Sample Rate; Sample Rate Versus Data Rate; Low-Pass Filter - Novanta ATI Axia80 Manual

Manual, F/T Sensor, Ethernet Axia
Document #9620-05-C-Ethernet Axia-02

5.3 Sample Rate

The power-on default sample rate is the rate a user sets before removing power. The sample rate is stored to
nonvolatile memory. The ADC rate controls the current sample rate. The following table lists the rounded
and exact sample rates.
Rounded Sample Rate
Exact Sample Rate

5.3.1 Sample Rate Versus Data Rate

The data rate is how fast data can be output over the Ethernet interface.
If the data rate is faster than the sample rate, the customer sees duplicate samples output over the
network until the next sample is read internally. A faster data rate could be useful so that the sensor
sends data at the same rate that other devices in a customer's system are outputting. For example: if
a device on the same application as the Axia is outputting data at 7,000 Hz, the customer may want
the Axia to be outputting data to the network at 7,000 Hz as well, even though the sensor is not
sampling that quickly internally.
If the sample rate is faster than the data rate, the customer does not receive the data from every
internal sample over the network. However, any filters that are enabled work based on the faster
internal sample rate, and so the sensor filters out higher frequency noise sources than if the filter is
operating at a slower data rate.

5.4 Low-Pass Filter

The power-on default selection is "no filtering." Users can issue a filter command via one of the Ethernet
software interfaces to control the current filter selection. The cutoff frequency (for example: -3 dB
frequency) is dependent on the sample rate selection, which is defined in
cutoff frequencies for the different sampling rates are listed in the following table.
Selected
Filter
0
1
2
3
4
5
6
7
8
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Table 5.5—Sample Rate
0.5 kHz
488 Hz
Table 5.6—Low-Pass Filtering
at 488 Hz at 976 Hz
Sample Rate Sample Rate
200 350
58 115
22 45
10 21
5 10
2.5 5
1.3 3
0.6 1.2
0.3 0.7
1 kHz 2 kHz
976 Hz 1953 Hz
-3dB Cutoff Frequency (in Hz)
at 1953 Hz
Sample Rate
500
235
90
43
20
10
5
2.4
1.4
C-27
4 kHz 8 kHz
3906 Hz 7912 Hz
Section 5.3—Sample Rate. The
at 3906 kHz at 7912 Hz
Sample Rate Sample Rate
1000 2000
460 935.10
180 364.04
84 169.52
40 81.24
20 39.84
10 20.31
4.7 9.37
2.7 5.47
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