widespread EM interference on electronics?

[JohnS]

If someone could somehow flood the frequencies of the EM spectrum with enough interference to prevent cell phones, radios and satellite signals to stop working... is it possible that other electronics could still work? (such as a computer on a hard line connected to the internet or a digital watch)

[RuthlessOptimism]

If you are strictly talking about noise / or intereference and not some kind of EMP then yes absolutely. I was just finishing a project in Digital Signal Processing yesterday, part of the project involves us filtering out noise from a signal. You can think of the EM interference as basically just being a loud background noise that washes out the intended signal. EM waves in this case are completely analogous to sound waves, for example its hard for you to talk to your friend in a normal volume of voice at a rock concert. You could try and create a bandpass filter, a device that would block frequencies other than the dominant frequency of your friends voice, but if there are frequency components of the noise that are equal to your friends voices dominant frequency you will still not recover your friends voice cleanly, perhaps not at all if the noise at that frequency is loud enough (has enough power). Noise in terms of electronic communications is literally noise, it doesn't actually do anything to the electronics itself it just washes out the recieved signal.

[swansont]

A lot of wiring is there to make sure that it doesn't pick up noise. Twisted-pair wiring, for example, is twisted so it doesn't act like an antenna.

[JohnS]

If you are strictly talking about noise / or intereference and not some kind of EMP then yes absolutely. I was just finishing a project in Digital Signal Processing yesterday, part of the project involves us filtering out noise from a signal. You can think of the EM interference as basically just being a loud background noise that washes out the intended signal. EM waves in this case are completely analogous to sound waves, for example its hard for you to talk to your friend in a normal volume of voice at a rock concert. You could try and create a bandpass filter, a device that would block frequencies other than the dominant frequency of your friends voice, but if there are frequency components of the noise that are equal to your friends voices dominant frequency you will still not recover your friends voice cleanly, perhaps not at all if the noise at that frequency is loud enough (has enough power). Noise in terms of electronic communications is literally noise, it doesn't actually do anything to the electronics itself it just washes out the recieved signal.

 

Ah! This is good. My next question is, why would cell phone devices break some electronics: In hospitals they affect ventilators which use no signals or communication transmissions. Pacemakers are another example. PMs sends electronic impulses to the heart via wires so how could the radiofrequency energy emitted from cell phones affect them... but not the circuitry of a microchip? Possibly a virtue of a semiconductor?

 

 

Thanks for the answer guys, BTW.

[RuthlessOptimism]

 

Ah! This is good. My next question is, why would cell phone devices break some electronics:

 

 

Thanks for the answer guys, BTW.

Sorry I don't really know the answer to that question. In your original question you asked about "interference", this kind of implies that what you meant was that something is interfering with the signal quality of cellphones radios etc. In that specific case as long as the electronics are shielded well (swansont described one way people do that) they will operate just fine, you will simply not be able to communicate, send / recieve electronic messages through the air very well because the data will be unrecoverable as there is a bunch of noise super positioned on top of it.

 

My guess is that in principle basically anything conductive can act like an antenna and absorb energy from electromagnetic waves. If there is a small piece of an electronic device that is acting like an antenna (intentionally or otherwise) and if the energy it is absorbing becomes too high for any circuit it is connected to to handle, the circuit will burn itself out.

[studiot]

 

Ah! This is good. My next question is, why would cell phone devices break some electronics: In hospitals they affect ventilators which use no signals or communication transmissions. Pacemakers are another example. PMs sends electronic impulses to the heart via wires so how could the radiofrequency energy emitted from cell phones affect them... but not the circuitry of a microchip? Possibly a virtue of a semiconductor?

 

 

Thanks for the answer guys, BTW.

 

 

It is about probabilities, not certainties.

There is a possibility that the EM radiation from a cellphone will activate circuitry in an unwanted way.

Therefore there is a finite probability of this.

 

Imagine, for a moment, that you are blind and standing by the side of the road to cross.

You could simple march across, like small animals do.

There is a possibility that you could get across without being hit by traffic and a possibility that you could become roadkill, like many small animals.

 

Would you take that chance?

 

Back to the cellphone.

Electronics works on electrical energy, and as the industry has developed the amount of such energy needed to create an electronic action in electronic devices has fallen dramatically.

Even the device leads and connections on a circuit can pick up EM (electrical) energy that is passing through.

Mostly this pickup falls beneath the threshold to alter circuit action , but as electronic devices uses less and less power, the gap between pickup and that threshold grows ever smaller.

However in order to communicate with a cellphone mast, the phone must broadcast a minimum quantity of EM energy.

This is not really getting smaller these days.

Further many other electronic devices nowadays operate in the same frequencies as cellphones, so pickup will be more efficient.

 

So there is a real possibility that ever more sensitive equipment will pickup a small pulse of EM energy from a cellphone suddenly communicating with a mast, and then malfunction.

 

Again would you like to take the risk of being connected to that most modern piece of medical gadegtry at the time?

 

Incidentally it has always been known that not only EM radiation, but ionising radiation and even neutrinos can affect computer memory by changing the charge on a single memory cell.

And the actual charge a memory cell requires to change/ indicate state is incredibly low these days.

 

So, even without cellphones, computers are vulnerable to memory degradation from passing radiation.

And medical devices (like many others) routinely incorporate memory these days.

Edited November 28, 2015 by studiot

[JohnS]

Great answers, this is exactly what I need. Thanks!

[DevilSolution]

Also the further you are from a mast the strong the microwave frequency will be, increasing the probability of interference.

 

Dont stand directly below an aircraft after it lands either, they emit such strong microwave energy it can literally fry you. Though i think they've plated them now, it used to be the case. Just a little trivia.

Edited November 29, 2015 by DevilSolution