CHAPTER 18 Non-Acoustical Inputs This chapter discusses the use of external transducers and devices to provide non-acoustical data to the Model 831. Included are the following: 831-INT 831-INT Interface Unit Weather (Wind, Temperature and Humidity) Location using GPS device For a detailed description of the design and use of the 831-INT, see the Larson Davis manual 831- INT.01. FIGURE 18-1 831-INT with Model 831 Mounted The 831-INT is a device that connects to the Model 831 through the 831 s I/O connector and enhances the capabilities of the 831 to include interfaces for all necessary components of a permanent noise monitoring system. These components include the following: Metrological Sensors: Wind Speed, Wind Direction, Temperature, Humidity Backup Battery Management and Charging Control Power Management: including switch over to battery power when mains power fails and support for solar panels Model 831 Technical Reference Manual Non-Acoustical Inputs 18-1
4-port Powered USB Hub 2 Digital I/O lines: 1 in, 1 out Weather Measurement Using 831-INT Note that the optional firmware 831-WTHR must be enabled in order to measure weather parameters with the Model 831. Larson Davis Sensors Setup The following devices are available from Larson Davis for the measurement of weather data: SEN028 Wind Monitor: Wind Speed and Direction SEN029 Anemometer (Low Cost): Wind Speed and Direction SEN030 Sensor: Temperature and Humidity These sensors connect to the Model 831 via the 831-INT. The parameters controlling the measurement of weather data are setup from the Weather tab shown in.figure 18-2. FIGURE 18-2 Weather-INT Setup Page 18-2 Weather Measurement Using 831-INT Model 831 Technical
The settings menu, shown in FIGURE 18-2, is used to select which weather parameters are to be setup. FIGURE 18-3 Weather Settings Menu Wind Setup The Wind Setup menu is shown in FIGURE 18-2. Most of the parameters call for direct input of numeric values based on the design parameters of the wind transducer or text based on the preference of the user. The scale setting allows the use of any pulse type of anemometer and permits the scaling to any wind speed metric. The Model 831 measures the frequency of the wind speed (or tachometer) signal. The displayed value is the measured frequency (Hz) multiplied by the calculated scale factor of the sensor. Below is a table showing the scale values to enter into the Model 831 for the SEN028 and SEN029 for various units of measure. The Units is the text label to enter into the Units field of the Model 831. Units of Measure (abbreviation) SEN028 Scale RM Young Wind Monitor SEN029 Scale Davis Anemometer Units label Meters per second (m/s) Kilometers per hour (km/h) Miles per hour (mi/h) 0.0980 1.0064 m/s 0.3528 3.6230 km/h 0.2191 2.2500 mi/h Table 18-1 Wind Sensor Scale Factor Model 831 Technical Reference Manual Weather Measurement Using 831-INT 18-3
Knots (kn) Feet per second (fps) 0.1904 1.9553 knots 0.3216 3.3026 fps Table 18-1 Wind Sensor Scale Factor Compass The compass menu, shown in FIGURE 18-4, provides a list of permitted formats. FIGURE 18-4 Weather Compass Menu Temperature Setup FIGURE 18-5 Weather Temperature Menu Humidity Setup FIGURE 18-6 Weather Humidity Menu 18-4 Weather Measurement Using 831-INT Model 831 Technical
Vaisala Weather Station Units Units are not configurable using the Vaisala Weather Station (SEN-031). However, they will follow English or SI units as configured in the System Properties dialog described in Chapter 17. English SI Wind mi/h m/s Temperature F C Relative Humidity % RH % RH Table 18-2 Vaisala Units Wind Setup The Wind Setup menu is shown in FIGURE 18-7. FIGURE 18-7 Weather Wind Menu Gust Dir: Choose Compass or Degrees for the display (i.e., ENE vs. 70.0 ) Threshold: If the wind speed is above this threshold, it is considered windy. Model 831 Technical Reference Manual Weather Measurement Using 831-INT 18-5
Temperature Setup Excd. Pause: If set to "Yes" and wind speed exceeds Excd. Level, sound exceedance are held off. Excd. Level: if Excd. Pause is set to "Yes" and wind speed exceeds this level, sound exceedance are held off. Hysteresis: If sound exceedance are paused due to a wind exceedance, wind speed must drop below (Excd. Level - Hysteresis) before sound exceedance are resumed. Note: This menu is informational only. FIGURE 18-8 Weather Temperature Menu 18-6 Weather Measurement Using 831-INT Model 831 Technical
Humidity Setup Note: This menu is informational only. FIGURE 18-9 Weather Humidity Menu When used with a Model 831, with the exception of precipitation data, the Vaisala weather station is configured to report measurements once per second. The reported values are the average over that one second interval. Wind Gust is the max speed detected over that interval. The Vaisala will send precipitation information every 10 seconds if precipitation has been detected. If the Model 831 is configured to include Vaisala weather data in the Time History, it will be this one-second data, even if the Time History period is set to something other than one second. This means that if the TH interval is less than one second, you will see a repetition of values until it is updated by the Vaisala. Conversely, if the TH interval is greater than one second, the reported value will be the average over the last second only. Precipitation data is not available in the Time History. Model 831 Technical Reference Manual Weather Measurement Using 831-INT 18-7
Display Live Display When weather has been enabled, the measured data will appear on both the Live and the Overall Pages. Instantaneous weather data appears on the Live Display tab shown in FIGURE 18-10 FIGURE 18-10 Live Weather Display 18-8 Weather Measurement Using 831-INT Model 831 Technical
Average Weather Average weather data appears on the Overall Display tab shown in FIGURE 18-11 FIGURE 18-11 Overall Weather Display Model 831 Technical Reference Manual Weather Measurement Using 831-INT 18-9
Location Measurement Using 831-INT The optional firmware 831-GPS must be enabled in order to utilize a GPS with the Model 831. Note that daylight savings time is not supported. To provide global positioning information to the Model 831, Larson Davis offers the GPS001 USB GPS Receiver with a magnetic mount. This device is connected directly to the USB port of the Model 831, Setup The GPS Mode field will only appear when the USB Host Port is set to On. The setup parameters for the GPS are entered using the Preferences tab page of the System Properties Page, shown in FIGURE 18-12 FIGURE 18-12 System Properties Page For a detailed description of the GPS setup procedure, see "GPS Mode" on page 17-15. 18-10 Location Measurement Using 831-INT Model 831 Technical
GPS Data Display When the GPS feature is enabled by the user, the display shown in FIGURE 18-13 will appear on the Live Display Page, just above the Time, Battery Voltage and Memory display shown in Figure 5-11 on page -5-11. FIGURE 18-13 GPS Display The GPS will turn on automatically at the beginning of every measurement run to acquire the current position information. The Live GPS display will show the data from previous acquisitions instead of clearing the data when the GPS is off. They will be cleared on if there is a GPS connect/ disconnect error. Model 831 Technical Reference Manual Location Measurement Using 831-INT 18-11
GPS Time-Sync The time-sync is made from the average of thirty readings from the satellite (thirty second average) as long as there are four or more satellites detected. The time-sync can be performed manually or automatically when the Daily Autostore mode is active. Note that the manual time sync can only be performed while the instrument is stopped. Manual A time-sync can be triggered manually by pressing the 5 key from the GPS display, shown in FIGURE 18-13. Daily Autostore A time-sync will be performed along with a Daily Autostore if the time is found to be more than one second off. In this case, the GPS is turned on two minutes prior to the autostore time in order to gather the time and create the time correction value that will be utilized. Datum The GPS uses WGS 84 as its default datum. The user can change the datum as described in the Ho lux manual. 18-12 Location Measurement Using 831-INT Model 831 Technical