Author Topic: The uBeam FAQ  (Read 231644 times)

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Offline PaulReynolds

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Re: The uBeam FAQ
« Reply #1150 on: November 24, 2017, 08:07:37 AM »

Not sure how you get that number for the phone. If at 150 dB that needs 0.005m^2 to get 5W, let's be super generous and say 10W with 50% efficiency of receive conversion, so 0.01m. An iPhone X is about 7.5 by 15cm so 0.01125m^2.



...  more transmit area can be applied to compensate for that loss and maintain the same power incident on the receiver, up until the point you run out of transmit area.

I'm not sure this is true,
Assuming some level power, say 145dB, 150dB, whatever.... is deemed unsafe
The power level at the receiver side cannot exceed this safe limit, can it?

So If the effective phone size is 70cm^2, and the maximal power density that's still safe (on either side) is 150dB than 7W can really be transmitted.

But...

Assume the transmitter is actually transmitting a few watts in 0% humidity.
A day later, a receiver receives 1% of the power,  can the transmitter increase it's output 100X?

It can't, for two reasons
1. To do that it must know what is the exact reason for the decline in received power is, if the reason is that my body absorbs 99% of the power I hope it's not going to increase it. Knowing the exact reason why something delivers less power, takes a human a day's work in the lab and is beyond the current capabilities of devices.
2. Such dynamic range means your costs are X100 higher, if your "dry day" cost is anywhere above $10, your wet day costs are sky high.

If someone were to follow the safety rules, I would agree that you should not have a power higher than that at any point - at transmitter, receiver, or inbetween. In that presentation, uBeam appeared to be saying there were no limits anymore. That was a surprise to me, and to those in the industry who chair that type of ultrasound safety group that I have spoken to since.

As sound travels, it loses power as heat, so as long as you do not increase the focus effect faster than you lose power in the air, you do not exceed even if you start at the limit. This is pretty standard in ultrasound medical imaging, and usually the numbers work out that the highest intensity is at the focus (and what the FDA usually worries about, in most cases that's the Mechanical Index).

And yes you're correct that at some level of transmitter area increase, you hit a hard physical limit. Is that limit within the range of normal use? What do you sacrifice as you add more transmit area? Loss of efficiency and reduction in the number of targets that can be served?

I think your numbers are a bit extreme, but yes temp and humidity do affect sound velocity and attenuation, for example here's some data for audio frequencies from NASA.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670007333.pdf - note responses aren't linear

And a simple tool for calculating loss (based on audio, but my recollection is that it's close enough)

http://www.sengpielaudio.com/calculator-air.htm

Best to worst cases you're looking at maybe 1 to 1.5 dB/m difference. Significant, but not 100x.

As Dave and others have pointed out - distance, orientation, and being obscured by hands etc are likely to be the much more significant issues.
« Last Edit: November 24, 2017, 08:43:28 AM by PaulReynolds »
 
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Offline EEVblog

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Re: The uBeam FAQ
« Reply #1151 on: November 24, 2017, 09:13:01 AM »
If someone were to follow the safety rules, I would agree that you should not have a power higher than that at any point - at transmitter, receiver, or inbetween. In that presentation, uBeam appeared to be saying there were no limits anymore. That was a surprise to me, and to those in the industry who chair that type of ultrasound safety group that I have spoken to since.

Unless they are absolutely sure about this, then it's a very deliberate act of misleading investors.

Quote
As Dave and others have pointed out - distance, orientation, and being obscured by hands etc are likely to be the much more significant issues.

They are showstoppers that make the entire idea demonstrably ludicrously impractical.
 

Offline EEVblog

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Re: The uBeam FAQ
« Reply #1152 on: November 25, 2017, 04:36:08 PM »
This is deeply disturbing.
From their due-diligence pack for investors.
They claim FCC/FDA approval and ZERO safety risk!

« Last Edit: November 25, 2017, 04:37:45 PM by EEVblog »
 

Offline djos

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Re: The uBeam FAQ
« Reply #1153 on: November 25, 2017, 05:32:06 PM »
It looks like someone has found something actually useful to use ultrasonic technology in.

https://www.fanaticalfuturist.com/2017/11/worlds-first-ultrasound-3d-printer-prints-and-assembles-electronics-in-situ/
The impossible often has a kind of integrity which the merely improbable lacks.
 

Online amspire

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Re: The uBeam FAQ
« Reply #1154 on: November 25, 2017, 05:56:15 PM »
It make me angry. I have had to recently deal with some old people who are loosing their eyesight with things like macular degeneration and diabetes.

Hearing becomes everything. You would hope that if uBeam becomes anywhere near to implementation, rules limiting continuous ultrasound levels in home/office/public situations to 80dB would be implemented.

Where is the due diligence from the investors? I hope the only future uBeam lawsuits will be from mislead investors, and not from damaged people.

The only good news is that uBeam promises become more and more feeble with each round of fundraising. 0.6W at 1 meter? Have you got to keep the phone pointing to the transmitter at a distance of 1 meter to just maintain charge? In what way is that "freedom of movement"?
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #1155 on: November 26, 2017, 12:38:42 PM »
0.6W-1W @ 1m+ is the first figures we've seen, and shows how close we were.

Magnetic Resonance - Risk of heating up surrounding metal objects.
uBean  -  Risk of heating up the whole room.

Offline PaulReynolds

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Re: The uBeam FAQ
« Reply #1156 on: November 29, 2017, 04:00:43 AM »
Is it just me it's not working for, or did someone at uBeam decide that investor video shouldn't have been set as publicly available? Looks to have been taken down.
« Last Edit: November 29, 2017, 05:11:08 AM by PaulReynolds »
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #1157 on: November 29, 2017, 08:43:48 AM »
Yep, the investor video has been taken down. Perhaps they have enough investors now, hiding the evidence, or they've shut up shop. :horse:

Offline sdpkom

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Re: The uBeam FAQ
« Reply #1158 on: November 29, 2017, 10:30:43 PM »
It was surprising it was publicly available. If you're not raising funds from the public... why show your pitch to the public (including the likes of us, as well as potential competitors).

They also have a potential risk of slander lawsuits by competitors and regulatory bodies.

Therefore, no surprise it was removed.
 

Offline StillTrying

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Re: The uBeam FAQ
« Reply #1159 on: December 08, 2017, 06:38:29 AM »
« Last Edit: December 09, 2017, 05:45:03 AM by StillTrying »
 

Offline Dubbie

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Re: The uBeam FAQ
« Reply #1160 on: December 08, 2017, 10:24:06 AM »
Not sure I am confused or if this has already been posted here:

3. uBeam $20,000,000
Round: Series B
Description: uBeam is a wireless power startup that transmits power to charge electronic devices over-the-air.
Industry: Consumer Electronics, Hardware, Internet of Things, Wireless
Location: Santa Monica
Date of funding: 15-Nov
Total equity funding: $30,750,000

From here:
http://www.latechwatch.com/2017/12/10-largest-la-startup-funding-rounds-november-2017/9/

Looks like they have another few million to squander.
 

Offline l0rd_hex

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Re: The uBeam FAQ
« Reply #1161 on: Yesterday at 08:59:56 AM »
It's kinda sad, reading a story like this: http://www.al.com/news/huntsville/index.ssf/2017/05/daniel_lewis_built_her_own_art.html where someone has built something to help mankind and giving it away for free versus Meredith who's blowing millions of VC money on ham and twitterrhea
"I haven't paid taxes in six years, and I'm not getting busted by a damn sandwich." - Benjamin Franklin
 


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