Spirent is getting involved in the sensor world as it crosses with their series of GNSS (satellite navigation) simulators. Inertial sensors, compasses, and satellites can work together, correcting each other and providing backup when the satellite signal is too weak or disappears inside a building.
Spirent’s SimSENSOR MEMS is a simulator intended to allow testing and tuning of the sensor fusion algorithms that combine the satellite and sensor signals to provide a unified location verdict. In particular, they focus on dealing with noise (use of an Allan variance model is part of what they consider their differentiation).
They use a generic sensor model that allows you to play with the noise, errors, drift, etc. If desired, one can add a model of a specific sensor through a .dll file.
In addition to the usual inertial sensors and compasses that provide positioning along the surface of the earth, they also simulate barometers so that altitude can be figured as well.
This is intended to provide a testing and tuning methodology that is easier and more reliable than constructing mechanical devices for use with real sensors. You can find more information in their release.