All you need to know about GPS
What type of GPS receiver works best?Some GPS receivers work better for receiving time signals. This is due to the default port used for time, which is considered by navigational receivers to be a secondary priority. You will have more accurate time if you use a receiver that has PPS (pulse per second) output available, and that this output is the priority.
How Does GPS work?GPS receivers integrate a radio and a navigation computer and can receive the faint, twenty-watt signals coming from the satellites. The computer uses these signals to calculate the distance between the satellites and the receiver. With this information, the computer can further calculate the position and velocity of the receiver.
The number of satellites visible to a receiver constantly varies between four and eleven according to time and location. Each satellite broadcasts a number of unique spread-spectrum codes, but only one, the Coarse Acquisition (C/A) code, is easily accessible for civilian use. The C/A in orbit 11,000 miles above earth, GPS satellites transmit at twenty watts a number of unique spread-spectrum code. The number of satellites visible to a GPS receiver constantly varies between four and eleven according to time and location. Code is effectively a timing signal synchronized to an international time standard-Universal Coordinated Time (UCT). UCT is kept by a world-wide ensemble of cesium and hydrogen maser frequency standard atomic docks. The highest-quality GPS receivers measure the C/A code to better-than- nanosecond precision.
Where can GPS work?
GPS reception is available around the globe. You will need to have a clear view of the skies so the receiver can triangulate at least three satellites. An office window works well, but my have problems in a condensed area of buildings.
Under specific conditions, GPS will not provide the time. For instance, the 1,542 MHz GPS signal does not penetrate buildings, which makes it difficult to receive signals indoors away from windows. Also the signal can be critically weakened by heavy foliage and interfered with by other sources such as poorly maintained television broadcasting equipment.
What type of hardware do I need?
You need a GPS receiver, antenna, power supply, data cable and serial port connector. These come standard with most GPS Units. You also need access to a power source. You may also purchase accessories, including mounting units from ATZ Audio. You can get all that you need to get started
here.
The only other requirement is a functioning Windows PC with an available USB or serial (COM) port, whichever type your unit is supplied with.
Do I need an Internet connection to use GPS?
No. GPS time synchronization does not require an Internet connection.
I already have a GPS receiver; will ClockWatch Star Sync work with it?ClockWatch Star Sync will work with most GPS receivers with NMEA 0183 data output connected to an available serial port on the computer running Star Sync software.
Why would I want to use GPS for time synchronization?Time syncing using GPS is a good alternative for remote or highly secured computers. ClockWatch Star Sync does not require an Internet or modem connection.
GPS time synchronization may potentially be more accurate than syncing over the Internet or by modem. The true accuracy depends on the receiver as well as the computer.
