Senseca ALS-2 Ambient Light Sensor for Runway Visual Range (RVR) Systems
Senseca ALS-2 Ambient Light Sensor for Runway Visual Range (RVR) Systems
Senseca ALS-2
The Senseca ALS-2 is an ambient light sensor for background luminance measurement, designed for use in instrumented Runway Visual Range (RVR) systems. It measures ambient light conditions at the runway side and provides the luminance data required for reliable RVR calculation in aviation applications.
The sensor measures background luminance from 0 to 40,000 cd/m² with a resolution of 1 cd/m², with values averaged over a 60 s period. The optical system has a 6° field of view and a spectral response from 420 to 675 nm, with a peak at approximately 565 nm, corresponding to the photopic sensitivity of the human eye.
The ALS-2 is designed to comply with ICAO, WMO, and FAA specifications and guidance for RVR applications.
For integration into meteorological and aviation systems, the sensor supports RS232, RS422, and RS485 serial interfaces. It can operate as a standalone device or connect directly to a compatible Senseca visibility or present weather sensor, with luminance values appended to the host sensor’s output data string.
Optional dual 0–10 V analog outputs are available:
- low range: 0–4,000 cd/m²;
- high range: 0–40,000 cd/m².
For reliable long-term outdoor operation, the ALS-2 includes a window heater as standard, together with window contamination monitoring and compensation. Extensive self-test and diagnostic functions are also provided.
The standard operating temperature range is -40 to +70 °C, extending down to -60 °C with optional internal heaters. The sensor operates at 0–100% RH and provides IP66 protection.
The sensor and window heater are powered from 9–36 V DC, while the optional hood and internal heaters use 24–28 V AC/DC.
The pole-mount bracket is suitable for poles with an outer diameter of 40–64 mm and allows elevation adjustment from 0° to 45° for correct sensor alignment.
For more information:
https://www.senseca.com/en/product/als-2-ambient-light-sensor-for-runway-visual-range-rvr
Technical Specifications – Senseca ALS-2
General Specifications
| Parameter | Value |
|---|---|
| Serial Data Outputs | RS232, RS422, or RS485 |
Power Requirements
| Parameter | Value |
|---|---|
| Sensor Power Supply | 9–36 V DC |
| Hood Heating Power Supply | 24 V AC or DC |
| Sensor & Window Heater Power Consumption | 2 W |
| Hood Heater Power Consumption | 12 W |
| Extended Heating Power Consumption | 18 W, including hood heater |
Additional Features
| Parameter | Value |
|---|---|
| Window Heater | Fitted as standard |
| Window Contamination Monitoring and Compensation | Fitted as standard |
Environmental Specifications
| Parameter | Value |
|---|---|
| Operating Temperature | -40 to +70 °C |
| Operating Temperature with Extended Heating | -60 to +70 °C |
| Operating Humidity | 0–100% RH |
| Ingress Protection Rating | IP65 |
Physical Specifications
| Parameter | Value |
|---|---|
| Material | Aluminium with powder-paint finish and hard-anodized base layer |
| Weight | 1.5 kg |
| Elevation Angle Range from Horizontal | 0°–45° |
| Warranty | 2 years |
| Lifetime | >10 years |
Certification and Compliance
- CE certified
- EMC compliance with EN 61326-1997, 1998, 2001
- RoHS and WEEE compliant
Measurement Specifications
| Parameter | Value |
|---|---|
| Measured Parameter | Background luminance / ambient light |
| Output | Serial data |
| Measurement Range | 0–40,000 cd/m² |
| Resolution | 1 cd/m² |
| Measurement Error | ≤10% of measured value or 2 cd/m², whichever is greater |
| Spectral Sensitivity Range | 420–675 nm |
| Peak Spectral Sensitivity | 565 nm |
| Spectral Response | Analogous to the CIE photopic luminous efficiency curve |
| Field of View | 6° |
| Averaging Period | 60 s |
Ordering Codes
| Option | Code / Description |
|---|---|
| Configuration | RC – regular configuration; SC – special configuration |
| Data Output – B | VPF connector, 1.5 m cable with connector |
| Data Output – D | SWS / RS232 output, 1.5 m cable with flying leads |
| Data Output – E | RS422 / RS485 output, 1.5 m cable with flying leads |
| Heating – EH | Extended heating |
| Heating – HV | With heating |
| Heating – NH | Without heating |
Example code: ALS2.HV.D.RC
Optional Accessories
| Code | Description |
|---|---|
| ALS-2.CAL | Ambient Light Sensor Calibrator |
| ALS2.WTY | 1-year extended warranty |
The sensor is supplied in sturdy recyclable foam-filled packaging with a pole mounting kit (1 × U-bolt and saddle), user manual, and calibration certificates.