3
\$\begingroup\$

I recently started working with the ADXL345 Accelerometer and got a bit confused on what's the difference between the data rate and bandwidth.

From the ADXL345 datasheet p14, we can see the different available data rates and bandwidth :

Output Data rates and Bandwidth that can be used

What confuses me more than anything is why don't they have the same values? Is the Output Data Rate, the rate of the data sent from the accelerometer to a microcontroller, or is that the bandwidth? I'm a bit confused so any help would be greatly appreciated.

\$\endgroup\$

1 Answer 1

5
\$\begingroup\$

I think that this is connected to the 'Nyquist–Shannon sampling theorem', which says that for sampling frequency fs, only signals with frequencies lower than fs/2 can be converted without the loss (or signals with bandwidth smaller than fs/2).

\$\endgroup\$
2
  • \$\begingroup\$ Does that mean that, the acceloremter is measuring data at a rate of 50 Hz and sending it at a rate of 100 Hz to a micro-controller? for example? \$\endgroup\$
    – B.Adlane
    Feb 20, 2022 at 14:35
  • 1
    \$\begingroup\$ @B.Adlane no, that means that the circuit is messuring (sampling) and sending data at 50hz, but that corresponds to maximum 25hz physical signal on accelometer. In other words: if accelometer is attached to oscillator with 25hz frequency you need at least 50hz sampling frequency to process that informattion without a loss \$\endgroup\$
    – klokaj
    Feb 20, 2022 at 18:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.