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Comment: Re:OMG, this is news?! (Score 1) 137

by introcept (#39605697) Attached to: Raspberry Pi Passes EU Electromagnetic Compatibility Testing

Doesn't every product, everywhere, pass this test?

Not always, unless you design a PCB with the test in mind there's a good chance that it will emit or be sensitive to RF noise. Most electronics simply deal with it by ignoring RF in the design and sticking offending electronics in a shielded enclosure, which isn't an option for a bare-bones PCB.

A good experiment is to put AM radio set next some of your cheaper electronics and see if you can 'hear' them while powered up.

Comment: Short Answer: No (Score 4, Informative) 274

by introcept (#39568763) Attached to: Ask Slashdot: Is a Home Drone Feasible?

I'm in the middle of writing my EE thesis is on embedded control systems for UAVs and this is as good a distraction as any, so here goes:
The kind of specs you're talking about you'd be lucky to get for high-end military and commercial (mini) drones. You'll either be spending tens(hundreds?) of thousands on an off the shelf model or a lot of time developing, testing, crashing and fixing your DIY solution. There are hundreds of DIY drones on the net but I doubt any of them have the kind of reliable autonomy you're talking about.

Autonomy is especially difficult, you'll need to learn a lot of control theory, kinematics, Navigation/AI and possibly computer vision. Then rememeber that you need to fuse sensor data from gyroscopes, acceleromters, GPS, compass, altitude and airspeed sensors, and that all of these sensors are unreliable/error prone. You need to be able to deal with loss of GPS link which means you need to have an alternate means of localisation(which is very difficult). Also, every commercial system I've seen requires an always on downlink and manned base-station for control, even if this isn't technically necessary, it's pretty much mandatory for safety.

Making an autonomous UAV only makes sense as a learning exercise or for R&D but it's not a good way to get any work done. If your goal is to get aerial photos, stick a camera on an RC plane, get some video goggles, a long range radio and some flying lessons.

Comment: Re:fuck the raspberry pi (Score 1) 82

by introcept (#39438647) Attached to: ModMyPi Raspberry Pi Case Offers 5% Back To the Foundation

At the risk of implying a consideration of the long term effect or *shudder* morality into capitalist economics, it is cheaper to have a local manufacturing base than rely completely on some rights-ignoring nation half way across the world. Hell, in under a year I'm sure they could get local manufacuring ramped up to the point that any cost difference is negligible.

That'd be great if it were true, but it simply isn't. There's a huge amount of capital equipment, skills and expertise that's needed for efficient electronics manufacturing and a few hundred thousand boards is no where near enough to support this kind of investment. Cheap labour might give China an edge, but it's economies of scales and manufacturing experience that make them hard to compete with.
  I've been involved in outsourcing electronics manufacture from Australia and the Chinese companies we've dealt with provide better quality, take half the time and charge half the price of local manufacture, and these aren't sweat shops.

Comment: Student computer club? (Score 1) 582

by introcept (#39170531) Attached to: Ask Slashdot: Dealing With University Firewalls?

See if there's an on campus computer club, that will almost certainly lead you to people, servers and networks that will help with outside access.

A few things I've seen used on campus:
-SSH proxy tunneling
-VPNs
-IPV6 related workarounds
-'partner' universities and organisation that can be accessed/tunelled through without going through the firewall
-wifi router/repeater with long distance wifi link (eg with a 'cantenna') to an off-campus house/building
-friends that work for campus IT, local ISPs and the university's ISP

Comment: Re:Climate change is not the problem with this. (Score 4, Insightful) 292

by introcept (#39156481) Attached to: Cars Emit More Black Carbon Than Previously Thought

Why does this treat particulates as only a concern because they contribute to climate change? That's a potential problem, to be sure, but particulate emissions are a much more immediate environmental concern for those breathing them in. If the levels have been underestimated this much, that's a problem for people's health, especially along highways and in cities. Why does climate change have to be the be all and end all of all environmental impact discussions? Is it because it's so contentious and the ongoing feud drives page hits?

Because a short term, localised and fairly minor reduction in people's health is a much smaller problem than an irreversible change to the climate and biosphere of the entire planet. Even if your only concern is health, people's health will suffer a lot more when they have to deal with economic hardship and resource shortages that could result from climate change.

Comment: Re:Arduino has been left in the dust long time ago (Score 3, Informative) 62

by introcept (#38772008) Attached to: Adafruit's Open-source Wearable Platform, Flora

There's always the AVR GNU toolchain for programming Arduino boards in C. It comes with the (free) WinAVR IDE/Debugger and works with any IDE that can handle GCC et al.
Personally, I can't stand the way TI have tied their products to Code Composer Studio. It's free for some of the cheaper devices but if you want to use it on anything with a bit of muscle you'll be shelling out $500+ just to be able to program/debug the hardware you own.

Comment: Re:Can it be done effectivly without an FPU? (Score 4, Interesting) 271

by introcept (#38760176) Attached to: Faster-Than-Fast Fourier Transform

Do you have math showing the compression consumes less power than just transmitting the raw data?

Lots of it, the power budget drives the design of the entire sensor.
The micro-controller uses a lot less energy than the packet radio so it makes sense to process the raw sensor data on-board and transmit information such as fourier coefficients, integrals and other statistics. Every packet saved is another fraciton of a second the radio can be powered down.

It's a fairly common technique with sensor networks to process raw signals at the point of collection and transmit only the useful information, it makes the most use of your bandwidth and in this case energy.

Comment: Re:Can it be done effectivly without an FPU? (Score 4, Insightful) 271

by introcept (#38759742) Attached to: Faster-Than-Fast Fourier Transform

While I too am sick of seeing dinky little Arduino projects, there are plenty of good reasons to be doing FFT on low power micros.
For example, the company I work for designs battery powered wireless sensors: They have to be compact, consume minimal power and have minimal components for manufacture. We've got a single ATMega processor that sits between a sensor and a radio, doing, among other things, FFT and other 'DSP' functions to compress the data before we spend our precious milliamps transmitting it.
It really is the cheapeast, lowest power way to get the job done, sometimes a hardware DSP is overkill.

Comment: Re:Can it be done effectivly without an FPU? (Score 4, Informative) 271

by introcept (#38759682) Attached to: Faster-Than-Fast Fourier Transform

The interesting thing is that the greater time window over which the FFT operates, you can observe finer frequency detail within that particular window at the expense of how quickly the graph or bars change over time (in simplistic terms). I wonder how this new algo will change the frequency detail/transient time detail trade-off. Do we see more detail in both domains? Less? The same?

This is a property of the Discrete Fourier transform itself. For a certain window size there are only a discrete number of frequencies that you can calculate.
  The larger your window-> The more frequenecies you can see (at the expense of a longer sampling time)

FFT algorithms simply try to compute the DFT quickly, this advance is significant for paractical applications but doesn't change the underlying mathematics.

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