The [answer][1] here describes the attitude determination goals of the future russian crew module federatsiya. The idea is to use two different GPS receivers at the end of the spacecraft, when the spacecraft is rotating(almost tumbling) and looses its absolute attitude reference, this method will be able to give attitude within certain time using signal delays of the signal.

ISS uses same technique, I think as Technology Demonstrator as mentioned in this [link][2]


  [1]: https://space.stackexchange.com/a/31206/18825
  [2]: https://www.nasa.gov/centers/johnson/news/releases/2002/j02-61.html