What was found
AFTER LIFTOFF APPROX 300 FT, ENCOUNTERED WAKE TURBULENCE FROM PRECEDING AIRCRAFT. THERE WAS NO -CAUTION WAKE TURBULENCE- STATEMENT FROM ATC. CREW REPORTED -TURBULENCE WASN'T EXTREMELY VIOLENT; CAUSED VERY ABRUPT LEFT AND RIGHT ROLLING MOTIONS THAT VERY BRIEFLY MADE THE AIRCRAFT SOMEWHAT UNCONTROLLABLE LASTING ABOUT 2-3 SECONDS. DURING THE WAKE TURBULENCE EVENT, THE CREW RECEIVED A MASTER CAUTION ALARM AND 3 AMBER MESSAGES ON THE EICAS: -SHAKER, ANTICIPATED AOA LIMIT FAIL, AND WINDSHEAR FAIL-. RETURNED TO ORD, DECLARED AN EMERGENCY AND LANDED WITHOUT INCIDENT. MX CYCLED A/C POWER, MESSAGES CLEARED. FHDB DOWNLOADED FOR FURTHER TROUBLESHOOTING. AIRCRAFT HAS NO HISTORY, DISCREPANCY HAS NOT REPEATED.