DFW LDAR II Owner/Operator/ User Reports

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DFW LDAR II Owner/Operator/User Reports
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Communications

• Used for command and control only
• 19.2 kbps radio modems
• Monitoring
• event rates
• GPS receiver status
• disk space on local hard drive (either 20 or 40
  Gb depending on sensor vintage)
• GPS 1 PPS signal (monitor signal flow and
  calibrate signal delay)
• Command and control
• sensor gains and thresholds
• sensor soft reset/restart
• delete data files that are old or do not contain
  useful information

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Sensor settings

• Center frequencies between 61-64 MHz depending
  on results of frequency survey
• 100-µsec epoch
• Gains and thresholds vary from sensor to sensor
• with 100-µsec epoch, we try to keep the data rate
  at a few hundred events per second when no
  lightning is in the area
• a couple of sites have intermittent noise
  problems event rates jump from 1000 to 9000
  events/sec
• can occur quite frequently during both day and
  night
• each noise burst usually lasts only a few seconds
• some sites are consistently relatively noisy and
  we have to keep gains down and/or thresholds up

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Data management

• Data are collected at each sensor in the form of
  files that encompass specific periods
• We used to use a fixed file size for data
  storage at the sensor, but this caused headaches
  for time alignment of data between sensors for
  processing at the LP
• Now all sensors file management is synchronized
  to 10-min intervals
• Data drives are collected periodically as
  necessary (when nearly full) and mailed to Tucson
• Data from all sensors are merged at the LP
• Raw and processed data files are stored
  permanently on DVD

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Network performance monitoring

• chi-square distributions
• timing deviations
• percentage of solutions contributed to by each
  sensor as a function of distance from the sensor
• visual inspection of data
• look for high-quality flash mapping
• compare with radar and NLDN data

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Future plans real-time operation

• communications
• trying for 600 kbps
• wireless microwave (5 GHz) spread-spectrum
  service from local ISP
• cost 250/month/sensor 1500/month for
  internet backhaul to aggregate sensor data and
  forward from ISP hub to central processor
• expected time frame May?
• data management
• LP in DFW area (either at NWSFO or co-located
  with ISP)
• Data housekeeping on central processor Vaisala
  RD (Demetriades)
• Network and communications monitoring Vaisala
  Data Services
• Regular writing of data to permanent storage ISP
• hard disks at sensors to be continued (along with
  current data management strategy) at least until
  we are sure that we really get 600 kbps into the
  LP reliably and continuously