What is the Effective Number of Bits (ENOB) for the NI-9239?Hardware: CompactRIO>>Analog Input Modules>>NI 9239
Problem: What is the effective number of bits (ENOB) for the NI-9239 analogue input C series module? Solution: Effective number of bits (ENOB) is a measure of the actual performance of an A/D converter after its various noise sources and non-linearities are included. The ENOB is computed as the signal-to-noise and distortion ratio of the A/D converter (in dB) minus 1.76, divided by 6.02. ENOB = (SINAD-1.76)/6.02 SINAD and ENOB are typically a function of signal frequency and amplitude. However, you can estimate low-frequency SINAD and ENOB from a board's noise specifications. The 9239 has an input noise of 70uVs RMS.The biggest sine wave that fits in the +/-10V ADC range is 10V/sqrt(2) rms; thus a good estimate of the SINAD is 10V/sqrt(2) / 70uV and expressed in decibels equals 100dB. Using the formula above leads to an ENOB of around 16.3. Related Links: NI High-Speed Digitizers Help: ENOB Attachments:
Report Date: 01/13/2009 Last Updated: 12/23/2009 Document ID: 4TC2PLVW |
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