Unifying the coordinate systems in GIS

[IKJude]

Hi there, 

Would anyone explain to me how I unify the coordinate systems between GPS and Total Stations measurements in GIS? I have the satellite image of the area of interest. GPS data is matched with the satellite images in GIS, but the Total stations data does Not (it is very far from the area of interest). I want to visualise the differences between GPS and Total stations positions. 

This is a summary of what I have done:

1- 20 points were observed by Leica GPS (example of GPS data: 177118.941, 34727.625, 86.568)

2- the same 20 points were observed again by total stations ( I assumed the coordinates of the first point is 1000,1000,1000, then the rest of points were measured relatively)

3- when I added the both measurement, spatial data from Total station appears in different location (far from GPS data)

4- I created a shape file and arc Catalog, to tell GIS that this data set is the same with the second data set, but it does Not work.

I would be so grateful if anyone would help,

[dotMorten_esri]

It sounds like a datum shift. Are you using the correct spatial reference and datum transforms for all your data?

[IKJude]

Yeh, I am using the same coordinate system (OSGB-1936). I setup both instrument on the same coordinate system and in GIS, I edit them at the same coordinate system. the starting point of GPS (let's call it GCP1)  was E177118.941;  N34727.625; H86.568 ). This data from GPS measurements and the rest of points were measured relatively. Then I setup another instrument ( called Total stations) over GCP1 and I assumed the coordinates of this point is 1000, 1000, 1000, then the rest of points measured relatively. So, maybe it is a datum shift because when I added both data in ArcGIS, they are totally in different in location (because they were measure from different instrument) . Any suggestion on how I put them at the same location in ArcGIS please?