Using the amplifier only

[Jonathan.Williams]

Detecting lightning within a certain radius of a location, with a single receiver, is almost impossible.
Lightning strikes are of various intensities. Some are small, (relatively) low current discharges, others are massive discharges which produce very powerful radio frequency signals.

How a single point station can possibly discriminate between the two eludes me. It clealy also eludes a great many other technical minds!

The only two ways I know of require a significant number of stations operating co-operatively.
Method 1 requires each station to use two antennas and to produce a direction and time. Somewhere, these directions (and time signatures) are merged to determine where the strike was.
Method 2 requires each station to precisely time-stamp the signal, and a co-operative system that analyses the signals to work out where the source must have been to satisfy all the measured signals.

Method 2 is what Blitzortung uses - a "Time-of-Arival" (TOR) system. It is simple in concept but complex in implementation and requires a significant investment in hardware and processing power.

A simple receiver plus threshold detector may tell you that there is lightning "somewhere within the receiving area", that area may be several thousand miles, and without discrimination, will almost certainly count every electrical circuit opening or closing, every arcing contact, every breaking down insulator, withing a great distance from your (single) receiver.

There is at least one study (Stanford?) that found lightning produces a typical signal, and the nature of the signal varies with distance due to phase velocity characteristics.

Anyway, I would not be surprised if, for BO stations that use H-field coils that are properly set up at right angles to one another, some direction finding is also possible (see the X-Y plots on lightningmaps.org). Given the variation in coil design, it's probably not as accurate for DF'ing as, say, the systems used in Lightning Radar or (ex-) Vaisala's National Lightning Detection Network, but since typical BO stations probably don't change configuration very often, it might at least be useful for elimination of some false positives.