sferic detection and localisation with DSP

P

phunkyman

Guest
Hi,

My project is to realise an handheld lightning locator designed around
a Digital Signal Processor.
From what i learnt about lightning, i think i can detect storm by
detecting sferic signals. For the detection, i think that just an
antenna+ADC+ FIR filter will be enough but for the localisation i
don't know how to do. Should i make a FFT? I thought that as the high
frequencies of the sferic signal (about 7-8 KHz) move more rapidly
than the lowest, i could determine the distance of the storm from the
determination of the time between the arrival of the high frequencies
and the lowest ones. What do you think about that? Does a FFT allow me
to do that?

I'll be grateful for your help!!

Thanks.
 
phunkyman wrote:
Hi,

My project is to realise an handheld lightning locator designed around
a Digital Signal Processor.
From what i learnt about lightning, i think i can detect storm by
detecting sferic signals. For the detection, i think that just an
antenna+ADC+ FIR filter will be enough but for the localisation i
don't know how to do. Should i make a FFT? I thought that as the high
frequencies of the sferic signal (about 7-8 KHz) move more rapidly
than the lowest, i could determine the distance of the storm from the
determination of the time between the arrival of the high frequencies
and the lowest ones. What do you think about that? Does a FFT allow me
to do that?

I'll be grateful for your help!!

Thanks.
Click to expand...
Nope,
all audio frequencies move at the same speed, but the higher frequency ones
are attenuated more by the atmosphere.
A completly different thing are the radio- and light frequencies emitted by
the spark. These move with the speed of light, and independently of the
frequency as well.
To estimate the distance you could start a counter by the em-wave and stop
it by the arriving thunder-noise. Look up "speed of sound", speed of light,
lightning detector etc. at google.com
BTW you didn't learn anything about lightning, didn't you?
--
ciao Ban
Bordighera, Italy
 
I read in sci.electronics.design that phunkyman
<phunky.data@caramail.com> wrote (in <e435cb3e.0403290225.77c5419a@posti
ng.google.com>) about 'sferic detection and localisation with DSP', on
Mon, 29 Mar 2004:
My project is to realise an handheld lightning locator designed around
a Digital Signal Processor.
From what i learnt about lightning, i think i can detect storm by
detecting sferic signals.
Click to expand...
Please explain what you mean by 'sferic signals'.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
I read in sci.electronics.design that Ban <bansuri@web.de> wrote (in
<WxU9c.116497$z23.4955836@news3.tin.it>) about 'sferic detection and
localisation with DSP', on Mon, 29 Mar 2004:

To estimate the distance you could start a counter by the em-wave and stop
it by the arriving thunder-noise. Look up "speed of sound", speed of light,
lightning detector etc. at google.com
Click to expand...
It's not very accurate, because of the effect of wind on the sound
signals.

BTW you didn't learn anything about lightning, didn't you?
Click to expand...
He seeks enlightningment here. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:lyk86eEukBaAFw8f@jmwa.demon.co.uk...
I read in sci.electronics.design that Ban <bansuri@web.de> wrote (in
WxU9c.116497$z23.4955836@news3.tin.it>) about 'sferic detection and
localisation with DSP', on Mon, 29 Mar 2004:

To estimate the distance you could start a counter by the em-wave and
stop
it by the arriving thunder-noise. Look up "speed of sound", speed of
light,
lightning detector etc. at google.com

It's not very accurate, because of the effect of wind on the sound
signals.

BTW you didn't learn anything about lightning, didn't you?

He seeks enlightningment here. (;-)
Click to expand...
I know of a company that builds lightning strike sensors that detect
distance of a strike with radio signals alone. I had the theory explained to
me once, but all I can remember is that it was very ingeniuos. I'm sure
google can turn out a few references.
 
The Real Andy wrote:

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:lyk86eEukBaAFw8f@jmwa.demon.co.uk...

I read in sci.electronics.design that Ban <bansuri@web.de> wrote (in
WxU9c.116497$z23.4955836@news3.tin.it>) about 'sferic detection and
localisation with DSP', on Mon, 29 Mar 2004:


To estimate the distance you could start a counter by the em-wave and

stop

it by the arriving thunder-noise. Look up "speed of sound", speed of

light,

lightning detector etc. at google.com

It's not very accurate, because of the effect of wind on the sound
signals.


BTW you didn't learn anything about lightning, didn't you?

He seeks enlightningment here. (;-)


I know of a company that builds lightning strike sensors that detect
distance of a strike with radio signals alone. I had the theory explained to
me once, but all I can remember is that it was very ingeniuos. I'm sure
google can turn out a few references.
Click to expand...
Long-path lightning noise _is_ frequency dependent. On a
single-sideband radio it makes a "fwip" sound with the frequency going
one way or the other depending on whether it's upper or lower sideband
(can't remember which is which). The speed of the "fwip" tells you the
distance if you know what you're doing. If this is what the original
poster would get on and clarify his thinking it would be a boon to us all.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
 
Hello,

I wanted to be sure what you meant, because there was apparent confusion
in your text between the propagation of electromagnetic and acoustic
signals.
Click to expand...
I'm sorry if you think there was confusion. In fact there isn't.

There is a lot of electromagnetic 'noise' below 10 kHz. You would do
well to reduce this by using a tuned circuit after your antenna. Because
the lighting signals are broad-band, and quite strong, you get a better
signal-to-noise ratio with some selectivity. Above all, you can cut out
interference from the mains power frequency and its harmonics, which can
extend at least up to 3 kHz.
Click to expand...
As I'm french i don't understand well what you mean by a tuned
circuit. Can you explain please?
As far as the power lines are concerned, i thought about it. But if we
get far from power line devices, i guess this issue won't last?

I thought i could determine the distance of the storm from the
intensity of the sferic signal recieved on the antenna. If it's
possible, does anyone know how the distance of the storm and the
intensity of the sferic signal are linked?

Thanks again.
 
I read in sci.electronics.design that phunkyman
<phunky.data@caramail.com> wrote (in <e435cb3e.0403302354.3fe78c5a@posti
ng.google.com>) about 'sferic detection and localisation with DSP', on
Tue, 30 Mar 2004:

As I'm french i don't understand well what you mean by a tuned
circuit. Can you explain please?
Click to expand...
En français, 'circuit résonnant'.

As far as the power lines are concerned, i thought about it. But if we
get far from power line devices, i guess this issue won't last?
Click to expand...
The power-frequency magnetic fields exist everywhere.
I thought i could determine the distance of the storm from the
intensity of the sferic signal recieved on the antenna. If it's
possible, does anyone know how the distance of the storm and the
intensity of the sferic signal are linked?
Click to expand...
There is only a poor correlation.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
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