Patent ID: 8260580

Claim:
A data acquisition apparatus, comprising: a first means providing a series of first digital sampled and dated data (X) at an imperfect sampling frequency (F E ) provided by a first local clock ( 2 ), a second gauging means ( 50 ) for measuring a frequency error (FD) of the first local clock ( 2 ) in view of a second reference clock ( 6 ), a third means for correcting the series of first digital sampled and dated data (X) based at least on the measured frequency error (FD), characterized in that the first means ( 3 ) comprises sigma-delta modulation means ( 3 ) arranged to produce said series of first digital sampled and dated data (X) sampled at said imperfect sampling frequency (F E ) provided by said first local clock ( 2 ), the third means comprises at least an interpolation means ( 4 ) to produce second digital data (Y) based on at least an interpolation of said series of first digital sampled and dated data (X) and compensating with the measured frequency error (FD), and at least a decimation filter ( 7 ) for producing third digital data (A) based on said second digital data (Y).