Stormscope

[Roland]

Does anyone know how a stormscope is able to sense the distance to the
lightning ...

[Scott Moore]

Roland wrote On 11/18/05 16:27,:
> Does anyone know how a stormscope is able to sense the distance to the
> lightning ...
>
>
>

It counts the difference between the flash and the cracking sound.

No, kidding, sorry. Lightning generates radio frequency energy, just like
any electrical current does. So the location solution can be found
just like they find a radio transmitter, by using directional antennas
and paralax.

[Jon Woellhaf]

"Roland" > wrote in message
...
> Does anyone know how a stormscope is able to sense the distance to the
> lightning ...

You will probably find some useful information about this subject by
Googling for <lightning sferics>.

Jon

[Ron Rosenfeld]

On Sat, 19 Nov 2005 01:27:20 +0100, "Roland" > wrote:

>Does anyone know how a stormscope is able to sense the distance to the
>lightning ...
>
>

It uses an algorithm based on the intensity of the strike signal. A strong
strike signal will therefore appear to be closer than it really is, and a
weak one further away.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

[vincent p. norris]

>Does anyone know how a stormscope is able to sense the distance to the
>lightning ...

The booklet that came with ours used the term "pseudo range." Ryan
(the inventor) measured the strength (amplitude) of a number of
lightning strokes, and calculated the average.

The stormscope assumes that every lightning strike is of "average"
intensity, and it calculates the distance from the signal strength.

A strike that is stronger than average will seem to be closer than it
actually is; a weak one will seem to be farther away. Hence "pseudo."

But it's good enough to provide safe guidance to the pilot.

vince norris


>
>

[Matt Whiting]

Roland wrote:
> Does anyone know how a stormscope is able to sense the distance to the
> lightning ...

I don't know for sure as they don't publish their algorithms, but most
folks use dispersion of the signal to estimate distance as different
frequency components of the signal travel at slightly different speeds
through the air. The farther they travel the more dispersed the signal.


Matt

[Stubby]

Roland wrote:
> Does anyone know how a stormscope is able to sense the distance to the
> lightning ...

The explanation I got seems better: The atmosphere attenuates some
radio frequencies more than other (I believe high frequencies are
attenuated more than low, but it may be way more complex.) A lighting
flash is an impulse and thus, has all frequencies present at the same
level. The distance sensor can measure the level of 2 frequencies and
derive the distance. In practice I've heard that 6 frequencies are used
but that implies 36 amplitude ratios are being used.

Take your pick.

[Dave Butler]

Stubby wrote:

> The explanation I got seems better: The atmosphere attenuates some
> radio frequencies more than other (I believe high frequencies are
> attenuated more than low, but it may be way more complex.) A lighting
> flash is an impulse and thus, has all frequencies present at the same
> level. The distance sensor can measure the level of 2 frequencies and
> derive the distance. In practice I've heard that 6 frequencies are used
> but that implies 36 amplitude ratios are being used.

Ding ding ding ding ding ding! Finally someone responded with the correct answer.

Dave

[RST Engineering]

Dong, dong, dong, dong, dong...


Perhaps the current Stormscope uses this method; Ryan's original work used a
spot frequency (50 kHz) and amplitude discrimination. And Ryan didn't
"invent" it. The seminal work was done by Smythe Research Associates in San
Diego on a field trip to the South Pacific.

Strikefinder was the first to use multiple frequencies across a rather broad
bandwidth.

Jim



"Dave Butler" > wrote in message
news:1132589727.740244@sj-nntpcache-3...
> Stubby wrote:
>
>> The explanation I got seems better: The atmosphere attenuates some
>> radio frequencies more than other (I believe high frequencies are
>> attenuated more than low, but it may be way more complex.) A lighting
>> flash is an impulse and thus, has all frequencies present at the same
>> level. The distance sensor can measure the level of 2 frequencies and
>> derive the distance. In practice I've heard that 6 frequencies are used
>> but that implies 36 amplitude ratios are being used.
>
> Ding ding ding ding ding ding! Finally someone responded with the correct
> answer.
>
> Dave

[Stubby]

Just for clarity, using multiple frequencies is not the key to its
working. A pair (2) will suffice. Using multiple frequency (ratios)
will probably increase the accuracy, however.

Hats off to whoever invented it. Very clever.



RST Engineering wrote:
> Dong, dong, dong, dong, dong...
>
>
> Perhaps the current Stormscope uses this method; Ryan's original work used a
> spot frequency (50 kHz) and amplitude discrimination. And Ryan didn't
> "invent" it. The seminal work was done by Smythe Research Associates in San
> Diego on a field trip to the South Pacific.
>
> Strikefinder was the first to use multiple frequencies across a rather broad
> bandwidth.
>
> Jim
>
>
>
> "Dave Butler" > wrote in message
> news:1132589727.740244@sj-nntpcache-3...
>
>>Stubby wrote:
>>
>>
>>>The explanation I got seems better: The atmosphere attenuates some
>>>radio frequencies more than other (I believe high frequencies are
>>>attenuated more than low, but it may be way more complex.) A lighting
>>>flash is an impulse and thus, has all frequencies present at the same
>>>level. The distance sensor can measure the level of 2 frequencies and
>>>derive the distance. In practice I've heard that 6 frequencies are used
>>>but that implies 36 amplitude ratios are being used.
>>
>>Ding ding ding ding ding ding! Finally someone responded with the correct
>>answer.
>>
>>Dave
>
>
>

[Matt Whiting]

Stubby wrote:

> Just for clarity, using multiple frequencies is not the key to its
> working. A pair (2) will suffice. Using multiple frequency (ratios)
> will probably increase the accuracy, however.
>
> Hats off to whoever invented it. Very clever.

God invented it. I don't remember who first discovered it, but
dispersion as a phenomena has been known for quite some time.

Matt