Section  4  —  Measurement  Types  and  their  Uses 
54 
 
Broadband  high  frequency  noise  (haystack) 
 
 
Analyze Demodulation Data 
 
Measuring,  recording,  and  viewing  data  is  exactly  the  same  for  a 
Frequency/Acceleration  spectrum.  You  can  also  transfer  the 
demodulation  spectra  to  Ascent  and  analyze  it  with  the  same 
techniques  used  for  normal  spectra  (e.g.  trend  plots,  alarms,  fault 
frequencies,  bearings,  and  gears). 
 
Here  are  some  points  to  remember  when  analyzing  demodulation  data: 
•  Bearing  tones  that  appear  in  the  demodulated  spectrum  but 
NOT  in  the  normal  spectrum  are  a  good  early  warning  indicator 
of  insufficient  lubrication  (and  other  problems). 
•  As  the  bearing  deteriorates,  the  baseline  noise  level  increases 
and  bearing  tones  develop  running  speed  sidebands. 
•  In  the  final  stages  of  bearing  wear,  the  bearing  tones  may 
become  less  prominent  as  cracks  and  pits  become  more 
rounded  and  distributed  over  the  race.