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$499 3-D Printer Drew Plenty of Attention at CES (Video)

wramsdel Re:Why is it so cheap? (155 comments)

I was at CES, and I specifically asked to see one of the filament cartridges. Assuming the ones on the show floor are the same design that will ship with the printer, there are no electrical contacts on the cartridge, so likely no "chip" as is the case with ink cartridges. It looked to me like it would be fairly straightforward to reload one of the cartridges with commodity filament.

about 8 months ago
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Group Kickstarting a High-Bandwidth Software Defined Radio (SDR) Peripheral

wramsdel Re:Lame (140 comments)

And speaking of front-ends, there's some funky stuff going on in the bladeRF's:
http://nuand.com/bladerf.pdf
C331, the receive switch blocking cap, is 6.8pF. At 300 MHz, it has a capacitive reactance of 78 ohms. Unless there's a good reason for that (e.g. RF tuning), that's pretty irregular. Typically switch blocking caps are chosen to have very low reactance at the frequency of interest, so as to minimally perturb the 50 ohm environment of the switch port. The reference curves in the switch datasheet were taken with 47pF caps.

Another oddity: the switch control lines are bypassed at the switches with 8.2pF. The bypassing itself is good practice, but again, I question the value. At 300 MHz that's not a very effective bypass. Bumping up the cap values and adding a series element, a ferrite bead or even a resistor, would provide better rejection of environmental RF. My guess is that those traces are run on the surface layer, unshielded, as well.

about a year and a half ago
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Group Kickstarting a High-Bandwidth Software Defined Radio (SDR) Peripheral

wramsdel Re:Lame (140 comments)

Okay, so most significantly what I'm hearing is superior weak-signal performance by virtue of good DSP. I'll buy that. Your point about front-ends and the "stick" SDRs is well taken. I've never taken these things seriously because I take a look at most of the front-ends and there's...nothing. No filtering, no shielding, no preselection. And to think that some of them are 8-10 bits and depend heavily on pre-converter gain management, with nothing more than a silicon VGA with a few hundred microamps at best of bias...wow. It's damn scary. I can't imagine taking any of them to a mountaintop somewhere that has 25 transmitters going full-bore on a dozen bands and having a good experience with it. Maybe I'm just an RF design bigot. Anyway, I'll look into the SDR-IQ, sounds like an interesting piece of gear.

about a year and a half ago
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Group Kickstarting a High-Bandwidth Software Defined Radio (SDR) Peripheral

wramsdel Re:Lame (140 comments)

Can you define what you mean by "performance" above? Nothing I've read about amateur SDRs has shown them to "wildly" outperform analog radios in:
MDS
Noise figure
Blocking dynamic range
Intermod
Desense
Third-order intercept
Power consumption
In fact, certain SDR architectures may include things like spurious-free dynamic range impairments that are significantly *inferior* to analog radios. I don't deny that there are many things an SDR can do that an analog radio simply can't, chief among them being accommodate new modulation schemes without hardware modification, but I think they're far from a complete replacement for analog.

about a year and a half ago
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Valve Unveils Steam For Schools, Portal In the Classroom

wramsdel I'm making a note here: HUGE SUCCESS (83 comments)

"Ms. GlaDOS, I need to go to the bathroom!"
"Certainly, Chell, it's out the door and right down that chute."

more than 2 years ago
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US and UK Zombies Demand Top Dollar

wramsdel Not true! (62 comments)

I saw one just the other day on the freeway on-ramp, holding a sign that said "Will work for BRAAAAAAINS!" The article must be talking about those exorbitant consultant zombies. Man, I'll never hire one of those again...talk about unimaginative business plans.

more than 3 years ago
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Video Shows Why Recharging Kills Batteries

wramsdel Re:Why can't they put a simple FET in there (111 comments)

Oh, they certainly exist. I design small consumer electronics devices, some of which have lithium-chemistry batteries. Many of the sub-amp battery charger ICs that I've used (case in point, the Intersil ISL6292) will drop to zero charge current at the end of the charge, when current into the cell drops below a certain threshold for a given voltage. I can't speak to current design practices for laptops, but I'd guess that they do the same. Of course, charging a device that's operating is an entirely different scenario and can be a real can of worms from a design standpoint.

more than 3 years ago
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Medical Researcher Rediscovers Integration

wramsdel Y'all just got Riemann-rolled (473 comments)

Did it ever occur to anyone that the author is nothing more than a publication troll, seeing what exactly he can get away with? It's possible that the joke's on the journal, not the author.

more than 3 years ago
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Arduino-Based, High Powered LED Lighting Over Wi-Fi

wramsdel Re:$800 ?! (114 comments)

Unfortunately you left out 4) amortized development costs, 5) what the market will bear, and potentially 6) licensing costs. Consider the engineering work that goes into something like this...easily a few hundred engineer-hours. Now consider that the fully-burdened cost for a junior engineer is close to $100/hr. It goes up from there. So now we're talking in the mid-five figures before you sell unit 1. That's *just* labor. Care to add in ancillary costs? As for what the market will bear, there are LED luminaries on the market ranging in price from $500-ish to well over $1000. $800's not unreasonable there, assuming this is a comparable fixture. Finally, they may well be paying a stiff royalty to Color Kinetics. If you want to have anything to do with intensity-controlled LED lighting, chances are you're infringing on a Color Kinetics patent. They've locked up all the approaches that a reasonable engineer would consider trivial, and they defend their patents zealously. If I were these guys, there's no way I'd go near this without either paying the piper or spending considerable time with a patent lawyer (mo' money) to make sure I didn't get shut down after the first unit sold.

But you're right, it sure does look bomb-proof.

more than 3 years ago
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Casio Unveils New Color Screen Graphing Calculator

wramsdel Re:Why? (313 comments)

In my experience it's the other way around. I used a calculator *way* more in school (electrical engineering) than I ever have in industry in the last ten years. Why? Well, mostly because the math's much easier now...I don't routinely deal with complex or matrix math, which means a laptop with Excel is sufficient for 80% of what I do, and the remainder can pretty much be done in my head (nb: remember common logarithms and exponentials). Since my laptop is pretty much always within arm's reach, I just keep an Excel scratchpad open at all times. It's also nice to have room to spread out, or adjust various parts of the equation real-time, without having to use an antiquated and constrained interface.

more than 3 years ago
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FCC White Space Rules Favor Tech Industry

wramsdel Not quite out of the woods yet (135 comments)

Note specifically the part about "the rules will require devices to be capable of knowing their location and using an online database to find out which channels are active in their area". Seems that presupposes that whitespace devices for all time, or at least until the rules are changed, will need both geolocation ability and WAN connectivity. I seriously doubt that users will ever be allowed to simply plug in the operating location to the device, as that would allow the whole system to be easily circumvented. Requiring geolocation and connectivity is fine for applications embedded in a cell phone or a laptop (which already has these facilities), but standalone devices will have a pretty steep cost burden. Even in the embedded scenario, now we need some way of ensuring that the device gets a GPS fix (how frequently?) and communicates that in some standard way to the whitespace system. Hopefully client devices will be relieved of this burden by virtue of their connection to a known base, but will that restrict the usable range of the system, given that you don't want a client to wander too far from the base? Be interesting to see how all this plays out.

more than 3 years ago
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Recycling an Android Phone As a Handheld GPS?

wramsdel Re:Cell phone GPS not the same... (328 comments)

That's because he's looking at LNA gain on an active antenna. Oops.

I can pretty much guarantee you that those helical and ceramic patch antennas won't be much more than +3 or +4 dBi. There are only two ways to improve antenna gain: directionality and physical size. Directionality (aside from "up") is exactly what you *don't* want in a GPS antenna. You ideally need 360 degree azimuthal and 180 degree elevational coverage, and that's only if you don't plan on ever tilting the device from the horizontal plane. As for physical size, well, all of those antennas are within the same order of magnitude of compactness, so I don't expect much variation there. Yes, structural design matters, but it's a few dB of matters, not tens.

more than 4 years ago
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Experts Explain iPhone 4 Antenna Problem

wramsdel Re:Cases (427 comments)

It'll insulate the metallic ring that's "part of the antenna system", which might mean "the antenna" or might mean "some other element that helps the antenna do its work" (i.e. a resonant grounding piece). Antennas are tuned, resonant, structures...think of a tuning fork that needs to oscillate at a certain frequency. Bridging the gap between the two exposed elements changes the electrical characteristics of it such that the antenna becomes detuned and reception is impaired. By applying a case, your hand can no longer come in contact with the ring, so the antenna isn't as severely detuned and the cell phone signal isn't as attenuated. I say "as severely" because there will always be some impact when your hand is in reasonable proximity to the device, but it won't be of the magnitude that direct contact would be.

more than 4 years ago
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New Plan Lets Top HS Students Graduate 2 Years Early

wramsdel Re:maturity? (425 comments)

I absolutely agree. It's probably going to sound curmudgeonly, but there's been a huge shift in the U.S. from guiding behavior to controlling environment. This is great...until the environment is no longer controlled. As soon as that happens, a child whose environment has been meticulously managed from birth suddenly finds her/himself completely unable to cope. Blech. My kid's only one, but my philosophy even now is to help him understand himself, characterize his environment, and act accordingly. It means letting him fail sometimes, because he chose wrongly, but it also means that he's much more in control when confronted with a new situation. I find it far less stressful for both of us.

more than 3 years ago
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CES Vendors Kicked Out of Hotels For Showcasing Wares in Room

wramsdel Re:That is positively asinine. (285 comments)

Everything you've said is true. You've also made largely ethical arguments, and ethics in business is dead. Yes, the parasites in the suites are costing the big guys money and face time. The big guys are also doing everything within their power to put the little guys at a competitive disadvantage. That's how business is done. That's not a justification, it's not an excuse, it's a statement of fact. The companies exhibiting in suites are, at worst, in breach of contract with the hotel, and it's quite likely that that breach is with the tacit consent of the hotel. You cannot convince me that an entity which spends tens of millions of dollars deploying surveillance hardware to catch people cheating or counting cards doesn't know exactly what's happening in each and every one of their rooms and suites. This time, the CEA got pissed and told the hotels to play ball, and they did. Individuals go to Vegas to gamble, it's not surprising that companies would do the same.

more than 4 years ago
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CES Vendors Kicked Out of Hotels For Showcasing Wares in Room

wramsdel Re:That is positively asinine. (285 comments)

You're damn straight, and there's nothing wrong with it. When 40-50 of your customers are in one place at the same time, you'd be an absolute fool not to go there and meet with them. It's the most bang for the buck you'll get all year. How far, exactly, do you need to be from the show floor before you're not trying to "get a free ride"? If I'm at CES and a buddy of mine's at CES, and we get together and talk business somewhere on the strip, are we trying to "get a free ride" because we're not buying the CEA's beer? Where's that line drawn?

more than 4 years ago
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CES Vendors Kicked Out of Hotels For Showcasing Wares in Room

wramsdel Re:That is positively asinine. (285 comments)

Seconded. I've been to CES a number of times with a wireless startup, and we've always been in suites in the hotels. There's no way they don't know exactly what's going on when they see us roll up in a loaded minivan with boxes that say "Dell" all over them. We chose suites for two reasons: the obvious expense aspect, and there is no way we'd try to demo on the show floor...the RF environment is just too congested. It's also a much nicer way to engage a customer, and gives them a break from the insanity of the floor. I can't imagine that the use of suites will ever go away...CEA will just find a way to drive the cost up.

more than 4 years ago
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Laptop Fires On Airplanes

wramsdel Re:I'll check my batteries... (560 comments)

It's a solved problem. I flew Northwest from Portland to Tokyo, an A330-300, pretty regularly between mid-2005 and mid-2008. 120V, 60 Hz was available in coach class forward of row 21, and throughout business and first. Seat Guru is your friend here. Sadly, after the Delta acquisition they moved the A330 elsewhere and replaced it with a ridden-hard-and-put-up-wet 767. At least I don't have to make the trip any more, I'd probably be bored senseless.

more than 4 years ago
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An Inside Look At the SpaceX Rocket Factory

wramsdel Re:No Sh!@ (50 comments)

Amen, brother Derek. Having worked for a startup, and with friends at many others, and now working on my own, I have to say I'm sick of the "Have a marginally clever idea, befriend an MBA, write a business plan, find an angel, work your ass off, get some venture capital, IPO" model. That's just not appropriate in so many cases. My role models are welders and plumbers, not Pets.com. Will it work out? Who knows. I do know that I'm not starving, I sleep well at night, and my son knows what I look like.

more than 5 years ago
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RIP the Campus Computer Lab, 1960-2009

wramsdel Bad idea (571 comments)

I'm sure this will come off as hokey and nostalgic, but put me firmly in the "bad idea" camp. I earned my BSEE 10 years ago now, and my hours in the engineering department's lab were some of the most memorable and useful of my undergrad years. They taught me how to work informally with my colleagues, bouncing ideas off of each other and helping each other out. They taught me the value of learning from the mistakes and successes of others, and how engineers truly work as a team, far better than any contrived design project could. They taught me the value of peer review far better than any "formal" design review could. I see the same spirit in the cubicle farm I inhabit in industry, or when a group of my co-workers and I sit down to lunch, that I saw in the lab with my classmates working feverishly on our lab reports at 2:00 in the morning on a Saturday in the engineering lab.

I think collaborative spaces are a good start, but there's still a place for big-iron workstations with large monitors that make it easy to point out things to your friends. As many other posters have pointed out, there's also the issue of tens (if not hundreds) of thousands of dollars of software licenses that in many cases aren't reasonable or appropriate to expect a student to have on his or her personal machine. It's far easier to secure a grant or donation to equip a lab with software than it is to procure a whole slew of student licenses.

more than 5 years ago

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