hwillis

173 ms·

1681.
by hwillis 12y ago
The range resolution would go from 8.5" to five yards if you changed the bandwidth to 30 MHz. Currently the radar could figure out the direction a person is facing to about 45 degrees. 5 yards would be good to find the orientation of
1682.
by hwillis 12y ago
It's in a legal band for any use, but you are correct, the output power is 300-600 times too high to be unlicensed.
1683.
by hwillis 12y ago
Good engineers can do dipole approximations in their heads. This would require a computer- there are just too many internal reflections.
1684.
by hwillis 12y ago
Actually no, a yagi would be very bad. The Radar has a 700MHz bandwidth, almost 12% of the center frequency, and yagis work for a fraction of that. A horn is pretty simple to make.
1685.
by hwillis 12y ago
No, the ripples show up for very simple reasons. Each bar is a reflection at a distance, the wider bars represent wider objects(which will reflect over a larger range of distances, since the radar beam is not very straight). He guesses wh
1686.
by hwillis 12y ago
The radio waves are collected at points and don't have any x or y data, so making an image out of it is pretty challenging and usually requires moving the radar beam. He just kept the beam still, so the only things you can really see
1687.
by hwillis 12y ago
Hah, there's a lot more to weaponized/spy SAR than just the radar; you have to have very good measurements of your movement as you record. It can be improved algorithmically as well but data is king
1688.
by hwillis 12y ago
It would be kind of grey. He was aiming for 5.8 which is an open band in the US, although his bandwidth was way above the width of that channel. Generally though unless you are actively impeding someone else or, god forbid, you're on
1689.
by hwillis 12y ago
http://ocw.mit.edu/resources/res-ll-003-build-a-small-radar-... http://www.amazon.com/Short-Range-Practical-Approaches-Elect... http://www.amazon.com/High-Speed-Digital-Design-Handbook&
1690.
by hwillis 12y ago
If you think thats cool, MIT students have been making Synthetic Aperture Radar (which uses "chirps" of radio waves and measures the time of flight) for the past few years, with enough resolution to image groups of push pins. Oh
1691.
by hwillis 12y ago
I would guess that the high incident angle makes it very difficult to accurately measure. You can see some trouble with the inside and bottom of the noses, and inside the mouth. Parts that are near orthogonal to the viewing plane look muc
1692.
by hwillis 14y ago
There also exist hybrid supercapacitors, which use a chemical reaction but act like capacitors. The best use of high-power capacitors is not as a replacement, its as a supplement. Current technology is not quite sufficient, but ideally it
1693.
by hwillis 14y ago
My first thought as well. But there is an argument to be made that the screen is a different world, and the black of the screen looks as unnatural as pure black in the real world. I think this would apply less to a phone or something with
1694.
by hwillis 14y ago
I worked on a similar satellite, the nanosat-5 (1m3 size), which also used magnetotorque for orientation. Odd choice using arduino, I guess for buzzwords? Also it looks like they are using very little shielding. We used several layers of
1695.
by hwillis 14y ago
Seconded, as someone formerly 6' 130lb, and a frequent back pain sufferer (partially due to injury). I started doing weightlifting about a year ago, and deadlifts in particular made the pain virtually disappear as well as improving many ot
1696.
by hwillis 14y ago
Working on chrome 19.0.1084.46 m (haven't updated in a while). Seems weird that so many people are having problems
1697.
by hwillis 14y ago
It takes a few seconds to start. The particles should pulse on each kick. You may not be able to hear it very well, its very bass-heavy.
1698.
by hwillis 14y ago
Neato, sophomore ECE here (been taking more CS so far). I've also built a tesla coil, however due to massive paranoia from 12V spot welds during FIRST robotics I have avoided getting shocked. I always had the skin effect quoted at me so I
1699.
by hwillis 14y ago
VALVe is also working on something similar: http://blogs.valvesoftware.com/abrash/valve-how-i-got-here-w...
1700.
by hwillis 14y ago
Hard to say. Maybe not much, due to the environment and the skin affect- high frequency electricity tends to flow near the surface of a material. This isn't a van der graff generator though, it can still produce a significant current, and
1701.
by hwillis 14y ago
Fun fact: that 100MW laser is in "cut the ISS in half in a fraction of a second" territory. 5KW lasers are used for cutting through 1/4" aluminum.
1702.
by hwillis 14y ago
Memristor-like components have existed since 1960 ( http://en.wikipedia.org/wiki/ADALINE ). There is no demand for a discrete component so I doubt anyone would start making them. You could make an analogous device with a microcontroller,
1703.
by hwillis 15y ago
really? Not even a voltage divider? That would kill anything plugged into it right quick