Calibration

Every room is different. Ceiling height, furniture, airflow and the space above the ceiling all affect the readings. This page shows per sensor what you can adjust and how to make a good comparison.

What You Can Adjust

How to Make a Good Comparison

• Wait at least 30 minutes after a start. The first SCD41 readings are not meaningful.
• Turn the LED ring off, so its heat and light do not play a part.
• Keep conditions stable: no open windows, no direct sun and no heating that just switched on.
• Use a reliable reference at the height of the sensor, not at desk height.
• Compare several readings over time, not a single value.

Radar: LD2412 + LD2450

Tune the LD2412 first. Move on to the LD2450 zones once Presence behaves well.

Dynamic Background Correction

This teaches the LD2412 what the empty room looks like. Run it after installation and when presence stays on in an empty room.

1. Empty the room: no people, no pets.
2. Stop moving objects such as fans and curtains.
3. Open the device page in Home Assistant.
4. Press LD2412 Start Dynamic Background Correction. You find it under Diagnostic.
5. Leave the room and wait until LD2412 Dynamic Background Correction is off again.

Important: If someone is in the room during the correction, the radar can learn that person as background.

Presence Timeout

LD2412 Presence Timeout and LD2450 Presence Timeout set how many seconds presence stays on after the last detection. Raise the timeout if presence drops out while someone sits still. Lower it if the room should read as empty sooner.

Distance Gates

The LD2412 divides its range into gates. At the default resolution of 0.75 m, each gate covers about 0.75 m, counted from the sensor and not across the floor.

• LD2412 Maximum Distance Gate (2 to 13) is the furthest gate it uses. Lower it when the radar sees past the room, for example through a thin wall.
• LD2412 Minimum Distance Gate (1 to 12) is the closest gate it uses.
• LD2412 Distance Resolution changes the length of a gate: 0.2 m, 0.5 m or 0.75 m. A smaller value gives more precision but a shorter range.

The current firmware has no thresholds per gate.

LD2450 Zones

The LD2450 has 3 rectangular zones in the radar. Coordinates are in millimeters, with the sensor at zero.

1. Walk through the area you want and note LD2450 Target 1 X and LD2450 Target 1 Y at the corners.
2. Enter them in LD2450 Zone 1 X1, Y1, X2 and Y2.
3. Set LD2450 Zone Type:
   • Detection: the radar only reports targets inside the zones.
   • Filter: the radar ignores targets inside the zones.
   • Disabled: no zone filtering.
4. Check LD2450 Zone 1 Target Count while you walk in and out of the zone.

LD2450 Multi Target Tracking switches between tracking several people and one person.

Polygon zones in the Room Designer will follow with release firmware for this configuration.

Radar: LD2460

The firmware runs the LD2460 in top installation mode. Leave Tracking Radar Installation Mode on top. Tracking Radar Installation Height and Tracking Radar Installation Angle are for wall mounting and are not needed on the ceiling.

Walk Test

Do this before you draw zones in the Room Designer.

1. Walk in a straight line through the room and watch Tracking Target 1 X and Tracking Target 1 Y. One of them should change clearly.
2. Walk at a right angle to that line. Now the other coordinate should change clearly.
3. Sit still in the area you care about and check that you stay detected.

The LD2460 reports coordinates in steps of 0.1 m, so small jumps are normal.

Detection Range

Tracking Radar Detection Distance, Tracking Radar Detection Start Angle and Tracking Radar Detection End Angle create one detection sector in the radar. On the ceiling the radar accepts 0.1 to 4.0 m and 0 to 360 degrees. The start angle must be lower than the end angle.

Use this to cut off a whole direction at the source. For irregular room shapes, use the polygon and exclusion zones in the Room Designer.

The radar stores these settings itself. After a restart the entities can show unknown for a moment, and changing a value can briefly pause target updates.

Reflections

Mirrors, metal wardrobes, windows and other large reflective surfaces can create a second stable target or shift a position.

1. Temporarily cover the surface to confirm the cause.
2. Remove a whole direction with the detection angles, or draw an exclusion zone in the Room Designer for a local area. The radar has two exclusion slots.

Sensitivity

Sensitivity of the LD2460 is not a Home Assistant entity. It is available through the HLK Radar Tool app, and the module stores the setting.

Radar: LD6002B

Tuning options for the LD6002B follow with the firmware, which is not finished yet.

Light Sensor

The sensor sits behind a light window in the ceiling, so it measures the light that reaches the ceiling and not the light on your desk. Illuminance Calibrated is still being refined before release, so its values can change with a firmware update. Thresholds in automations may then need adjusting.

To compare with a lux meter, hold the meter just below the sensor with the LED ring off and compare at several light levels. There is no offset entity for light. For automations, simply use the value the entity shows when the room is as bright as you want it.

CO2

Automatic self-calibration is on. The SCD41 corrects itself over time, as long as the room regularly gets fresh air. Give it 1 to 2 weeks after installation. The current firmware has no button for manual CO2 calibration.

To check the reading, ventilate the room well with no people in it. Fresh outdoor air is about 400 to 430 ppm.

Temperature and Humidity

Recessed mounting and heat from electronics influence the temperature reading. Use temperature mainly for trends and wait until the sensor has stabilized after a start before you judge it.

Temperature Offset and Humidity Offset correct the readings without reflashing. They run from -50 to +50 in steps of 0.1, start at 0, are added on top of the factory correction and are kept after a restart.

1. Make a comparison as described at the top of this page.
2. Calculate the offset: reference minus reading.
3. Enter the value on the device page under Configuration.

Examples:

• SCD41 Temperature reads 24.5 °C and your reference reads 23.8 °C: set Temperature Offset to -0.7.
• Humidity reads 48% and your reference reads 52%: set Humidity Offset to 4.

Temperature Offset only changes the temperature that is shown. It does not recalculate humidity, so check humidity separately.

Air Pressure

Air Pressure needs no calibration and has no offset entity. BMP388 Temperature is the temperature inside the device, so do not compare it with room temperature.

Good to Know

• Keep notes of the settings and offsets you changed.
• Check the calibration again after you move the sensor.
• Radar settings are stored in the radar module. LD2412 Factory Reset and LD2450 Factory Reset put them back to factory settings.

Related

• Sensor Definitions
• Radar and Sensor Modules
• Troubleshooting