zoomed into a country as opposed to a continent.
To perform a calculation, click the orange button.
There are two modes of operation for the interface: Basic or Advanced to cater for tactical radio users and strategic radio engineers alike. Novice and new users should start in Basic mode which enables only three of the six input tabs. Experienced users should select the Advanced option to enable all tabs and features.
The geographic location used for the calculation will be the centre of the screen view. The co-ordinates can be manually edited within the second ‘Transmitter’ tab.
Keep your Google earth view looking straight down to keep the button in the middle.
The first tab contains the most important values and the calculate button which is used to perform the calculation.
Save your settings as a template by clicking the star icon
The second tab contains geographic and units information including the transmitter’s location, heights for the transmitter and receiver (above ground level) and distance units.
The metres or feet toggle will change distance units for heights, clutter and radius
The third tab contains advanced settings related to antenna radiation patterns. It allows a choice between pre-made 3D templates or a custom 3D pattern based upon user supplied values. For both methods, there will be two adjacent images shown which depict the horizontal (bird’s eye view) and vertical (side on) radiation patterns. Most users should find a template to suit their needs and will only need to rotate the antenna by defining the ‘direction’ (degrees from north) field.
Novice users should select ‘Dipole.ant’ (Omni-directional)
Save your pattern by downloading the .ant file in the middle
ERP = Transmitter Power * Feedline Loss * Antenna GainThis value, once changed is automatically set on the first ‘Calculate’ tab as well.
The fourth tab contains advanced settings relating to the receiver(s) settings. An incorrect value here can result in unrealistic output.
|Irregular Terrain model (ITM)||20-20,000MHz||US NTIA general purpose model used by the FCC|
|Line of Sight (LOS)||All||Line of sight model used to determine existence of obstacles.|
|Okumura Hata (Urban)||150-1500MHz||Cellular model optimised for urban areas where transmitter is >30m AGL.|
|ECC33||150-3500MHz||ECC33 model for cellular and microwave communications|
|SUI (WiMax)||1900-11,000MHz||Stanford University Interim for WIMAX|
|COST231-Hata (Urban)||1500-2000MHz||European GSM1800 and CDMA2000 cellular model optimised for urban areas where transmitter is >30m AGL.|
|Free space path loss||20-100,000MHz||ITU-R P.525 model which assumes no terrain obstacles exist in the path.|
|Irregular Terrain model with obstructions (ITWOM)||20-20,000MHz||Debatable enhancement to ITM model with increased loss|
|Ericsson cellular||150-11,000MHz||Ericsson model for cellular communications up to 11GHz|
The ITM model is an advanced general purpose model ideal for most users
|Path Loss||dB||Ignores RF power. Used for showing terrain loss|
|Received power||dBm||Shows received signal based on all options|
|Field Strength||dBuV/m||Shows electric field strength based on all options|
|Bit Error Rate||BER (%)||Digital comms. Converts to a dBm value by looking up modulation mode and SNR.|
The Bit Error Rate (BER) mode will reveal two hidden input values for modulation and noise floor
|QPSK||Works with low SNR|
|32PSK||Requires highest SNR|
The receiver sensitivity is very important and must be set carefully to create accurate output, Use -80dBm if you are not sure
1 Watt repeater with -125dBm receiver sensitivity
Same site with -75dBm receiver sensitivity
The fifth tab lists advanced options for defining man made obstacles (clutter) and ground conductivity. The features here will help advanced users achieve the most realistic coverage plot for an area, especially in suburban or extreme climatic environments.
|Personal||Only my clutter items|
|All||Everyone's clutter items|
If your system's antenna is low or at ground level (Groundwave propagation), the terrain type will greatly affect signal attenuation
If your system's antenna is high above the ground (Spacewave propagation), the radio climate will affect signal attenuation
|Maritime temperate (Land)|
|Maritime temperate (Sea)|
The sixth tab’s options do not affect actual propagation results with the slight exception of resolution which changes the granularity of the output. They determine formatting of results after calculation.
Speed up your calculations by selecting a lower resolution
The Path Profile Analysis (PPA) feature allows a point to point (P2P) study from the transmitter (Tx) which generates a 2D profile graph and text report highlighting obstructions. To use the PPA feature select a radio coverage layer and then focus the viewer on to a point within the coverage area where you would like to have a receiver (Rx). Expand the layer’s components within the left hand layer tree to reveal the ‘Path Profile Analysis’ network link, select it and press Ctrl-R to run a PPA. (Alternatively, right click the layer then select ‘refresh’)
After a brief delay, a signal strength icon will appear on the map centred on the centre of view with a value representing the signal strength. Click this icon to view the report and 2D graph with Fresnel zones.