It doesn't quite work this way. This is going to be a bit technical, but you asked a technical question, so bear with me. Yes, I am a ham (since you asked for one), and I've also done some commercial RF data systems.
As others have pointed out, cellular telephone systems aren't like broadcast systems. You really can "put up more towers" to increase the amount of "service" (available data transfer per unit time, number of simultaneous voice calls, etc.) in a given geographic area without using more RF bandwidth. The reason for this is that you can turn the power on the base and handset down to reduce the coverage of the cell allowing reuse of the RF bandwidth more frequently within a certain geographical space. This is already done: cells on rural highways are much larger than cells within a city. In fact, the cells on rural highways would often be capable of covering an entire city from a geographic point of view, but there wouldn't be enough capacity to handle all that traffic, so smaller (lower power, lower antenna angle, etc.) cells are placed in cities allowing reuse of that RF bandwidth. Broadcast services can be thought of as "cellular" with very large cells (depending on the service, up to and including the entire planet for HF "shortwave" radio, for example) if you want, but that's not a traditional interpretation.
As for how much bandwidth it takes to attain a certain information rate, that varies with a number of factors. Assuming a uniform RF environment (noise, propagation, etc., which of course isn't true but is handy for discussion), the key tradeoff is made by how "aggressive" your modulation scheme is. A more aggressive modulation scheme packs more data into a certain amount of RF bandwidth, but it requires a stronger signal to noise ratio at the receiver to demodulate and recover the data. The exact relationship between how much data you can chuck into a given amount of RF bandwidth and the required receiver SNR varies with your chosen modulation scheme and receiver design. The reason data rates have been increasing with time is that newer, better (easier to demodulation) modulation schemes and better (mostly less noisy, but also more cost effective for a given complexity) receivers are being developed. More cells are also being added (see above) to lessen "competition" for the channel's bandwidth, but we're also seeing a lot more users and demand, so that probably averages out. The amount of RF bandwidth allocated to the cellular telephone services has remained roughly constant since the late 90s (800MHz cellular band + 1900MHz PCS band, though other bands are also used regionally, and some of these are new).
In a two-way scenario like a cellular telephone, you also get to play with the fact that the two directions don't behave equally. The base-to-handset link (downlink) has the advantage of no access contention (there's just one base, and it knows everything it's doing), expensive equipment (there's only one, so the company can pump some money into it), and lots of power available (it's plugged into the wall). The handset-to-base link (uplink) is messier: it has access contention (multiple handsets coordinated remotely by the base), cost sensitive equipment (consumers don't like to pay thousands of dollars for their handsets), and limited power (batteries). Antennas are something of a wash since antennas are effective about equally in both directions. What all this means is that it's easier to use a more aggressive modulation scheme (and hence cram more bits per second into a given chunk of RF MHz) on the downlink than the uplink. Fortunately, this is roughly in-line with consumer demand: most consumers want to transfer large stuff to their phones, not from them. FWIW, Cable Modems have similar concerns, and a similar situation results.
You also seem to assume a TDMA based uplink channel. Modern standards are all CDMA based. While the theory of operation is totally different, the effect is the same: multiple people contend for the same resource. Various
It's not unheard of in the world of Music games at all, which may explain why the genre has trouble with the US market. If you're familiar with Konami's Bemani series (which, I might add, has much of this functionality since Guitar Freaks and Drum Mania can be linked, and are in fact on the same disc when sold for the home market), expensive controllers are the way things work. A beatmania controller is about 7000Yen (~$70US) in Japan, and pop'n mini controllers are comparable. If you want *good* (so-called "Arcade Style"), full arcade size controllers, you can expect to drop upwards of $300 on a single controller for these games. A good controller for Drum Mania (a MIDI drum set) can cost over $1000! Even a cheap-o DDR pad will run you $25 here in the US. A good one is usually in the $75-120 range for foam insert based ones, and $200+ for a sturdy metal one.
The Japanese are more gadget oriented than USians, though, and this may explain at least some of the success of the series in the Japanese market as compared with its difficulty here in the USA.
Having torn apart several REAL DDR stages (including solo stages), I can say there is absolutely no wood in a doubles stage. I don't recall there being any in a solo stage either, though I've only taken one of those apart. The crappy Namco knockoffs are made of wood. They also suck big time. The springyness of a real DDR stage comes from compressing the pressure sensors as well as the thin layer of rubber foam on top of the L-bracket. There is then a hard stop from the slots on the L-bracket to prevent damage to the sensor itself.
If you want to see what the inside of a DDR stage looks like, check out Inside a DDR Stage: The Naked Truth Revealed! for a good look, as well as some hints at how to make them perform pretty well, even if they've seen a lot of wear and tear. The stage pictured in the article is certainly very, very different from an arcade DDR stage, but I'd have to reserve judgement of "better" until after playing it. A real DDR stage in good shape (I've also played a nearly brand new machine) is very responsive, firm, and good to play on. There are a lot of very poorly (and just plain dead due to play) machines out there, but if you maintain a DDR stage properly, they're amazingly resiliant.
I don't know about telco demarc boxes where you live, but around here that's perfectly legit, as long as you do it right.
See, on the box there's two sides: customer access and telco access. The telco access side opens up the whole box and has their binding posts on it. Newer installations these will often be punch 110, but older boxes are thread based binding posts. If they install it right (keep the twist until it gets to the actual posts), that doesn't really matter.
Now, the fun part is that those binding posts or punch slots connect to RJ11s on the "customer access" side. You can actually just plug a regular phone right in to that jack for testing purposes - they encourage this if you think you may be having internal wiring issues. For normal use, there's another set of binding posts (or again, punch 110s) that connect to short stubs with RJ11 terminations on them to plug into these jacks.
My solution is generally to wire the place right: structured cabling with a punch block in the basement or back. You take a line from the demarc (I use outdoor/in-wall rated CAT5e) and run that to a punch66 or punch110 (I usually use a 66 and snake spare pieces of CAT5 down the middle for distribution - ugly but it works well). Then just punch all your internal jacks down.
The more modern solution would be to use two punch110s - one duplicating all the incoming telco stuff and the other having every phone/network jack in the site. Then you can patch jacks as ethernet or phone (or ATM, or RS-485, or whatever else the hell you want to run over twisted pair) as needed.
As sites with DSL, I go a step further and install one of those stupid filters on the line that runs into the punchblock. I then run a separate line for the DSL that is, of course, unfiltered.
Of course, all this works slightly better at offices where you're installing new infrastructure anyway, but it can be easilly applied to new builds or even retrofitted into older homes. The telcos don't mind one bit: it makes their job easier, too, if they have to do something in the house (though I've gotten some odd looks when it comes to the "phone wire snaked down the middle of a punch66").
ATSC channels (USA over-the-air digital broadcast) have a total data rate of a little over 19.5Mbit/sec. Using MPEG2 video compression (see below), most stations fit a main HD feed (their network feed) at either 720p or 1080i and a standard def subchannel at usually 480i, maybe 480p if you're lucky, into that channel.
However, using h.264, HD 720p video can be run at rates as low as 4Mbit without significant artifacting, mostly due to h.264's incredible behavior when presented with resolution bumps. SD channels can be run as low as 384kbit (yes, you read that right...) at acceptable quality. However, set-tops capable of decoding HD h.264 are currently expensive and not widely deployed, and currently employed digital cable and broadcast standards in the USA call for MPEG2, so this is not likely to be used when compatibility with existing infrastructure is required.
However, even using h.264, 15Mbit leaves you with room for 3 HD channels and no extra internet bandwidth. That's really pushing it. The cable companies have really got the edge in infrastrcuture here. Their infrastructure was built to move high-bandwidth signals directly into the home (most cable systems have an available bandwidht of at LEAST 400MHz), while the telephone infrastructure was originally designed to carry only baseband voice (bandwith ~= 10kHz).
While others have indicated the old ctl/alt/+ and ctl/alt/- hotkeys for X mode switching, I'm guessing that doesn't QUITE do what you want. That will create a virtual desktop who's logical size is as large as the largest defined mode.
However, the X RandR extension allows for on-the-fly resizing of the root window, as well as selecting just about any valid defined mode.
I can select from the following:
SZ: Pixels Physical Refresh *0 1280 x 1024 ( 325mm x 260mm ) *75 60 1 1152 x 864 ( 325mm x 260mm ) 75 2 1024 x 768 ( 325mm x 260mm ) 75 70 60 3 800 x 600 ( 325mm x 260mm ) 75 72 60 56 4 640 x 480 ( 325mm x 260mm ) 75 73 60 5 512 x 384 ( 325mm x 260mm ) 75 70 60 6 400 x 300 ( 325mm x 260mm ) 75 72 60 56 7 320 x 240 ( 325mm x 260mm ) 75 73 60 8 1280 x 960 ( 325mm x 260mm ) 60 9 1280 x 800 ( 325mm x 260mm ) 60 10 1280 x 768 ( 325mm x 260mm ) 60 11 832 x 624 ( 325mm x 260mm ) 75 12 640 x 512 ( 325mm x 260mm ) 75 60 13 720 x 450 ( 325mm x 260mm ) 60 14 640 x 400 ( 325mm x 260mm ) 60 15 576 x 432 ( 325mm x 260mm ) 75 16 640 x 384 ( 325mm x 260mm ) 60 17 416 x 312 ( 325mm x 260mm ) 75 Current rotation - normal Current reflection - none Rotations possible - normal Reflections possible - none
Note that your window manager has to handle the resize sanely. Unfortunately, few do (but then most window managers suck, especially the default ones that come with most distributions). My preferred window manager, FVWM, has some support for it. The reason is that this exention, while not new (I used it on my ipaq over 3 years ago), is still relatively new to the desktop crowd due to the XFree86/X.Org fiasco. Hopefully window manager support will catch on soon.
As far as copy/paste, I just copy/pasted that list up there from my xterm. It seemed to work OK. The biggest problem I have is apps that try to adopt the windows copy/paste paradigm of ctl+c/ctl+v instead of sticking with the normal X one of highlight/middle click.
I use all 5 buttons on my mouse, just tell xorg that you have 5 buttons in the config file. After 5, you have to do some hackery with xmodmap (and that is NOT fun...) if you want your wheel to still work right. Someone should fix that.
I've had mixed experiences with binary applications and drivers in Linux. Drivers that have wrappers that are maintained usually work OK (like the nVidia driver). "Hostile" binary drivers usually are pretty much stuck on whatever kernel they were built against. This sucks, though MODVERSIONS helps with this. I've had binary applications that work fine (Eagle CAD, UT2003, UT2004), work fine once you manually install them since their installer was broken (Maple 9, original UT), and applications linked against a glibc from 1997 that I'm too lazy to hunt down and install (Xilinx ISE 6). Let's face it, Win32 binary compatibility from 1997 or so is kinda iffy with XP. How many complex apps (and you're kidding yourself if you don't think Xilinx is complex) built for Win95 will work on XP?
Things certainly need fixed, but a lot of the problems people have is just breaking out of the Windows paradigms and getting used to the UNIXish ones. I personally can't stand hunting my way through badly designed GUIs in Windows anymore (a recent patch broke my DCOM, I finally ended up just reinstalling windows after the MSDN instructions failed to fix the problem). Give me my plain text config files!
Basically, while BPL can pollute the entire MF/HF spectrum, amateur radio operators were the group that made the biggest stink (also affected are lots of emergency operations, some older fixed links, international shortwave broadcasters, etc.). Amatuers are allocated certain bands (there's a giant poster if you google for "US Frequency Allocations"). Since the amateurs are the most likely to notice and complain, they simply don't use those frequencies (and maybe lower fundamentals that could have harmonics within those bands, depending on thier signalling methods). This is called notching.
Since the amateur bands are relatively small, this doesn't remove very much capacity from their data services, but makes the amateur service happy. A good test would be to go examine noise levels outside the amatuer bands.
Also, realize that on a normal SSB phone receiver, high-bandwidth, high-symbol-rate digital signals such as this can sound very much like naturally occuring noise. The lower HF bands can be noisy anyway (especially during the day), so it may be difficult to tell if noise is natural or from something like a leaky data system (there have been problems with leaky cable systems up on VHF as well). Working 40m or 80m can be difficult enough with all the natural noise, let alone any added noise from a system like power line broadband.
If it were possible to turn the BPL system on and off at will for a test, it would be much easier to examine noise levels. Just get yourself a spectrum analyzer and a wide-bandwidth antenna (maybe a log periodic or something). Take some data points (or maybe just a picture of the full HF spectrum) with the system on, then with it off. Compare. This is much like the procedure used to test consumer electronic devices for FCC part 15 compliance (whether they be intentional or non-intentional radiators).
I see a lot of people badmouthing BPL or Amateur Radio over one-another. I'm an amateur radio operator, and I'd oppose BPL even if it didn't interfere with the amateur service (as some implementations don't: they notch out the amateur bands since the ARRL has been so vocal).
It really is a silly idea. Let's run MF/HF/VHF signals over this really long, unshielded wire to deliver internet to people's houses. Of course we can't actually get it to the house because of those pesky transformers, so we still need to retrofit our grid and use something else (like wifi) for the last 100 yards. Then there's that pesky issue of power lines being really bad transmission lines at those high frequencies (they're definately not constant impedence), so we'll have to throw a lot of power into those lines (at RF) to get the signal where we want it. What? It radiates? Hum, oh well.
The obvious solution is to string real transmission lines (like coax, twisted pair, or, obviously, fiber) along those poles (protected in some kind of harder casing) and underground. But that's expensive? Duh, retrofitting something meant to deliver huge amounts of energy at one frequency (50 or 60Hz, depending on your side of the pond) to deliver data at high rates of speed isn't going to be cheap. At least don't be half-assed about it.
Also, just so people know. The amateur service doesn't really have all the bandspace people make it out to have. Some bands are surprisingly small: the voice section of 17m, for example, is from 18.110MHz to 18.168MHz - only 58kHz of bandwidth, or enough for 20 single-sideband voice conversations if everyone plays *really* nice and lines up perfectly. There are giant posters like this one that show the major service to which each frequency band is allocated to in the US (many of which are also assigned internationally by ITU, at least down in HF). The first 3 rows (3kHz-30MHz) are the bands likely to be given problems by BPL. The amateur service is teal-green colored on that poster. Look for yourself how little is actually given to the service on many bands. 80m (3.5MHz) is about the only one that you're likely to even spot quickly below 30MHz!
A mathematical proof is nothing but a manner of convincing someone (other mathematicians) that what you assert is indeed correct, given the following presumably known, accepted as true, or otherwise previously proven "things". The whole point of a proof is that someone else knows wtf it is talking about.
I could assert that 2+2=4. You may believe me, but have I really proven it to you? Not yet, so you don't need to believe me. If I instead say that the the cardinality of the union of two disjoint sets, each of cardinality 2, is 4, then I've (sort of) showed you that 2+2=4, assuming you accept my definitions of disjoint sets, set union, and set cardinality (which presumably I've proven elsewhere, or taken from some other source). Now do you believe me that 2+2=4?
I could assert anything. You may or may not know if it's true. A proof is just something to back up my assertion and convince you that I'm right. Hence, if a proof is unintelligable, it's pretty darn worthless.
Yes, by local I mean "national". I guess it's true that in most countries there are many levels of government below the national government. It's all about scale...nations are local compared to worldwide:)
For the upper bands, the local governments have quite a bit of say in how thigns are alloted due to the fact that those signals just don't go very far beyond line of sight under normal circumstances. There are some exceptions that are dictated by the ITU and the US pays attention to those. These exceptions are mostly for research quiet zones (and those are pretty small), non geo-sync sats, etc.
The HF bands (which readily propagate around the world), VHF and lower UHF (which can propagate distances significantly beyond those you would expect) have some ITU regulations attached to them. The FCC does pay attention to these international regulations of the RF spectrum.
The US also has agreements regarding allocations up in the microwave ranges along its borders with other nations to avoid interference.
Depends on your operating environment. Stock Zaurii running Qtopia and things running OPIE will draw directly on the framebuffer as Qt/E sort of expects to. You most certainly can run X on an ipaq (and I believe a Zaurus too). My ipaq in fact runs X. I've done some crazy X forwards to it in the past (including Starcraft, running in Wine on my desktop).
There's no reason it shouldn't run on an X based desktop. I know it runs on ipaqs running Linux (which generally run X) and Zaurii, so there's no reason it shouldn't compile for x86 (or whatever floats your boat) and run on your Linux/BSD/Solaris/HP-UX/AIX/ desktop. Now, if you're running Windows, you're on your own (though that may work fine too).
Now be fair. The bad capacitors that you're referring to were caused by some shoddy manufacturer cutting corners (and a fair bit of industrial espionage gone wrong too, I've heard). In general, that was considered a product *failure*. True, there were some motherboard makers who refused to provide replacements (whom I, for one, will never buy from again), but on the whole, leaking electrolytic capactitors (at least over any reasonable term) is considered to be component failure. Capacitors are not considered user replacable, and certainly aren't considered disposable.
Also, I don't know about you, but my Li-Ions don't "last for a year or two". Sure, after a couple years they're not like they were at first, but neither is a Ni-Cd or Ni-MH, and you're forgetting that most battery types aren't rechargable at all. The world of batteries hasn't caught up with the uses of batteries yet. It's not like there's some other product on the market that's not "disposable" or that similar products in the past were more reliable. The only battery I can think of that handles recharge/discharge cycling better is good ol' Lead-Acid (like in your car), and I'm doubting you want to lug one of those around to power your PDA (they don't scale down to that size very well).
I agree, though, that Plasma TVs are silly. I personally like a good DLP for larger sizes or a direct view LCD or CRT in smaller sizes (depending on the use). Even projection CRT is still viable up at larger screen sizes (and, while they require continuous twiddling to keep a good picture, they generally don't fail completely in any reasonable term). Plasmas just don't cut it in my opinion. They're expensive and subject to burn-in. There's no real reason to buy a plasma unless you absolutely need to hang a large screen (bigger than a feasable direct view LCD) on your wall, in which case, like the batteries I mentioned before, there's no feasable alternative, so you have to accept the state of technology.
Now, hard drives that aren't rated for "continuous or *heavy duty* use" (emphasis mine) is silly. What exactly constitutes "heavy duty" use? I would say that basically any use of a hard drive is normal use. Continuous I could understand if the normal failure mode for hard drives wasn't the stress of power-on...
Tyan isn't targeting you. Tyan is targeting people who want to build PC workstations. These are people who have uses for multiple gigabytes of RAM (think simulations) or PCI-X slots (SCSI RAID controllers). Tyan isn't really targeting PC gamers here. They're obviously trying to appeal to the market, but Tyan has traditionally gone for the workstation and low-end server crowd (people who do work with their computers) with their Thunder series.
Asus is generally the maker of boards in your target range. Check them out. Yes, they do charge a premium, but they make high quality motherboards in my experience.
<rant>
Gigabyte doesn't. I have a 7VTXH and it's a marvel of engineering badness. There's a finicky timing issue whenever all three DRAM slots are populated that I have yet to resolve (and yes, the RAM is on their approved list and is of generally high quality, and no, the RAM is not faulty). I had to ship it back to them no less than three times due to a bad flash chip. Once is acceptable (it didn't immediatley go bad and so could probably pass initial QA), but it would have been nice if they'd just replaced it or extensively tested it after reprogramming it. Also, fat lot of good their "dual BIOS" feature did; I still had a brick. If they'd not solder the damn chip to the board (socket it, folks), I could at least program it myself since I do have a flash programmer.
The board's ACPI is also a bit flakey, but being a desktop board of the age it is, I can live with that (it's good enough that I can usually get by with leaving ACPI enabled).
Actually, Sony did that, just in Japan only. You most certainly can (or at least could, dunno now with the slim models) buy a "Sakura Pink" PS2. NTSC/J region only (though I'd probably find that more useful than my NTSC/UC). The PS2 was also available in white, and some sort of blue IIRC.
And there's the ARRL VHF sweepstakes this weekend. Should certainly be fun. 6m was open tonight (was hearing Florida in Indiana), but things may change over the weekend.
I'm not very familiar with VHF/UHF propagation modes. Anyone have any hints on what this may do to propagation on the VHF and up bands?
Hum, I also do a fair amount of RF work, but not normally A/V work. I was given the impression that component video was spec'd for like a 300-600 ohm characteristic impedance. If it's actually supposed 75 ohm at each end, then clearly 75 ohm coax is the way to go.
I really hate throwing adapters on everything. There's always insertion loss with putting adapters in the line. Obviously RCA connectors don't have constant impedance, but I would have thought it would be better to terminate it (carefully) into the connector that would actually be used, rather than throw adapters on everything. There are RCA connectors that are designed for coax, rather than simple parallel wires (ala speaker wire); the problem is finding one that actually fits on the end of a piece of RG-6/U. That cable is rather large stuff (not nearly as big as what I'm used to working with though, which is mostly LMR-400 Ultraflex and similar).
I'm certainly not going to buy Monster branded stuff. It's good, sure, but guaranteed to be overpriced. I can get very high quality adapters from a local distributor. He also sells real 75 ohm Amphenol BNC connectors, as well as off-brand ones if you're not willing to pay the premium (I usually am, if only so that I can look up all the measurements on amphenol's website), not just 50 ohm ones.
I was going to make a nice set of component cables out of RG-6/U. RG-6/U is pretty much the best coax that's reasonable to use for component video applications (the impedence is still low, but 75ohm coax is reasonable to acquire, things like 300 or 600 ohm coax are not).
The problem is, most RCA connectors won't fit on a piece of RG-6/U. BNC connectors will fit just fine, but neither my TV, nor my DVD player have BNC connectors. BNC connectors have advantages over RCA connectors, from both technical and use perspectives. From the user's point of view, they're nice because they lock on securely. From the technical point of view, they're nice because they can be had in a constant 75ohm impedence. This isn't of particular concern in this application (since it won't be matched to the source or load anyway), but it will cut down on the number of total abrupt impedence changes, resulting in less reflection.
I don't want to put BNC connectors on my cable only to have to change it to RCA connectors for my equipment. Adapters do exist (and can be had at a reasonable price, though not from Monster, since everything they sell is overpriced), but it's pointless if you can choose the connector in the first place.
I think I found a set of RCA connectors that will fit on my cable, but I need to get a micrometer out and measure to be sure. It'll be a tight fit.
One problem that (especially cheaper, and often very noticable on really cheap) DVD players have is noise on the black. My DVD player is a rather high quality (back when it was new) Sony that does OK (not progressive scan though). The picture is excellent, but there's noticable noise on the black levels on my 46" DLP, even using a rather high quality component connection (I haven't busted out the RG-6/U yet since I can't find good RCA connectors, why we're not using BNC is beyond me though).
With a digital signal, you won't have this noise problem, which may be due to the DACs on the DVD player (probably is), not just interference over the cable run. Good digital to analog conversion is a tough problem, especially at the higher bandwidths required for video signals (even at baseband). With digital TVs (like DLP) becoming popular, it makes sense to just skip that step, and save yourself the noise (and, in theory, cost - good DACs are expensive).
Part of the problem, especially with very low end MP3 players that use dedicated hardware decoding is that (to my knowledge) there is no integrated solution (I hate that word, but it's appropriate here) for decoding Vorbis in hardware.
There are a few chips for doing MP3 easily (I've actually got a couple of STA013s here that I've been meaning to make into an MP3 player very similar to this one, but using an 8051 or z80 instead of a PIC). I don't know of any like that for doing Vorbis.
Of course, this doesn't apply to systems decoding in software. There is a fixed point decoder for Vorbis available, so the lack of an FPU (common) isn't a problem (it was until about a year ago). Decoding Vorbis does require a little more CPU time than MP3, but it's not too big if you're already decoding in software, the problem is dedicated hardware decoders. There's no STA013V (or whatever) that will do Vorbis in a nice package like there are for MP3.
Another good thing to try is to get an older radio (yes, it will probably have tubes, the horror). I acquired a Heathkit DX-60B for $0. Yes, that's right, it was completely free (the person even dropped it off at the local club shack IIRC).
When I got it, it did at least turn on, but it wouldn't tune up at all. The electrolytic caps, being ~40-50 years old, were completely shot. Replacing those has restored it to almost 100% working order. The bias on the oscillator tube is still off by a few 100 volts, but that's just because the bias network resistors (carbon composition, and 10% tolerance at that) have drifted with age as well. Replacing those should get me back in shape (and the newer metal type resistors last a lot better too).
These rigs are quite user-servicable. They usually do require more maintaince than a newer rig may, but at least you can easily do it yourself using even the most crudely large of soldering guns.
The key is to find a good small time electronics distributor in your area. If you're in a semi-major city there's probably one somewhere nearby. Indianapolis, for example, has MAI Prime Parts (don't be fooled by their website trying to sell you Monster Cable, they actually sell real stuff too, not to mention that the Monster Cable is actually at a reasonable price). They're not always easy to locate since they don't do business with the "general public" as it were, but only because that's not their target market. Most are perfectly happy to sell you a capacitor, a few resistors, or a premade inductor or coil-form. MAI is really like a EE candy store. There's a whole isle of just capacitors, for example.
Yes, Radio Shack has certainly gone down hill. I've taken to calling them "cell-phone shack" recently, though they do still sell soldering irons. I should know, I just had to run out and get one to repair a blown keyboard fuse on a PC motherboard. Total cost for the soldering iron and solder (since I left mine at another location)? About $12.
Slashdot Mirror
It doesn't quite work this way. This is going to be a bit technical, but you asked a technical question, so bear with me. Yes, I am a ham (since you asked for one), and I've also done some commercial RF data systems.
As others have pointed out, cellular telephone systems aren't like broadcast systems. You really can "put up more towers" to increase the amount of "service" (available data transfer per unit time, number of simultaneous voice calls, etc.) in a given geographic area without using more RF bandwidth. The reason for this is that you can turn the power on the base and handset down to reduce the coverage of the cell allowing reuse of the RF bandwidth more frequently within a certain geographical space. This is already done: cells on rural highways are much larger than cells within a city. In fact, the cells on rural highways would often be capable of covering an entire city from a geographic point of view, but there wouldn't be enough capacity to handle all that traffic, so smaller (lower power, lower antenna angle, etc.) cells are placed in cities allowing reuse of that RF bandwidth. Broadcast services can be thought of as "cellular" with very large cells (depending on the service, up to and including the entire planet for HF "shortwave" radio, for example) if you want, but that's not a traditional interpretation.
As for how much bandwidth it takes to attain a certain information rate, that varies with a number of factors. Assuming a uniform RF environment (noise, propagation, etc., which of course isn't true but is handy for discussion), the key tradeoff is made by how "aggressive" your modulation scheme is. A more aggressive modulation scheme packs more data into a certain amount of RF bandwidth, but it requires a stronger signal to noise ratio at the receiver to demodulate and recover the data. The exact relationship between how much data you can chuck into a given amount of RF bandwidth and the required receiver SNR varies with your chosen modulation scheme and receiver design. The reason data rates have been increasing with time is that newer, better (easier to demodulation) modulation schemes and better (mostly less noisy, but also more cost effective for a given complexity) receivers are being developed. More cells are also being added (see above) to lessen "competition" for the channel's bandwidth, but we're also seeing a lot more users and demand, so that probably averages out. The amount of RF bandwidth allocated to the cellular telephone services has remained roughly constant since the late 90s (800MHz cellular band + 1900MHz PCS band, though other bands are also used regionally, and some of these are new).
In a two-way scenario like a cellular telephone, you also get to play with the fact that the two directions don't behave equally. The base-to-handset link (downlink) has the advantage of no access contention (there's just one base, and it knows everything it's doing), expensive equipment (there's only one, so the company can pump some money into it), and lots of power available (it's plugged into the wall). The handset-to-base link (uplink) is messier: it has access contention (multiple handsets coordinated remotely by the base), cost sensitive equipment (consumers don't like to pay thousands of dollars for their handsets), and limited power (batteries). Antennas are something of a wash since antennas are effective about equally in both directions. What all this means is that it's easier to use a more aggressive modulation scheme (and hence cram more bits per second into a given chunk of RF MHz) on the downlink than the uplink. Fortunately, this is roughly in-line with consumer demand: most consumers want to transfer large stuff to their phones, not from them. FWIW, Cable Modems have similar concerns, and a similar situation results.
You also seem to assume a TDMA based uplink channel. Modern standards are all CDMA based. While the theory of operation is totally different, the effect is the same: multiple people contend for the same resource. Various
It's not unheard of in the world of Music games at all, which may explain why the genre has trouble with the US market. If you're familiar with Konami's Bemani series (which, I might add, has much of this functionality since Guitar Freaks and Drum Mania can be linked, and are in fact on the same disc when sold for the home market), expensive controllers are the way things work. A beatmania controller is about 7000Yen (~$70US) in Japan, and pop'n mini controllers are comparable. If you want *good* (so-called "Arcade Style"), full arcade size controllers, you can expect to drop upwards of $300 on a single controller for these games. A good controller for Drum Mania (a MIDI drum set) can cost over $1000! Even a cheap-o DDR pad will run you $25 here in the US. A good one is usually in the $75-120 range for foam insert based ones, and $200+ for a sturdy metal one.
The Japanese are more gadget oriented than USians, though, and this may explain at least some of the success of the series in the Japanese market as compared with its difficulty here in the USA.
Having torn apart several REAL DDR stages (including solo stages), I can say there is absolutely no wood in a doubles stage. I don't recall there being any in a solo stage either, though I've only taken one of those apart. The crappy Namco knockoffs are made of wood. They also suck big time. The springyness of a real DDR stage comes from compressing the pressure sensors as well as the thin layer of rubber foam on top of the L-bracket. There is then a hard stop from the slots on the L-bracket to prevent damage to the sensor itself.
If you want to see what the inside of a DDR stage looks like, check out Inside a DDR Stage: The Naked Truth Revealed! for a good look, as well as some hints at how to make them perform pretty well, even if they've seen a lot of wear and tear. The stage pictured in the article is certainly very, very different from an arcade DDR stage, but I'd have to reserve judgement of "better" until after playing it. A real DDR stage in good shape (I've also played a nearly brand new machine) is very responsive, firm, and good to play on. There are a lot of very poorly (and just plain dead due to play) machines out there, but if you maintain a DDR stage properly, they're amazingly resiliant.
I don't know about telco demarc boxes where you live, but around here that's perfectly legit, as long as you do it right.
See, on the box there's two sides: customer access and telco access. The telco access side opens up the whole box and has their binding posts on it. Newer installations these will often be punch 110, but older boxes are thread based binding posts. If they install it right (keep the twist until it gets to the actual posts), that doesn't really matter.
Now, the fun part is that those binding posts or punch slots connect to RJ11s on the "customer access" side. You can actually just plug a regular phone right in to that jack for testing purposes - they encourage this if you think you may be having internal wiring issues. For normal use, there's another set of binding posts (or again, punch 110s) that connect to short stubs with RJ11 terminations on them to plug into these jacks.
My solution is generally to wire the place right: structured cabling with a punch block in the basement or back. You take a line from the demarc (I use outdoor/in-wall rated CAT5e) and run that to a punch66 or punch110 (I usually use a 66 and snake spare pieces of CAT5 down the middle for distribution - ugly but it works well). Then just punch all your internal jacks down.
The more modern solution would be to use two punch110s - one duplicating all the incoming telco stuff and the other having every phone/network jack in the site. Then you can patch jacks as ethernet or phone (or ATM, or RS-485, or whatever else the hell you want to run over twisted pair) as needed.
As sites with DSL, I go a step further and install one of those stupid filters on the line that runs into the punchblock. I then run a separate line for the DSL that is, of course, unfiltered.
Of course, all this works slightly better at offices where you're installing new infrastructure anyway, but it can be easilly applied to new builds or even retrofitted into older homes. The telcos don't mind one bit: it makes their job easier, too, if they have to do something in the house (though I've gotten some odd looks when it comes to the "phone wire snaked down the middle of a punch66").
ATSC channels (USA over-the-air digital broadcast) have a total data rate of a little over 19.5Mbit/sec. Using MPEG2 video compression (see below), most stations fit a main HD feed (their network feed) at either 720p or 1080i and a standard def subchannel at usually 480i, maybe 480p if you're lucky, into that channel.
However, using h.264, HD 720p video can be run at rates as low as 4Mbit without significant artifacting, mostly due to h.264's incredible behavior when presented with resolution bumps. SD channels can be run as low as 384kbit (yes, you read that right...) at acceptable quality. However, set-tops capable of decoding HD h.264 are currently expensive and not widely deployed, and currently employed digital cable and broadcast standards in the USA call for MPEG2, so this is not likely to be used when compatibility with existing infrastructure is required.
However, even using h.264, 15Mbit leaves you with room for 3 HD channels and no extra internet bandwidth. That's really pushing it. The cable companies have really got the edge in infrastrcuture here. Their infrastructure was built to move high-bandwidth signals directly into the home (most cable systems have an available bandwidht of at LEAST 400MHz), while the telephone infrastructure was originally designed to carry only baseband voice (bandwith ~= 10kHz).
However, the X RandR extension allows for on-the-fly resizing of the root window, as well as selecting just about any valid defined mode.
I can select from the following:
Note that your window manager has to handle the resize sanely. Unfortunately, few do (but then most window managers suck, especially the default ones that come with most distributions). My preferred window manager, FVWM, has some support for it. The reason is that this exention, while not new (I used it on my ipaq over 3 years ago), is still relatively new to the desktop crowd due to the XFree86/X.Org fiasco. Hopefully window manager support will catch on soon.
As far as copy/paste, I just copy/pasted that list up there from my xterm. It seemed to work OK. The biggest problem I have is apps that try to adopt the windows copy/paste paradigm of ctl+c/ctl+v instead of sticking with the normal X one of highlight/middle click.
I use all 5 buttons on my mouse, just tell xorg that you have 5 buttons in the config file. After 5, you have to do some hackery with xmodmap (and that is NOT fun...) if you want your wheel to still work right. Someone should fix that.
I've had mixed experiences with binary applications and drivers in Linux. Drivers that have wrappers that are maintained usually work OK (like the nVidia driver). "Hostile" binary drivers usually are pretty much stuck on whatever kernel they were built against. This sucks, though MODVERSIONS helps with this. I've had binary applications that work fine (Eagle CAD, UT2003, UT2004), work fine once you manually install them since their installer was broken (Maple 9, original UT), and applications linked against a glibc from 1997 that I'm too lazy to hunt down and install (Xilinx ISE 6). Let's face it, Win32 binary compatibility from 1997 or so is kinda iffy with XP. How many complex apps (and you're kidding yourself if you don't think Xilinx is complex) built for Win95 will work on XP?
Things certainly need fixed, but a lot of the problems people have is just breaking out of the Windows paradigms and getting used to the UNIXish ones. I personally can't stand hunting my way through badly designed GUIs in Windows anymore (a recent patch broke my DCOM, I finally ended up just reinstalling windows after the MSDN instructions failed to fix the problem). Give me my plain text config files!
Basically, while BPL can pollute the entire MF/HF spectrum, amateur radio operators were the group that made the biggest stink (also affected are lots of emergency operations, some older fixed links, international shortwave broadcasters, etc.). Amatuers are allocated certain bands (there's a giant poster if you google for "US Frequency Allocations"). Since the amateurs are the most likely to notice and complain, they simply don't use those frequencies (and maybe lower fundamentals that could have harmonics within those bands, depending on thier signalling methods). This is called notching.
Since the amateur bands are relatively small, this doesn't remove very much capacity from their data services, but makes the amateur service happy. A good test would be to go examine noise levels outside the amatuer bands.
Also, realize that on a normal SSB phone receiver, high-bandwidth, high-symbol-rate digital signals such as this can sound very much like naturally occuring noise. The lower HF bands can be noisy anyway (especially during the day), so it may be difficult to tell if noise is natural or from something like a leaky data system (there have been problems with leaky cable systems up on VHF as well). Working 40m or 80m can be difficult enough with all the natural noise, let alone any added noise from a system like power line broadband.
If it were possible to turn the BPL system on and off at will for a test, it would be much easier to examine noise levels. Just get yourself a spectrum analyzer and a wide-bandwidth antenna (maybe a log periodic or something). Take some data points (or maybe just a picture of the full HF spectrum) with the system on, then with it off. Compare. This is much like the procedure used to test consumer electronic devices for FCC part 15 compliance (whether they be intentional or non-intentional radiators).
I see a lot of people badmouthing BPL or Amateur Radio over one-another. I'm an amateur radio operator, and I'd oppose BPL even if it didn't interfere with the amateur service (as some implementations don't: they notch out the amateur bands since the ARRL has been so vocal).
It really is a silly idea. Let's run MF/HF/VHF signals over this really long, unshielded wire to deliver internet to people's houses. Of course we can't actually get it to the house because of those pesky transformers, so we still need to retrofit our grid and use something else (like wifi) for the last 100 yards. Then there's that pesky issue of power lines being really bad transmission lines at those high frequencies (they're definately not constant impedence), so we'll have to throw a lot of power into those lines (at RF) to get the signal where we want it. What? It radiates? Hum, oh well.
The obvious solution is to string real transmission lines (like coax, twisted pair, or, obviously, fiber) along those poles (protected in some kind of harder casing) and underground. But that's expensive? Duh, retrofitting something meant to deliver huge amounts of energy at one frequency (50 or 60Hz, depending on your side of the pond) to deliver data at high rates of speed isn't going to be cheap. At least don't be half-assed about it.
Also, just so people know. The amateur service doesn't really have all the bandspace people make it out to have. Some bands are surprisingly small: the voice section of 17m, for example, is from 18.110MHz to 18.168MHz - only 58kHz of bandwidth, or enough for 20 single-sideband voice conversations if everyone plays *really* nice and lines up perfectly. There are giant posters like this one that show the major service to which each frequency band is allocated to in the US (many of which are also assigned internationally by ITU, at least down in HF). The first 3 rows (3kHz-30MHz) are the bands likely to be given problems by BPL. The amateur service is teal-green colored on that poster. Look for yourself how little is actually given to the service on many bands. 80m (3.5MHz) is about the only one that you're likely to even spot quickly below 30MHz!
A mathematical proof is nothing but a manner of convincing someone (other mathematicians) that what you assert is indeed correct, given the following presumably known, accepted as true, or otherwise previously proven "things". The whole point of a proof is that someone else knows wtf it is talking about.
I could assert that 2+2=4. You may believe me, but have I really proven it to you? Not yet, so you don't need to believe me. If I instead say that the the cardinality of the union of two disjoint sets, each of cardinality 2, is 4, then I've (sort of) showed you that 2+2=4, assuming you accept my definitions of disjoint sets, set union, and set cardinality (which presumably I've proven elsewhere, or taken from some other source). Now do you believe me that 2+2=4?
I could assert anything. You may or may not know if it's true. A proof is just something to back up my assertion and convince you that I'm right. Hence, if a proof is unintelligable, it's pretty darn worthless.
Yes, by local I mean "national". I guess it's true that in most countries there are many levels of government below the national government. It's all about scale...nations are local compared to worldwide :)
For the upper bands, the local governments have quite a bit of say in how thigns are alloted due to the fact that those signals just don't go very far beyond line of sight under normal circumstances. There are some exceptions that are dictated by the ITU and the US pays attention to those. These exceptions are mostly for research quiet zones (and those are pretty small), non geo-sync sats, etc.
The HF bands (which readily propagate around the world), VHF and lower UHF (which can propagate distances significantly beyond those you would expect) have some ITU regulations attached to them. The FCC does pay attention to these international regulations of the RF spectrum.
The US also has agreements regarding allocations up in the microwave ranges along its borders with other nations to avoid interference.
Depends on your operating environment. Stock Zaurii running Qtopia and things running OPIE will draw directly on the framebuffer as Qt/E sort of expects to. You most certainly can run X on an ipaq (and I believe a Zaurus too). My ipaq in fact runs X. I've done some crazy X forwards to it in the past (including Starcraft, running in Wine on my desktop).
There's no reason it shouldn't run on an X based desktop. I know it runs on ipaqs running Linux (which generally run X) and Zaurii, so there's no reason it shouldn't compile for x86 (or whatever floats your boat) and run on your Linux/BSD/Solaris/HP-UX/AIX/ desktop. Now, if you're running Windows, you're on your own (though that may work fine too).
Now be fair. The bad capacitors that you're referring to were caused by some shoddy manufacturer cutting corners (and a fair bit of industrial espionage gone wrong too, I've heard). In general, that was considered a product *failure*. True, there were some motherboard makers who refused to provide replacements (whom I, for one, will never buy from again), but on the whole, leaking electrolytic capactitors (at least over any reasonable term) is considered to be component failure. Capacitors are not considered user replacable, and certainly aren't considered disposable.
Also, I don't know about you, but my Li-Ions don't "last for a year or two". Sure, after a couple years they're not like they were at first, but neither is a Ni-Cd or Ni-MH, and you're forgetting that most battery types aren't rechargable at all. The world of batteries hasn't caught up with the uses of batteries yet. It's not like there's some other product on the market that's not "disposable" or that similar products in the past were more reliable. The only battery I can think of that handles recharge/discharge cycling better is good ol' Lead-Acid (like in your car), and I'm doubting you want to lug one of those around to power your PDA (they don't scale down to that size very well).
I agree, though, that Plasma TVs are silly. I personally like a good DLP for larger sizes or a direct view LCD or CRT in smaller sizes (depending on the use). Even projection CRT is still viable up at larger screen sizes (and, while they require continuous twiddling to keep a good picture, they generally don't fail completely in any reasonable term). Plasmas just don't cut it in my opinion. They're expensive and subject to burn-in. There's no real reason to buy a plasma unless you absolutely need to hang a large screen (bigger than a feasable direct view LCD) on your wall, in which case, like the batteries I mentioned before, there's no feasable alternative, so you have to accept the state of technology.
Now, hard drives that aren't rated for "continuous or *heavy duty* use" (emphasis mine) is silly. What exactly constitutes "heavy duty" use? I would say that basically any use of a hard drive is normal use. Continuous I could understand if the normal failure mode for hard drives wasn't the stress of power-on...
One hundred milli hertz? A whole whopping one cycle every 10 seconds?
:)
No, I'm guessing it wouldn't run well on that
Tyan isn't targeting you. Tyan is targeting people who want to build PC workstations. These are people who have uses for multiple gigabytes of RAM (think simulations) or PCI-X slots (SCSI RAID controllers). Tyan isn't really targeting PC gamers here. They're obviously trying to appeal to the market, but Tyan has traditionally gone for the workstation and low-end server crowd (people who do work with their computers) with their Thunder series.
Asus is generally the maker of boards in your target range. Check them out. Yes, they do charge a premium, but they make high quality motherboards in my experience.
<rant>
Gigabyte doesn't. I have a 7VTXH and it's a marvel of engineering badness. There's a finicky timing issue whenever all three DRAM slots are populated that I have yet to resolve (and yes, the RAM is on their approved list and is of generally high quality, and no, the RAM is not faulty). I had to ship it back to them no less than three times due to a bad flash chip. Once is acceptable (it didn't immediatley go bad and so could probably pass initial QA), but it would have been nice if they'd just replaced it or extensively tested it after reprogramming it. Also, fat lot of good their "dual BIOS" feature did; I still had a brick. If they'd not solder the damn chip to the board (socket it, folks), I could at least program it myself since I do have a flash programmer.
The board's ACPI is also a bit flakey, but being a desktop board of the age it is, I can live with that (it's good enough that I can usually get by with leaving ACPI enabled).
</rant>
Actually, Sony did that, just in Japan only. You most certainly can (or at least could, dunno now with the slim models) buy a "Sakura Pink" PS2. NTSC/J region only (though I'd probably find that more useful than my NTSC/UC). The PS2 was also available in white, and some sort of blue IIRC.
And there's the ARRL VHF sweepstakes this weekend. Should certainly be fun. 6m was open tonight (was hearing Florida in Indiana), but things may change over the weekend.
I'm not very familiar with VHF/UHF propagation modes. Anyone have any hints on what this may do to propagation on the VHF and up bands?
Hum, I also do a fair amount of RF work, but not normally A/V work. I was given the impression that component video was spec'd for like a 300-600 ohm characteristic impedance. If it's actually supposed 75 ohm at each end, then clearly 75 ohm coax is the way to go.
I really hate throwing adapters on everything. There's always insertion loss with putting adapters in the line. Obviously RCA connectors don't have constant impedance, but I would have thought it would be better to terminate it (carefully) into the connector that would actually be used, rather than throw adapters on everything. There are RCA connectors that are designed for coax, rather than simple parallel wires (ala speaker wire); the problem is finding one that actually fits on the end of a piece of RG-6/U. That cable is rather large stuff (not nearly as big as what I'm used to working with though, which is mostly LMR-400 Ultraflex and similar).
I'm certainly not going to buy Monster branded stuff. It's good, sure, but guaranteed to be overpriced. I can get very high quality adapters from a local distributor. He also sells real 75 ohm Amphenol BNC connectors, as well as off-brand ones if you're not willing to pay the premium (I usually am, if only so that I can look up all the measurements on amphenol's website), not just 50 ohm ones.
I was going to make a nice set of component cables out of RG-6/U. RG-6/U is pretty much the best coax that's reasonable to use for component video applications (the impedence is still low, but 75ohm coax is reasonable to acquire, things like 300 or 600 ohm coax are not).
The problem is, most RCA connectors won't fit on a piece of RG-6/U. BNC connectors will fit just fine, but neither my TV, nor my DVD player have BNC connectors. BNC connectors have advantages over RCA connectors, from both technical and use perspectives. From the user's point of view, they're nice because they lock on securely. From the technical point of view, they're nice because they can be had in a constant 75ohm impedence. This isn't of particular concern in this application (since it won't be matched to the source or load anyway), but it will cut down on the number of total abrupt impedence changes, resulting in less reflection.
I don't want to put BNC connectors on my cable only to have to change it to RCA connectors for my equipment. Adapters do exist (and can be had at a reasonable price, though not from Monster, since everything they sell is overpriced), but it's pointless if you can choose the connector in the first place.
I think I found a set of RCA connectors that will fit on my cable, but I need to get a micrometer out and measure to be sure. It'll be a tight fit.
One problem that (especially cheaper, and often very noticable on really cheap) DVD players have is noise on the black. My DVD player is a rather high quality (back when it was new) Sony that does OK (not progressive scan though). The picture is excellent, but there's noticable noise on the black levels on my 46" DLP, even using a rather high quality component connection (I haven't busted out the RG-6/U yet since I can't find good RCA connectors, why we're not using BNC is beyond me though).
With a digital signal, you won't have this noise problem, which may be due to the DACs on the DVD player (probably is), not just interference over the cable run. Good digital to analog conversion is a tough problem, especially at the higher bandwidths required for video signals (even at baseband). With digital TVs (like DLP) becoming popular, it makes sense to just skip that step, and save yourself the noise (and, in theory, cost - good DACs are expensive).
Part of the problem, especially with very low end MP3 players that use dedicated hardware decoding is that (to my knowledge) there is no integrated solution (I hate that word, but it's appropriate here) for decoding Vorbis in hardware.
There are a few chips for doing MP3 easily (I've actually got a couple of STA013s here that I've been meaning to make into an MP3 player very similar to this one, but using an 8051 or z80 instead of a PIC). I don't know of any like that for doing Vorbis.
Of course, this doesn't apply to systems decoding in software. There is a fixed point decoder for Vorbis available, so the lack of an FPU (common) isn't a problem (it was until about a year ago). Decoding Vorbis does require a little more CPU time than MP3, but it's not too big if you're already decoding in software, the problem is dedicated hardware decoders. There's no STA013V (or whatever) that will do Vorbis in a nice package like there are for MP3.
Well, let me decidely say that he does not work for Intel, and he knows way too much about Intel ARM chips, specifically the newer PXA series.
Another good thing to try is to get an older radio (yes, it will probably have tubes, the horror). I acquired a Heathkit DX-60B for $0. Yes, that's right, it was completely free (the person even dropped it off at the local club shack IIRC).
When I got it, it did at least turn on, but it wouldn't tune up at all. The electrolytic caps, being ~40-50 years old, were completely shot. Replacing those has restored it to almost 100% working order. The bias on the oscillator tube is still off by a few 100 volts, but that's just because the bias network resistors (carbon composition, and 10% tolerance at that) have drifted with age as well. Replacing those should get me back in shape (and the newer metal type resistors last a lot better too).
These rigs are quite user-servicable. They usually do require more maintaince than a newer rig may, but at least you can easily do it yourself using even the most crudely large of soldering guns.
The key is to find a good small time electronics distributor in your area. If you're in a semi-major city there's probably one somewhere nearby. Indianapolis, for example, has MAI Prime Parts (don't be fooled by their website trying to sell you Monster Cable, they actually sell real stuff too, not to mention that the Monster Cable is actually at a reasonable price). They're not always easy to locate since they don't do business with the "general public" as it were, but only because that's not their target market. Most are perfectly happy to sell you a capacitor, a few resistors, or a premade inductor or coil-form. MAI is really like a EE candy store. There's a whole isle of just capacitors, for example.
Yes, Radio Shack has certainly gone down hill. I've taken to calling them "cell-phone shack" recently, though they do still sell soldering irons. I should know, I just had to run out and get one to repair a blown keyboard fuse on a PC motherboard. Total cost for the soldering iron and solder (since I left mine at another location)? About $12.