Data Anti Aliasing; Vehicle Profiles; Odometer Pulse Length; Odometer Automatic Pulse Length Calibration Procedure - Advanced Navigation Spatial OEM Reference Manual

range this causes the filter to become completely inaccurate and in some cases it can cause the
filter to reset.
By default Spatial comes configured in the lowest sensor ranges. In this configuration it is possible
to send the gyroscopes over range by quickly rotating the unit in your hand. It is recommended to
watch what happens in Spatial Manager when you do this.
The sensor range can be set through the sensors option in the configuration menu in Spatial
Manager or through the Sensor Ranges Packet.
7.8

Data Anti Aliasing

Internally Spatial's filters update at 800 Hz. When Spatial outputs data, most applications require
the data at a much lower rate (typically < 100 Hz). This causes a problem for time based data such
as velocities and accelerations where aliasing will occur at the lower rate. To prevent this problem,
if the output rate is lower than 800 Hz, Spatial will low pass filter the values of the time dependent
data between packets to prevent aliasing. This is only the case when a packet is set up to output at
a certain rate. If the packet is simply requested no anti aliasing will occur. Additionally there is no
anti aliasing for non time dependent fields such as position.
7.9

Vehicle Profiles

Spatial supports a number of different vehicle profiles. These vehicle profiles impose constraints
upon the filter that can increase performance. If your application matches one of the available
vehicle profiles, it is recommended to select it for use in the filter options dialog in Spatial Manager
or the Filter Options Packet. For a list of the different vehicle profiles please see section 9.9.6.1.
Please note that if the wrong vehicle profile is selected it can cause a significant decrease in
performance.
7.10

Odometer Pulse Length

For Spatial to use a wheel speed sensor or odometer input, it must know the pulse length of the
signal. The pulse length is the distance in metres between low to high transitions of the signal. The
odometer pulse length can either be entered manually or automatically calibrated by Spatial. To
enter the pulse length manually, please use the odometer configuration dialog in Spatial Manager
or the Odometer Configuration Packet. To automatically calibrate the odometer pulse length please
use the procedure listed below in section 7.10.1. By default the odometer will automatically
calibrate itself.
7.10.1

Odometer Automatic Pulse Length Calibration Procedure

1. Ensure that the signal is connected correctly and that the GPIO pin is configured as an
odometer input using the GPIO configuration dialog or the GPIO Configuration Packet.
2. Open Spatial Manager, connect to Spatial and open the odometer configuration dialog. In
the odometer configuration dialog tick the automatic pulse length calibration check box and
press the write button. If using the packet protocol this can be done using the Odometer
Configuration Packet.
3. Wait until Spatial has a continuous GNSS fix and then drive 1000 metres over flat terrain
with as little turning as possible.
4. If Spatial loses a GNSS fix for any extended period of time during the calibration, the
Spatial OEM Reference Manual
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