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Updated : 16/10/2016

GHowSAW Weather Lightning Calibration

Introduction

Apart from checking that the lightning sensor actualy counts electro-magnetic impulses there is little to do as regards calibration but you can get an indication of the instrument sensitivity.

Function check

You can check the funtion od the lightning detector using a piezo-electric gas lighter. Read the count value of the DS2423 counter then hold the lighter close to the antenna and click the lighter several times and then re-read the counter. If the second reading is higher than the first then the detector is working.If you can't seem to get your detector to count, make then:-

  1. Ensure that you have connected a fresh battery.
  2. Did you connect the detector to a good earth ground?
  3. Did you get the right serial number?
  4. Hold the lighter a little closer to the antenna and try again.

Installation

Depending on where you install your lightning detector, it could pick up extraneous noise and EME. Sitting on my test bench, the lightning detector triggers every time I turn on or off the room light. Electric motors, refrigerators, and electrical appliances can generate considerable EME that can be detected with this sensor.When installing your lightning detector outdoors, try to keep it as far away from electrical appliances as possible.

Sensitivity

To make an assessment of the sensitivity of the lightning detector you will require the assistance of a convenient thunderstorm!

Lightning discharges produce thunder so since light travels at 299,792,458 m/s we see the lightning immediately whereas sound travels at only 340.29 m/s in air at sea level and therefore we hear the thunder several seconds later. (If you see the flash and hear the thunder simultaneously then you are in serious trouble!).

By timing the period between seeing the lightning and hearing the thunder then you can estimate of how far away the strike occured by multiplying the time interval in seconds by 0.34 to get the distance in km. Then check the detector to see if it detected the strike. If it did then you have a first indication of the sensitivity. If it did not then you will have to gamble on how long you are prepared to leave your system switched on as the storm approches. Don't forget that not all discharges release the same amount of electrical energy so you may see some discharges in the distance, especially at night, that your sensor does not detect. However, if you hear the thunder and the sensor does not detect the strike then something is wrong and you must re-check your system.

Repeat this procedure until you are satisfied that you have a reasonable value for the range of your detector.

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