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New Chip Promises Longer Battery Life

ScuttleMonkey posted more than 8 years ago | from the only-for-the-first-week-then-it-dies dept.

188

Roland Piquepaille writes "It always happens when you need it the most: the battery of your cellphone just died. But now, researchers of the University of Rochester have developed a wireless chip that needs ten times less power than current designs. The new chip relies on a technology named injection locked frequency divider (ILFD) which dramatically reduces the time needed to check for transmission frequencies which are performed several billion times per second by your current phone. The new chip uses five transistors and can perform divisions by 3 instead of only 2 by previous circuits, allowing a perfect communication between two phones communicating at 2.0001 and 2.0002 gigahertz respectively."

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188 comments

Thats interesting and all (-1, Offtopic)

TheRealMindChild (743925) | more than 8 years ago | (#15182556)

but what I want to know is, why is it when Im looking at a red digital clock and Im eating something crunchy, the lines in the numbers all jumble, but nothing else does?

Re:Thats interesting and all (3, Informative)

Bruce Perens (3872) | more than 8 years ago | (#15182575)

The various segments of the readout are wired in a sort of square matrix to save wires at the chip outputs and driver transistors inside the chip or on the circuit board. They can't all be on at once because of the wires they share. They have to be driven in sequence. So, you see a sort of strobe light effect where each different part of the number is flashed at a different point while your head and eyes vibrate in a sort of arc.

Bruce

Re:Thats interesting and all (1, Informative)

sqrt(2) (786011) | more than 8 years ago | (#15182671)

Hey mods, this isn't off-topic. Only a top level comment can be off topic, this answers the question in the parent and thus is on topic.

Re:Thats interesting and all (0)

Anonymous Coward | more than 8 years ago | (#15182883)

Sorry but moderation is with respect to the story, not thread.

Re:Thats interesting and all (0)

Anonymous Coward | more than 8 years ago | (#15182912)

I just spent the better part of the last two months springing my brother from jail in Guangdong province, China. Your inflexibility and deference to "the system" and its undefined rules remind me of the behavior of the Chinese authorities.

Re:Thats interesting and all (0)

Anonymous Coward | more than 8 years ago | (#15183030)

I'm sure your Brother would be happy to hear about your heroing ordeal and how you barely escaped losing karma.

You're the real victim, not him.

Re:Thats interesting and all (0)

Anonymous Coward | more than 8 years ago | (#15182611)

Try reading a CRT while using an electric toothbrush. Wacky.

Re:Thats interesting and all (0)

hackwrench (573697) | more than 8 years ago | (#15182613)

Because they are all red, and red bends more than other colors.

Re:Thats interesting and all (2, Funny)

Anonymous Coward | more than 8 years ago | (#15182620)

You have brain cancer. Check into a hospital immediately.

Re:Thats interesting and all (1)

Dis*abstraction (967890) | more than 8 years ago | (#15182631)

Because loud noises, such as from crunchy foods, jiggle the electronics in the LED. The same thing happens when you sneeze, if you can keep your eyes open to watch.

Re:Thats interesting and all (3, Interesting)

ltbarcly (398259) | more than 8 years ago | (#15182755)

The red cones in your eye react more slowly than the other color receptors. Therefore when you are looking at the red led, which is a pure red light surrounded by darkness (not common in nature btw) what you are actually seeing is the vibration due to the crunch momentarily after they happen. Your brain adjusts so that you do not notice the vibration in your vision, except it cannot take into account the slight delay in the red cones. Therefore the red light appears to jump around.

Not A Big Deal (4, Informative)

Bruce Perens (3872) | more than 8 years ago | (#15182557)

The PLL component this is supposed to replace is a small-signal component. It is not a major user of the power budget of a cell phone. The big power users are the transmitter and the microprocessor. The PLL is not heat-sinked and does not run warm. If it's not hot, it's not a power hog.

Bruce

Re:Not(?) A Big Deal (1)

thestuckmud (955767) | more than 8 years ago | (#15182628)

I don't use my cell phone much. Having several weeks of standby time would be convenient, even if talk time is not increased significantly.

Re:Not(?) A Big Deal (4, Interesting)

green1 (322787) | more than 8 years ago | (#15182658)

the problem is, even in "standby" the phone does a lot of transmitting, and that transmitting is still a power hog.

I'm not quite as negative as the grandparent poster, in that I'm happy if any component uses less power (every bit helps) but in reality, it's the transmitter that uses the lions share of the juice, not the reciever (even in standby).

Re:Not A Big Deal (5, Informative)

geoskd (321194) | more than 8 years ago | (#15182693)

The PLL component this is supposed to replace is a small-signal component. It is not a major user of the power budget of a cell phone. The big power users are the transmitter and the microprocessor. The PLL is not heat-sinked and does not run warm. If it's not hot, it's not a power hog.


The Problem is not that the PLL uses lots of energy, the problem is that digital circuitry, which the PLL feeds, uses power that is proportional to the frequency at which the PLL drives it. If you have a digital circuit at 2 GHz, it will use one tenth of the power of a circuit which runs at 20 GHz. This is important because traditional digital circuits which communicate with each other on specific frequencies, do so by running a clock speed of at least 10 times the communication frequency, and then using a microporcessor to count up clock pulses in order to exactly equal the right frequency. If you are running at 10x the communication frequency, then you need to count ten clock pulses for each communication signal cycle. If you need greater accuracy, then you need more clock pulses per communication cycle to get that accuracy. Thus, your digital circuits are in effect running at much higher clock frequencies than are necesary to actually achieve the communication. This is why your little 2 watt tx/rx chip actually consumes closer to 20 watts when it is communicatng actively.

What these researchers have done is found a way to adjust the frequency of the digital circuitry to exactly match the communication frequency, so instead of counting pulses, we can safely assume that 1 digital signal cycle = 1 communication cycle. This is just as good as clock pulse counting when it comes to processing digital communication signals, but up until now there was no way to adjust the source frequency with any real accuracy, so you had to run the source frequency very fast and count up pulses to get accuracy. Now, we no longer have to count, we just use one pulse / cycle, and were all set.

To explain in a slightly different way, we'll use the analogy of trying to accurately count a mountain of pennies. The easiest way to do so, is to weigh the whole pile, and then divde by the average weight of a single penny, and you get the total number of pennies. The question is how you get the "average weight" of a single penny. If you weigh just one penny, and use that as the average, then you have some total inaccuracy X. If you instead weigh 10 pennies and divde the weight by 10, the inaccuracy is much less: roughly X/10. This is how the old method of PLL circuit design worked. The greater the frequency, the more pennies you used to find the average weight, and so the greater the accuracy you could get in finding out the total number of pennies in the whole pile, or the exact frequency.

The new method described in the Article is roughly analagous to modifying all of your pennies to ensure that the variation in the weights of the pennies is much lower, so you can rely on just one penny to provide you with the precision needed to determine the total number in the pile.

I hope this cleared up some of the confusion.

-=Geoskd

Re:Not A Big Deal (5, Funny)

Dis*abstraction (967890) | more than 8 years ago | (#15182740)

Actually, I'm still a little confused. Could you try an analogy using cars instead? Thanks.

Re:Not A Big Deal (5, Funny)

alx5000 (896642) | more than 8 years ago | (#15182775)

To explain in a slightly different way, we'll use the analogy of trying to accurately count a mountain of cars. The easiest way to do so, is to weigh the whole pile, and then divde by the average weight of a single car, and you get the total number of cars. The question is how you get the "average weight" of a single car. If you weigh just one car, and use that as the average, then you have some total inaccuracy X. If you instead weigh 10 cars and divde the weight by 10, the inaccuracy is much less: roughly X/10. This is how the old method of PLL circuit design worked. The greater the frequency, the more cars you used to find the average weight, and so the greater the accuracy you could get in finding out the total number of cars in the whole pile, or the exact frequency. The new method described in the Article is roughly analagous to modifying all of your cars to ensure that the variation in the weights of the cars is much lower, so you can rely on just one car to provide you with the precision needed to determine the total number in the pile.

Re:Not A Big Deal (1)

Kent Recal (714863) | more than 8 years ago | (#15182794)

How does this translate to libraries of congress?

Re:Not A Big Deal (1)

djupedal (584558) | more than 8 years ago | (#15182832)

...try an analogy using cars instead?

If an end-to-end mobile phone system was a used Portland taxi, the meter would never come off polling, the user would be the rear view mirror and you would be an old penny lost long ago under the right front seat.

Re:Not A Big Deal (4, Informative)

chriso11 (254041) | more than 8 years ago | (#15182767)

No, the digital circuitry does not run at the PLL frequency in a cell phone. The stable reference frequency from the crystal is upconverted to what is called the LO - this LO is mixed in with received signal from the antennea to downconvert the signal to a lower frequency. No digital processing occurs at 1.8GHz/1.9GHz on a cell phone - it is all much lower in frequency. That also goes for Bluetooth and WiFi.

The article is really short on details. The real power hog in a cell phone is the transmitter - it will draw 3Amps of current - while the rest of the receiver and up-conversion components are maybe 10% of that. And transmitters are already quite efficient - generally, ~50% of the input DC power winds up going out as RF power.

The lower power version of the PLL will be useful, since it needs to run constantly, even while not actively in a call.

Re:Not A Big Deal (1)

stevesliva (648202) | more than 8 years ago | (#15182807)

I think part of the confusion is that this circuit is proposed to replace the PLL. The "digital circuitry" referred to that is running at the PLL frequency is the PLL itself, using a bunch of mixed-signal magic to take an input clock and spit out a very specific frequency. This new thigamabob proposes to take a very-high frequency quartz oscillator as an input signal and divide it down to a specific frequency using some analog magic. Although to say that this PLL replacement avoids digital logic entirely would imply no rebuffering of reference oscillator or clock anywhere along the line...

You are right. The article and parent are wrong. (0)

Anonymous Coward | more than 8 years ago | (#15182888)

The article implies that the transmit frequencies are being checked at a 2 GHz rate. The parent implies that there is something in the cell phone with a clock rate of 20 GHz. Both are wrong. You are right. There is no digital processing at anywhere near that frequency.

There are two issues about frequency. One is precise control of the transmit frequency. It is, as you point out, done by a phase locked loop. The other issue is which frequency to transmit on and that is negotiated between the cell and the phone. The transmit power is also negotiated between the cell and the phone.

Actually, there is a lot going on. It would be pretty much impossible to build a modern digital cell phone without using some kind of processor. If you were to try to implement the same functions with discrete circuitry, your cell phone would probably weigh ten pounds. Given all that is going on, it's impressive that cell phone batteries last as well as they do. As you point out keeping the clock rate as low as possible is what achieves that.

Re:Not A Big Deal (1)

kinzillah (662884) | more than 8 years ago | (#15182820)

You could probably hire mexicans to count them cheaper than you could buy a scale capable of weighing a mountain of pennies. Along with that massive scale you would also need front end loaders and cranes, and union workers. Ideally, you could get the mexicans to feed them into those coinstar machines, though capacity may be an issue.

Re:Not A Big Deal (0)

Anonymous Coward | more than 8 years ago | (#15182841)

This is why your little 2 watt tx/rx chip actually consumes closer to 20 watts when it is communicatng actively.


P=IV

Modern cell phones tend to run on 3.6V batteries. So 20 Watts at 3.6V requires 5.5555555555555555555555555 Amps, give or take a few decimal places.

Most standard cell phone batteries are rated at 950 mAh. Assuming you are correct on "20 Watts when ... communicatng", this would mean modern cell phones only get about 10 minutes of talk time. That's pretty low, so I can see why this new technology could be exciting!

I hope this cleared up some of the confusion.


It's always good to have a little bit of hope!

Re:Not A Big Deal (1)

Proudrooster (580120) | more than 8 years ago | (#15182995)

Cell phones have low power transmitters in the .5W to 3W of power range. A digital transmitter using a CDMA/TDMA scheme sends a transmission pulse every 6ms (or so), thus the power consumption is not continuous but works out to about 50% on, 50% off. I would have to look at my cell, but 20W of power consumption while transmitting seems very high and it seems like your head would definately notice the heat being generated by the phone, not to mention that the efficiency of the phones electronics would be a mere 10% (2W/20W = 10%).

This new 5-transistor frequency divison technique looks interesting, but it still relies on averaging and rounding which sounds like it will lead to imprecise clocking. I am still bitter that my PCs CMOS clock (RTC) can't keep decent time when running off battery. Maybe Wu's new method could help out there too. :)

no it doesn't... (2, Informative)

YesIAmAScript (886271) | more than 8 years ago | (#15182915)

20W in use? Give me a break.

Let's say I'm running at 1W (max for 1800/1900, half max for 850/900). I'm transmitting 1/8th of the time (due to TDMA slotting).

Thus I would use 1/8Wh per hour just to transmit. My phone has a 3Wh battery (800mAh @ 3.8V). So I would have a talk time of 24h, if my phone didn't use power for anything else at all. It does, so the talk time on my phone is 8H.

Now, let's try out your version. I'm using 22W when transmitting, 1/8th of the time. So I'm using 2.8Wh per hour. So, if my phone did nothing else, I would get just over 1 hour talk time.

Except my phone is rated at 8 hours, and tests show 9.

This would be impossible if you were correct.

The way a PLL actually works, yes, a small amount of circuitry in the PLL runs at many times the actual output frequency. But all the circuitry it is designed to drive, which is attached to the output of the PLL runs only at the actual frequency.

In the system I use, the entire power consumed by a PLL is 0.4mW. If they increased the efficiency infinite-fold due to lowering clock rates inside the PLL, it would take 0mW, and the resulting reduction in power used would still be insignificant, because the rate the circuitry the PLL is driving would still be running at the same speed and thus using the same amount of power.

Basically, it appears to completely fail to understand what a PLL is and why it is different from clock-skipping.

Re:Not A Big Deal (3, Informative)

Jeff DeMaagd (2015) | more than 8 years ago | (#15183042)

Another issue with your claims is that the power needed to operate a CMOS digital circuit goes up not linearly but by the square. A circuit that operates at 20GHz would consume about 100x the power as the same circuit that operates at 2GHz. I'm not aware of any commercial digital IC that can operate at 20GHz anyway.

Re:Not A Big Deal (1)

fireweaver (182346) | more than 8 years ago | (#15182822)

Bruce Perens: "The PLL component this is supposed to replace is a small-signal component. It is not a major user of the power budget of a cell phone. The big power users are the transmitter and the microprocessor. The PLL is not heat-sinked and does not run warm. If it's not hot, it's not a power hog."

But it runs continuously. Why else would the battery run down when the phone is not in use? Anything which minimises the standby drain on the battery is a Good Thing (tm).

Re:Not A Big Deal (1)

Achromatic1978 (916097) | more than 8 years ago | (#15182980)

I would have said the LCD displays would also chew a fair bit of power - especially on phones like my Nokia N90 [nokia.com] with two of them, one a very high res one (352x416). Not to mention people who are high users of accessories, in particular MP3 players and cameras.

division (0)

Anonymous Coward | more than 8 years ago | (#15182559)

"he new chip uses five transistors and can perform divisions by 3 instead of only 2 by previous circuits, allowing a perfect communication between two phones communicating at 2.0001 and 2.0002 gigahertz respectively."

But what does it mean? Since when do you need to divide by 3 instead of 2?

When you date triplets. (1)

Naruki (601680) | more than 8 years ago | (#15182790)

Not a common thing, but when it happens... Pixpls.

"ten times less power"? (2, Interesting)

oldenuf2knowbetter (124106) | more than 8 years ago | (#15182561)

Would "ten times less power" be anything like "one tenth as much power"?

Re:"ten times less power"? (1)

Paradise Pete (33184) | more than 8 years ago | (#15182590)

Would "ten times less power" be anything like "one tenth as much power"?

At least. It might one eleventh. Numerical comparisons using less and more, rather than the accurate "as much" form, tend to be ambiguous.

Re:"ten times less power"? (2, Insightful)

Paradise Pete (33184) | more than 8 years ago | (#15182607)

Stick a "be" in there for me, would ya? Anyway, as long as I'm following up on my own post, I'l try to restate it in a less pompous way. What would "two times less" mean? It certainly shouldn't mean half as much, but it would have to in order to be able to state one tenth as "ten times less." So the original comparison form is simply broken.

Re:"ten times less power"? (1)

NewbieProgrammerMan (558327) | more than 8 years ago | (#15182612)

Wish I had mod points for you....assuming you meant that to be funny, of course...

Re:"ten times less power"? (1)

Paradise Pete (33184) | more than 8 years ago | (#15182622)

Well I almost always mean to be a little funny, even when I'm trying to make a point. But that "two times more powerful!" stuff is a pet peeve of mine. And every once in a while it gets out of its cage. (There. that last part was me trying to be a little funny. Very little, I know.)

Re:"ten times less power"? (0)

Anonymous Coward | more than 8 years ago | (#15182621)

It means it can power 9 of the current chips.

Re:"ten times less power"? (4, Funny)

Guuge (719028) | more than 8 years ago | (#15182685)

Imagine all the power the old chip doesn't use. Multiply this number by ten. This is the amount of power the new chip doesn't use. So you end up not using ten times as much power as you used to not use.

Re:"ten times less power"? (1)

mattcoz (856085) | more than 8 years ago | (#15182707)

No, it would be "negative nine times as much power", so we're talking infinite battery life, truly a breakthrough.

Re:"ten times less power"? (0)

Anonymous Coward | more than 8 years ago | (#15182785)

Negative power isn't the same as zero power, you idiot. Using the phone a negative amount of time *will* drain the battery.

Re:"ten times less power"? (1)

alexmipego (903944) | more than 8 years ago | (#15182821)

Would "you" be anything like "a human"?

Conversation (5, Funny)

LiquidCoooled (634315) | more than 8 years ago | (#15182562)

Dude: Hui Wu invented this new chip that saves loads of power.

Bloke: Who?

Dude: Yes

Bloke: so who invented this chip.

Dude: Hui did.

Bloke: Thats what I'm asking you.

Dude: Yer I know, Hui did.

Bloke: Quit it and tell me who invented the chip.

Dude: Im not joking, Hui did.

Re:Conversation (1)

jdbartlett (941012) | more than 8 years ago | (#15182664)

Oh no, not again. [slashdot.org]

Re:Conversation (1)

ralph alpha (956305) | more than 8 years ago | (#15182725)

Too bad the joke is invalidated because "Hiu" isn't pronounced like "who."

Hiu as 'he' (1)

hackwrench (573697) | more than 8 years ago | (#15182894)

Funny, I thought he was trying to pronounce Hiu as 'he'

Re:Conversation (0)

Anonymous Coward | more than 8 years ago | (#15182743)

I believe it is pernounced more like "Hwee" than like "Hoo-ee".

get your pronounciation right (1)

nihaopaul (782885) | more than 8 years ago | (#15182914)

hui should be pronounced like `hway`

Re:get your pronounciation right (3, Funny)

phlipped (954058) | more than 8 years ago | (#15183004)

1: "Hoo" invented this new chip
2: No "Hway"!
1: YES way!
2: That's what I said
1: What?
2: The name of the guy is pronounced "Hway", not "Hoo"
1: Oh. I thought it was "Hoo"
2: No it's "Hway"
1: I see
2: Yes. Well ... Um ... I have to go ... over ... there now
1: Ok ...

Battery power (1, Flamebait)

cr@ckwhore (165454) | more than 8 years ago | (#15182601)

"It always happens when you need it the most: the battery of you cellphone just died. But now, researchers of the University of Rochester have developed a wireless chip that needs ten times less power..."

Ok, but that still doesn't solve the "I need my phone now but I was too lazy to charge it last night" problem. So what, this chip can run from a dead battery? No.

It really doesn't matter how much power the phone uses... the fact is that it still uses power. Consuming power from a limited source means that it will reach a point when the battery is depleted, except now it just takes 10 days longer than before.

Murphy says, you will still be inconvenienced.

Re:Battery power (2, Insightful)

MobileTatsu-NJG (946591) | more than 8 years ago | (#15182720)

"It really doesn't matter how much power the phone uses... the fact is that it still uses power. Consuming power from a limited source means that it will reach a point when the battery is depleted, except now it just takes 10 days longer than before."

You're absolutely right. I don't even know WHY they're bothering! *places hands on his and sadly shakes his head*

wind up? (0)

Anonymous Coward | more than 8 years ago | (#15182728)

We have wind-up flashlights, why cant we have wind-up cellular phones?

do they take more power than a flashlight? what if i wound it for 5 min instead of 2? would that be enough?

Re: usb to 9v battery charger (5, Informative)

cheekyboy (598084) | more than 8 years ago | (#15182798)

Finally, an excuse to drive fast (1)

jdbartlett (941012) | more than 8 years ago | (#15182953)

Hey, I'd like to stick that wind turbine charger on my car roof!

Re:Battery power (1)

jdbartlett (941012) | more than 8 years ago | (#15182729)

You are correct in saying cellphones use electricity. You are incorrect in saying this does not solve the I was too lazy to charge it last night problem. It does. It does not, however, solve the I was too lazy to charge it last week problem. Still, I'm sure you agree, it's a step forward. Eventually, we'll design cell phones powered by thought. I have one interesting device that has enabled me to communicate up to hundreds of feet using no electricity. Just gives me a bit of a sore throat is all.

Re:Battery power (0)

Anonymous Coward | more than 8 years ago | (#15182778)

[i]Eventually, we'll design cell phones powered by thought.[/i] Not likely, this cuts off their core demographic. Posting anonymously so as to not undo moderation. NemosomeN

Re:Battery power (1)

NemosomeN (670035) | more than 8 years ago | (#15182786)

Undoing moderation to Comment #15182575
Undoing moderation to Comment #15182612
Undoing moderation to Comment #15182623
Undoing moderation to Comment #15182652
Undoing moderation to Comment #15182671

Fuck. I totally fucked up last post. Guess I shoulda logged out.

Re:Battery power (0)

Anonymous Coward | more than 8 years ago | (#15182846)

So it was you who moderated this subthread [slashdot.org] "offtopic"? Sure, it's technically true--but you're still a petty asshat.

Re:Battery power (1)

mikej (84735) | more than 8 years ago | (#15182860)

It does matter how much power the phone uses. Your phone using 1/10th the power, which is ultimately from the same source as all your domestic energy, means almost nothing; A million, 10 million, or 100 million phone users all using 1/10th the power, well... it adds up. Sure your use profile isn't going to change, but you get the same utility for less power. That's basically the modern definition of Good.

Why are we still using batteries? (1)

El Cubano (631386) | more than 8 years ago | (#15182609)

But now, researchers of the University of Rochester have developed a wireless chip that needs ten times less power than current designs. The new chip relies on a technology named injection locked frequency divider (ILFD) and permits to dramatically reduce the time needed to check for transmission frequencies which are performed several billion times per second by your current phone.

Out of curiousity, why have we not yet figured out how to wirelessly power devices? I mean, we can send lots of RF energy through the air. Why can we not use that same energy to power the device as well as send it information? I can see where it would be a problem for something that requires lots of power, but for small devices this should be possible, no?

Re:Why are we still using batteries? (2, Funny)

stevesliva (648202) | more than 8 years ago | (#15182623)

I mean, we can send lots of RF energy through the air. Why can we not use that same energy to power the device as well as send it information? I can see where it would be a problem for something that requires lots of power, but for small devices this should be possible, no?
Dude, you just re-invented RFID tags! You'll make me smile next time I unlock the doors at work.

Re:Why are we still using batteries? (1)

El Cubano (631386) | more than 8 years ago | (#15182652)

Dude, you just re-invented RFID tags! You'll make me smile next time I unlock the doors at work.

OK:

  1. Coffee first
  2. Post on Slashdot second

Re:Why are we still using batteries? (0)

Anonymous Coward | more than 8 years ago | (#15182649)

We can, but not for something as power-hungry as a cell phone that needs a transmitter capable of communicating with a base station a mile away. It takes a lot of energy.

Re:Why are we still using batteries? (1)

LoverOfJoy (820058) | more than 8 years ago | (#15182845)

It could make a cool watch, though.

Re:Why are we still using batteries? (0)

Anonymous Coward | more than 8 years ago | (#15182694)

Because enough power to run your laptop will likely cook bacon?

Re:Why are we still using batteries? (2, Interesting)

m85476585 (884822) | more than 8 years ago | (#15182698)

If you have a 2-way radio (I don't know if a cellphone would work), go to Radioshack and get a low-current light bulb (not LED) and connect solid leads about 8" long to each lead of the bulb. Make them both into a coil, slip one over the 2-way radio antenna, and transmit. The lightbulb should glow bright. Unfortnately RF energy decreases as inverse square.

Re:Why are we still using batteries? (5, Informative)

Com2Kid (142006) | more than 8 years ago | (#15182751)


Out of curiousity, why have we not yet figured out how to wirelessly power devices?

Short answer: We already have, it is just so inefficient that nobody uses it. (in fact it was invented over 100 years ago!)

Long answer: Electromagnetic waves radiate outwards. Either you have a simple non-directional antenna that radiates in all directions at the same time (in a sphere basically) and you lose power REALLY fast, or you have a directional antenna that radiates power in a cone at a target destination.

The omni-directional radiators suck so much that they are absolutely useless. Inverse square means 1/(x^2). Basically (and this is crappy math but gets the point across) if you have 10 watts at 1 feet, you would have 10*(1/(2^2)) = 2.5 watts at 2 feet. At 3 feet you would have 10*(1/9) = 1.11 watts. Please ignore that you would use meters instead of feet and that all my units are all messed up in various other ways as well. The point is that your power drops off REALLY fast.

So what about those directional antennas?

Well, you have to find some way to really accurately track someone's cell phone position, and have a world-wide array of directional antennas so that you can beam power to them no matter where they are at.

Oh and remember to keep those power levels low, else you will fry anything that gets in the way.

People worry about cell phones causing cancer as it is, directional power beamed at your head WOULD cause some serious issues!

Wireless power is possible, just not feasible!

Re:Why are we still using batteries? (1)

Bloater (12932) | more than 8 years ago | (#15182849)

Is it that all that 7.5 Watts is dissipated by the transmission distance increasing from 1ft to 2ft? Or is it that the EMF at the receiver reduces by distance^2?

Re:Why are we still using batteries? (1)

Com2Kid (142006) | more than 8 years ago | (#15182957)

Since we are talking about spherical radiation the energy is still there, it has just been radiated in, literally, every other direction.

Err, it makes a lot more sense when drawn on a board. :) The 1/x^2 thing is actually just due to the surface area of a sphere. (as I said, I dropped a ton of constants out!)

You can imagine in that you have "X watts" that are initially bundled up in a single point (the round little tip top of the radiating antenna, which in perfect physics land, is a single point. :).

Because EMF energy is radiated in a sphere when coming from a single point source, you have this ever increasing sphere. You basically have to "stretch" those "X watts" out over the surface area of the sphere.

(my humble apologizes to any actual physicists out there!)

Re:Why are we still using batteries? (2, Insightful)

Schraegstrichpunkt (931443) | more than 8 years ago | (#15182992)

IANAPhysicist, but to put it another way, if you take an omnidirectional antenna, and draw a sphere around it, the total energy over that sphere will be the same, regardless of the distance. However, the energy density (e.g. energy per square foot) decreases drastically as distance increases. Since the receiving antenna has a fixed size, the amount of energy captured by your antenna decreases equally drastically.

As you said, it's pure geometry.

Re:Why are we still using batteries? (1)

PopeRatzo (965947) | more than 8 years ago | (#15182802)

But won't all that power floating around in the air cook all the birds?

Re:Why are we still using batteries? (1)

livewire98801 (916940) | more than 8 years ago | (#15182932)

So, we solve the world's hunger problem along with DC power problems. . . talk about killing two. . . [clears throat]

Re:Why are we still using batteries? (0)

Anonymous Coward | more than 8 years ago | (#15182956)

Killing two birds with one phone?

Re:Why are we still using batteries? (0)

Anonymous Coward | more than 8 years ago | (#15182829)

I can see where it would be a problem for something that requires lots of power, but for small devices this should be possible, no?

On the other hand, I can see where it would be a problem for something that has a small RF cross-section, but for large devices this should be possible, no?

Re:Why are we still using batteries? (4, Interesting)

darthwader (130012) | more than 8 years ago | (#15182918)

A while ago, Mythbusters did a "free energy" show. They collected a bunch of plans from "the Internet", built the devices, and tested them.

One of the devices that surprised me was a 50' long aerial, attached to some simple circuitry. The aerial absorbed RF energy, and the electronics converted it into a somewhat useful DC power supply. I think it was producing somewhere around 1 volt, no idea how much current, indoors. IIRC, they said it was "almost as good as a AA battery".

So, not only is is possible in theory, it's possible in practice. But it's still wildly impractical.

I think it's episode 24 (http://dsc.discovery.com/fansites/mythbusters/epi sode/episode_06.html [discovery.com] ).

Re:Why are we still using batteries? (1)

mikiN (75494) | more than 8 years ago | (#15182937)

Out of curiousity, why have we not yet figured out how to wirelessly power devices?

Well, there's this great ball of fire boiling away in space that sends part of its goodness our way, the most obvious way to wireless energy transfer.

Trouble is, not many devices are taking advantage of it yet (apart from watches, calculators, environment monitors and the lot), partly because of power requirements being too high, partly because of lack of cheap and efficient solar panels.

Of course, if you live in a sunny place, you could buy a solar power battery charger for your phone.

Re:Why are we still using batteries? (1)

null-sRc (593143) | more than 8 years ago | (#15183054)

you don't think cell phones cause enough brain cancer? now u wanna send power to them too :|

Billion? (0, Offtopic)

sapgau (413511) | more than 8 years ago | (#15182610)

Like in gazillion?

Re:Billion? (1)

Schraegstrichpunkt (931443) | more than 8 years ago | (#15183000)

In America, we call it a gajillion. You're clearly not with us, here. (Does that mean you are with the terrorists? Hmm?)

Two/Three (5, Funny)

samkass (174571) | more than 8 years ago | (#15182697)

The new chip uses five transistors and can perform divisions by 3 instead of only 2 by previous circuits


Bender: "Ahhh, what an awful dream. Ones and zeroes everywhere... and I thought I saw a two!"
Fry: "It was just a dream, Bender. There's no such thing as two."

One idea (2, Interesting)

thePig (964303) | more than 8 years ago | (#15182738)

The transmitter would be the one which would be using the max power in any cellphone.
In that case, make the antenna directional.
But then, we do *not* know the direction to which I have to sent the signal.
That can be done by maybe -
1. Changes needed for Towers
      Sent downstream a small pilot signal of the same freq as the upstream signal which the phone emits for that call.
2. Changes needed in the Cell
      Have a direction sensor in your mobile for this pilot signal. Once direction the highest amp for the pilot signal is obtained, sent the signal back in the same direction.

Instead of the wasted signal going all around, we have a signal which has very good directional properties. Thus the power of the signal to be sent can be reduced to maybe even 1/10th or 1/100th.
Thus the battery life also will have a propotional increase.

Adv of this system -
1.We dont care how many changes in direction the signal took and all.. Since the pilot came this way, my signal (almost the same freq, so almost the same refractive/reflective properties)will reach the tower proper.
2. Worries about your head getting fried by signal now over. Supposing that your head occupies 90 degrees of the phone directionality, now there is 1/4th time the power goes through you. In anycase, I dont think there is a high probability of the max amp pilot signal coming through your head.. So much less say1/10th of the time upstream signal goes through you.

Prob -
Changes needed in all towers.
Is a antenna which can change direction depending on a signal already there ? If not the idea wont work at all.

Just an idea.

Re:One idea (1)

scruff323 (840369) | more than 8 years ago | (#15182763)

One problem: In this case, you couldn't turn around while talking, you would have to remain in the same position basically for the whole time. This seems like a big pain in the ass. I pace all the time while talking on the phone.

I say just get rid of all those extra features like color screens and cameras if you are worried about battery life. My phone is an old LG phone without color or fancy ring tones and stuff. The battery can literally last 4 or 5 days on standby.

Re:One idea (1)

thePig (964303) | more than 8 years ago | (#15182795)

Why ?
We can turn around.
The pilot signal would be coming full time. So the signal direction where it is sent also will be changing full time.
This is a real -time system, which I trying to concieve.

So methinks no issues in this regard

Re:One idea (1)

snilloc (470200) | more than 8 years ago | (#15182833)

Lasting 4-5 days on standby isn't spectacular. My old monochrome nokia used to do it (until the battery started flaking out after 3 years of continuous use). My brand new samsung model (with color screen, external display, and funky ringtones) has been doing about that much, and weighs 2/3 what the Nokia did.

More to your original point however, it wouldn't be unthinkable to have a monochrome display on a very basic phone and have it last ten days with current battery technology... but almost nobody (save for you and me) would buy the phone.

Re:One idea (1)

letxa2000 (215841) | more than 8 years ago | (#15182941)

As someone else said, it doesn't much matter if it lasts 10 times longer or not. At some point, if you don't charge it, you're going to run out of power.

I just charge my Treo each night when I go to bed. I use it as my alarm clock so when I set my alarm, I make sure it's plugged in and charging. I've never gotten below about 70% even on heavy-talk days. If it could use 10% as much energy, I guess that would mean that at the end of the day I'd be at 97% instead of 70%. But it doesn't really matter either way as long as I charge at the end of the day.

Re:One idea (2, Interesting)

planetmn (724378) | more than 8 years ago | (#15182793)

Is a antenna which can change direction depending on a signal already there ? If not the idea wont work at all.

A combination of multiple "antennas" with a 120degree coverage (for three) rather than a single antenna with 360 coverage, and phased array (look at phased array radars) could make this possible. Power savings though, might not happen because of the processing required.

-dave

But would I have to stand still? (1)

PopeRatzo (965947) | more than 8 years ago | (#15182811)

Or keep the phone oriented in the same direction? And what's this about frying your head? My girlfriend is always on her cellphone. Oh.

Re:One idea (1)

woolio (927141) | more than 8 years ago | (#15182868)

Is a antenna which can change direction depending on a signal already there ? If not the idea wont work at all.

Yes, it is possible to have a directional antenna without it physically having to move in order to change directions. I think they have been around for a long, long time. Mutliple antennas/elements are required. (phased array?) . But the consumer wants a cell phone, not a porcupine.

I *think* something might be done like this in current MIMO research. I believe the problem of finding the direction is more complicated than just a pilot tone. It usually required multiple antennas and gets confused by multipath. (e.g. which one do you aim at)? I have briefly heard of MIMO guys using multiple antennas and doing beamforming with them.

Also, what happens if someone in a car,train, etc? (changing angles at high rate of speed). I wonder how well existing hand-off algorithms would work with directional antennas.

Also, it would seem that a directional phone would be forced to use lower transmit power (so that the max Effective Radiated Power to the head was the same/lower).

Also for cell phones, I wonder if directioality would be limited to 2D or 3D? (after all, the towers are usually fairly close by).

Respectively? (1)

General Wesc (59919) | more than 8 years ago | (#15182753)

The new chip uses five transistors and can perform divisions by 3 instead of only 2 by previous circuits, allowing a perfect communication between two phones communicating at 2.0001 and 2.0002 gigahertz respectively.

Respectively? Are you saying the 2.0001 divides by 3 and the 2.0002 divides by three? But they both can divide by either, is the point, right?

(Am I just begging for a 'You must be new here' post for not instantly assuming it's just lack of good editing?)

Re:Respectively? (-1, Troll)

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Re:Respectively? (0)

Anonymous Coward | more than 8 years ago | (#15182827)

The point is dividing down from a terahertz reference by powers of 2 alone allows 500 GHz, 250Ghz, 125Ghz, etc... Can't get to 2.0001GHz.

Dividing down from a terahertz by numbers that are factored down to 2 and 3, however, may allow you to get 2.0001GHz -- haven't bothered to figure whether a terhertz is fast enough.

"Ten times less" (2, Funny)

Anonymous Coward | more than 8 years ago | (#15182814)

What the hell does "ten times less" mean? If it uses 1 watt now, does that mean it now uses 1 - (10 * 1) = -9 watts? So using htis actually generates energy?

Re:"Ten times less" (0)

Anonymous Coward | more than 8 years ago | (#15183023)

Okay Mr Pedantic Idiot, I guess you need a lesson in English. Ten times more means you take the number, it's more than, multiply it by ten--that's your number. "Ten times less", the opposite of "ten times more", means you do the opposite of that, In other words, you would take the number and divide it by ten. The alternate construction, "a tenth as much" is also acceptable, however it requires a complete rephrasing.

What a crock (4, Informative)

amjohns (29330) | more than 8 years ago | (#15182815)

This is mostly BS. First off, the PLL is a small fraction of the power consumed by a modern phone, even though it is running all the time. Far more power is consumed in the rest of the receiver chain, from the LNA (low nose amplifier) and the digital demodulator. And no, this does not do a thing to minimize the demod, as it is running all the time too, to detect an incoming call notification.

Second, the statement that a "phase-locked loop multiplies the pulse from a highly-stable reference clock, such as a quartz crystal oscillator, up to the desired frequency" is 100% false. The function of a PLL is to lock (in phase...) a divided down version of a totaly independent RF oscillator, called a VCO, to a divided down version of the reference clock. The distinction may appear subtle, but it's enormous. Multipliers are large, power consuming IC's, while dividers are fairly small and efficient. There are NO multipliers in a PLL, period. Also, PLL's can already do split division, it's called a fractional-N PLL.

Mobile, battery powered electronics will never achieve decent battery life beyond a few GHz. There are several effects coming into play, from cosmic noise to H2O and O2 molecular resonances to increased multipath effects, and most importantly path loss. RF power spreads in a spherical wavefront, so there is a 1/R^2 power falloff. BUT, you need to recognize that this is in terms of wavelength (lambda), which is mathematically equal to C/f (speed of light / frequency). The net result is that doubling the frequency on a radio link incurs a 4-fold power fallof for a fixed distance.

So if I want to go from say just under 2GHz w/ a current GSM system to say 8GHz, then I need an effective 16 times the power output from my transmitter. I say effective, because you can use antenna gain, but not in the mobile handset (it needs to be omnnidirectional), and base stations directionality is very limited, since they need to support many users on the same antenna, and can't steer the beam to all of them simultaneously. You wouldn't be allowed ot put out that much powr form a safety perspective, never mind the power consumption and heat requirements in the power-amplifier. Handsets are at 600 milli-watts now, we're not going to put out >10 watts!

Re:What a crock (2)

Compuser (14899) | more than 8 years ago | (#15182908)

So, if I may ask, why do you say that "battery powered electronics will
never achieve decent battery life beyond a few GHz"? It would seem that
as base stations grow in density of coverage we will be able to drop
power requirements. Imagine a base station every 10 m (like e.g. in
every lamppost). Already today cell phone coverage is only good in
civilized places, i.e. where roads go, so this would not drop
quality of service compared to what we have now.

Re:What a crock (2, Funny)

Luveno (575425) | more than 8 years ago | (#15182982)

Every once in awhile, someone comes along with a post that restores your faith in /.

Well, I *used* to be an RF engineer... (0)

Anonymous Coward | more than 8 years ago | (#15182835)

... until my head exploded.

Move along, nothing to see here (cleanup on Aisle 12!), move along.

actually (0, Redundant)

cparisi (136611) | more than 8 years ago | (#15182910)

The battery in me cell phone lasts quite a long time...

die scuttlemonkey (-1, Troll)

Anonymous Coward | more than 8 years ago | (#15182933)

die scuttlemonkey die

division by 3 (0)

Anonymous Coward | more than 8 years ago | (#15183032)

"The new chip uses five transistors and can perform divisions by 3 instead of only 2 by previous circuits,"

Does this mean it operates on trinary logic instead of binary?

(In some of R A Heinleins stories the computers were trinary)

If i binary digit is called a bit, what is a trinary digit called?

New Chip Promises Longer Battery Life (1)

m1chael (636773) | more than 8 years ago | (#15183057)

When a chip breaks its promise it doesn't feel remorse.
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