Timing of data streams onboard the MTi and in XDA (10/100-series)

The three diagrams below shows the (simplified) system architecture of the three Output Configuration presets in MT Manager: Onboard processing, XDA Processing and XDA Processing with SCR data. 

Only when using XDA processing with SCR data, it is possible to output calibrated inertial data at 2000 Hz. However, it is not the recommended setting as onboard processing will provide the shortest latency with data availability directly from the connector.Timing_XDA_and_onboard.png

The table below shows the latency of the various output configurations. Every SampleTimeFine increment is 0.5 ms. This means that when starting up the MTi, the first available calibrated data is available after 2.5 ms and first available orientation is available after 11.19 ms and then every 2.5 ms. This excludes latency from start up and the low pass filters (1.19 ms). 

SampleTimeFine increments      
   Onboard  XDA processing  XDA processing with SCR
After Calibrated data   1..25, etc (not outputted)  1..25, etc (not outputted)  1..25, etc
After SDI  5, 10, 15, 20, 25, etc  5, 10, 15, 20, 25, etc  5, 10, 15, 20, 25, etc
After XKF  5, 25, etc (not outputted)  5, 25, etc (not outputted)  5, 25, etc (not outputted)
After Sample mixer  5, 10, 15, 20, 25, etc  5, 10, 15, 20, 25, etc  5, 10, 15, 20, 25, etc

The PacketCounters and SampleTimeFine of the XDA output correspond to the PacketCounter of the SCR data and/or SDI data coming from the MTi connector. Because of the Sample Mixer, the latency is determined by the SDI output and not by the Sensor Fusion Algorithm XKF.  

Note that the MTi 1-series has a 1000 Hz output from the digital IMU and the architecture is therefore a little bit different from the MTi 10-series and MTi 100-series.





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