# Sampling rate of data, interval times

Hi there,

1. I would like to know the sampling rate (ODR= output data rate) of the Acc./Gyro/Mag , Displacement, Tilt/inclination sensors?

2. If I set the “Delay” in Node-red software to “90”, does it mean the time interval between getting samples is every 90 seconds? (for example if the sampling rate of Acc. is 50 Hz and the total number of samples is 3400 it takes 68 seconds. Now by setting the dalay=90, the device will go into sleep mode and after the 90s it will wake up and start recording samples for 68 s?)
I am so confused, so any clarification on this matter would be highly appreciated.

Best,
Nasrin

ODR is 900hz
yes delay means time between two readings. during this time device will sleep and wont take any samples

Hi there,

I believe 900Hz may not be the correct answer. When I set the delay to 90 seconds, I receive just “one” row of data every 90 seconds. However, based on my understanding, if the sampling rate is, for example, 50Hz, I should receive “50 rows of data in just one second.”

You are asserting that the sampling rate is 900Hz, implying that I should be receiving 900 rows of data per second, which is not occurring.

I appreciate your assistance in clarifying this discrepancy.

Best regards,
Nasrin

Hi @nasrin , I am not NCD, just another customer, but wanted to share what I think you are experiencing.

The 900Hz ODR is what the sensor samples at, for that one second, and likely computes the data of those 900 samples over 1 second, and then transmits them. It then goes to sleep for 90 seconds before doing the same operation again.

The same behavior applies to the Vibration Sensors, you can set the ODR quite high, but that sampling rate only applies to that one second that it is sampling.

A better term for the 90 seconds inbetween the samples is ‘interval’. The interval is 90 seconds, or in the case of vibration sensors we use 30 minutes in between samples.

Interval (between samples): 90
ODR (when it takes a sample): 900Hz

In 5 minutes you would end up with three samples (transmissions) from the sensor.
Each transmission was taken at that 900 samples per second, but likely the data about it is aggregated.
On the vibration side we end up wiht the RMS (Root Mean Squared) values of the data taken at the ODR.

This may not entirely apply to your case, and I dont want to speak for NCD, but the sensors tend to strike a good balance between battery life, range, and sampling intervals.

Having all the data all the time, like 50 transmissions a second would be quite difficult, to still have great battery life and great range on the sensor as well.

I am assuming you are talking about the white box transmitter line of sensors with an Xbee in them.

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