FYI: Smart Phone games are being used to launder money.
This is huge in places like Vancouver. Look at where app development companies are located and follow the money.
He found that online role playing games provide "an easy way for criminals to launder money". This tends to involve opening numerous different accounts on various online games – such as Second Life and World of Warcraft – to move money. These games use credits that players can exchange for real money. By using the virtual currency systems, criminals can send virtual money to associates in another country, which can then be transferred into real money.
http://www.wired.co.uk/article/money-laundering-online
Find the spec sheet for the Piezoelectric accelerometer everyone posts and you will see that it is sensitive to a specific frequency on the power rail.
Taking down an aircraft could be as easy as targeting the Piezoelectric Accelerometers
Amplification at Resonance
At resonance, significant amplification occurs. Typically, at about 1/5 the mounted resonant frequency the accelerometer is a positive 5% deviation from the actual vibration level. At about 1/3 the resonant frequency, the accelerometer is at a positive 10% deviation. At about 1/2 the resonance, the deviation has grown to 3 dB (positive 41%). At resonance, the amplification is typically 30 dB (over 30x).
The amplification that occurs at or near resonance is significant and must be avoided, or at least identified. When I used to offer support to customers of our Slam Stick vibration data loggers that have an embedded triaxial piezoelectric accelerometer, I found myself frequently fielding questions that could be answered with the plot shown in Figure 4. Picture the following scenario:
You may have a test where the true acceleration level is 10g and you are using a 100g accelerometer - you have plenty of clearance to prevent clipping! But… if this 10g acceleration level is at or near the resonant frequency of your accelerometer - watch out! That thing will be experiencing and reporting an acceleration of 300g. Its resonant frequency (or the resonance of the mounting you used) amplified the acceleration levels to such a degree that it made the accelerometer useless.
Amplification due to resonance can not be prevented or filtered out electronically - it's purely a result of the mechanical structure inside the accelerometer and/or the coupling between it and your test fixture - i.e. mounting matters too! The only way to prevent this amplification is to a) avoid using an accelerometer with a resonance within the frequency range of your test environment or b) mechanically filter the frequency through the use of double sided tape, duct seal putty, or even vibration isolators. Some accelerometers will also be available with internal damping to reduce this amplification at resonance - but this typically reduces the bandwidth of the accelerometer.
Saturation of the Charge Amplifier
Another drawback of the amplification that occurs at high frequencies and resonance, is that the amplification can cause the accelerometer to experience a shock amplitude that exceeds its measurement range. When the input acceleration levels (including those amplified by mechanical resonance) exceed the sensor's measurement range - this will saturate the internal charge amplifier.
Figure 5 provides a few plots from testing one of our engineers did on an AR15 rifle with two Slam Sticks: one with a piezoresistive accelerometer and the other with a piezoelectric accelerometer. The data from the piezoresistive accelerometer indicated that the shock levels should be "only" around 500g. The piezoelectric had a ±6,000g measurement range, should be plenty wide enough to capture the event. But the vibration from the gun shot had significant high-frequency content in it that excited the piezoelectric accelerometer's resonance. This caused the output of the accelerometer to saturate its internal charge amplifier which results in an exponential decay that lasted about one second.
piezoelectric vs piezoresistive accelerometer firearms testing
Engineers typically see this type of data and immediately assume that there is something wrong with their sensor and/or the electronics. But that's not the case, the high-frequency content in the test simply excited a resonance in your sensor and/or the mounting. This exponential decay is the key indicator of amplifier saturation. Either mechanical damping is needed, or a different sensor type or measurement range.
PCB Piezotronics has a great white paper with more information on this exponential decay that occurs from charge amplifier saturation.
https://blog.mide.com/piezoelectric-accelerometers-how-they-work-and-where-to-buy
WHATS WRONG WITH MY PIEZOELECTRIC
ACCELEROMETER?
http://www.pcb.com/Contentstore/MktgContent/LinkedDocuments/Technotes/TN-30-what's_wrong_Lowres.pdf
The one that is always noted on here (I don't remember the model) has a very specific resonant frequency noted on the power rail in the spec sheet.