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Offline EEVblog

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Re: The uBeam FAQ
« Reply #575 on: December 06, 2016, 10:29:27 PM »
One interesting thing from that IEEE vid was the initial aim to transfer one watt, which even at the time would have been useless for phone charging, more so nowadays.

I've got calcs (using proper industry simulation data) that show with a @45KHz 155dB 1500Pa 2900W/sqm source, the likely typical efficiency is:
@1m = 1.8% giving 53W/sqm
@2m = 0.3% giving 8W/sqm
@3m = 0.05% giving 1.6 W/sqm
@4m = 0.01% giving 0.2 W/sqm available

The surface area of a typical iPhone thingo is about 0.01sqm
Assuming 100% efficiency on the receiver, a power density of 100W/sqm is required to charge at 1W
Even at 1m using a massive power hog transmitter and ideal receiver they would barely get 0.5W, quickly dropping to bugger all.
They claim a 4m radius  :-DD

Absolute best case calcs are not much better at distance.
And the more power you pump in, the closer the saturation and nonlinearity happens.
« Last Edit: December 06, 2016, 10:31:06 PM by EEVblog »
 

Offline mikeselectricstuff

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Re: The uBeam FAQ
« Reply #576 on: December 06, 2016, 10:32:59 PM »
One interesting thing from that IEEE vid was the initial aim to transfer one watt, which even at the time would have been useless for phone charging, more so nowadays.

I've got calcs (using proper industry simulation data) that show with a @45KHz 155dB 1500Pa 2900W/sqm source, the likely typical efficiency is:
@1m = 1.8% giving 53W/sqm
@2m = 0.3% giving 8W/sqm
@3m = 0.05% giving 1.6 W/sqm
@4m = 0.01% giving 0.2 W/sqm available

The surface area of a typical iPhone thingo is about 0.01sqm
Assuming 100% efficiency on the receiver, a power density of 100W/sqm is required to charge at 1W
Even at 1m using a massive power hog transmitter and ideal receiver they would barely get 0.5W, quickly dropping to bugger all.
They claim a 4m radius  :-DD

Absolute best case calcs are not much better at distance.
And the more power you pump in, the closer the saturation and nonlinearity happens.

Yeah but they're now using a phased array - antenna gain FTW!
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Offline coppice

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Re: The uBeam FAQ
« Reply #577 on: December 06, 2016, 10:56:09 PM »
Yeah but they're now using a phased array - antenna gain FTW!
They always said they were using a phased array.
 

Offline EEVblog

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Re: The uBeam FAQ
« Reply #578 on: December 07, 2016, 12:17:33 AM »
Yeah but they're now using a phased array - antenna gain FTW!

Shame that the power output from a phased array system varies with the angle though, that pesky Lambert's cosine law ;D
It ain't no magic bullet.

IIRC I believe they have demoed to certain investors a circa 1W output from a meter or something? I don't doubt they can do that straight on with enough input power. Doesn't make a practical system though, not by a long shot.
« Last Edit: December 07, 2016, 12:33:24 AM by EEVblog »
 

Offline The_Next_Theranos

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Re: The uBeam FAQ
« Reply #579 on: December 07, 2016, 02:06:28 AM »
Or maybe the guy is a lot smarter and just a lot more unethical than I am presuming.  He says uBeam works but glosses over the singular huge issue - efficiency - by saying it would be impossible to refute every point. 

And that's the thing. There would not be a single competent engineer on this planet who says it can't actually work, and Perry keeps harping on about how us clueless engineers said it "wouldn't work". If she actually listened to the engineers and was able to comprehend it
On the other hand, maybe Perry is smarter than we are giving her credit for, and maybe she herself understands the difference between "won't work" and "orders of magnitude away from working", but instead made a conscious choice -- like the "smarter and just a lot more unethical" VC investor -- to misrepresent the issue to a gullible public, casting it as an easy-to-understand, "down-to-earth-innovator-vs-those-stuck-up-so-called-intellectuals" type of story. Such a framing of the story might have been a calculated move designed specifically to garner sympathy and funding.
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #580 on: December 07, 2016, 07:17:11 AM »
Yeah but they're now using a phased array - antenna gain FTW!

Without thinking too deeply, I don't think a transmitting phased array gives any power gain over the inverse square losses.

Offline Howardlong

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Re: The uBeam FAQ
« Reply #581 on: December 07, 2016, 08:19:33 AM »
Yeah but they're now using a phased array - antenna gain FTW!

Without thinking too deeply, I don't think a transmitting phased array gives any power gain over the inverse square losses.

Not sure I follow. Aside from non-linearities of fluid medium in extreme scenarios, a phased array of transmitters will work as the reciprocal of a similarly constructed phased array of receivers.

I did some very rough back of the envelope calcs earlier today, for 1m^2 at 45kHz you'd get a half power beamwidth in the far field of about 0.4 degrees and a gain of about 50dB. You'd use of the order of 15,000 transducers at that wavelength in that area and a similar configuration for the receiver to attain equivalent directivity. That's assuming a simple single handset. Problem is this isn't far field: in relation to aperture size it's near field, so it's a 3D not a 2D problem which is going to make life quite a bit harder to track and target the handset.

I'm not clear if they were using ultrasonics bidirectionally, though, although there was some talk of using it for data as well as power. It will need some means of bidirectional communication though in order to configure the phased array for power transfer, but that might be out of band on WiFi instead.
 

Offline The_Next_Theranos

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Re: The uBeam FAQ
« Reply #582 on: December 07, 2016, 12:19:25 PM »
I would be genuinely curious what Perry does every day.
Pose for photos like this one, released 8 hours ago?
https://twitter.com/meredithperry/status/806190586051133440

There's also a cryptic tweet before that, "December 5, 2016, 3:30pm PT.  Greatest day in uBeam history.  I am so proud of my team."

I wonder what happened to make this the "greatest day in uBeam history" -- did Meredith quit? ;D
 

Offline EEVblog

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Re: The uBeam FAQ
« Reply #583 on: December 07, 2016, 01:06:24 PM »
There's also a cryptic tweet before that, "December 5, 2016, 3:30pm PT.  Greatest day in uBeam history.  I am so proud of my team."

Ooh... Have they shipped something?  :o
Maybe got another round of funding?

 

Offline EEVblog

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Re: The uBeam FAQ
« Reply #584 on: December 07, 2016, 01:07:54 PM »
Burn:
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #585 on: December 07, 2016, 01:52:24 PM »
Not sure I follow. Aside from non-linearities of fluid medium in extreme scenarios, a phased array of transmitters will work as the reciprocal of a similarly constructed phased array of receivers.

Me neither, I just saw phased array and antenna gain in the same sentence and had a thought!

I might be thinking wrong, but I'd say that a phased array of receivers gathers some of the off-beam/out of phase energy and corrects it's phase/timing so that it can be added to the main beam signal.
Simply swapping receiver to transmitter means that as well as the main beam you're now transmitting off-beam/out of phase energy which can never be used by the receiver because the receiver never receives it.

I can imagine a US transducer near the edge of the array where only a very small amount of it's transmitted energy covers the target area, but I can't imagine it needing any less drive power because only a small amount of it's energy is landing in the right spot, how would it know!

Of course, if there's another way of thinking about it....



Offline StillTrying

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Re: The uBeam FAQ
« Reply #586 on: December 07, 2016, 02:03:25 PM »
Perhaps someone has told her that they've finally got the receivers in, and she's misunderstood ?
 
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Offline Corporate666

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Re: The uBeam FAQ
« Reply #587 on: December 07, 2016, 02:28:02 PM »
Perhaps someone has told her that they've finally got the receivers in, and she's misunderstood ?

LOL!
It's not always the most popular person who gets the job done.
 

Offline Corporate666

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Re: The uBeam FAQ
« Reply #588 on: December 07, 2016, 02:42:19 PM »
I would be genuinely curious what Perry does every day.
Pose for photos like this one, released 8 hours ago?
https://twitter.com/meredithperry/status/806190586051133440

There's also a cryptic tweet before that, "December 5, 2016, 3:30pm PT.  Greatest day in uBeam history.  I am so proud of my team."

I wonder what happened to make this the "greatest day in uBeam history" -- did Meredith quit? ;D

She's young... if it wasn't for the fact that I know that SHE knows this technology doesn't work, I would feel bad for her.  I know what it's like to be wrapped up in the whirlwind of a funded company and have it start to go off the rails.  You feel like it was your big shot and you just don't want it to end. 

But the one thing I never did was squander investors money and spend all my time fucking around giving speeches and taking pictures and acting like I believed the hype I was creating instead of actually trying to deliver on the stated goal of the business. 

By spending all of her time trying to be a caricature of a spunky, gutsy CEO that bucks trends and disrupts industries, she is achieving nothing but setting herself up to be a laughing stock when this whole thing implodes.  She will be remembered for being the powerpuff girl CEO's and it will be seen that it was her hubris that caused the whole thing to implode.  Guys like Sutter (or whatever his name is) can say "I will be first to invest in her next company" all he likes, but when he's on the other side of the table at an investment meeting, faced with stroking that check... there's no way he won't look back at this whole sordid affair and all of this shite was just that.  What they needed was an experienced CEO who had run a business, knew the technology, had industry experience and was committed to developing the tech and delivering product - not who was mostly interested in building their brand.

Perry will parlay her brand into a downward spiral of successively less impressive executive jobs until she fades into obscurity within a few years, I think.
It's not always the most popular person who gets the job done.
 

Offline EEVblog

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Re: The uBeam FAQ
« Reply #589 on: December 07, 2016, 04:36:09 PM »
What they needed was an experienced CEO who had run a business, knew the technology, had industry experience and was committed to developing the tech and delivering product - not who was mostly interested in building their brand.

A CEO that simply listened to the internal experts who wanted to pivot the product and tech would have sufficed. They might have been able to turn this (probably very decent ultrasonic tech) into a some niche win for them. But instead they rode this donkey of a dream all the way into town.
 

Online amspire

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Re: The uBeam FAQ
« Reply #590 on: December 07, 2016, 06:27:13 PM »
There's also a cryptic tweet before that, "December 5, 2016, 3:30pm PT.  Greatest day in uBeam history.  I am so proud of my team."

Ooh... Have they shipped something?  :o
Maybe got another round of funding?


I gather that Ubeam had promised in 2015 that they will be able to show demos to people outside the investors in 2016. So my guess is that with their $23 million dollars (or whatever they have received), they have finally got enough hardware working to do some kind of demo. Probably not the "totally safe" 1.5W at 4 meters they have promised, but we might see the voltmeter come out of retirement.

Over half uBeam's money is in debt, and they haven't had any new funding for a year, so some kind of public demo to "prove" the technology could be a desperate need.
 

Offline Cerebus

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Re: The uBeam FAQ
« Reply #591 on: December 08, 2016, 01:12:10 AM »
But the one thing I never did was squander investors money and spend all my time fucking around giving speeches and taking pictures and acting like I believed the hype I was creating instead of actually trying to deliver on the stated goal of the business. 

The other day I heard a 'celebrity' on the TV talking about "building my brand" (he'd released a perfume). Now, all this guy has ever actually done is to be the son of a very famous footballer.

Sometime in the last few years some idiots have decided that a 'brand' is worth something on its own, rather than representing the goodwill acquired over many years by a well operated business. Consequently people talk about 'brand building' as an end in itself, rather than providing a better product, service, working environment etc. Many young people (particularly Americans, especially from the West Coast) have bought into this, not knowing that a 'brand' or reputation once meant something more than mere surface appearance. Furthermore, 'brand' and personal reputation have become conflated as if one's reputation is some sort of commodity. I suspect that Ms Perry has bought into all this and is working hard at 'building her brand' not understanding that for it to be worth anything there has to be some substance underneath the gloss.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Online Fungus

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Re: The uBeam FAQ
« Reply #592 on: December 08, 2016, 01:43:02 AM »
Shame that the power output from a phased array system varies with the angle though, that pesky Lambert's cosine law ;D
It ain't no magic bullet.

I think the idea is to have an array of these all around the room so you're always square on to one of them.

Just don't hold the phone wrong or put it on a table and you might get a whole Watt of recharge.
 

Offline zapta

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Re: The uBeam FAQ
« Reply #593 on: December 08, 2016, 04:09:35 AM »
There's also a cryptic tweet before that, "December 5, 2016, 3:30pm PT.  Greatest day in uBeam history.  I am so proud of my team."

Ooh... Have they shipped something?  :o
Maybe got another round of funding?



The team decorated the conference room for Christmas party.
Drain the swamp.
 

Offline Harrkev

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Re: The uBeam FAQ
« Reply #594 on: December 08, 2016, 05:36:33 AM »
Without thinking too deeply, I don't think a transmitting phased array gives any power gain over the inverse square losses.

It does prevent losses.  A phased array is just another fancy name for a directional antenna, except that you can steer it electronically.  A laser manages to beat 1/(r^2) pretty handily by not radiating its energy in all directions.
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #595 on: December 08, 2016, 03:46:19 PM »
"A phased array is just another fancy name for a directional antenna, except that you can steer it electronically."

Yep, that's what I was thinking. In this case a flat US array about 30cm x 30cm facing a target about 8cm x 7cm about 2m away.

"It does prevent losses."

Nope! After some thinking and googling, I've still come to the same conclusion that a transmitting phased array only produces losses. It doesn't matter how well you focus the main beam on to the target the power there will always only be a fraction of the power you've put in - unlike a parabolic reflector where you can get near 100% of the power into the main beam.
I think the only way to recover more of the transmitted power would be for the receiver to cover all of the steerable area at all times, but then you don't have any steerable area, and it's not the case here.

The wavefronts aren't to scale for US in this wiki, but it shows the affect of how little of each wavefront is actually heading towards the target/focus.

https://commons.wikimedia.org/wiki/File:Phased_array_beam.svg

...Still thinking....
http://www.olympus-ims.com/en/ndt-tutorials/intro/advantages

« Last Edit: December 08, 2016, 03:49:39 PM by StillTrying »
 

Offline zapta

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Re: The uBeam FAQ
« Reply #596 on: December 08, 2016, 05:18:30 PM »
Nope! After some thinking and googling, I've still come to the same conclusion that a transmitting phased array only produces losses.

That was also my thinking but it requires a proof. The phase shifts and amplitudes of the array elements are chosen to active cancellation on the side beams but this is like canceling heating with air conditioning, the total is neutral but takes a lot of energy.

This is of course a hand waving style explanation and a more rigorous analysis is required. It's possible that the canceling energy from one element actually reduces the power of the other elements by creating synchronized pressure wave that affects the traducers' impedance.

But, even of the phase array has lower efficiency, having the power directed still has safety benefits because it reduces the overall sound energy in the room.
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Offline coppice

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Re: The uBeam FAQ
« Reply #597 on: December 08, 2016, 07:09:04 PM »
After some thinking and googling, I've still come to the same conclusion that a transmitting phased array only produces losses.
That will come as quite a surprise to radar engineers.
unlike a parabolic reflector where you can get near 100% of the power into the main beam.
That will also come as a surprise to radar engineers.

I think it would really shock them to find that all these years of pushing parabolic reflectors (and offset parabolics, cassegrains, etc) aside, in favour of the superior beam forming performance of passive phases arrays was a misdirection.
 

Offline coppice

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Re: The uBeam FAQ
« Reply #598 on: December 08, 2016, 07:13:11 PM »
Nope! After some thinking and googling, I've still come to the same conclusion that a transmitting phased array only produces losses.

That was also my thinking but it requires a proof. The phase shifts and amplitudes of the array elements are chosen to active cancellation on the side beams but this is like canceling heating with air conditioning, the total is neutral but takes a lot of energy.
Heat is Gaussian noise. Radar signals from all the nodes of a phased array are coherent. Its a completely different situation. If you think a large amount of energy is lost in the beam forming of a phased array, where does it go? Conservation of energy says it can't just vanish.
 

Offline EEVblog

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Re: The uBeam FAQ
« Reply #599 on: December 08, 2016, 07:30:21 PM »
Heat is Gaussian noise. Radar signals from all the nodes of a phased array are coherent. Its a completely different situation. If you think a large amount of energy is lost in the beam forming of a phased array, where does it go? Conservation of energy says it can't just vanish.

Look at the numbers I posted above. Saturation of the air occurs at quite small distances. It's not just a beam forming problem, the losses are in driving the air molecules.
If it was a simple beam forming problem then uBeam would have been a cake walk and done long ago (Perry wasn't the first with the idea, by several decades)
« Last Edit: December 08, 2016, 07:32:27 PM by EEVblog »
 


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