Recently many organizations give a free automatic processing web based online services for processing the
GPS observations for any place in the world whether relative GPS Processing solution or Precise Point Positioning (PPP)
technique. In this research, baseline lengths of GPS network in Egypt are obtained by using the free automatic processing
web based online services and compared with the baseline lengths computed by relative solution using the Trimble
Baseness Center (TBC) commercial software at different observation times 1,2,3 and 4 hours. The automatic processing
web based online services used in this research are with relative GPS solutions (AUSPOS and Trimble CenterPoint RTX
post-processing) and with PPP technique (CSRS-PPP). The network baseline lengths at different observation times 1,2,3
and 4 hours are compared with the baseline lengths computed by a total time of observations by using the above different
approaches. The maximum vector length errors obtained by using TBC, Trimble RTX, AUSPOS and CSRS-PPP at 1
hour are 0.015 m, 0.093 m 0.235 m and 0.075 m respectively, at 2 hours are 0.009 m, 0.066 m, 0.033 m and 0.061 m
respectively, at 3 hours are 0.008 m, 0.017 m, 0.033 m and 0.016 m respectively and at 4 hours are 0.005 m, 0.019 m,
0.014 m and 0.021 m respectively. The relative GPS solution software (TBC) are observed to give better result at all
observation times.