Just for fun - LF/VLF receiving with ADC and one-two magnetic loop - lightning detector/tracker Re: Hurra Richard! Wofson WM8753 ; ) doing distance messuring with ultrasonic?

Robert Michel openmoko at robertmichel.de
Tue Dec 12 23:07:52 CET 2006

Salve Richard!

Robert Michel schrieb am Dienstag, den 12. Dezember 2006 um 17:58h:
> > I'm not an audio engineerologist, however a quick read of the
> > datasheet shows input/output rates of up to 96kHz.. so the theoretical
> > highest frequency at that level would be 48kHz.. meaning there may be
> > room in the non-audible spectrum for comms depending upon the
> > sensitivity of the mic/speaker components.
> :))
> Doing distance messuring with ultrasonic? 
> ;))
> 40kHz example:
> http://www.parallax.com/dl/docs/prod/audiovis/Distance28015.pdf

BTW 40kHz, there is a time signal radio in Japan broadcasting on 40kHz:
Just adding a magnetical loop into audio in and use it for receiving
the lowest part of LF and VLF - ok -this isn't yet a "killer
application" but it would be educational to play with that,
and someone in Japan could be happe to have beside GPS a
backup for a time signal.

Military Neos could have a build in VLF loop so that some 
informations are received on this way:

And maybe next generations of audio ICs would have an ADC with a
much higher frequency range for low cost LF receiving?
(I know that this would not be not so battery efficient like
a hardware receiver, but probably cheaper)

Just a magnetical loop and a frequency that is broacast free
will make a fine lightning detector I don't know if 2 channels
are enough to track the distance of lightning, I once saw
a page with a 3 channel detector - but it could be that the
3 channel is only needed to know the side of the lightning
(2 channels = non unique solution ?) 
Maybe an I/O of the SoC could work as third AD.

But multiple Neos in one city could be a solution to do
this with a distributed system - the accurate time 
and position with AGPS helps:
(But consider that you would share your position as well)
(Such a distributed detector system could work with 
audio as well (in open fields) - try to detec where a bang/noice 
came from)

So when the Neo1973 case would have a build in simple magnetic loop
switchable to one audio in, it could become possible to use the
Neo1973 for tracking lightning :)
OKOKOK audio in connector would be good enough to play
with this and the idea of an internal magnetic loop antenna
switchable to one audio-in would be for the Neo v2.
The distributed system could share lightning events via
GPRS or (future: Bluetooth, Wi-Fi, packet radio via PMR/DMR).

Richard, you are right, the 96Khz range of the ADC give some
new playfield... :)


PS: and ultrasonic cold maybe used for some material scan
    (to detec hollow space or fractures..)

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