ADIS16201 - Output data rate? - Alternatives with wide bandwidth?

Thank you for your post. The sample rate is independent of the SPI requests.  The ADIS16201 will support up to 4096 SPS and the sensor's response will support a response up to 1kHz.  We would suggest using the data ready function (DIOx, via MSC_CTRL register) to synchronize your reads to the ADIS16201's sample production.  The range for the sensor in the ADIS16201 will be close to +/-2g but the specifications only assure +-1.7g. 

Out of curiosity, what are you trying to measure?  There might be other products that are better suited for what you are trying to do.

Hi,

Thanks for your fast answer.

We need to measure very small accelerations generally below 1g, but sometimes a little above 1 g and we do not want the accelerometer to saturate. Thus we require high sensitivity, very low noise and a measurement frequency range between 100 Hz and 1 KHz.

We have faced some issues because sometimes the manufacturers say that the accelerometer has >1 kHz bandwidth but it is in fact its output data rate or maximum sample frequency and thus the real bandwidth of the measurement is 500 Hz or below.

Any suggestion is welcome !

1- For instance we have tested several accelerometers by vibrating them with an increasing frequency  and the amplitude measured by the accelerometer was attenuated as the frequency increased. This happens because the samples per acceleration period decreased with the increasing frequency and  therefore, the sample taken does not always exactly match the acceleration peak.

In order to reliably measure a vibration at 1kHz we should have, theoretically, a sampling rate of at least the double. In reality it would be better if we have even more, lets say >4kHz.

2- Less of 3dB of attenuation

3- two

4- I do not understand the question, we would prefer digital output, SPI if possible. Analog could be considered.

5- If possible the noise should be below 100 ug/sqrt(Hz)

Thanks,

Thank you!  I would probably start with the ADXL350.

http://www.analog.com/adxl350

Tagging a couple of to make sure but it seems to be closest to everything you are asking for.  The noise density is not specified but the total noise associated with the 100Hz ODR setting in Table 1 seems to back out to a number that is ~122ug/sqrt(hz) if I assume that the roll-off is equivalent to a single pole filter.

I hope that helps!

Hi,

Thanks a lot for the advise.

My only concern with the sensor that you propose is that the resolution and sensitvity of the device does not seem very good.

Ideally we would like to have a sensitivity higher than 1024 LSB/g. If I understood correctly the ADXL350 can only provide up to 10 bits for a range of +-2g.

Is there any other specific reason to preferably use the ADXL350 instead of ADIS16201.

Thanks again and kind regards,

Laura

The key thing that was driving this was the 2g range. The ADIS16201 sensor might provide this but the assured level of +/-1.7g. The ADXL350 provides a third axis, is smaller, lower cost and appears to have lower noise. You may not need the third axis but it might give you some orientation flexibility, but the z-axis noise is a bit higher.

With respect to the LSB weight, what is driving that requirement for you?  Is that influenced by noise?  If you are running this product at its maximum ODR, we can project the total noise to be sqrt(32) greater than the 100Hz ODR setting, assuming a flat response with respect to frequency.  This results is a total nose of 6.2 mg (rms).  If we assume a normal distribution, the peak level associated with the noise behavior will be 3.3x higher, or ~20.5 mg. If I am doing my math correctly, that is 10x higher than the LSB weight for the +/-2g setting (4g/[(2^11)-1]).

In other applications, we have seen cases where noise > LSB has enabled resolution extension, through capture bit growth from the filter mathematical operations. Not sure if that helps, but I figured that it was worth mentioning.

Hi,

Thanks for your answer that's indeed quite helpful.

I did see 0.37 LSB/sqrt(Hz) as noise density for the ADIS16201, but I did not see the 22 LSB rms!

I'll have to discuss it with the software people to know exactly the level of noise allowed in the range 100-1kHz in order to review the noise and sensitivity requirements accordingly.

Thanks for your advice!