Experimental Work for Evaluation the Time Saving Between Different GPS Techniques for Makkah- Jeddah Region

Nowadays, there are available in technology, devices, Techniques such as GNSS and CORS and use the VRS techniques. Although for previous technology, some application just needs for the ordinary GPS techniques. So, the current research work is done by field experiments to assess the time saving and accuracy between GPS different techniques such as Stop & Go, Kinematic, and Kinematic ON THE FLY Techniques especially in mountain areas like MAKKAH region. There are three post-processed GPS kinematic techniques. These techniques are stop &go, kinematic, and kinematic on the fly techniques. Stop& go and kinematic techniques require the so-called initialization process, which must be repeated in each cycle slip due to satellite-signal blockage. This is a time consuming and practically reduces the surveying productivity. On the other hand, the kinematic on the fly technique does not require the initialization process. This leads to increase the surveying productivity. The current paper makes a comparative study between GPS stop &go, kinematic, and kinematic on the fly techniques, from points of view of accuracy, time elapsed for the initialization process, observation time for each surveyed point and the surveying productivity. The results supported by appropriate statistical tests showed that positional discrepancies between stop-go and kinematic techniques have mean value of 22 mm (S.D) of ± 7 mm. Also, the positional discrepancies between the stop& go and kinematic on the techniques are statically and practically insignificant, where the results showed that the positional discrepancy between the two techniques has a mean value of 22 mm with (S.D) of ± 2 mm. In this context, the kinematic on the fly technique is increasing the surveying due to using a recording data of about 3-seconds for each surveying point, and also because this technique does not require any initialization process which takes a lot of time especially in case of surveying near tree, road, mountains, and advertising frames specially when internet and communication with the CORS station is missed or disconnected. Finally, in case the issues to use RTK or VRS due to communication problems specially the regions within mountains areas such as MAKKAH in this situation the GPS kinematic on the fly technique is highly recommended to replace the stop-go and kinematic techniques, in all the surveying works of medium scale. Also, the distance between the surveyed point and the reference receiver does not affect the resulted coordinates for about 7 km.