Antenna Bearing Tool Help

[Nov 2016]

 

Antenna Bearing Tool [ABT] is an alternative to a magnetic compass for antenna installers to determine the required compass bearing. ABT uses known landmarks as a reference bearing and the “offset” is calculated.

ABT has two modes:

1. Cellular mode for “Base station Transmitter Sites”. [BTS]

2. Point to Point mode for microwave systems. 

The land mark in either case must be visible and identifiable.

NOTE: [BTS = Cell Phone Tower]

 

There are a many reasons for using this method in preference to using a compass:

1.      Antenna bearings are usually referenced to True North and it is a common mistake to apply the correction for a magnetic bearing in the wrong direction, therefore doubling the offset.

2.      In many cases steel work or electric power sources affect the compass.

 

BTS MODE:

The principle of use is simple:

1.      The Icon for the BTS   is located on the map at the transmitting site. 

2.      The Icon for the Land Mark  is located on the map at the land mark.

3.      The desired antenna bearing [degrees true] is entered via the pop-up keyboard. [Tap the text to activate the keyboard entry]

4.      The two lines on the map show the line to the land mark [RED] and the desired antenna bearing.

You can then point the Red line towards the land mark and aim the antenna along the Green line.  Alternatively the Offset can be read from the screen and a protractor/theodolite used in place of the phone.

 

BTS Icon Location:

The BTS Icon can be located on the map in three ways:

1.      Touch/hold/drag the icon to position

2.      Enter the Latitude and Longitude to the display via the keyboard.  [Tap the text to activate the keyboard entry]

3.      Press and Hold the “BTS Here” button.  The icon will move to your current location if you have GPS lock.

 

Land Mark Icon Location:

The Land Mark Icon can be located on the map in two ways:

1.      Touch/hold/drag the icon to position

2.      Enter the Latitude and Longitude to the display via the keyboard.  [Tap the text to activate the keyboard entry]

 

Map Control

1.      The map centre can be moved by dragging, zoom is controlled by two finger pinch.

2.      Click the “Map Type” button.  The map will toggle between Road Map and Satellite views.

3.      Click the “Auto Zoom” button.  The map will move and centre to show the icons.

 

Save

The “Save” button will save the screen as a Portable Networks Graphic [png] file.  The user enters a file name without the .png extension

 

Files

The “Files” button allows the user to view and delete saved files.

 

 

POINT to POINT MODE:

Point to Point mode operates in basically the same way as Cellular mode except that there are three icons: “A” end, “B” end and Landmark.

The offset is calculated from the “A” end to “B” end bearing line.  Path distance and “A” to “B” bearing are also calculated.

Path distance can be displayed in either kilometre or miles.  The units [Km/Mls] can be toggled by clicking on “PATH DIST”.

 

 

SUNDIAL:

The Sun Dial function is a “Last Resort” option when operating in an environment with no identifiable land marks. [Deserts, snowfields]

This function is turned on/off with the Sun Dial button at the bottom left corner of the map.  A sun symbol, a shadow line are displayed and the map is  rotated.  With the device in the horizontal the sun symbol is pointed towards the sun [as a land mark] and the antenna bearing line is aligned correctly.

Alignment with the sun can be eased by placing a small object [inverted golf tee, pencil stub, etc.] to act as a gnomon.

NOTE1: This method ceases to be valid at less than 24degrees from the equator, this function will not work at these latitudes.

NOTE2: This method may be useful if orienteering through mountains in iron ore country.

 

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