EvilBill is quite right. A superheterodyne radio receiver will radiate. The technical explanation is, well, technical. Google is the friend of the curious.
"What you hear on the speakers isn't interference with the electronics but rather interference with the magnetic coils."
It is actually the radio waves from the phone being picked up by the amplifier that drives the speakers. The PN junctions in the transistors rectify the RF, just like in a crystal radio, then the resultant audio signal is amplified.
The "off" phone will be drawing a very small amount of power, and radiating at an extremely low level (I should do some tests, I have equipment at work).
In fact, when off the phone probably radiates as much as my standard Kindle while I am reading - the Kindle is a very low power design because electronic paper uses no power when the page is not "turning".
There are technical standards covering emissions (interference generated) and susceptibility. Neither is ever zero. Every phone must comply with those standards, so there is no need to "test every phone".
Likewise, every device must be tested for susceptibility. In this context even a 747 is a device, and you can bet the FAA is a lot tougher than the FCC.
Close to the mark, I reckon. I have long held the view that what's needed to cope with the technological change is a social change.
We hold certain values to be self-evident, like the work ethic.
It was not always thus. Ancient Greece had a society where slaves did all the menial work. Substitute robots, or more generally all-pervasive automation, for slaves, and you have the potential to create a similar society but without the misery.
It "only" needs us to change our current value system, which is by no means eternal or immutable. We need to learn to value "non-productive" pursuits, and to educate people into following such pursuits as art, theater, invention and design, maths, teaching the young and the old, etc etc.
Maybe the open source (software, 3D printing) movements are signs of things to come, with millions of people producing very useful things for no financial reward.
I am an electronics engineer, so I have some knowledge of this.
I put my phone into flight mode, to save hassle with the flight attendants. Also, stopping its radio transmitter will eliminate the greatest potential hazard from interference.
That said, if the EMC immunity of the aircraft were so poor that a phone could upset it, I wouldn't be on that plane (and the plane would never have passed FAA certification tests).
The amount of interference from a phone, MP3 player, Kindle, noise cancelling earphones, or DVD player or laptop are all miniscule compared to a cellphone actually transmitting. And compared to all those other gadgets, the potential interference from a phone using in-flight WiFi is HUGE.
So why is inflight WiFi OK but my Kindle is not? Either profound ignorance on the part of the airlines, or superstition based play-it-safe rules.
The turn-it-off rule has no valid technical basis.
It seems to me that an awful lot of what's wrong with patents could be fixed by fairly simple remedies. The patent holders' rights can be protected within reason, without stifling competition.
Simple fix: Reduce the protection period to about 3-5 years.
The patent laws were written in an age when things moved slowly. Today the whole life cycle of a new product can be measured as a very few years. A shorter protection term will still give the inventor, in a modern world, time to establish a product and a strong market position.
I am actually thinking of two levels of protection: Total exclusivity for 3 years, then for the next 5 (say) years, protection but a compulsion to grant licenses, much like patents that underlie technical standards.
After that, open slather.
With such a system inventors would be rewarded, but there would still be opportunities for new innovation.
As for patent trolls: Apply the same "use it or lose it" rules that apply to trade marks. "Use it" means that the actual company that owns the patent is actually producing a product and can be challenge in court is only paying lip service to that requirement.
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Re: Re:
Well then, you'd better read the post @ 3:13am by G Thompson! He actually seems to be talking from knowledge, not supposition.
Re: Re: FM Radios
EvilBill is quite right. A superheterodyne radio receiver will radiate. The technical explanation is, well, technical. Google is the friend of the curious.
Incorrect
"What you hear on the speakers isn't interference with the electronics but rather interference with the magnetic coils."
It is actually the radio waves from the phone being picked up by the amplifier that drives the speakers. The PN junctions in the transistors rectify the RF, just like in a crystal radio, then the resultant audio signal is amplified.
Re: Re: Off topic....
John, you are quite right.
The "off" phone will be drawing a very small amount of power, and radiating at an extremely low level (I should do some tests, I have equipment at work).
In fact, when off the phone probably radiates as much as my standard Kindle while I am reading - the Kindle is a very low power design because electronic paper uses no power when the page is not "turning".
Re:
There are technical standards covering emissions (interference generated) and susceptibility. Neither is ever zero. Every phone must comply with those standards, so there is no need to "test every phone".
Likewise, every device must be tested for susceptibility. In this context even a 747 is a device, and you can bet the FAA is a lot tougher than the FCC.
Google electromagnetic compatibility.
Anything else is folk lore and superstition.
The new Socrates
"I call dibs on being the new Socrates."
Close to the mark, I reckon. I have long held the view that what's needed to cope with the technological change is a social change.
We hold certain values to be self-evident, like the work ethic.
It was not always thus. Ancient Greece had a society where slaves did all the menial work. Substitute robots, or more generally all-pervasive automation, for slaves, and you have the potential to create a similar society but without the misery.
It "only" needs us to change our current value system, which is by no means eternal or immutable. We need to learn to value "non-productive" pursuits, and to educate people into following such pursuits as art, theater, invention and design, maths, teaching the young and the old, etc etc.
Maybe the open source (software, 3D printing) movements are signs of things to come, with millions of people producing very useful things for no financial reward.
I am an electronics engineer, so I have some knowledge of this.
I put my phone into flight mode, to save hassle with the flight attendants. Also, stopping its radio transmitter will eliminate the greatest potential hazard from interference.
That said, if the EMC immunity of the aircraft were so poor that a phone could upset it, I wouldn't be on that plane (and the plane would never have passed FAA certification tests).
The amount of interference from a phone, MP3 player, Kindle, noise cancelling earphones, or DVD player or laptop are all miniscule compared to a cellphone actually transmitting. And compared to all those other gadgets, the potential interference from a phone using in-flight WiFi is HUGE.
So why is inflight WiFi OK but my Kindle is not? Either profound ignorance on the part of the airlines, or superstition based play-it-safe rules.
The turn-it-off rule has no valid technical basis.
A fix for a broken system?
It seems to me that an awful lot of what's wrong with patents could be fixed by fairly simple remedies. The patent holders' rights can be protected within reason, without stifling competition.
Simple fix: Reduce the protection period to about 3-5 years.
The patent laws were written in an age when things moved slowly. Today the whole life cycle of a new product can be measured as a very few years. A shorter protection term will still give the inventor, in a modern world, time to establish a product and a strong market position.
I am actually thinking of two levels of protection: Total exclusivity for 3 years, then for the next 5 (say) years, protection but a compulsion to grant licenses, much like patents that underlie technical standards.
After that, open slather.
With such a system inventors would be rewarded, but there would still be opportunities for new innovation.
As for patent trolls: Apply the same "use it or lose it" rules that apply to trade marks. "Use it" means that the actual company that owns the patent is actually producing a product and can be challenge in court is only paying lip service to that requirement.