Of Cable Information and GPS Antennas

  • By Garry
  • February 20, 2020
  • Comments Off on Of Cable Information and GPS Antennas

What are global positioning systems or GPS antennas? It is a radio-navigation system dispersed around the globe. This is a vast network, comprised of 24 satellites, each single one of them is perpetually orbiting the earth.

Inside each GPS antenna, there are several atomic clocks which are precisely synchronized to UTC or Universal Time Coordinated as provided by the USNO or US Naval Observatory. These satellites are made to broadcast coded signals with respect to the exact position and time of the satellite.

GPS receivers need to make use of an antenna just so they can receive these broadcast signals. By virtue of an GPS receiver optimized not for position but for time, there is a good possibility that you can get time synchronization with respect to the atomic clocks of a satellite.

The GPS satellite signal works in the L1 band or 1575.41 MHz “semi-visible” spectrum. Its minimum signal level is approximately -162.0 dBW. Considering such a low signal strength, it is paramount for the GPS antenna to have access to the open skies in order to efficiently obtain signals. And that it should be mounted on a roof, or you can have it installed in a window system instead.

With regard to their size, this type of antenna is relatively smaller, way too smaller than the size of a coffee cup or perhaps even much smaller. Linking them to a GPS receiver can be made possible by the use of a coaxial cable.

GPS signal is a very weak signal, and for this reason the antenna needs to amplify the signal in order to drive it through  the cable, then eventually drive it also to the receiver. However, antenna cable comes with a significant amount of resistance, and while the GPS signal travels down the cable, its strength will gradually attenuate.  The sensitivity of the GPS receiver is finite, and for this reason if the length of the cable is far too long, the resulting signal will be rendered as too weak and with that the receiver is not likely to detect it.

Consequently, knowing the distance between the receiver and the antenna is very important because this will help you determine the proper cable solution that you can actually install.

Placement and Mounting of GPS Antenna

GPS timing receivers can be utilized with just 2 types of basic antenna, a window mounted type and a roof mounted type. GPS clocks, which are far more accurate, require roof mounted antenna since it requires at least 3 satellites to be in view at all times in order to maintain and keep up its timing accuracy. 

Now as for the window mounted antenna, they are highly applicable for the network time servers which are working on a lesser level of accuracy, usually in microseconds or at times in milliseconds to UTC. Additionally, they will still operate even with just a few intermittent satellites in range. Roof mounted antennas are always preferable since the very nature of their location gives them the best view of the surrounding sky. 

A GPS Up/Down converter is a roof antenna variation which is usually used for long cable runs. These are qualified by industry experts as special type of GPS antennas that can receive GPS signals and transform it to a lower frequency, which will run down the cable. 

Up next to the GPS receiver is a converter which transposes or reverts the signal to its original frequency. It is then delivered to the GPS receiver.