CloudRF

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inputs


Once logged in you will be presented with a large map and collapsible input form. All input variables are entered into the form by expanding the relevant section and entering either a value or choosing from an option.
Beneath the side-form are two buttons: SAVE will store your settings as a template so you can recover them quickly in the future and CALCULATE will perform a calculation using those settings and present the output on the map.
Beneath the map are function buttons which provide access to additional features.
To the right of the map is a colour key which represents received signal strength in either dB, dBm or dBuV/m.

Click on the map to place your transmitter

MAPPING

The system uses OSM based web mapping offering high accuracy street mapping and satellite imagery for the entire world. To flip between the layers, click the layers icon in the top right. You can also manage radio layers on the map from here.


You can navigate the map by clicking and dragging then zoom using either your mouse rollerball or the controls in the top left.

The map uses EPSG 3857 (Spherical mercator) projection which layers are re-projected to for total accuracy

TRANSMITTER

The first panel contains the most important values needed for any calculation:

Template search

The template search will let you search for saved sites/templates previously created using the ‘Save’ button beneath the panels. Type in at least 3 characters to search your templates. Click a search result and the saved settings will automatically populate the relevant fields within the form, including geo-location which can be updated by clicking within the map. To save a site/template, click the SAVE button. For more on sites/templates, see the data section.

Name

The name is the memorable label for the calculation and will be visible in the archive in the future. Default is just 'Tx'.

Save your settings by clicking the SAVE button

Network

The network is a logical grouping of calculations which is critical to the functionality of the best server and mesh APIs as well as the network filter function on the archive. Another way to think of the network tag is like a project. If you need to group your work under a common project so it can be isolated or recovered quickly later then this is a useful way of doing that.

If you plan to use the best server API then getting this field right is essential.

Frequency

Enter the channel frequency of the radio system in megahertz (MHz). Acceptable values are 20 to 100,000MHz (100GHz) with 3 decimal places accuracy eg. 446.025.

Power

Enter the transmitter power (RF) of the radio system in Watts. Advanced users can enter the antenna gain (dBi) to calculate the total effective radiated power (ERP) within the ANTENNA section (#3). Maximum power value is 5MW (5,000,000W). Minimum value is 10mW (0.01).

To calculate the total effective radiated power (ERP), enter the antenna gain within the ANTENNA section

Radius

Enter the maximum distance in either kilometres or miles for the coverage plot. This should be no more than the range of the most distant station. To change distance units, click metres or feet within the LOCATION tab. The maximum value possible is determined by your plan type with a maximum of 300km.

For a GSM cell tower use 30km radius

LOCATION

The second section contains geographic information including the transmitter’s location, heights for the transmitter (above ground level) and distance units.

There are three available co-ordinates formats: Decimal degrees, Degrees-minutes-seconds and NATO Military Grid Reference System (MGRS). Select a format and then click in the map to have the location automatically update.

You can override the values with a custom location or click the Google earth icon to synchronise the location with Google earth (requires Google earth sync layer from bottom left menu to be open first).

The update mode can be further controlled by disabling the orange icon in the middle of the screen making it manual entry only. Click the orange icon next to the longitude box to disable it.

Height above ground

Enter the height of the transmitting antenna above the ground. If your antenna is 4 metres above ground which is 100 metres above sea level, the height will be 4m.

Distance units

The metres or feet toggle will also change distance units for all other distance measurements within the form including radius, receiver and clutter height(s).

The metres or feet toggle will change distance units for heights, clutter and radius

ANTENNA

Keyhole Radio Google earth
The third section contains advanced settings related to antenna radiation patterns. It allows a choice between pre-made templates or a custom 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. For more on antenna patterns see the
antenna patterns section.



Novice users should select the default DIPOLE.ANT (Omni-directional monopole)

Custom

The custom option allows users to create a pattern on the fly by defining key fields (Azimuth, down-tilt, horizontal beamwidth, vertical beamwidth, forward gain and front-to-back ratio). As values are changed within these fields, the pattern will automatically update. You can download the pattern in ant format via the hyperlink underneath the images.

Save your pattern by downloading the .ant file beneath the image

Polarisation

Antenna polarisation (US: polarization) describes the physical orientation of the antenna relative to the ground. Most broadcast and handheld systems are vertical, whilst some data systems are horizontal to reduce (vertical) interference. The default is vertical.

Direction

The horizontal angle (azimuth) the antenna is pointing referenced to grid north. Values of 0-360 are allowed. Not to be confused with beamwidth.

Down tilt

The down-tilt is the vertical angle the antenna is pointing relative to the horizon. Acceptable values are -10 to (+)90 degrees where angles above the horizon (pointing up) are negative and angles toward the earth (pointing down) are positive. A directional antenna parallel to the ground would be 0 degrees. This value is used typically when a directional antenna on top of a hill is pointing down toward low ground. It would have a positive downtilt. A similar antenna down in a valley would have a negative downtilt as it would be looking up the hill. Default is zero (no tilt).

Horizontal Beamwidth

This describes the angle in degrees between the two half power (-3dB) points of a directional antenna in the horizontal plane. For example, a directional ‘one third’ panel on a GSM cell tower would have a beamwidth of 120 degrees. This setting can only be applied in ‘custom’ pattern mode.

Vertical Beamwidth

This describes the angle in degrees between the two half power (-3dB) points of a directional antenna in the vertical plane. For example, the previously mentioned 120 degree (horizontal beamwidth) GSM panel may have a smaller vertical beamwidth of only 30 or 45 degrees, otherwise it will be wasting energy radiating the sky above it. This setting can only be applied in ‘custom’ pattern mode.

Gain

The directional gain of an antenna measured in dBi (or occasionally dBd). For CloudRF, This is a numerical value between 0 and 50. For 1:1 gain (no additional power) then a default figure of 2.14dBi should be used. A high gain antenna would be greater than 3dBi. Adjusting this will result in an automatic adjustment to the ERP value on both the antenna tab and the initial ‘calculate’ tab.

You can manipulate the gain value to accomodate other gains and losses in your system. For example, a system with 9dB antenna gain and 3dB line loss could be said to have a positive gain of 6dB.

Front to back ratio

This ratio measured in dB relates to the difference in power between the front and the back of the antenna. A value of 3dB would mean the antenna was twice as powerful to the front as to the rear. This defaults to twice the forward gain so a 5dBi antenna would have a 10dB FBR. Maximum value is 70dB.

ERP

Effective Radiated Power (ERP) is the total RF output of a system and is automatically calculated using the following formula. Other losses (eg. feedline) can be factored in to the link budget by removing them from the antenna gain value at either end.

ERP = Transmitter Power - Feedline Loss + Antenna Gain

Example: 25dBm ERP = 20dBm Tx RF - 3dB feedline loss + 8dBi antenna gain.
This value is for information only. To change it, edit either the Power on section one or the antenna gain.

RECEIVERS

The fourth section contains advanced settings relating to the receiver(s) settings. An incorrect value here can result in unrealistic output.

Height(s) Above Ground Level

As per the transmitter height, this value is measured above the ground so a 4m antenna that is 100m above sea level will be 4m AGL. Distance units are defined within the LOCATION section. For a man holding a hand-held radio or phone, set this to 2 metres.

Receiver (Rx) gain

Much like the transmitting (Tx) antenna gain, the receiver gain is a ratio of directional gain measured in decibels relative to an isotropic radiator (dBi). The default value is 2.14dBi. A high gain 5.8GHz dish would be about 16dBi. This value will be added to the Tx gain on the server to produce a total link gain. Losses can be deducted directly from these values so with Tx 10dBi, Rx 10dBi and 3dB losses the server would use a value of 17dB gain.

Units of measurement

The output units determine how to represent the propagation. 'Path loss' will ignore the Power output (ERP) and depict the path loss caused by the terrain. Handy for identifying high loss black-spots in the terrain.
'Received Power' dBm (decibel milliwatt) will factor in all variables and depict the radio coverage. This is the most common value often called Received Signal Strength Indicator (RSSI).
'Field strength' dBuV/m (Decibel microvolts per metre) will show the electrical field strength present in the ground.
ModeUnitsDescription
Path LossdBIgnores RF power. Used for showing terrain loss
Received powerdBmShows received signal based on all options
Field StrengthdBuV/mShows electric field strength based on all options
Bit Error RateBER (%)Digital comms. 50% = 0.01, 60% = 0.001, 70% = 1E-4, 80% = 1E-5, 100% = 1E-6.

The Bit Error Rate (BER) mode will reveal a hidden input value for modulation / Signal to Noise Ratio (SNR). The noise floor is fixed at -114dBm for a 1MHz wide signal.

Modulation (BER mode only)


Different modulation modes have different error rates at a given signal to noise ratio (SNR). To calculate the SNR, the mode and noise floor must be selected.
ModeDescription
QPSK11dB
4PAM14dB
16PSK18dB
64QAM18dB
32PSK24dB

Propagation model

This drop down selection allows the planning algorithm to be selected. There are different models optimised for different parts of the radio spectrum and geographic scenarios. For example the free space path loss model is well suited to a SHF point to point microwave link where there are no terrain obstacles whilst the Hata urban model is especially designed for UHF cellular planning in urban areas where tall buildings are present. Picking the right model will enhance accuracy. Picking the wrong one will deliver inaccurate results. If in doubt, choose the ‘Irregular Terrain Model’.
ModelFrequencyDescription
Irregular Terrain model (ITM)20-20,000MHzUS 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)150-1500MHzCellular model optimised for urban areas where transmitter is >30m AGL.
ECC33700-3500MHzECC33 model for cellular and microwave communications
SUI (WiMax)1.9-11GHzStanford University Interim for WIMAX
COST231-Hata (Urban)1500-2000MHzEuropean GSM1800 and CDMA2000 cellular model optimised for urban areas where transmitter is >30m AGL.
Free space path loss20-100,000MHzITU-R P.525 model which assumes no terrain obstacles exist in the path.
Irregular Terrain model with obstructions (ITWOM)20-20,000MHzClaims to be an enhancement to ITM model with increased diffraction logic but has been found to be unreliable above UHF.
Ericsson 9999150-1900MHzEricsson model for cellular communications up to 1900MHz
Egli VHF/UHF30-1000MHzGeneral purpose VHF/UHF model. More conservative than FSPL

The ITM model is an advanced general purpose model ideal for most users and comes with knife edge diffraction built in.

Next to the model selection is a fine tune option which offers either a reliability percentage level (for the ITM model) or discrete variances based on environment. An urban variant is much more conservative than a rural/open variant.
The reliability (time and situations) is represented as a percentage so the model can be tuned to be compliant with TSB-10 (Revision F) standards for microwave communications which defines a reliability of 80% for a long term loss and 99% for a short term loss. The default value is 80%.

Knife edge diffraction

Where a terrain obstacle like a hill is present, diffraction and shadowing will occur on the far side of it. Not all the propagation models factor this in by default so you can manually enable this effect. This option is not necessary for the default Irregular Terrain model where it is a core feature. The diffraction algorithm used is a custom linear model which uses the obstacle’s height, distance and angle from transmitter to determine the resultant diffraction impact.

Receiver sensitivity

The coloured key and selected value changes according to the measurement units selected above it. For all units, a strong signal is to the left (yellow) and a weak signal is to the right (blue). An optimistic result can be achieved by setting the slider to -120dBm whilst in 'received power' mode. A strong signal limit of -75dBm would provide a more pessimistic result and can be increased further to simulate losses associated with urban environments where ground clutter is not available to simulate concrete screening and absorption. If you do not know your receiver sensitivity then -80dBm is a good limit. If you want to factor in a fade margin eg +15dB then just add it to receiver sensitivity so -90dBm plus fade becomes -75dBm.

1 Watt handheld PMR with -70dBm receiver sensitivity

Same with unrealistic -120dBm receiver sensitivity

The receiver sensitivity is very important and must be set carefully to create accurate output, Use -80dBm if you are not sure

ENVIRONMENT

The fifth section 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.

Random clutter (height above ground)

Wide area obstacles can be rapidly simulated using the slider, up to 50 metres (150 ft) high. This will artificially increase the ground height around the site to simulate a layer of buildings above ground level.
The width of each clutter item is determined by the output resolution. For the default resolution of 1200 pixels per degree this is 90m wide.

Point clutter

A much more precise simulation of man-made buildings can be done by uploading an overlay of points to mark building locations via the database button to the right. If you choose to have this enabled then your buildings will be factored in to future calculations, otherwise they will be ignored.
This overlay should be a KML overlay containing either placemarks, polygon corners, line points with heights in metres defined in the point properties.

A quick way to define a row of wind turbines is to use Google earth's 'path' feature and click once per turbine then set the path’s altitude to 30 metres in Google earth (Relative to ground). Save off the path as a .kml file and upload it using the 'Upload a KML' link.
A single click will create a 90mx90m wide building. To define a larger building, click each corner or use the polygon feature.

Landcover clutter

To enhance the underlying digital terrain with ground clutter like trees and buildings you can enable landcover. This MODIS product has an accuracy of 0.083 degrees (~850m) so will define the presence of an urban neighbourhood but not a street for an example. For building level accuracy see LIDAR.

Terrain conductivity

The conductivity option allows you to compensate for different environments using a dielectric value which describes electrical conductivity through the ground. A city has very poor conductivity whilst a wet marsh has very high conductivity. This is relevant for radio systems which operate at ground level such as hand held radio.

If your antenna is at ground level (Ground wave propagation), the terrain type will greatly affect signal attenuation

GroundDielectric constantAttenuation
Water80Very low
Good ground25Low
Farmland, Forest15Average
Mountain, Sand13Higher
City5High

Radio Climate

The radio climate slider allows you to compensate for different environments using a climate code which affects propagation through space. This is relevant for radio systems which operate high up such as over the horizon microwave links.

If your system's antenna is high up above the ground (Space wave propagation), the radio climate will affect signal attenuation

Radio climate
Equatorial
Continental subtropical
Maritime subtropical
Desert
Continental temperate
Maritime temperate (Land)
Maritime temperate (Sea)

OUTPUT

The final section's options do not affect propagation results although in the case of resolution they do alter the granularity. They only determine the cosmetic formatting of results after calculation.

Terrain data

The system has two primary sources of terrain data: SRTM and LIDAR. SRTM dates from 2000 and has global coverage at 90m and the USA at 30m. These are 1200 and 3600 pixels per degree respectively. Resolution increases towards northern latitudes due to the way lines of longitude converge and SRTM tiles are bounded by degrees. A lower resolution of 180m / 600 pixels is available for broadcasters performing regional studies. Calculation time is affected significantly by the resolution. LIDAR data is very high resolution 3D data usually sourced with lasers and for CloudRF is accurate down to 1m. Coverage exists for select locations within the system (England is covered at 2m, New York and San Francisco at 1m...). When selected, a selection list of loaded tiles will be shown but this is cosmetic only. Selecting the LIDAR button with your cursor over a target area will cause a tile overlay to be rendered if one exists. If you attempt a LIDAR plot without a tile you will receive an error message.

Colour schema

The colour schema of the output file can be set here. The default schema 'Cellular' has 5 bands representing 5 bars on a mobile phone. For single colours like ‘Reds’ a range of dark and light reds will be used to denote strong and weak signals. A key is supplied with each layer for reference. Custom RGB schemas exist whereby you can define the limits for each colour. Alternatively you can use automatic colour assignment based upon frequency.
The number in brackets is the number of colours in that scheme.

inputs.txt · Last modified: 2017/05/06 20:09 by alex