I am trying to access the physical un-calibrated gyroscope sensor. But I am unable to. Since I can only access the calibrated one, I want to know what method is used for drift compensation in the gyroscope sensor used in the Tango Device.
Nobody knows exactly what Tango uses for drift compensation, my own guess would be that they are heavily reliant on Structure From Motion techniques. If you're asking how to calibrate an already calibrated gyro (calibration quality is a different issue :-) ), that's a topic for an entire stack overflow site, not a single answer :-) And it would leave you battling for computation resources with Tango - if you want to experiment, any phone with 3DOF attitude sensing and a decent camera is a good starting platform for learning about this, but be warned - it's really complex - much nicer to have it packaged and take what you get.