Determining lightning polarity (positive or negative) by raw signal processing?
#12
Hi All, I agree with Richo. They are selling their system and using semi-technical "explanations" to sell this to people that have even less knowledge.

"Though the antenna shows receiving capability up to about 1 MHz, an upper limit is
set to 400 kHz in order to serve anti-alias properties, and a digital filter can be adjusted
in the range 100-400 kHz in order to reduce influence of radio signals; the wave form
distortion due to the actually chosen band-width limitation remains acceptable for the
present purposes.
Signal timing is achieved by means of a separately mounted commercial GPS clock
with an accuracy of 100 ns (initially 300 ns, module 2). Special measures are taken
to transport this level of basic accuracy as far as possible to the actual event timing.
Signal amplification, filtering, AD-conversion and data processing are performed with
a single plug-in card (module 3) in a remotely positioned standard PC (module 4).
The effective sampling rate was set to 1 MHz and incoming signals are recorded with
14 bit resolution in a continuous mode. Triggered events are transferred to and processed
in a parallel unit so that no data loss occurs and no allowance for rearm time
must be provided (zero deadtime). Signal rates of up to approximately 1 kHz can be
handled. Each station collects data and transmits packets of condensed information
to the central station at Garching. Depending on the type of chosen line-connection
this transmission can take place immediately after completion of an individual signal
analysis, or within pre-selected time intervals for a group of signals which has been
accumulated within this interval. Due to transmission line band width the transfer is
presently limited to some 100 signals/s which is plenty even during strong thunderstorm
activity."
(Geophysical Research Abstracts, Vol. 7, 00685, 2005
SRef-ID: 1607-7962/gra/EGU05-A-00685
European Geosciences Union 2005
Modern Lightning Detection and Implementation of a
New Network in Germany
H.-D. Betz, W. P. Oettinger, K. Schmidt, and M. Wirz
Physics Department, University of Munich, D-85748 Garching, Germany)

We are actually doing things far better, our timing is order of magnitude better, 10ns, and our reduced bandwidth does not have to deal with broadcast and military stations and other sources of interferrence that exist in the LF/VLF band that they profess to be using (Up to 1 MHz?)
I am also not certain that the vertical radiation pattern of a loop type antenna is sufficient to deal accurately with the difference in height between C to C and C to G type lightning.
A multi-antenna system is better.
For Europe especially Germany we have a better network density with more stations used in the detection and location of strokes, in another part of this document they talk of a delay time between being able to calculate individual strokes, therefore they are not actually recording all the strokes.
The internet speed and the computing power and timing accuracy has also increased and we are constantly updating our algorithm.
We do not suffer from commercial inertia, therefore if we have not already done so, eventually we we will overtake them and our system will be better.
Analyzing data is always the bottleneck, I read that NASA has accumulated data from the various space probe missions that even if it stopped now would take over 15 years to be reviewed and analyzed.

Brian.
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RE: Determining lightning polarity (positive or negative) by raw signal processing? - by readbueno - 2017-08-21, 09:37

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