Dan's Data letters #30

Publication date: 20-Feb-2003.
Last modified 03-Dec-2011.

 

Pullin' cable

I have a computer in the study, with a ATI All-In-Wonder 8500 and a Game Theater XP (along with DVD drive and MP3 collection of course). Sounds like a great start to a entertainment system. However, our TV and stereo are at the far end of the house. If I were to run audio and video cables through the attic, it would be about 100-150 feet. Can the composite video and 5.1 channel audio output from my computer make it that far? Or would I need an amp along the way? I tried a wireless AV transmitter system, but there's too many walls in the way to get a clear signal (plus, it only did two channel audio). Any recommendations on how to do this as cheaply as possible?

Tim

Answer:
Regular RG-59 coax, if that's what you're using for your composite video lead, will attenuate the video signal by something in the order of four decibels per hundred feet. 100 to 150 feet of the stuff may leave you with an unacceptably dark image; super-premium 75 ohm cable (RG-6, say) will be a bit better, but probably still too dark.

You don't need an amplifier in the middle of the cable, though - just at the start. Putting it at the start means you'll be amplifying the minimum amount of noise.

So run your cable, see what the picture looks like, and then see how you feel about dropping $US25 or so for a basic composite video amplifier from your local half-decent electronics store. Or, alternatively, run a different cable with lower loss - Category 5 ("Cat5") unshielded twisted pair (UTP) network cable is a popular choice. To make it work you'll have to put a "balun" transformer at either end for impedance matching, but once you've done that you can get very long composite video runs out of Cat5.

You shouldn't need any sort of booster for the audio cable, since you'll be connecting it to a pre-amp at the other end; you can just turn the volume up further and you should be fine. Mains hum can be an issue for long audio cable runs, though; you may well get noticeable 60Hz hum, if you just use coaxial cable for your audio. So, you guessed it, you can run that down Cat5 as well - and you probably won't need a balun for it, just a suitable adapter plug (Cat5 video and audio runs often use regular network cables with RJ45 connectors on each end).

Twisted pair cable is naturally noise-resistant, and ought to save you from having to mess around with grounded conduit and/or using a balanced line driver and three-wire-per-channel cable (see here for some info about balanced and unbalanced cables), assuming you're not running the audio cable right next to power conduit, over fluorescent light battens, et cetera.

If you want a Cat5 audio cable with RCA plugs on the end, it won't be an off-the-shelf item, but it's a trivial soldering job. It's running the darn wire through deity-forsaken pieces of house that's the annoying part.

Handy Hint: When running all of the cables you need, run some more that you don't. It's not likely to be much harder. The extras don't need any connectors on the ends; just some slack with a "Spare Cable #3" label will do. That way, if one of your in-use cables meets with disaster (and that disaster doesn't sever all of the others as well...), or if you decide to connect another gadget, you've got the wire already there and your Profanity Allowance need not be spent.

You'll actually be running more wires than you need if you use Cat5 anyway, as standard Cat5 cable has four pairs. You'll need to drag two Cat5 lines for 5.1 channel audio, which'll leave two pairs of the eight unused.

Oh, and make sure to use "plenum rated" cable, too. It's a bit more expensive, but if one part of it should (for instance) catch fire, it won't burn like a fuse through all of your walls.

 

Long wires

How long does a network cable have to be before some sort of signal amplification is needed??

Pete

Answer:
If you're talking about 10/100BaseT cable, there's no hard limit, but the generally accepted maximum is between 100 and 150 metres. Or a bit more, if you're using really high grade cable.

 

Further PS2 plugging

I have a Playstation 2 that I've been running through a video capture card on my PC to play on my monitor. Right now, it goes through the RCA input on my VCR, which connects (also through RCA) to the PC. This results in pretty poor picture quality - the smaller text in most games is a bit tough to read, and "motion blur" takes on a whole new meaning. I had figured that I'd just have to live with it, but now, I think I may be able to do better. I recently read somewhere that the PS2 can output signals at up to 1024x768... I think it was in a piece about the PS2 Linux kit. Anyway, I figured that if there's a way to pass a signal at that res to my monitor, it would greatly improve picture quality. I'm writing to you to see if you know the best way to accomplish that. From what I've seen, there's a few options:

1. S-Video connections: I know there are S-Video cables that replace the in-box RCA ones, and my video capture card has an S-Video input. I could still leave the VCR hooked to the RCA in, then switch between them in the capture-card viewing software. I don't think this is the best option for hi-res PS2 video, though. Is S-Video "higher resolution" than RCA, or just less noisy?

2. A VGA scan-doubler, like the Redant VGA Box. This appears to plug directly into the PS2 SCART output connector and generate a VGA signal by doubling the scan rate from about 15kHz to a bit over 30. It has a VGA pass-through, so you just flick a switch to choose between PC input and PS2. Sounds pretty good, but I don't know if the video quality would be any better than with S-Video. Should I even be worried about resolution per se, or just how it looks in the end?

3. A true VGA adapter. I've only seen one of these, made by Blaze, called the "Xploder" (bit of an ill omen for monitor compatibility, eh?). There's a Web site, but it seems to be a bit broken at the moment.

As near as I can tell, this is similar to whatever VGA dongle the PS2 Linux kit gives you, but a) has no pass-through, meaning I'd have to re-connect my monitor constantly, and b) only works for games that explicitly support hi-res, which isn't that many, to my understanding.

Ideally, I'd like to be able to either run the best possible signal to my capture card, or get a dongle of some sort that has the best possible picture quality for a given game, monitor pass-through so I don't have to re-plug anything once it's set up, and isn't terribly expensive.

James

Answer:
Yes, the PS2 can output 1024 by 768, but that fact won't help you, because, as you say, it won't do it with most games. You can get a better image than you're getting now, though. The VGA scan doubler's your best option, and ones with passthrough connectors, like the Redant one you suggest, will indeed save you from having to buy a separate switch-box.

The PS2 can connect to TVs with any kind of input - composite, Y/C, Y/Cb/Pb, Y/Cr/Pr, and sync-on-green RGB; that last one includes some but not all computer monitors (see here for a list). But the PS2 won't, normally, directly drive a PC monitor.

The PS2 graphics hardware can output various resolutions between 256 by 224 and 1280 by 1024, but a television can't clearly display anything better than about 640 by 480. Even super-spiffy sets just don't have the tube resolution to do it. That's why a quality 20 inch TV costs a third as much as a quality 21 inch computer monitor.

So, usually, the PS2 doesn't bother running in high resolution. Games are hard-coded to run in lower resolutions, which allows them to trade pixels-you-can't-clearly-see-on-a-TV for fancy effects and steady frame rate. See here.

"Scan doublers" or "upscan boxes" that convert a TV video signal of one flavour or another into a computer monitor VGA-type RGB signal - which is usually not sync-on-green, and which will therefore work with pretty much any monitor - can't put back image detail that wasn't there in the first place. But they're your best option when you're playing games, which typically don't have any sort of resolution control.

When you're using software that's in TV mode, the PS2 will be locked to a 15625Hz horizontal scan frequency for PAL video, or 15750Hz for NTSC models. That's exactly what you need for the 25 or 30 frame per second, 625 or 525 line displays of the two TV standards, but it's rubbish by computer standards. 1024 by 768 at 75Hz needs a 57600Hz horizontal scan frequency.

An upscan box just doubles lines and frames to get a higher frequency output. You may get a steadier picture with less obvious scanlines, but you don't get any more real resolution.

Upscan boxes are not at all the same as the "VGA Boxes" for the Sega Dreamcast; those bypass the Y/C or composite stage completely and let the Dreamcast, in theory at least, put a 1600 by 1200 image on a computer monitor that's as sharp as if it came from a PC.

S-Video is sharper than composite (what you're using now, with one RCA-plug lead for video), but it's still TV resolution.

I think the Blaze "Xploder" is actually a cheat CD, but they've got a VGA adapter as well. According to this review it uses extra software to raise the resolution of games, which sounds interesting, but I have no data of my own on it. And, as you say, their Web site's currently a one page wonder.

 

Killing George

I saw your review of the USB MP3 players. I own the "George" MP3 player and I think I have to warn you on this - don't format it using Windows format, because it will make the player useless. I think it erases the firmware. After formatting it the player won't power on.

The software included with George has a built-in format utility and it only formats in FAT16. I accidentally formatted mine without reading the manual. After formatting it, it won't turn on, and Windows won't detect the USB drive unless it's powered on.

Good thing it was still under warranty :).

Dennis

Answer:
I think you formatted the player to a different file system. I did format that player using Windows XP, which detected the filesystem in use as being FAT12. FAT12 is only supposed to allow a 16Mb maximum partition size, but it appeared to be the filesystem in use by the 64Mb "George" player, and the player worked fine after formatting, so go figure.

If your version of Windows thought the player was using a filesystem that it wasn't, or if you accidentally changed the filesystem yourself, then yes, you'd probably render the player unable to read its own memory. If Windows can still detect the mis-formatted drive then you ought to be able to reformat it with the correct filesystem; you might have to do it from the command line or via Disk Management (depending on your Windows flavour), though. If the thing can't turn on any more, though, then you have indeed painted yourself into a corner.

 

More Georgery

Four months ago I became the proud owner of a "George" MP3 player, though this one was called a Duex Mp-304. My player is identical in size, shape and colour to your George. I was happy with my purchase because it met all my needs, except for being Plug and Play without drivers. However this was no problem as I was assured by the distributor (Unitech) that new firmware would be released to update the player. My satisfaction in the product turned to dissapointment when no update was released for my player and Unitech ignored my emails.

What I want to request of you is to ask your contact at SigmaTel whether a firmware update will be released to the public for the MP3 players that have the older firmware. Is it possible to update these players?

Mark

Answer:
The SigmaTel guy who e-mailed me, and whose contributions I mention in the review, expressly mentioned to me that they don't do firmware updates for MP3 players that use their chips. You have to talk to the company that made the MP3 player.

I speculated about which company would be less likely to do a darn thing about this - the Taiwanese manufacturer with a half-broken Web site that makes "George", or Creative, who make the not-so-good MuVo. I concluded that they're about equal.

So yes, it's possible to update the firmware, but you'll probably never be able to. No update is available, because there's really nothing much in it for the manufacturers - if the player already does what it's meant to do, releasing a firmware updater has no real upside for them, beyond vague goodwill from the relatively few geeks who're going to be bothered using it. That goodwill will be more than outweighed by the support annoyances from people who yanked the cable halfway through the update procedure, and turned their MP3 player into a Christmas tree decoration.

 

Blinded by the... monitor?

I just read your review of the Samsung LCD 512B and I bought it. It's a nice monitor, but it is so bright! Even if I set brightness and contrast to zero, the display is still really bright.

I've never used an LCD before. When I use a CRT the display will show dark/black when I make brightness zero. I thought it would be the same with LCD.

Is this normal?

Joels

Answer:
I don't know exactly how bright "really bright" is, but yes, LCDs can't display a proper black. I mentioned as much in my review of the 152B; some of the light from the backlight will always leak through the LCD panel, no matter how hard it tries to block it.

Is it normal? That depends on how bad it is. Maybe the monitor has a defect that stops it from turning its pixels as black as it should be able to; maybe it's just normal LCD light leakage, which you're not used to seeing. Sorry, but I really couldn't say without looking at the thing.

 

Brrrr...

I've read many articles on how to cool down your PC, and that's great for the summer, but in the dead of winter in PEI, Canada it's -19C outside right now, with a windchill of -31C.

I'm cold! What's the best way to maximize heat output without frying my computer?

TJ

Answer:
Wrap up warm, go to your nearest electrical appliance store, and buy any old electric heater.

A PC produces heat as a byproduct, and is exactly as efficient at doing it as a regular resistive electric heater (which is to say, not as cost-effective as various other heating technologies, given reasonable prices for piped gas, reverse cycle air conditioning, and the like).

Electric heaters are all, by definition, 100% efficient; all of the power that goes into an electrical appliance must eventually end up as heat, thanks to the wonders of entropy. And practically all of the power that goes into an electric heater is converted into heat directly and immediately and usefully. Only a little bit ends up as sound (for a fan heater) or light (for a radiant heater) or air movement (convection and/or fan breeze).

PCs are basically just funny shaped fan heaters, from an outside-the-box thermal standpoint, but they're not very powerful. A stacked PC sucking down 300 watts continuously is only going to give you 300 watts of room warming, and if it's in the usual configuration it'll be blowing its warm air out the back of the case at the wall, not towards you. A CRT monitor will be good for maybe another hundred watts, but its heat just convects straight out the top towards the ceiling.

For comparison, lots of dicky little fan heaters have 1500 watt output, and lots of other electric heaters have similar or higher ratings. A PC or three buzzing away will add a bit more, and will do much more interesting things with the electricity before it becomes heat. But if you want more heat than the PC outputs, just get a heater.

 

Scanner quest

I've got a friend (yeah, honest, I do) who does a lot of library research, and at the moment they just photocopy anything they want to read later (or use for research), but that is costly, wasteful and just so last millennium. They just bought a laptop (for use in said libraries and other localities) and they've been using a flatbed scanner at home for sometime to store and OCR documents. So after explaining the hassle with photocopying and then scanning at home, I said the obvious thing to do would be to get a hand held scanner, and i offered to find them one!

D'oh.

In days of yore all the best scanners (OK, not best, but the only ones I could dream of affording) were hand held. They had the advantage that you could scan big books and walls and stuff with them, which is cool. But after looking around online the only current model I could find was this one which seems to force feed the paper, meaning books might lose pages to it, which is not really the done thing in a library.

So then I thought, eBay! But all the models on there come with an ISA card, which ain't so good for a laptop.

Do you have any ideas? She can't be the only person in the world for whom a flatbed ain't the best idea.

Richard

Answer:
Yup, hand scanners are pretty much extinct.

The reason why hand scanners died out is that they were, as you may recall if you ever tried one, a pain to use. It was difficult to get a straight scan out of them; despite their side guide wheels, hand wobble and poor indexing of wheel revolutions to scan timing gave all sorts of awful stretch and squish and skew problems. Hand scanners also couldn't scan the whole width of larger pages in one go, so you had to do it in two stripes and then "stitch" them together. Even without that step, many of them were also pretty darn slow.

There are now better options.

The fastest and most compact one is a digital camera. A 2000-by-1500-ish "3 megapixel" camera can manage adequate dots per inch for OCR on A4 targets, assuming you're not dealing with extremely small text. Since it's just black and white text, you can shoot in colour (if there's no smaller greyscale image mode option available), then crank the heck out of the contrast in an image editor later, and end up with something that OCRs pretty well.

Some people pump through amazing numbers of pages for OCR, using consumer digital cameras and a couple of cheap accessories - a copy stand and a dirt cheap tabletop tripod will do. With those, the camera and subject can easily be lined up well, and they'll stay still enough relative to each other that you can use long-ish exposures to get a good bright image in even subdued library lighting (flash shots won't make you popular in a library, and if you're shooting glossy paper then on-camera flash won't work anyway).

With a setup like this you can just flip the page and shoot again, and again, and again. If you're only shooting the occasional page, though, then just making like a secret agent - putting the book on a table and hand-holding the camera - will be OK, provided there's enough light.

If you want a scanner, there are sheetfed scanners that come apart; the scan head part can be used like a big hand scanner for subjects that can't be fed through the slot. They're not too easy to find any more, but they pop up on eBay now and then for cheap. You'd want one with a parallel port interface, not some awful custom ISA card that you (obviously) can't use with a laptop, and you'd also want to make sure that drivers exist for the OS you're running on the laptop.

Also, there are various super-slimline USB-powered letter-size flatbed scanners that aren't a great deal bulkier than a laptop. You can fit a laptop and one of those scanners in an unremarkable backpack, and as long as you remember to park the scan head and click the lock switch before you move the scanner, it ought to live for a long time.

There are also the HP Capshare scanners, which apparently were quite good (you'd want 'em to be, for $US500; they're standalone devices with their own little screen - see here), but they don't make them any more. There are a few on eBay, at no discount at all.

Personally, I'd go for the digital camera option.

If you want to ask me a question, feel free - but please read this and this first.

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