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ADB Safegate 6498 Product Manual

Present weather and visibility sensor
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Model 6498
Present Weather and Visibility Sensor
PRODUCT MANUAL
6498/Rev E

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Summary of Contents for ADB Safegate 6498

  • Page 1 Model 6498 Present Weather and Visibility Sensor PRODUCT MANUAL 6498/Rev E...

  • Page 2: Disclaimer / Standard Warranty

    Material Handling Precautions and Storage precautions that must be followed. ADB SAFEGATE reserves the right to examine goods upon which a claim is made. Said goods must be presented in the same condition as when the defect therein was discovered. ADB SAFEGATE furthers reserves the right to require the return of such goods to establish any claim.
  • Page 3 Model 6498 Present Weather and Visibility Sensor Revision History Revision Date Summary of Changes 2014 Oct 30 Initial release 2017 Nov 20 Added Day/Night Sensor and updated calibration instructions Updated options in Section 1.3 and corrected fuse part number, added Chapter 3...

  • Page 4: Table Of Contents

    Model 6498 Present Weather and Visibility Sensor Contents 1. Overview ................................... 6 1.1 Features6 1.2 Models 6 1.3 Options And Parts List 7 2. Visibility .................................... 8 2.1 Definitions 8 2.2 Units And Scales 9 2.3 Meteorological Requirements 9 2.4 Measurement Methods 9 2.5 Basic Equations 10...
  • Page 5 Model 6498 Present Weather and Visibility Sensor 7.4 Trouble Shooting 47 8. Calibration ..................................48 8.1 Connections 49 8.1.1 Direct Connect Sensors 49 8.1.2 Standalone Sensors 50 8.2 Calibration Procedure 52 8.2.1 Analyzing the Calibration Values  56 8.3 Dirty Window Zero Calibration 57 9.

  • Page 6: Overview

    The 6498 uses the well-established forward-scatter system for visibility measurement, using a 42° scatter angle. The 6498 uses high- speed sampling to reduce missed events such as rain and hail, and improves response to other suddenly changing conditions. It identifies precipitation particles from their scattering properties and fall speeds, and combines this with a temperature measurement to identify the weather type.

  • Page 7: Options And Parts List 7

    † Improves Present Weather reporting at or near freezing temperatures (used outside the U.S.) Table 2. Model 6498 Options The replacement parts and accessories in Table 3 are available for the Model 6498 Present Weather and Visibility Sensor. Part Number Description...

  • Page 8: Visibility

    Model 6498 Present Weather and Visibility Sensor 2. Visibility 2.1 Definitions Visibility was first defined for meteorological purposes as a quantity to be estimated by a human observer, and observations made in that way are widely used. However, the estimation of visibility is affected by many subjective and physical factors. The essential meteorological quantity, which is the transparency of the atmosphere, can be measured objectively, and is represented by the meteorological optical range (MOR).

  • Page 9: Units And Scales 9

    , but only scaled miles units are output for the extinction coefficient in the 6498 output data. 2.3 Meteorological Requirements The concept of visibility is used extensively in meteorology in two distinct ways. Firstly, it is one of the elements identifying air- mass characteristics, especially for the needs of synoptic meteorology and climatology.

  • Page 10: Basic Equations 10

    Model 6498 Present Weather and Visibility Sensor Instrumental methods measure the extinction coefficient from which the MOR may be calculated. The visibility may then be calculated from knowledge of the contrast and illuminance thresholds, or by assigning agreed values to them. However, fixed instruments are used on the assumption that the extinction coefficient is independent of distance.

  • Page 11: Meteorological Visibility In Daylight

    Model 6498 Present Weather and Visibility Sensor (0.05) P=x. This equation is used as a basis for measuring MOR with transmissometers. 2.5.1 Meteorological Visibility in Daylight The contrast of luminance is: where L is the luminance of the horizon, and Lb is the luminance of the object.

  • Page 12: Meteorological Visibility At Night

    Model 6498 Present Weather and Visibility Sensor 2.5.2 Meteorological Visibility at Night The distance at which a light (a night visibility marker) can be seen at night is not simply related to MOR. It depends not only on MOR and the intensity of the light, but also on the illuminance at the observer’s eye from all other light sources.

  • Page 13: Principle Of Operation

    Model 6498 Present Weather and Visibility Sensor 3. Principle Of Operation The 6498 has an emitter and detector aligned as shown in Figure 1. Figure 1. Sample Volume The emitter produces a beam of near infrared light pulsed at 1 kHz. A detector has a field of view which overlaps the beam and is inclined at 42 degrees to it.
  • Page 14 Model 6498 Present Weather and Visibility Sensor The 6498 is capable of identifying weather type in addition to measuring visibility. It does this by analyzing the amplitude and width of spikes in the signal corresponding to particles of precipitation passing through the sample volume. The amplitude of the signal is a guide to the size of the particle and the width, because it represents the time taken for the particle to fall through the sample volume, is proportional to the fall speed, see Figure 2.

  • Page 15: System Description

    Model 6498 Present Weather and Visibility Sensor 4. System Description Figure 3 compares the installation of the standalone and Direct Connect Present Weather/ Visibility sensors. The optional Background Luminance Sensor accessory described in Section 9.2 is also shown. Figure 3.

  • Page 16: Sensor Heads 16

    Model 6498 Present Weather and Visibility Sensor 4.1 Sensor Heads The 6498 has two sensor heads, the emitter head and the detector head. Figure 4. Present Weather and Visibility Sensor Heads The sensor heads are heated to prevent dew, frost, and snow from building up on the lenses, and are self-regulating devices.

  • Page 17: Universal Power And Communication Module (Upcm)

    Figure 5 shows the layout of the enclosure. The UPCM serves as the interface between the 6498 and the data processing system such as the Central Data Processor in an Automated Weather Observing System. It provides the power to the 6498, and collects the data to forward in response to a poll.

  • Page 18: Installation

    The Model 6498 sensors may be mounted on the top of a building is acceptable if it located near the center of the building away from the wind turbulence that may occur near the edges. The installation must be rigid so that wind- induced vibration does not cause false alarms.
  • Page 19 Model 6498 Present Weather and Visibility Sensor FAA Order JO-6560-20C provides specific locations and elevations where the Present Weather and Visibility Sensor must be sited with respect to the runway, taking into account whether RVR instrumentation and precision instrument runways are present.

  • Page 20: Mast Installation 20

    Model 6498 Present Weather and Visibility Sensor 5.2 Mast Installation The sensor head mounts near the top of a 1.5” (38 mm) mast section and the electronics enclosure for the standalone sensors mounts near the top of the 2.5” (64 mm) mast section, which provides the necessary rigidity for the mast. Construct a foundation for the mast according to the details in Figure 7.

  • Page 21: Conduit And Junction Boxes 21

    Model 6498 Present Weather and Visibility Sensor 5.3 Conduit And Junction Boxes For most installations, conduit should be routed to the sensor to accommodate the power line to the standalone sensor and the signal line from any sensor to the host computer or Data Collection Platform (DCP). For ease of connection, junction boxes can be installed near the base of the mast, and rigid or flex conduit installed between the junction boxes and the UPCM enclosure.
  • Page 22 Model 6498 Present Weather and Visibility Sensor Figure 9 shows the conduit and junction box installation details for Direct Connect sensors. Figure 9. Sensor Conduit and Electrical Junction Box Installation for Direct Connect Sensors CODE& Edition UM-5055, Rev. 1.1.26, 2024/11/13 125...

  • Page 23: Sensor Installation 23

    Model 6498 Present Weather and Visibility Sensor 5.4 Sensor Installation There are two stages to the sensor installation, first the sensor head and then for standalone sensors the electronics enclosure. The sensor head and electronics enclosure are mounted to a pole that is installed into a study foundation. (Figure 10) Only the sensor head is mounted for Direct Connect sensors.

  • Page 24: Sensor Head Installation 24

    Model 6498 Present Weather and Visibility Sensor 5.4.1 Sensor Head Installation A pole mounting kit is supplied with the 6498 sensor head. The mounting kit will attach the sensor head near the top of a 1.5” (38 mm) pipe. Position the top clamp as shown in Figure 11. Tighten the U bolt using the nuts and washers provided.

  • Page 25: Electronics Enclosure Installation (Standalone Sensors Only)

    Model 6498 Present Weather and Visibility Sensor 5.4.2 Electronics Enclosure Installation (Standalone Sensors Only) Attach the electronics enclosure to the pole using the hardware supplied with the UPCM. Two U-bolts are used to secure the enclosure to the pole. These additional steps will help keep the mounting secure and corrosion-resistant.

  • Page 26: Grounding 26

    5.4.3 Grounding The 6498 sensor heads and electronics inside the electronics enclosure must be properly grounded using the grounding lug in the lower section of the sensor head (Figure 14) and the bottom of the electronics enclosure for standalone sensors (Figure 15).
  • Page 27 Model 6498 Present Weather and Visibility Sensor To install grounding, follow the steps below (see Figure 16). Drill and tap a ¼ -20 hole in the mast. Install a grounding clamp in the hole. Connect one end of a length of ground cable to the grounding clamp on the mast.

  • Page 28: Electrical Connections 28

    5.5 Electrical Connections The 6498 has two IP67 rated cable connectors with cables to connect the sensor head to the electronics enclosure (standalone sensors) or to the Model 1192 DCP (Direct Connect sensors). One cable carries DC power and data communications, the second cable connector carries 24 V AC for the sensor hood heaters.

  • Page 29: Direct Connect To Model 1192Dcp

    Figure 18 summarizes the connections to the Model 1192 DCP . Figure 18. Model 6498-DC Present Weather and Visibility Sensor Direct Connect Signal and Power Wiring CODE& Edition UM-5055, Rev. 1.1.26, 2024/11/13 125 © ADB SAFEGATE, All Rights Reserved...

  • Page 30: Electronics Enclosure (Standalone Sensors)

    Model 6498 Present Weather and Visibility Sensor 5.5.2 Electronics Enclosure (Standalone Sensors) Figure 19.shows the external connections at the bottom of the electronics enclosure. • AC power conduit • Power and data cable from sensor • Heater cable from sensor •...
  • Page 31 Model 6498 Present Weather and Visibility Sensor Figure 20 shows the inside of the electronics enclosure. Figure 20. Present Weather and Visibility Sensor Enclosure (inside view) CODE& Edition UM-5055, Rev. 1.1.26, 2024/11/13 125 © ADB SAFEGATE, All Rights Reserved...
  • Page 32 5.5.2.2 Summary of Signal and Power Wiring Connections (Standalone Sensors) Table 4 provides the power and serial connections for the 6498 Sensor. The Universal Power and Communication Module may also be configured to provide RS-232 signals for the computer or Data Logger connection to Serial Output 1 (SER0 in the UPCM configuration parameters).
  • Page 33 Model 6498 Present Weather and Visibility Sensor Standalone Signal and Power Wiring Figure 22 shows the signal and power wiring of the Model 6498 Present Weather and Visibility Sensor to the UPCM through the Maintenance Interface Module. Note that the sensor hood heaters are wired directly to P2, the 24 VAC output on the UPCM.

  • Page 34: Configuring Serial Output 1 34

    UPCM. If it becomes necessary to change the configuration, contact ADB Safegate., for a microSD card that already has the desired configuration. If it is desired to modify the configuration file locally do the following: remove the existing microSD card, place it in an adapter or a USB microSD card device, and use a computer to edit the configuration file using a text editor such as Notepad.
  • Page 35 Model 6498 Present Weather and Visibility Sensor This procedure explains how to remove and replace the microSD card containing the configuration file. Turn the DC power supply off (DC on/off switch). Remove the microSD card containing the configuration file. Replace the microSD card containing the new configuration file.

  • Page 36: Operation With An Awos

    6. Operation With An AWOS 6.1 Direct Connect sensors The Direct Connect Model 6498 Present Weather and Visibility Sensor is a polled sensor. The responses are space delimited with a unique start and end character using the SYNOP Full Format message.

  • Page 37: Standalone Sensors 37

    PWR00TOPIC <Topic#>|<Topic#> etc…|<Topic#> <CR><LF> All of the valid topics that can be polled from the 6498 sensor are shown in Table 6. The definition of the 6498 Visibility Status Word and ALS Status Word (Topic 652 and 457) is shown in Table 7.
  • Page 38 Model 6498 Present Weather and Visibility Sensor The sensor is polled once a second and the current present weather and visibility information is updated. The present weather and visibility information is formulated into the poll response once a poll command is received. The parameters are below the poll response.
  • Page 39 Model 6498 Present Weather and Visibility Sensor The following SYNOP codes from WMO Table 4680 can be output by the 6498. No significant weather observed Drizzle and rain, slight Haze, smoke, or dust in suspension in the air, Drizzle and rain, moderate or heavy visibility ≥...
  • Page 40 SYNOP codes 20–25 are used to report precipitation, fog (or ice fog) at the station during the preceding hour but not at the time of observation. SYNOP codes 45, 47 & 89 require the M482264-00 Radar Precipitation Detector to be present The following METAR codes from WMO Table 4678 can be output by the 6498 using the topic poll command. Unidentified Precipitation –...

  • Page 41: Cp Sensor Poll Commands 41

    6490 Present Weather sensor. The 6498 sensor must be enabled at the factory to operate with these poll commands. If the 6498 is only replacing one of these sensors and not both, the 6498 sensor must only be enabled for the command that matches the sensor it is replacing.
  • Page 42 Line Feed The CRC is a 4-character CRC that is calculated as explained in Section 6.3. The following METAR codes can be output by the 6498 using the PRWX00 poll command. CODE& Edition UM-5055, Rev. 1.1.26, 2024/11/13 125 © ADB SAFEGATE, All Rights Reserved...
  • Page 43 Model 6498 Present Weather and Visibility Sensor Status Data Light Rain Moderate Rain Heavy Rain Light Snow Moderate Snow Heavy Snow Light Precipitation Moderate Precipitation Heavy Precipitation Light Drizzle Moderate Drizzle Heavy Drizzle ____ No Precipitation Table 13. 6498 – PRWX00 METAR Codes...

  • Page 44: Checksum Calculation 44

    Model 6498 Present Weather and Visibility Sensor 6.3 Checksum Calculation The CRC is calculated using a standard crc-16 formula for both types of poll commands. For reference the algorithm is as follows. /* CRC routine used with AWOS remote sensors USE:...
  • Page 45 Model 6498 Present Weather and Visibility Sensor crc = ival; while(length--) crc = crc_vals[(*string++ ^ crc) & 0xff] ^ ((crc >> 8) & 0xff); return crc; /* end crc16 routine */ CODE& Edition UM-5055, Rev. 1.1.26, 2024/11/13 125 © ADB SAFEGATE, All Rights Reserved...

  • Page 46: Maintenance And Troubleshooting

    Verify the operation of the Day/Night Sensor by accessing the Setup Menu as described in Sections 8.1 and 8.2 Enter ADB Safegate instead of the numbers shown in Step 2 in Section 8.2 and press Enter, then type 10 and press Enter on the screen that appears to access Menu 10, the ADB Safegate menu.

  • Page 47: Trouble Shooting 47

    Model 6498 Present Weather and Visibility Sensor 7.4 Trouble Shooting The troubleshooting action response to the four levels of sensor status is shown in Table 15. Status Troubleshooting Action No fault No action required. Check the sensor heads for insects, insect nests or spiders.

  • Page 48: Calibration

    In the event that the ambient air temperature is outside this range, an offset equation can be used as described in Step 7, Section 8.2. The following resources are required to calibrate the Model 6498 Present Weather and Visibility Sensor. •...

  • Page 49: Connections 49

    This section explains how to use the built-in features of the Model 1192 Data Collection Platform to perform visibility calibrations for the 6498-DC series of Present Weather/Visibility sensors. Note that these instructions apply only to the Direct Connect sensors, which have DC in their model number.

  • Page 50: Standalone Sensors 50

    Model 6498 Present Weather and Visibility Sensor Click on Terminal in the list on the left and set Local echo to Force off and Local line editing to Force off. Click Open. The 6498 setup menu will appear. 8.1.2 Standalone Sensors...
  • Page 51 Stop Bits: 1 Flow Control: None Click OK Set Transmit in the Terminal Setup to CR+LF. Leave Local echo unchecked. Click OK. The 6498 setup menu will appear. CODE& Edition UM-5055, Rev. 1.1.26, 2024/11/13 125 © ADB SAFEGATE, All Rights Reserved...

  • Page 52: Calibration Procedure 52

    0 NOTE The “0” corresponds to the Sensor ID number. The sensor ID is always 0 for the 6498 sensor. The setup menu should now be displayed. If the menu does not appear, check the terminal emulation utility settings, then type the command again.

  • Page 53: Starting Calibration

    Model 6498 Present Weather and Visibility Sensor Type 1 to start the calibration. You will then be asked to confirm that you would like to perform a calibration. Do you want to perform a calibration Y/N? Type Y to start the calibration. You do not have to press return. Once you have entered yes at this point, you will not be able to exit until the test is complete.
  • Page 54 Model 6498 Present Weather and Visibility Sensor When you have entered the calibrator information, the sensor will wait for you to place the calibration blocks/ bungs into the sensor hoods. These inserts are designed to block all light from the outside reaching inside the head.
  • Page 55 Model 6498 Present Weather and Visibility Sensor 11. Remove the blocks/bungs once the sensor instructs you to. Place the calibrator into the volume by fastening it to the central mounting point. NOTE This is also a good time to clean the lenses or at least verify they are clean Figure 25.

  • Page 56: Analyzing The Calibration Values

    Alarm Value - Last visibility reading: 63004M - Overall system status: No faults - ADB Safegate 6498 Calibrator Serial No: - 2000 - ADB Safegate 6498 Calibrator Constant: 23.7 - Calibration value Fac offset: -0.004 - Calibration value Fac scale: 0.02099...
  • Page 57 Record the Scale Change and the Offset Change values used to determine sensor ageing if needed for an inspection record. • Contact ADB Safegate, if the ageing calculation Scale Change is more than 5% or the Offset Change is more than 0.1. •...
  • Page 58 Model 6498 Present Weather and Visibility Sensor Type 3 to access the calibration menu. The following text should now be displayed. CALIBRATION - MENU 3 ID 0 S/N 1009 (1) Perform calibration (2) Restore the factory calibration (3) Perform dirty windows zero offset calibration...

  • Page 59: Accessories

    Model 6498 Present Weather and Visibility Sensor 9. Accessories Either a Day/Night Sensor or a Background Luminance Sensor must be used with the Model 6498 Present Weather and Visibility Sensor to provide the most accurate possible visibility readings. • Day/Night Kit (M403326-01) •...

  • Page 60: Specifications 60

    The sensor mounts just below the 6498 Present Weather and Visibility Sensor heads. The sensor functions as an independent sensor and does not require the Present Weather and Visibility Sensor head.

  • Page 61: Specifications 61

    Model 6498 Present Weather and Visibility Sensor 9.2.1 Specifications Parameter Specification Sensing Element Photodiode Accuracy ±10% Field of View 6° Spectral Response CIE 1931 Measurement Range 5 cd/m2 to 45,000 cd/m2 -40 to +70ºC Operating Temperature Range (-40 to +158ºF) -40 to +85ºC...

  • Page 62: Specifications

    Model 6498 Present Weather and Visibility Sensor 10. Specifications Parameter Specification SYNOP Codes Reported Per WMO Table 4680 METAR Codes Reported Per WMO Table 4678 NWS Codes Reported L, R, S, SG Precipitation Detection Sensitivity 0.05 mm/h Visibility Measuring Range 0.005–75 km...
  • Page 63 Model 6498 Present Weather and Visibility Sensor Parameter Specification Environmental Operating Temperature -40 to +70ºC (-40 to +158ºF) Storage Temperature -40 to +85ºC (-40 to +185ºF) Operating Wind Speed Max. 60 m/s Relative Humidity 0–100%, noncondensing Mechanical Sensor Sealing IP66 (NEMA 4X) Mounting 32.0–52.5 mm dia.

  • Page 64: Warranty

    Any defect in design, materials, or workmanship which may occur during proper and normal use during a period of 1 year from date of installation or a maximum of 2 years from shipment will be corrected by repair or replacement by ADB Safegate.
  • Page 65 Optimizing Airside Operations From approach to take-off SMARTER. BETTER. NOW. w w w . a d b s a f e g a t e . c o m...

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