Lightning in XM weather

On Wed, 15 Aug 2007 12:03:41 -0400, Jonathan Goodish wrote:

The network displays
cloud to ground strikes.

How does it work that it can discern the difference?

- Andrew

On Wed, 15 Aug 2007 08:02:51 -0400, "Peter R."
wrote:

On 8/14/2007 7:51:18 PM, Peter Clark wrote:

It should be noted that the KDR510 FIS uplink unit from Bendix/King
has also been obsoleted with 6/08 EOL. Their replacement is the
KDR610 XM unit.

Interesting. What is Bendix doing to transition their customers to this new
unit? Providing the equipment for free? Labor to install it?

Little to nothing. They're providing the equipment at reduced cost
(pro-rated based on when you purchased it, assuming you have a current
working FIS subscription). Antenna is extra, installation is extra
(and of course you have to yank the headliners out to run the cabling
for the on-top-of-aircraft antenna rather than the underneath FIS
antenna, etc etc etc). Including labor it's looking like around $3500
- $5500 per aircraft to upgrade depending on time since the KDR510 was
purchased. They already turned off the annual subscription option too
so you're down to 30 or 90 day increments with the commeserate
increase in cost over the old annual package. They really want people
off this stuff right now.

Personally I'm going to a GMX200 and GDL69A in my Malibu when the time
comes this fall. I'm going to have it done as part of the dual 530W
upgrade (since everything has to be ripped apart anyway, Piper didn't
put the good enough the GPS antenna wiring in when it was
manufactured) once Meggitt/S-Tec comes out with the MAGIC software
update. Haven't decided what to do with the Cessnas yet.

On 8/15/2007 4:34:45 PM, Peter Clark wrote:

Little to nothing. They're providing the equipment at reduced cost
(pro-rated based on when you purchased it, assuming you have a current
working FIS subscription). Antenna is extra, installation is extra
(and of course you have to yank the headliners out to run the cabling
for the on-top-of-aircraft antenna rather than the underneath FIS
antenna, etc etc etc). Including labor it's looking like around $3500
- $5500 per aircraft to upgrade depending on time since the KDR510 was
purchased.

Wow, it seems that B/K is making a customer's decision to move over to XM or
WSI a bit easier.

--
Peter

"Jonathan Goodish" wrote in message
...
In article .com,
Paul kgyy wrote:

Someone asked a while back what the source was for the opinion that XM
shows only cloud to ground lightning.

This is explicitly stated in the XM manual that came with my new 396.

Most weather providers obtain lightning data from the National Lightning
Detection Network, which is operated by Vaisala. The network displays
cloud to ground strikes.

WSI uses data from their own lightning detection network, which can
detect both cloud to cloud and cloud to ground. I'm not sure what their
InFlight product displays.

In any case, both products pale in comparison to sferics devices for
in-flight lightning detection.

The engineer in me is dying to know how the sensors knows the difference
between cloud to ground and cloud to cloud. Anybody know.

Danny Deger
www.dannydeger.net




JKG

"Jonathan Goodish" wrote in message
...
Most weather providers obtain lightning data from the National Lightning
Detection Network, which is operated by Vaisala. The network displays
cloud to ground strikes.

Thanks! I just learned something. You can get a free lightning map he
https://thunderstorm.vaisala.com/tux...r/explorer.jsp
It is for the entire USA, and only updated every 20 minutes, so you can hardly
use it to pick your way through the cells, but it could sure help you decide if
it is healthy to go flying.

"Danny Deger" wrote in message ...

The engineer in me is dying to know how the sensors knows the difference between cloud to ground and cloud to cloud.
Anybody know.

Danny Deger
www.dannydeger.net



Polarity? Maybe something with the pulse shape?

On Aug 15, 8:16 pm, "Danny Deger" wrote:
The engineer in me is dying to know how the sensors knows the difference
between cloud to ground and cloud to cloud. Anybody know.

Cloud to ground lightning creates a unique RF signature. By
recording these radio waves and by using time from GPS satellites to
corrdinate those receptions, then the NLDN could pinpoint those ground
strikes. When too many ground strikes occur, the network tends to
become overloaded; does not detect all strikes.

Then the NY Times made some inquires in response to a lightning
strike in the area of the former WTC that killed one person. Direct
lightning strikes known to have hit both the WTC and Empire State
Building (on average 25 and 40 times annually) were not detected;
apparently did not create that RF signature. No followup information
is available as best I can tell.

"w_tom" wrote

Cloud to ground lightning creates a unique RF signature. By
recording these radio waves and by using time from GPS satellites to
corrdinate those receptions, then the NLDN could pinpoint those ground
strikes. When too many ground strikes occur, the network tends to
become overloaded; does not detect all strikes.

In a gross simplification, cloud to ground flashes produce disturbances in
the LF and VLF EM bands. They are received over very long distances, so
they are easier to get a map of over a complete region, even with a sparse
location of sensors. Probably why it is desirable.

Cloud to cloud flashes are mainly in the VHF range, and therefore are line
of sight.

For a very complete explanation, see
https://www.thelightningpeople.com/htm/about/events/ildc/ildc2000/docs/03_CUMMINS.pdf
--
Jim in NC

On Aug 17, 2:35 am, "Morgans" wrote:
In a gross simplification, cloud to ground flashes produce disturbances in
the LF and VLF EM bands. They are received over very long distances, so
they are easier to get a map of over a complete region, even with a sparse
location of sensors. Probably why it is desirable.

Cloud to cloud flashes are mainly in the VHF range, and therefore are line
of sight.

Now explain why the system saw no strikes when 25 and 40 direct
lightning strikes hit the Empire State Building and WTC annually. I
have long been waiting for that answer. Do strikes to tall buildings
not create LF and VLF EM radiation?