Answer #10:

Most forest and weather services now use the wide band magnetic gate design lightning detector manufactured by Lightning Location and Protection Inc. (LLP) of Tucson, Az. The LLP lightning detection system determines the time and location of a lightning flash by triangulating information from direction finder stations situated in the network These data are stored on magnetic tape. Maps can be processed to show the location and polarity of lightning flashes that occur over a period of time.

The LLP lightning detection system has three components: the direction finder, the position analyzer and the remote display processor.

The direction finder (DF) senses the electromagnetic field radiated by a lightning flash using two erect, orthogonal wire loop antennas and a horizontal flat plate antenna. The antenna's bandwidths are from 1 kHz to 1 MHz. The radiated field of a lightning flash induces a current in the loops. The voltage signal measured in the loops is related to the flash's generated magnetic field strength by the cosine of the angle between the loop antenna and the direction to the flash. By comparing the voltage signals from the two loops, a direction to the flash can be determined. The flat plate antenna is used to resolve the 180 degree ambiguity associated with the calculations.

The direction finder can discriminate cloud-to-ground flash from other forms of lightning or noise by the electromagnetic signature. When the stepped leader reaches the ground, the return stroke is triggered producing a sharp voltage rise. This telling factor distinguishes a cloud-to-ground flash from other electromagnetic noise.

The direction finder sends the data of each registered lightning flash to the position analyzer (PA). The position analyzer triangulates data from direction finders to locate the position of a lightning flash. If the flash is in line with or directly between two direction finders (called the baseline), the position analyzer uses the ratio of the signal strengths as well.

From the position analyzer, users can view a map of the lightning dataon a remote display processor (RDP). The display can focus on desired time and location windows covered by the detection network, and can show up to 30,000 flashes.