When establishing current demodulation band alarms for belt frequencies associated with a 2-pulley belt driven system, remember both the 1x belt frequency and 2x belt frequency should be taken into consideration. Initial band alarms for the 1x belt frequency are recommended at baseline + 10% for caution and baseline +20% for severe. Initial band alarms for the 2x belt frequency are recommended at baseline +25% for caution and baseline +50% for severe. Based on test results from known defects, analysis of the 1x belt frequency focuses more on the system alignment while 2x belt frequency focuses more on belt condition and looseness.
For more information on establishing band alarms for mechanical defects read the short article “Advanced Spectral Analysis” found on the PdMA website.
http://www.pdma.com/pdfs/Articles/Advanced_Spectral_Analysis.pdf