| Similar to those used in cars, these units work off Global Positioning System satellites which transmit information to ground equipment. These receivers passively collect information – they do not transmit any. Each satellite continually transmits data about its position and the current time. The lapse in the time taken for this information to be received from each satellite varies enabling the receiver to estimate, based on a minimum of four satellites, its position in three dimensions. Technical stuff! To harness this wealth of data for golfers means that someone needs to identify grid references, at the very minimum, for the green. The unit then knows where you are and the distance to it. More sophisticated units can take in much more information such as the position of bunkers, water hazards and tree to mention but a few. Some even more sophisticated trace the green’s perimeter enabling distances to be calculated from any approach angle. One of the main advantages in this type of system is that you don’t have to aim at the target to get a reading. Ideal where there is no line of site as a result of a hidden green, a dogleg or a stray drive in the woods! This aiming can be rangefinders Achilles heel resulting from wobbles and the problems of very small targets, although better units have stabilising systems. But all GPSs have disadvantages too - someone has to survey the course first and you have to down load and possibly pay for it, although there are some units that you can program but that in itself can waste valuable time. So if you only play a few courses this may not be a problem for you. GPS Units  |
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