# Choosing sampling rate according to the bandwith reponse in accelerometer datasheet

In an accelerometer's datasheet, the bandwidth response in the x and y axis is 350 Hz.

• There is another information related to the internal sampling rate (shown below). I don't know how these two are related to each other. What is the maximum frequency at which I can acquire data from this accelerometer?

• I would like to get the acceleration data as accurate and fast as possible. What sampling rate do you recommend?

Edit

I'm using an Arduino Mega. The sensors is a tri axis accelerometer mma7260Q, here is the complete datasheet.

Maybe the Bandwidth response values are related to the internal low pass filter.

• Can you share which accelerometer you're using so I can take a look at the rest of the datasheet? Also, what kind of device are you using to read from it? – skrrgwasme Dec 9 '14 at 23:16
• Please see my edit – UserK Dec 10 '14 at 0:11

See the relevant notes on the data sheet:

5. Use an RC filter with 1.0 kΩ and 0.1 µF on the
outputs of the accelerometer to minimize clock noise
(from the switched capacitor filter circuit).

8. A/D sampling rate and any external power supply
switching frequency should be selected such that
they do not interfere with the internal accelerometer
sampling frequency (11 kHz for the sampling
frequency). This will prevent aliasing errors.


Looks to me like the bandwidth numbers of 350 and 150 are the ones you should use. The RC values they supply are at about 1.5 kHz.

There seems to be an switched cap filter clocked at 11 kHz that shapes your signals. Also, the system depends on a resonance in the nano-elements in the 3-6 kHz range, but that doesn't mean that it can detect or report acceleration in that range.

The 11 kHz signal, and maybe some of the resonance is going to bleed through, and that's why they want you to filter at 1.5 kHz. That said, because they actually prefilter internally for you, you just need to cover the bandwidth of the accelerometer (at 350 and 150) with your sample rate. 800 Hz sampling should be fine!!

• That's perfect! The internal filter is well suited for statical applications. But in presence of vibrations a low pass digital filter is required. Thanks – UserK Dec 10 '14 at 13:15