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Lufft Ceilometer CHM 8k

Highest confidence under low clouds with maximum data availability and minimum maintenance

The new Lufft CHM 8k ceilometer empowers meteorologists at weather services and airports to make the right decisions with highest confidence and minimal maintenance. Especially in the critical height below 1 km, the Lufft CHM 8k detects cloud bases in any place and season with outstanding precision and reliability. Internal data storage and a battery backup enable unmatched sensor uptime and data availability even at the harshest conditions.

Using the Lidar technology, it detects backscatter aerosol profiles / structure in multiple layers, cloud bases, cloud penetration depths as well as vertical visibility and issues the sky condition index. It has an operating range of up to 8,000m (26,200 ft) and is equipped with an integrated controller offering a fully embedded real-time calculation of all target parameters and comfortable user interfaces.

  • Aerosol backscatter profile, cloud base height, cloud penetration depth, aerosol layer height, cloud cover, vertical visibility, Sky Condition Index
  • Optical (LIDAR)
  • Measuring range of up to 8 km (26.246 ft), simple & eye-safe, service-friendly due to modularity, various data telegrams, sensitivity in the range of the Lufft CHM 15k, suitable for the most demanding environments
  • RS485 (ASCII communication), LAN (Web-Interface, (S-)FTP, NetTools); optional: DSL modem, RS485 full-duplex
  • 8349.01-010
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Advantages of the Cloud Height Sensor / Ceilometer CHM 8k

These are the advantages of the ceilometer CHM 8k:

  • Confident detection of low clouds with minimum False Alarm Rate (FAR) and an outstanding Probability of Detection (POD) even at extreme conditions.
  • Maximum sensor uptime and data availability thanks to integrated data storage and a robust battery backup (-40 °C to 60 °C).
  • Minimum maintenance from self-cleaning construction: Snow gets melted, water flows down and washes dust away.
  • Safe and certified operation in compliance with UL50e (North America), TÜV (Europe), ICAO GRF.
  • Easy installation and handling thanks to self-contained design – no additional computer needed.
  • High flexibility from support of multiple communication protocols and software standards.

Interested in more information about the cloud height sensor CHM 8k? Reach out to us and talk to one of our experts!

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Example of use of the Cloud Height Sensor / Ceilometer CHM8k

The fields of application / users / insallations sites of the Lufft CHM8k ceilometer are:

  • Weather / meteo services
  • Automated Surface Observing Systems (ASOS)
  • Airports / aviation
  • Environmental Protection Agencies or universities (for environmental studies of air quality, fine dust & mixing layers)
  • Heliports

Interest in more information about the cloud height sensor CHM 8k? We can recommend you to download our free CHM 8k sensor guide, where you can find additional insights on measurement comparisons, product features and more:

You need support or advice? Contact us!

Brochure - Lufft - Ceilometers CHM 8k and CHM 15k
Certificate IEC61010
TÜV Certification - CHM15k, CHM8k
EU declaration of conformity - Lufft CHM8k
EU declaration of conformity - Lufft CHM8k
Firmware - Lufft - CHM 1.130_552
Please check compatibility via CHM web interface
Manual - Lufft - CHM 8k (EN)
Download as PDF
Measuring principle Lidar (light detection and ranging)
Measuring parameters
Aerosol backscatter profile
Measuring range 0 m … 10 km (0 … 32,808 ft)
Time resolution 2 … 600 s
Range resolution 5 m
Reported Range resolution 5 - 30 m in 5 m steps
Cloud base heights, Cloud penetration depths 1 - 9 layer (configurable);
3 layer preset
Cloud detection range 5 m … 8 km (16 … 26.246 ft)
Distance measurement accuracy against hard target 'Greater of ±5 m (±16 ft) or ±0.2%
Additional measuring quantities Cloud cover in octas (WMO 2700), Vertical visibility, Aerosol layer heights (mixing layer, boundary layer), sky condition index
Quality and auxiliary values External and internal temperature; window, laser and receiver status, input voltage control, humidity
Standard interfaces RS485 half-dublex (ASCII communication), LAN (Web-Interface, (S-)FTP, NetTools)
Optional interfaces DSL modem, full dublex
Electrical parameters
Power supply 230 VAC or 115 VAC, ±10 %
Mains frequency 50, 60 hz
Power consumption 250 W (w/o housing heater)
450 W (with housing heater)
UPS functionality (opt.) Internal backup battery for electronics (1 hour covering all operating conditions)
Laser-optical parameters
Light source Laser diode
Wavelength 905 nm
Pulse energy 2 μJ max. (1,6 μJ typ.)
Pulse repetition frequency 8 kHz
Filter Bandwidth 25 nm
Field of view receiver 1.1 mrad
Operating Safety
General Safety IEC 61010-1 (TUEV Rheinland certified)
UL 61010-1 (TUEV SÜD certified)
AS 61010.1 (Australien und Neuseeland)
CAN/CSA-C22.2 No. 61010-1 (TUEV SÜD certified)
Laser protection class 1M, IEC 60825-1:2014; complies with CFR 1040.10
Protection level housing IEC 60529: IP66
EMC EN 61326 - 1 Klasse B
FCC: 47 CFR Part 15, Class B
Certifications CE (230 VAC); 115 VAC version compatible with FCC/ CSA
International standards Complies with ICAO frangibility requirements
Operating Conditions
Operating Conditions ISO 10109 - 11
Temperature range -40...+60 °C
Relative humidity 0...100 %
Wind load 60 m/s
Dimensions 500 x 500 x 1550 mm
Weight 70 kg (130 kg incl. Packaging)
Download as PDF

CHM 8k / CHM 15k: Does the device have a window contamination control?

Depending on the degree of soiling of the windows, a corresponding NetCDF variable (state_optics) is reduced from its original value of 100. A warning is issued when a certain limit value (70) is reached and the status code of the device is changed. This can be used as a recommendation for cleaning the windows.

CHM 8k / CHM 15k: Is it possible to get the device-specific overlap data for own calculations?

The overlap data corresponding to your device can be sent to you in the form of a file. Please contact us at

CHM 8k / CHM 15k: How should the device be installed in relation to the sun?

How should the device be installed in relation to the sun?

The device side with the door should face south. In case of high solar radiation (south of 35° northern latitude), the device should additionally be tilted to the north via an adapter angle in order to keep the influence of solar radiation as low as possible.

This applies to the northern hemisphere. For the southern hemisphere, the opposite cardinal directions apply.

Please consider that measurements against the sun are not possible for an optical measuring device.
We offer corresponding angle adapters as accessories. Please feel free to contact us on this subject.

CHM 8k / CHM 15k: Can the status of the NTP query (time server) be verified?

As of firmware version 1.020, the web interface / page "Process Status" displays the server name, status of availability, current time offset, query interval, etc.

Note: If the time offset exceeds 1000 s (approx. 17 minutes), the iterative adjustment via the NTP protocol no longer works. The time must then be set manually, e.g. via the web interface, or the device must be restarted. The time is newly set at system startup when the NTP server is available.

CHM 8k / CHM 15k: What are the maximum cable lengths for the CHM 8k / CHM 15k?

The standard cable length for power supply and data transfer is 10 m. Longer cable connections are also possible. Please feel free to contact us for this.

CHM 8k / CHM 15k: In which cases does the case fan start?

When the device is started: for typ. 2 minutes, in case of dirty or wet panes as well as detected rain, for cooling at interior temperatures > 39 °C and per default every hour for removal of dust, pollen, etc. To minimize possible noise pollution, the activation of the fan can be limited via the BlowerMode parameter. Please pay attention to the correctly set parameter TimeZoneOffsetHours for compliance with possible night/rest times. Further information can be found in the manual, chapter 8.1

CHM 8k / CHM 15k: Why is Cloud Cover -2 displayed after starting the device?

For the calculation of the cloud cover at least the last 30 minutes of the measured data are used. Without the complete data (temporal) no calculation is possible -> "-2" is output.

CHM 8k / CHM 15k: What should be considered with regard to the use of SD cards?

Cards with a memory capacity of up to 32GB can be used from Speed Class 10 on. We recommend industry standard. Formatting must be done with FAT32 file system. Formatting via the web interface is possible and recommended. To change the card, the device must be shut down and externally disconnected from the power supply and secured against being switched on again.

CHM 8k / CHM 15k: Why is there a delay in displaying data in the web interface or why is it only displayed after clicking "Update"?

Automatic display has been disabled on the Viewer page to keep traffic low on low data rate connections. The other data is updated every 15s. On the Process Status page, the data is updated every 60s.

CHM 8k / CHM 15k: How should the NetCDF variables "time" and "range" be interpreted?

"time" means the end time of the measurement

"range" means the beginning of the range

CHM 8k / CHM 15k: Can the device be operated, restarted or deactivated remotely?

The device can be configured, restarted and shut down conveniently and password protected via the RS485 interface as well as via LAN/WAN and web interface.
Both the firmware and the operating system are restarted via 'restart system'.
Via 'shutdown system' the system is shut down and must be switched on again for a restart on site. Please take this into account, especially if the device is not installed in the immediate vicinity.
Please find a detailed description of the functionality in the manual.

CHM 8k: What is the minimum distance between two devices in order to prevent mutual interference of the backscatter signals?

A distance of 10 m between the devices is unproblematic. A distance of down to 3 m is possible by slightly tilting both units by 0.5 ° each via the leveling screws in the opposite direction. For even smaller distances, adjustments can be made by OTT HydroMet. Please feel free to contact us for this purpose at