Best Cell Tower

7/29/2019 Best Cell Tower

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Finding the Best Cell Tower for your Antenna

If you need to use an external antenna on your Rocket Hub or Rocket Stick you

must know where to aim it in order to get the best reception. External antennas,

such as a yagi, are quite directional and need to be aimed correctly to get good

performance. To do this, you need to know the location of the cell towers in your

surrounding area and which direction their antennas point. If the antennas of a

close-by cell tower points away from you it is not a good choice to aim towards.

In this document we will learn how to get our locations longitude and latitude,

use this to determine what cell towers are in our area and then map information

about each tower onto a graphic. From this we can discover which towers are

best for our needs.

Step 1 Getting your location

In order to figure out which tower you must aim toward, we must have the

latitude and longitude of your location. To gather this information go to the web

site at http://itouchmap.com/latlong.html and enter your street address, city and

province into the address box. Your latitude and longitude, in the required format

will appear at the bottom of the page.


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For my location the latitude is 49 deg 4 min 33 sec and the longitude is 122 deg 6

min 34 sec. To use this information later we must put it in the format of DDMMSSfor latitude and DDDMMSS for longitude. For this location, then, the values are

Latitude 490433

Longitude 1220634


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We will use this location data next to gather information about cell towers in our

area.

Step 2 Get Information on the Towers in Our Area

Once we have our location data, we can gather information about the cell towers

in our area. The government maintains a database on every radio tower in

Canada and this includes all cell towers. To search this database, go to the web

site at http://sd.ic.gc.ca/pls/engdoc_anon/web_search.geographical_inputand fill

out the required fields and check the necessary boxes. The following pictures

shows which fields must be filled in and which boxes are to be marked to obtain

the desired data.

In this part we enter the Latitude and Longitude in the format we created earlier.

The Search Radius can be expanded if the towers in your area are farther away

than 10 km. A larger radius will show more towers in the database search list.


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Check off the boxes as shown in the picture above to get data about the towers

antennas. We are only interested in the transmission part of each antenna, since

the receiving antenna is very similar.

When all the required boxes are checked, click on the Find button. You will then

be shown a web page containing the results of the database search. Keep this

information handy, as we will be using it later. You can copy the table from the

web page and paste it into a Word document, if desired, giving something that

looks like this :

Search Results

Tx

Frequenc

y (MHz)

Rx

Frequenc

y (MHz)

Station

Location

Tx

Antenna

Polarizati

on Code

Tx

Antenn

a

Azimut

h (deg)

Azimut

h (deg)

Distan

ce

(km)

Licensee

Name

TxAnten

na

Model

Numbe

r

869.0000

00

824.0000

00

W0561-CHILLIWAC

K BC

FOREST

SERVICE

B 335.0 96.73 6.03

Rogers

Communicati

onsPartnership

7750-

00_ME

869.0000

00

824.0000

00

W0561-CHILLIWAC

K BCFOREST

SERVICE

B 335.0 96.73 6.03

RogersCommunicati

ons

Partnership

SRL-

410C5-

869.000000

824.000000

W1987-

ABBOTSFORD BC 47.47

M SOUTH O

B 30.0 252.48 8.60

Rogers

Communications

Partnership

KRE-101-20

Since Rogers uses both the 850 mhz and 1900 mhz bands for cell phones we may

find the same Station Location for each band. Generally the data is the same for

both frequencies so we will work with the 850 mhz antennas only.


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Step 3 Show a Map of the Cell Towers

Next, we must get a map of the cell towers in our area. Go to the web site

http://loxcel.com/celltower and enter your city or town name in the Enter a

Location box. Change the carriers box to Rogers to see only Rogers towers.

This will zoom the map to our area. Scroll around to get to your specific location

and zoom in until you can see the towers in the Search Radius you used in Step 2

above. Rogers towers show up as green dots on the map. In this case, there are 5

Rogers towers in the area around my location.


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Click your mouse on a dot and information about the tower will pop up in a

balloon box.

We are interested in the Rogers code for each tower, in this case W5121. We can

use this to reference the Search Database results and get information about the

tower. Gather the codes for all towers in your area. In my case the codes are

W5121, W5172, W1987, W0561 and W2745.

The next step will be to plot the direction of the antennas on each tower to see if

they point towards us. We must first copy our Cell Tower Map from our browser

to our favorite graphics program. To copy the Cell Tower Map to the Clipboard in

Windows press Alt-Print Scrn and then paste it into the graphics program.

Step 4 Plotting the Tower Data

Using the tower codes gathered in Step 3 we can reference the Search Database

results and plot the direction of each antenna on each tower. Search through the

results to find the tower code in the Station Location column. You may find the

same tower code in multiple rows. This indicates that the tower has multiple

antennas that may point in different directions. For example, the tower code

W5121 appears in 3 rows in the database.


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Tx

Frequenc

y (MHz)

Rx

Frequenc

y (MHz)

Station

Location

Tx

Antenna

Polarizati

on Code

Tx

Antenn

a

Azimut

h (deg)

Azimut

h (deg)

Distan

ce

(km)

Licensee

Name

Tx

Anten

na

Model

Numbe

r

869.0000

00

824.0000

00

W5121-

ABBOTSFO

RD BC 4304DIXON

ROAD

B 30.0 301.89 1.29

RogersCommunicati

ons

Partnership

KRE-

101-20

869.0000

00

824.0000

00

W5121-

ABBOTSFORD BC 4304

DIXON

ROAD

B 100.0 301.89 1.29

Rogers

Communicati

onsPartnership

KRE-

101-20

869.000000

824.000000

W5121-ABBOTSFO

RD BC 4304

DIXONROAD

B 230.0 301.89 1.29

Rogers

Communications

Partnership

KRE-101-20

From the Tx and Rx Frequency columns we can see these are 850 mhz antennas.

You will also notice that the Tx Antenna Azimuth (deg) column value is different

for each antenna one is 30, the second is 100 and the last is 230. This tells us

that each antenna points in a different direction.

Azimuth is a direction where North is 0, East is 90, South is 180 and West is 270

degrees. Therefore, an antenna with an azimuth of 30 degrees points in the

direction 30 degrees East of North.

By drawing a line at the correct angle from the cell tower location on our Cell

Tower Map graphic we can immediately see if that antenna points in our

direction.


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The easiest way to get the direction onto the map graphic is to use a Screen

Protractor. A Screen Protractor is a small program you run that displays a movable

transparent protractor on the screen. You can line it up over each cell tower dot

and move the angle line to each azimuth value. This shows the antenna direction

precisely. I use the free MB Ruler program that can be found at

http://www.markus-bader.de/MB-Ruler/index.htm. This is a versatile program

that works well for this job, once the settings are changed from default.

Download and install this program and, once it is running, right click on the grey

center circle and choose Options. In the Generaltab move the Size slider to a

desired size. In the Distance&Angle tab set theAngle Measure Direction to

clockwise and theAngle Origin to middle.

Bring up the map on the screen and move the MB Ruler so the center of the

bottom line is on the tower dot. The ruler is moved by putting the cursor over the

center of the bottom, holding the left mouse button down and dragging the

protractor.

With the protractor in place, move the mouse so the bottom value in the grey

circle is at the desired azimuth angle. The red line is the direction of the antenna.

In your graphics program, the protractor does not interfere with any drawing

tools so I use the line drawing tool to draw a line at the exact azimuth angle.

Repeat this for the azimuth on every antenna in your area. This only needs to be

done for the 850 mhz antennas, as the 1900 mhz antennas will use the same

azimuth.


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To close the MB Ruler, right click on the grey center circle and click on Close.

At this point you can immediately see which towers have an antenna that points

in your direction. In my case the map looks like this


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My location is the black outlined blue box near the top of the graphic.

It is obvious which tower is the best choice for me, W5121. It is the only tower

which is pointing in my direction and it is close.

From the Database results, if we look at the Distance (km) column, we can see

how far away from my location this tower is 1.29 km.

And the Azimuth (deg) column tells me what direction I should point my antenna

to aim directly at the tower 301 degrees or 59 degrees West of North.

The polarization of the antenna is specified by the Tx Antenna Polarization

Code column. If the entry is an A my antenna must sit horizontal and if it is B my

antenna sits vertical. An antenna sitting horizontal has the elements parallel to the

ground. A vertical polarization has the elements straight up and down.

Step 4 More Data Plotting

Even if you dont have an antenna pointing directly at you, you can still receive a

good signal from a tower. Directional cell tower antennas dont put out their

signal in a narrow line but rather in a wedge shape, with the point of the wedge at

the tower. The angle of the wedge is called the Beamwidth and is given in

degrees.


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In the above graphic the red line is the azimuth or direction of the antenna. The

blue lines are 32.5 degrees away from the azimuth line, giving the antenna aBeamwidth of 65 degrees. The power of the antennas signal decreases as you

move from the red line to the blue lines, with it decreasing by half at the blue line.

This corresponds to a signal decrease of 1 bar on a cell phone or modem. As you

move farther away from the blue line the signal decreases even more until, at

some point, it drops too low to be usable.

If your location is inside the wedge defined by the blue lines, you will receive a

good signal from the tower and, if you are located close but outside the blue

lines, you will receive an adequate signal.

So, we now need to obtain the Beamwidth of each antenna and place that

information on our map. Unfortunately, the database does not contain the

Beamwidth of the antenna. However, it does contain the model of the antenna

and, with some research we can find the Beamwidth of the model. The antenna

model is found in the Tx Antenna Model Number column.

The following table lists the Beamwidth of some of the commonly used cell towerantennas.

Antenna Model Beamwidth in Degrees

Powerwave 7750 65


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Powerwave 7482 90

PowerWave 7721 65

Ericsson KRE 101-xx 65

Amphenol PCSX065-13 65

Andrew RR33-20-00 33

Amphenol X65-20-AAA 65

Amphenol BCD-80010 360

Taking the values from the above table, we can use MB Ruler to draw lines

representing each antennas Beamwidth onto our map graphic.

As you can see, even though W5172 doesnt point particularly close to me, I am

still within its Beamwidth. This tower would give an adequate signal in the

absence of any other option.

I am outside of the Beamwidth of W0561 by about 15 degrees so, while I may

receive a signal, it will not be of a good power level. This is born out in real life, as


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I can get a medium power signal from this tower. If there were no other towers in

the area it would be a viable option.

Checking the Terrain

Using Google Earth, in conjunction with the data we have already acquired, we

can see what the terrain is like between our modem location and the cell tower. If

you dont have Google Earth (not the Google Earth Plug-in) installed go to

http://www.google.com/earth/index.html

and download and install it. If you wish to have the measurements on the map in

metric, when you run Google Earth, go to Tools->Options->3d View and change

the Units of Measurement to Meters, Kilometers.

When you run Google Earth you are presented with a Search Box.


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Enter your address in the box and press Search. The map will zoom to your

location.

On the tool bar above the map click on the Push Pin button.

A popup box will appear and a flashing box will appear around your location.

Enter a name in the Name box to identify this as your home location. I used the

name FarmHome. Then press the OK button.


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Next, we need to go back to the cell tower database and gather information onthe location of the towers of interest to us. Specifically, we need the latitude and

longitude of each tower.

As before, go to the web site at

http://sd.ic.gc.ca/pls/engdoc_anon/web_search.geographical_inputand fill out


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the required fields and check the necessary boxes. In addition to those we used

before we must check the latitude and longitude boxes for the towers.

Press the Find button and get the new data. We end up with this new information

Tower Code Latitude Longitude

W0561 490410 1220138

W1987 490309 1221319

W5172 490202 1221315

We have to convert this to degrees, minutes and seconds for Google Earth. This

then becomes

W0561 49 deg 4 10 lat and 122 deg 1 38 long



Next we go back to Google Earth and press the Push Pin button in the tool bar

above the map.


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This will cause a popup box to appear once again.

Enter the name of one of the cell towers in the name box and change the Latitude

and Longitude data to the correct values for that tower.


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Be careful not to add any extra spaces in the latitude and longitude boxes. Itwont work if you do. Then press OK.


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A new location will appear on the map. Repeat these steps for all the desired

towers in your area. You may have to zoom out the map to see all of them. Make

sure you do this as you must see the towers on the map for the next step.

Next we will draw a path between our location and each of the towers. Click onthe Path button on the tool bar above the map.

A popup box will appear. Move it so you can see both your location and the tower

you are drawing the path to. Enter a name for this path in the Name box.

While this popup is still open (dont press OK just yet) take the mouse cursor (now

a crosshair box) and click once on your location and once on the tower location. A


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line will appear between the two locations. Now press OK in the popup box. You

have created a Path between your location and the tower. Repeat this for all the

towers.

To get a profile of our terrain, place the cursor over one of the paths and right

click. A popup menu will appear.


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Select Show Elevation Profile. The profile of the terrain will appear at the bottom

of the map.

Moving the cursor over the profile will give information on the altitude and slope

at that point. A red arrow will follow along the path to show where you are on the

map. Your home location is to the left of the profile.

From this terrain profile you may be able to see if you have a clear line of sight to

the tower. If it is not obvious if you have line of sight or what height the antenna

must be, a bit more analysis is in order.

Use Alt-Print Scrn to copy the map as an image to the clipboard. Paste it into your

graphic program and save as an image file.

Once again we need to go back to the cell tower database and get information on

the height of the towers. As before, go to the web site athttp://sd.ic.gc.ca/pls/engdoc_anon/web_search.geographical_inputand fill out

the required fields and check the necessary boxes. In addition to those we used

before we must check the Tx Antenna Height Above Ground Level (m) box in the

Tx Information section.

Press the Find button and get the new data. We end up with this new information


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Tower Code Height in Meters

W0561 26

W1987 30

W5172 30

We will be looking at tower W5172 to see if we have line of sight.

Return to your terrain profile image in your graphic program and measure the

scale of the image.

In my case, the distance between the 10 m line and the 15 m line was 44 pixels.

Therefore, 5 m = 44 pixels or 1 m = 44/5 = 8.8 pixels. The tower is 30 m in heightso the tower would be 30 * 8.8 = 264 pixels high. Now draw a 264 pixels line up

from the tower location on the right side of the profile.


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By drawing a line from the top of the tower line to our home location on the left

we can see how high our antenna must be to clear the intervening terrain.

From this we can see that our antenna can see the tower from practically any

height. No terrain interferes with the line of sight. Repeat this for all towers to

find what antenna height is needed to give line of sight to the tower.

Conclusion

By gathering information about the cell towers in our area we can figure out

which tower we should be pointing our antenna towards. The closer we are to the

Beamwidth area of the antenna, the better the signal we can receive.

Other factors come in to play as well. Terrain can play a major role in which

towers we can use, as some may be blocked by hills. Trees and buildings can block

a signal and can disqualify a tower from consideration.

Signals also can be reflected off terrain and can arrive at our location from

different directions. If you cannot get a good signal pointing directly at the tower,

due to obstacles, you may get it from a reflection in a different direction. Antenna

testing is required in this case.

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