Domain: techmind.org
Stories and comments across the archive that link to techmind.org.
Comments · 8
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Re:Keep the phone ban
I like to use this ABM1 - Passive Air Band Monitor when flying. I keep it discreet as I'm sure most flight crews won't understand how it's different from a typical radio receiver. I regularly hear that "bzz bzz bzz" of cell phones with this device. I then ask my girlfriend sitting next to me if she put her phone in airplane mode. If she hadn't and does it the noise usually goes away. If she had her's in airplane mode then I assume it's someone else sitting near me.
Correct so far.
Phones do cause interference in the aircraft frequency bands (at least at short range).
And... you go off the rails.
GSM phones cause interference in audio-frequency circuits because the phone transmits in regular bursts every 4.62 ms (this is why it doesn't affect CDMA, UMTS, etc., only 2G GSM/GPRS/EDGE, because they use TDMA). It turns out audio amplifiers generally tend to serve as decent wide-band AM receivers, so this is very easily picked up as a 217Hz buzz. However, this is all happening on the audio-frequency side, so calling it "interference in the aircraft frequency bands" is just plain wrong -- it will affect practically any unshielded or insufficiently-shielded device (it's only a couple watts or so transmitter, but within a meter or less the inverse-square law says you do need better shielding than a lot of consumer electronics have) with an amplified audio output, including all sorts of radios, and non-radio devices from MP3 players to cassette players.
(for more on this, google or start here)
Fortunately, it's a really easy problem to solve -- just keep your phone out of the cockpit. Thanks to the inverse-square law, it's really only a practical issue at very short range.
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Re:easiest is best right?
You could also get an attachment for taking photos of slides to transfer them back to film so you can develop them as prints. Before VCRs people would point a film camera at their TV screen, and splice wiring into the speaker to record the sound to tape. The BBC used to make film transfers of TV shows to sell to overseas broadcasters using a special camera too, and when the programme was originally in colour it made very fine noise on the film that was invisible when broadcast but which has now been used to reconstruct the colour information after they wiped the original tapes.
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Re:This effect has been explained in C't recently
You're talking about frame inversion. Many LCDs use line inversion (row inversion) actually. The voltages are altered (not always reversed) every line.
One thing you also should have mentioned is that the amount of twist (the brightness of the pixel, roughly) is determined only by the difference in voltages between the vertical and horizontal gridlines and not the polarity. As such, swapping the voltages between the two doesn't change the brightness if it is done correctly, negating both voltages doesn't either, since neither of these operations changes the difference in voltages between the two gridlines.
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Wrong - GSM max power output is 2W
Average power is lower, but peak is 2W, lowest power is 20mW. The handset varies its output power depending on how it's being received by the base station. In a bad location, the base station would command the handset to increase power.
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Re:What the hell is "bubble fusion"?
Found it - have a look at http://www.techmind.org/sl/ - okay, so it doesn't include the fusion bit, but it explains how to set up the sonoluminescence experiment. Ah, the bubbles...
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Re:Those fat borders are ugly.
I used to be a syncmaster fan myself, but samsung failed me on two requirements:
1 - Their wide screen displays were either too expensive ($2000+) or too crappy (low contrast ratios, narrow and assimetric view angles);
2 - They removed the OSD controls from newer displays in favor of software.
Since I was looking for a wide screen monitor with high contrast ratio, the widest possible view angle, a reasonable AVERAGE response time, and the best possible color accuracy, I ended up choosing an HP F105 instead of a syncmaster. While the design of the monitor is not the best, its performance was the best I had ever seen back when I bought it.
For people looking for new LCDs with quality in mind, I recommend this LCD technology and tests page, especially the color and viewing angle dependency test page as it tells a lot about the quality of the display, and be very suspicious about the claimed latency values, because vendors always tell the fastest response time, not the average. -
Re:Those fat borders are ugly.
I used to be a syncmaster fan myself, but samsung failed me on two requirements:
1 - Their wide screen displays were either too expensive ($2000+) or too crappy (low contrast ratios, narrow and assimetric view angles);
2 - They removed the OSD controls from newer displays in favor of software.
Since I was looking for a wide screen monitor with high contrast ratio, the widest possible view angle, a reasonable AVERAGE response time, and the best possible color accuracy, I ended up choosing an HP F105 instead of a syncmaster. While the design of the monitor is not the best, its performance was the best I had ever seen back when I bought it.
For people looking for new LCDs with quality in mind, I recommend this LCD technology and tests page, especially the color and viewing angle dependency test page as it tells a lot about the quality of the display, and be very suspicious about the claimed latency values, because vendors always tell the fastest response time, not the average. -
Re:Wow
3.3 was great for floppy-based systems. They added support for hard drive partitions over 32 meg, in 4.0 I believe. 4.01 was largely forgotten, and 5.x added good memory tools, himem and emm386. The 6.x series was mostly about doublespace/drivespace, which was Microsoft's take on Stacker.
Somewhere in there, I think with 5.0, the interactive Qbasic editor, also known as Help, also known as Edit, came on the scene. It brought with it mouse-awareness, and funny things like clickable links in the helpfile.
Anyway, as far as video goes, I recall seeing a parallel-port frame grabber that worked fine under DOS on a 286. Actually you didn't want to use it on a multitasking OS because of interrupt latency! Various versions exist, with the Dirt-Cheap Frame Grabber being the simplest.