If you use GT-Position standard or GT-position Plug & Play there are 2 receivers (satellites) available. It is a very simple setup, however please remember to put the satellites somewhat outside and above the layout. As a minimum 200 mm.
The reason is that we only have a 2D method available and if you drivee UNDER the line between the receivers we will divide by 0.
Please always let your receivers be hanging from the ceiling with som 45 degree downwards with the ultrasound sensor pointing towards your layout. Also in fiddle yards the 30-60 degree is the best giving maximum openings to the sensor.
A Fiddle Yard is normally 2D only, except for the ramp. You can extend the 2 receivers with a 3rd receiver on the same line which will help the precision in the corners, or you can insert a 3rd receiver so that you use 3D. Do not spread the receivers too much, it is the best to pack the receivers together with som 1,5-2 m maximum between the receivers. In narrowareas you can go down to 750 mm between receivers.
It is hard to track the trains on a circular ramp (helix) making any good projections of the position. The advice it to kepp the total helix as one block, then normally only having one train a time on the ramp.