Instead of relying on ground stations for orbital determination and correction, the now included Satellite Navigation System ASN-K (Russian: АСН-К, Аппаратура Спутниковой Навигации) relying on GLONASS and GPS signals for navigation. It uses four fixed antennas to achieve a positioning accuracy of 5 m (16 ft), with the objective to reduce that number to as little as 3 cm (1.2 in) and an attitude accuracy of 0.5°.
However, I am so far unable to verify from the references currently linked in that paragraph that the plan is to derive "attitude accuracy of 0.5°" from GLONASS and GPS signals.
If this is the plan, could someone help find a reliable source that states this explicitly, and hopefully explains at a least a little bit how that works?
It's certainly true that with a multi-antenna configuration GNSS signals can be used to determine attitude, but I'd like to confirm that Soyuz is set up to test or use this.