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Global Position Timing

The Cell Site A Brief Overview

Overview Developed by Ted J. Pappas

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Global Positing Timing Satellite Timing

Timing and synchronization is so important

to the current Macro cell technologies that

without it a Service Provider Client would

be unable to process a mobile call and

hand-off from site to site.

The time and alignment delta between macro cell sites is

better than 1 millisecond (1 thousandth of a second)

alignment and it becomes more like 1 millionth of a second

precision when you include Small Cell.

Ted J. Pappas

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The GPS Signal The GPS signals are actually two (2) carriers. The L1 carrier is 1575.42 MHz and carries both the status message and a pseudo-random code for timing. The L2 carrier is 1227.60 MHz and is used for the more precise military pseudo- random code.

The actual signal is so complicated that it almost looks like random electrical noise. Hence the name "Pseudo-Random."

There are several good reasons for that complexity: First, the complex pattern helps make sure that the receiver doesn't accidentally sync up to some other signal. The patterns are so complex that it's highly unlikely that a stray signal will have exactly the same shape.

Ted J. Pappas

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The GPS Antenna and Cable

The GPS antenna has a high-gain (26

dB) Low Noise Amplifier built in.

There are distance limitations on

cable length (distance based upon

cable type) that may require offset

calculations to be provided to the

Mobile Switching Center or entered

into the local “integration” software at

the cell site

Ted J. Pappas

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GPS Antenna Placement The need for correct GPS Antenna placement has NEVER been more important

Unlike a TV Satellite Antenna who receives

its signal from a single direction the GPS

Antenna receives multiple signals from

multiple directions

The best placement for the GPS Antenna is as

close to the GPS Equipment as possible while

provide a 270 degree view of the sky

Ted J. Pappas

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GPS Antenna Placement

Where does it go?

The antenna should be installed to provide the best available view of the entire sky.

It is recommended to have a clear view of the sky

above a 30 degrees from the horizontal in all directions, and above 10 degrees from the horizontal with a southern view for northern latitudes and a northern view for southern latitude sites.

To minimize any damage due to lightning, it is required

to always mount the antenna below the top of the lightning rod by a distance greater than 6 feet.

The GPS antenna should also never be located more

than 6 feet away from a lightning rod in the horizontal direction. This allows the Base Station Timing Module to select the best combination of GPS satellites for best performance.

Ted J. Pappas

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GPS Antenna Cable Length

At the GPS receive frequency loses at high in the GPS Cable and as such requires a special “low Loss” cable (RG-58) and/or in-line amplifier depending on distance / length.

The standard length cable that comes with the it is nominally 100

feet. Cable runs longer than 100 feet may require another solution such

as offsets and in-line amplification.

Ted J. Pappas

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A Ground Plane?

It is recommended to use a ground plane in

the installation to minimize the signal

degradation due to reflections.

Fading may also be caused by reflected

signals from vertical surfaces which are above the plane of the base of the antenna.

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The Correct Antenna?

The Standard Rooftop Antenna

Ted J. Pappas

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The Shelter Antenna

For locations where the

antenna MJST be flush

with the surface once

installed

Ted J. Pappas

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A High EMI Antenna

This antenna should be deployed at locations with a

high degree of Electro Magnetic Interference (EMI).

Ted J. Pappas

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Thank You