Setting up Tag Filters

A tag filter is a set of rules and conditions that you can configure to define, for example, the height at which the tag is likely to be found, and the speed at which the tag is likely to move. These filters are used by sensors to sight and track tags.

To configure and apply a tag filter:

  1. Create a filter.

  2. Configure the required parameters, including the height, speed, and model type for the filter.

  3. Optionally, experiment with different values to obtain better locations, by using command-line tools—see the advanced documentation described below.

  4. Apply the filter to either a tag, a tag type, or a range of tags.

This section explains how to define basic filter parameters that you can use with, for example, car tags and tool tags.

Additional information about configuring tag filters, including Flags and Limits, is given in Filter Configuration.

Creating a Filter

You can set up a filter for either a particular tag, a tag type, or a range of tags. To configure different filter settings for different sets of tags, ensure that you create a separate filter for each set of tags.

To create a filter, on the Set up tag filters tab, add a new filter and then configure filter parameters to define how the tags must be tracked.

Configuring Height and Speed

For each filter that you create, configure the height and speed parameters that are listed in the following table.

Parameter Description

Default Height

This height is used during initialization, if the true height of the tag cannot be determined.

If you are not sure which value to use, specify a value that lies half way between the maximum height and minimum height.

Horizontal Speed

The maximum speed at which the tag can move, before the calculated position starts to lag. We recommend that you set this value to slightly higher than the fastest speed at which the tag is likely to move.

If you set this to a very high value, the reported location jumps too quickly in response to new measurements.
Maximum Height The maximum height that the tag is likely to reach. Any sightings of a tag that are above this value will be rejected.
Minimum Height The minimum height that the tag is likely to reach. Any sightings of a tag that are below this value will be rejected.

Height

  • Although the maximum and minimum heights do not have to be very accurate, ensure that they are approximately the same as the actual heights at which the tags are used. For example, for tool tags that are carried by people:

    • 0.5 m (knee height).

    • 1.0 m (waist height).

    • 1.5 m (shoulder height).

  • If the sensor groups have a clipping region, ensure that the height that you specify is in relation to the floor of the clipping region of the sensor group that detects the tag. If you have set the height of sensors and the clipping regions to the correct absolute heights, the same filter parameters will work, for example, if the tag is used on two different floors of the same building.

Speed

Use an estimated value for the speed at which the tag is likely to move. A common value that you can use for speed is 2.5 m/s (5.5 mph or 9 kph), which is slow jogging speed.

If your site requires precise locations, you can experiment by using various values to identify the values that provide the most reliable results.

Setting the Motion Model

The Model Type parameter specifies the motion model, which is used for extrapolating the movement of the tag.

In most situations, you can set this parameter to 2 (Stationary).

Option Description
1 (Planar) The tag position moves in a fixed-height horizontal plane.
2 (Stationary) The tag can move horizontally and vertically, with a minimum and maximum height limitation.

Always select this option for all regular location tracking scenarios.

Applying a Filter

You can apply a filter to either:

  • A tag range, by specifying the filter to be assigned to a range of tag IDs.
  • A tag type, by specifying the filter to be assigned to a tag type (this takes precedence over a tag range).
  • A particular tag, by specifying the filter to be assigned to a specific tag ID (this takes precedence over a tag type).

Tag ranges must not overlap. However a tag range that is a subset of another tag range is supported, as shown in the following example.

Filter Range Supported (Yes/ No)
Filter 1 range:

00:11:CE:00:00:00:01:00 to 00:11:CE:00:00:00:01:FF

Filter 2 range:

00:11:CE:00:00:00:01:C0 to 00:11:CE:00:00:00:02:40

No. The tag ranges overlap from 01:C0 to 01:FF.
Filter 1 range:

00:11:CE:00:00:00:01:00 to 00:11:CE:00:00:00:01:FF

Filter 2 range:

00:11:CE:00:00:00:01:C0 to 00:11:CE:00:00:00:01:DD

 Yes. Tags in the smaller range use Filter 2. Tags in the larger range (excluding tags in the smaller range) use Filter 1.

To apply a filter to a tag, tag type or tag range:

  1. On the Set up tag filters tab, do one of the following:

    • To apply a filter to a set of tags, double-click <Add new tag range>. Specify the range of tag IDs, in hexadecimal format.

    • To apply a filter to a tag type, double-click <Add new tag type>. Specify the name of the tag type, and (optionally) the name of a different tag type to use as a template for this new tag type. (See Tag Types and Monitoring Tag Battery Usage for further information.)

    • To apply a filter to a particular tag, double-click <Add new tag>. Specify the tag ID, in hexadecimal format.

      You can find the tag ID on its case.

  2. Apply the required filter.

  3. Save your changes.

The sensors start tracking the tag, the set of tags, or tag types according to the filter settings.

You can change the filter assigned to a tag, tag type or tag range by slowly double-clicking on a current filter to display a menu of available filters to choose from.

Checking Filters

To check that the filters are working as expected:

  1. Review events, as described in Reviewing Location Events.

  2. Check the performance of filters by comparing new events with previous events.

    You can also use command-line tools for this.