Bruel & Kjaer - 4913 Stroboscope
Applications :
http://www.cieri.net/Documenti/Misure%20audio/Bruel%20&%20Kjaer%20-%20Flutter%20Compensation%20(Technical%20Review%20No.4-1982).pdf
http://www.technicalaudio.com/pdf/Bruel&Kjaer/Bruel&Kjaer_Exciter_Control_Vibration_1050.pdf
https://www.bksv.com/media/doc/bp0298.pdf
