Kapanadze and other FE discussion

[stivep]

my notes to the article :
BackDoor: Making Microphones Hear Inaudible Sounds Nirupam Roy, Haitham Hassanieh, Romit Roy Choudhury University of Illinois at Urbana-Champaign
https://nsr.cse.buffalo.edu/mobisys_2017/papers/pdfs/mobisys17-paper01.pdf

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The diaphragm of the microphone should exhibit some sensitivity
at the high-end frequencies (> 30kHz). If the diaphragm
does not vibrate at such frequencies, there is no opportunity for non-linear mixing of signals.

(3.1 Measurements and Validation page#4)
[/font]

The second order coefficient A2 needs to be adequately high to achieve a
meaningful signal-to-noise ratio

(3.1 Measurements and Validation page#4)
A1 or A2..3..4 is a complex gain that can change the phase and/or
amplitude of the input frequencies,
(Linear and Non-linear Behavior page#4)
Note: You may need to connect microphone to your spectrum analyzer using separating capacitor for DC Power supply  elimination.
if you  put DC  to input of spectrum analyzer than your instrument  gets damaged.
---------------------------------------------
Note: 1st order, 2nd order,3rd order are the harmonics.
(Figure 5: (a)The intermodulation distortion of signal (b) Harmonic distortion. page 5)
Note:

Thus far, the shadow signal is a trivial tone carrying one-bit of information (presence of absence).

(4.1 Communication page 5)
Conclusion :So they are talking  about a "shadow" seen at digital output.-  not in physical XYZ space.
[/font]

our actual goal is to modulate the
high frequency signals at the speaker and demodulate the
shadow at the microphone to achieve meaningful data rates

(4.1 Communication page 5)

any modulation that generates waveforms
with non-constant envelopes [45] is likely to suffer this problem.

Note: AM modulation is not applicable due to severe problems.
(Failure of Amplitude Modulation (AM) page 5, look also at Figure 7  )
Ok I'm giving up for today - the rest of the article is easy to understand.
Wesley

[stivep]

I used two dynamic heads, type 6gdv.
The frequency was fed to one 20 kHz, to the second 21 kHz.
Sound was received by the device ВШВ003
For some reason, I did not hear a sound at 1 kHz.

Технические характеристики ВШВ-003-М2:

Частототный диапазон, Гц 2 – 18000 = 18kHz !!!!!!!!!!!!!!!!!!!!!!!!!
Динамический диапазон, дБ 22 – 140
Частотные корректоры A, B, C, Lin
Временные характеристики Slow, Fast, 10c
Класс точности 1,0  class 1
Октавные фильтры со среднегеометрическими частотами, Гц 1 – 8000
Питание сетевое и автономноеМасса, кг 5,5.
______________________________________________________________

Few Questions:
How come you made measurement  with the device that goes max to 18kHz?
How did you fed  2 signals at the same time  with two
two dynamic heads, type 6gdv. into instrument that has only  one  probe input?
http://www.tehno.com/product.phtml?uid=B00120039561
objections and problems:
-20 kHz and 21 kHz is out of range of this instrument.



______________________________________________________________

Sound was received by the device ВШВ003

again this device when belongs to group of  class 0 or class 1 has limit of frequency  maximum to 18kHz.
https://www.prostanki.com/board/item/73931
Технические характеристики ВШВ-003-М3:
Частототный диапазон, Гц 2 – 18000kHz
Динамический диапазон, дБ 22 – 140
Частотные корректоры A, B, C, Lin
Временные характеристики Slow, Fast, 10c
Класс точности 1,0
Октавные фильтры со среднегеометрическими частотами, Гц 1 – 8000
Питание сетевое и автономноеМасса, кг 5,5.


objections and problems:
-20 kHz and 21 kHz is out of range of this instrument.
Wesley

[kolbacict]

No, no lie, it was a joke.
I thought an alcoholic was resting under your table ...
I am a man with humor, without which it is unbearable to live in this country.

Частототный диапазон, Гц 2 – 18000 = 18kHz !!!!!!!!!!!!!!!!!!!!!!!!!

Yes you are right. I studied the documentation poorly.
I have had it for ten years, and have not really studied it.
ok, we will continue to work.
True, I lowered the frequency to 16 kHz later(I don't hear that either), but the difference frequency beats were not apeared as well.

[stivep]

Question to Wesley?
( can we do it ? Is it useful/scalable ?
https://overunity.com/18977/carat-trax-forever-battery/msg561622/#new
Chet K

Yes you can . Nothing new.
However  the heat coming  from central heating pipe  helps.
We know that in cold temperature  failure of some  forms of batteries is evident.

The Zinc and Copper Battery In a zinc-and-copper battery, the chemical reaction
involves the transfer of electrons from solid zinc to copper ions.
The zinc is therefore the anode; solid zinc is oxidized. The copper is the cathode; copper ions are reduced

.
https://education.seattlepi.com/happens-battery-zinc-sulfate-mixed-copper-sulfate-6031.html
Wesley

[kolbacict]

I found a microphone from an ultrasonic TV remote control telefunken.
There is no marking. TV set in 1976. Data and connection diagram find are unrealistic.
But most likely the type is capacitor. And the maximum frequency should be quite high.