We are using the ICM-20689, for vibration measurements purposes.
We are using the low pass filter in 420Hz and then the data rate is 1kHz. We take this data and made a FFT to inform the frequency and amplitud of the vibration.
Now we detect the we have an aliased frequencies. We detect the frequencies above 500 Hz appears aliased, eg. the 510Hz appear as 490Hz with an attenuation, but if we increment the vibration frequency the measured amplitude increments. We are thinking there is an digital filter response.
Did any have an experience with frequency response of the ICM-20689?
If we use the full frequency range (4kHz), any have data about the wide band of the data output?
Thanks
Martin
Hello,
Were you able to solve your issue?
Hi, we are not able to solve the issue. We are still seeking for information to understand the issue.
Thanks
Martin
Hi,
So you set your cut-off to 420hz via ACCEL_CONFIG2 register, and followed the instructions on the DS. You are using the ICM-20689 in low noise mode right?
Also, I want to point out that ICM-20689 is an End-of-Life product. You can check out our newer products here: https://invensense.tdk.com/products/motion-tracking/6-axis/
On another note, If you set ACCEL_FCHOICE_B to 1 via ACCEL_CONFIG2 register you can set data rate to 4kHz and have a wider bandwidth.
Hi Mustafa, you are right we are using the low power mode. We know the EOL state of 20689, we take count to the shared link for to the new product to replace te actual.
In case we set the data rate to 4 kHz, we don't found in DS the bandwidth of the data, do you know this bandwidth?
Regards
Hi,
I attached DLPF table from the datasheet for your reference. Also, try using low pass filter in 420Hz and then the data rate is 1kHz while device is on low noise mode as well.
Sorry, what I meant was I don't found was the type of filter. That is to say the if the 420Hz filter is an first order low pass and the same question about the 1kHz bandwidth what is the roll-off.
Regards,
Martin