RVR Sensor Options
Visibility Sensors
Luminance / Ambient Light Sensors
Runway Light Intensity Monitor
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Current Monitoring |
Belfort 6000 Visibility Sensor
Belforts 6000 Visibility Sensor is designed to monitor visibility conditions over a range of 0 - 10 miles (0 - 16 km). The Model 6000 includes RS-485 and 4-20 outputs. These allow for much more flexibility in deployment, as they can be sent long distances. This is the sensor that is being used in the U.S. Air Forces OS-21 FBS stations.
Belfort has applied its proven experience with visibility technology in designing this new sensor for applications which still require high accuracy, but over a more limited range of visibility.
Visibility is detected using widely accepted principles of forward scattering. A high output infrared LED transmitter projects light into a sample volume, and light scattered in a forward direction is collected by the receiver. The light source is modulated to provide excellent rejection of background noise and natural variations in background light intensity. The sensor's analog output signal is proportional to visibility.
The housing is greatly improved in this model, minimizing the number of seals, improving the type of seal, and reducing the connectors to one. The 6000 can be installed on a simple pipe mast. They are constructed entirely of corrosion resistant materials for durability. The standard unit includes small heaters to prevent condensation on the optics. Optional hood heaters are available for areas where the sensor will operate in freezing weather. Transmitter and receiver hoods are designed to divert precipitation away from the optical paths.
| SPECIFICATIONS – BELFORT 6000 VISIBILITY SENSOR | |
| Range | 20 ft. to 10 miles |
| Accuracy | +/- 10% or 10 feet |
| Scatter Angle | 42º Nominal |
| Light Source | Infrared LED |
| Output | RS-232, and RS-485 300 to 38,400 baud |
| Temperature | -40º C to +55º C |
| Humidity | 0 - 100% |
| Power Requirement | 7W @ 12 VDC or 10W @ 110/220 VAC |
| Pwr Req. with Low Temperature Option | 90W @ 12 VDC |
| Dimensions | 41 in. x 11 in. x 21 in. |
| Weight | 20 lbs. |
Vaisala FS11 Visibility Sensor
The FS11 incorporates a new technique that measures and compensates for the attenuation effect of window contamination. It ensures that measurement accuracy is maintained throughout the recommended interval between window cleanings - and it lengthens this interval.
This visibility sensor offers a measurement range of up to 75 km and meets WMO, ICAO and FAA specifications for visibility measurement in civil aviation.
Four main design features are combined in the FS11 to ensure that it operates reliably in the harshest weather. The first is the window contamination compensation technique. The second is the "head-down" design of the optical heads, which protects them against virtually all wind-blown particles (even those flying horizontally). High power heaters are the third feature, each with its own temperature monitoring and control mechanism to prevent snow accumulation during the heaviest snow storm. As a final measure, there is optical path clearance to verify that measurement is not affected by obstructions.
| SPECIFICATIONS - VAISALA FS11 VISIBILITY SENSOR | |
| Range | 17 ft. to 40 miles with 1, 3 and 10 min.averaging |
| Accuracy | +10% range 17 ft. — 6.21 miles +20% range 6.21 miles — 47 miles |
| Scatter Angle | 42º |
| Light Source | Near Infrared LED |
| Output | Serial line RS-232 or opto-isolated RS-485 (2 wire) or optional data modem |
| Temperature | -40º C to +65º C, optional -55º C to +65º C |
| Humidity | 0 - 100% |
| Power Consumption | 300 VA maximum (60 VA +240 VA defrosting heaters) |
| Dimensions | 71 in. x 23 in. x 13 in. |
| Weight | 81.6 lbs. |
Biral HSS VPF-730 Visibility Sensor
The types of Present Weather that can be measured with this sensor are: Drizzle, Rain, Snow, Fog, Haze, Mixed Precipitation, Dust, Smoke, as well as Precipitation and Fog at the same time (many others cannot do this, especially below 1 km).
HSS was the first company to produce a Forward Scatter Meter using an infrared light source, nearly two decades ago, and has remained ahead of the competition ever since. The BIRAL HSS sensors have unmatched reliability, accuracy, and durability.
There will never be any corrosion on any BIRAL sensors due to the fact that we only use hard anodized aluminum combined with a salt dip brazing process. Although expensive, this process has proven worthwhile for accuracy and durability.
Readings of precipitation and fog at the same time cause many other manufacturers problems with shallower angles. BIRAL is the only manufacturer to provide both visibility and precipitation data with reduced visibility. Others report only precipitation (and not fog) when visibility drops below thresholds associated with shallower angles.
The wavelength of the light source is 0.88 um, and is considered to be the best for accuracy where it counts most... visibilities around 1 mile or less. The choice of the wavelength is critical when deciding how the sensor performs in terms of accuracy and shifts in light spectrums. The 0.88 um used by BIRAL is perfect for the shift in light from white (visibility below 1 mile) to blue (visibility from 1 mile to several miles) as almost all sensors using Forward Scatter Metering can detect the white spectrum well, but BIRAL is the only manufacturer to detect the shift from white to blue, and thereby maintaining accuracy values to much higher visibility ranges.
The lenses look out on a completely horizontal plane, therefore, the measurements are not influenced by the surface below or around the sensor volume. This is a common problem when there is a snow pack surface below the sensor, or a thin layer of water reflecting the signal back to the receiver on the other surfaces. The issue of the lenses becoming obscurred from blowing snow or drifting snow, and thereby affecting the measurements, has been dealt with by the use of anti-dew window heaters and/or hood heaters in the BIRAL design.
| SPECIFICATIONS - BIRAL HSS VPF-730 VISIBILITY SENSOR | |
| Range | 33 ft. to 47 miles |
| Accuracy | +/- 2% within the first mile, +/- 10% thereafter up to 10 miles, +/- 20% thereafter up to 47 miles |
| Scatter Angle | 45º |
| Light Source | Infrared LED |
| Output | Digital only (RS-232, RS-422) |
| MTBF | 8 years |
| Weight | 15.4 lbs. |
Belfort 6300 Ambient Light Sensor
The ambient light sensor is used at a single point at the airport. It is typically co-located with one of the visibility sensors, and can integrate its data with that sensor, eliminating the need to run a separate communication line to the ambient light. Most installations have the ambient light sensor co-located with the centerfield visibility sensor. The physical package for the sensor is the same proven design used in over 1000 ASOS visibility sensors. Window, hood, and electronic heaters are employed for low temperature and blowing precipitation conditions.
Extensive self-diagnostics are employed, and because this sensor is an "upward" pointing sensor, diagnostics are also included to alert the user to fouled or blocked windows.
| SPECIFICATIONS - BELFORT AMBIENT LIGHT SENSOR | |
| Range | 0.5 to 30,000 FC/M2 |
| Field of View | 6.0º |
| Output | RS-232 |
| Temperature | -55º C to +60º C |
| Humidity | 0 - 100% |
| Power Requirement | 1W @ 12 VDC or 10W |
| Pwr Req.with Low Temperature Option | 11W @ 24 VDC |
| Weight | 2.5 lbs. |
Vaisala LM21 Ambient Light Sensor
The LM21 provides similar monitoring and contamination compensation features as the FS11, and raises background luminance measurement to a new level of reliability.
Biral PDN-21 Ambient Light Sensor
The PDN-21 (ICAO) ambient light sensor is a precision photometer. The ambient light sensor will provide accurate day/night indications within the specified levels of illumination when subjected to any temperature within the range of -40º C to +49º C.
A combination of three factors; the detector configuration, the window aperature, and the window precipitation shield, provide the photometer with an angular field-of-view coverage in excess of 50º.
The spectral response of the photodiode is tailored to that of the human eye by means of an integral IR rejection filtration. Peak response is at 555 nm and transmission of wavelengths greater than 750 nm is less than 3%.
| SPECIFICATIONS - BIRAL PDN-21 AMBIENT LIGHT SENSOR | |
| Range | Output: 0 - 10 Volts Luminance: 0 -12,000 CD/M2 |
| Field of View | Greater than 50º |
| Output Impedance | Less than 50 Ohm |
| Temperature | Operating: -40º C to +49º C Survival: -67º C to +93º C |
| Humidity | 0 to 100% |
| Power Requirement | Electronics: Less than 1W No Dew Window Heater: 3W |
| Weight | 0.5 kg |
