Theo Verelst Local Diary Page 16


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Tue Jan 20 2003   14:14

 
     Sunrise in a park in Amsterdam city

Reproduced without explicit permission from an electronics magazine:



Interesting that the modern LiIon cells (they must be al little over penlight size) can do so much. 3.6 Sec for 0-90 KM/H or so is quite fast, on a 900 kilogram car I'd say normally you'd need a few hundred horsepower...

In sunny countries or on sunny days, how long would it take to fill her up using solar cells the size of your roof? Pretty long. Pretty long, probably. A field full of them would be better. Regular cell panels can yield about a hundred watts per square meter in sunlight, and immedeately 1/10th and less outside direct sunlight. I just saw a nasa page where almost a double as effective a solar panel is described as coming from the helios solar powered high altitude model plane I mentioned some years ago. Of course that was while browsing for the mars lander latest pictures and data, which btw can also be at certain time be seen discussed live over the internet (if you have a access download bandwidth of 150 kb/s at reasonable quality) using realplayer from here.


One can always use a generator, as long as there is fossile fuel and as long as it doesn't get stolen...

    (see also my contributions to photo.net)


String Simulation, still

Years ago, under not so nice circumstances, I started the design and software prototyping of a physical string simulator, with the intention of audio synthesis. I'm now preparing an article on the latest version (of some time ago already) of the String Simulator Synthesis Program, It's not at all ready, and not published anywhere else than on the web, but I will present a short talk on the subject in februari at FOSDEM in Brussels, an (not so small) open software conference in Belgium, close to the European Union headquarters, where I read there are demonstrations agains adverse software patent laws.

See the schedule here.

Art photo

I made this picture composition based on a photo from an actual painting and three girls (whom I don't know) sitting in from of it in centre pompidou in Paris.

Most other parts are also based on photos I made myself, for instance the lights on top, which were blended in as technical fun, the statue which is from on top the well of the inner court (binnenhof) of the dutch gourvernment site, the rose as a part of a specially lit flower picture I made in mid france ( processed into a blue rose ) , of course the arc de triomf on the right also from paris, a special spanish whine jug with red substance taken from household stuff, a goose body and a sign from in front of a church in Köln (germany) and some people I supposedly worked with/for who didn't pay me decently for a lot of work and generaly treated me so like crap in the end I didn't even bother seeing them about it. New age inspired fascism is one tough religion to battle, and some probably will never learn. Or are simply not willing/cut out to ever become reasonable citizens.



Click the image to go to the photo.net contribution, see also their (not from me) pictures of the week.


I put a comment on the site of a groep of dutch wanting to 'renew' the only reasonable remaining dutch political party, called D66, which sounded so new-agey I though I'd have to at least make clear I don't agree: here.

The regular site is fine enough, though of course there too there are weird anti american sentiments and one of the euro women I don't think I can agree with at all,but eh, what are politics for. I put stuff on the forum already more than a little while ago (under my own name), worth a read, but Jeez, the level of discussion and thinking in this country... Lucky this isn't germany, and the year isn't '39.

Quality Audio in modern times

One of my earlier, though not earliest, audiophile top band/artist influences was the english rock band Queen, of course through their top scoring chart hits, but also I had some albums, or at least had them on high quality tape, and I used to play them a lot. In around '80 that would be while doing homework (not always recommended) and probably pretty soon on my 2x75 Watt RMS self made amplifier and speakers, though maybe at first on an old 2x4 wat tube (...) amplifier.

These kinds of albums and bands, like led zeppelin, the eagles, even fleedwood mac (which I had only later on) of course were high quality and high level art level, not famous for nothing. So it is worth quoting this song again from the famous queen album 'A Night At The Opera', which also contains 'Bohemian Raphsody', which is about the year 39, when the nazis where using the power they obtained in germany to invade their neighbouring countries, in a totalitarian, violent cruel and absolutely brutal way. Why? Or: how come? Because people believed in the lies from the biggest liar of them all and his servants, and didn't want to understand they should listen to the prophets send by God (see the 'prophet song' on the same album) which don't delude you to believe the new-age like crap which make you give up everything worth while for some 'grrrrreat battle' into a millenium you wouldn't want to live in in your right mind even if you and your peers would get world dominion.
'39  by Qeen

In the year of '39 assembled here the volunteers
In the days when the lands were few
Here the ship sailed out into the blue and sunny morn
Sweetest sign ever seen

And the night followed day
And the story tellers say
That the score brave souls inside
For many a lonely day sailed across the milky seas
Ne'er looked back, never feared, never cried

Don't you hear my call though you're many years away
Don't you hear me calling you
Write your letters in the sand
For the day I take your hand
In the land that our grandchildren knew

Aah, aah, aah, aah

In the year of '39 came a ship in from the blue
The volunteers came home that day
And they bring good news of a world so newly born
Though their hearts so heavily weigh
For the earth is old and grey, little darling we'll away
But my love this cannot be
Oh so many years have gone though I'm older but a year
Your mother's eyes from your eyes cry to me

Don't you hear my call though you're many years away
Don't you hear me calling you
Write your letters in the sand for the day I take your hand
In the land that our grandchildren knew

Don't you hear my call though you're many years away
Don't you hear me calling you
All your letters in the sand cannot heal me like your hand

For my life
Still ahead
Pity me

In the time I heard the song regularly (how many twice 45 minutes tapes go between return from school and diner, and between diner and TV? it varied), it was considered high-end material, and also the audio quality was pretty high, even though I think the album was recorded still in the seventies. In the time when people and artists had an interest in making also big studio efforts to give their project extra tracks, special sounds, high audio quality through hard work, and a lot of instruments rendered to sound good on a decent HiFi system. Which at the time weren't gadgedized or monopolized (much) and therefore still understood that foremost one could strife for uncolored reproduction, making it possible to listen to various kinds of music, all with their own sound palette and impressions.

Queen at the time was one of the traditional instuments bands, though electrical guitar isn't that traditional, I remember reading 'no synthesizers were used on this album'... Later that changed, but 'A night at the opera' in this song even features acoustical guitar, a whole array of varying drums and percussion, and as I said excels in its use of the studio equipment from that time, such that most modern music could learn a lot from it in many ways. To begin with my making something which actually sounds good and interesting at all, and preferably where that is used for a good or interesting purpose, such as a good song.

These songs all qualify, and are therefore completely worth listening to in this time, and seriously, on a decent stereo system they sound better than most all crap of these days, where even without mpeg compression detailing, stereo image, sonic design of such things can probably be spelled by the producers, but are virtually absent for anything up to these levels. Degeneration, not evolution, getting old verelst? Not that much, though of course I'm hardly 19, but seriously, there's contemporary music that I like, too, progressive music (like jazz/fusion) of which even the basics aren't touched by modern popular artists. And house-like music per se, I mean seriously...

When boys and girls were taught that elvis, the rolling stones, the beatles and who else were nearly the devil incarnate, that wasn't because they didn't know their way with the buttons on the drum computer well enough, it was because their music rocked or made young people expecially realize there were (much) better things than nazi march rythms or gregorian chant sh*t, as long as you have a moderately open mind and are willing to learn quality and about a better life, or at least some honesty.

I wouldn't like to break down all the obviously not intended to rule the world modern clips just like that, but seriously there is a major difference between lets say 'le freak' and somthing called modern R&B. When Chuck ('Roll over Beethoven'- Berry) wanted 'a shot of  R and B' I'm sure he didn't mean some colored fellow humans who might better have not learned indeed to hit the buttons on a drum computer equivalent, and show it.

Maybe some motown stuff, maybe he'd have liked even some (Jimi) Hendrix, with or without a drug (use) problem, sex outside marriage issues, freedom and free information using content, satanist and affeliates bashing attitude, and I'm sure many youngsters, even when not an extreme musician, would agree. I mean seriously, the 70's were nicer than the clinton administration (what a term), period. And the belief in the 'brave new world', seriously, I gotta puke.

Which is easy to say maybe, or lets say detached, so lets break the rules a little and see what a song like '39 sounds like for those who may not find it easy to go to a record store and buy it blind (which is no risk, even if only to hear freddy and friends on more than just the rapsody) or borrow it from a CD library (as I did some time ago...) and who after normal modern modes want instant one click away gratification of the urge hopefully raised by this paragraph.

That illegal? Possibly, don't know, cdnow.com (which was MUCH MORE fun some years ago) has a total of a few minutes sample per album, so why couldn't I. Maybe you could share some of your favority music, too. Anyhow, wouldn't want to run into some heavy metal dude after that, of course... Oh no, I sort of covered one of their songs in the studio, THAT is permitted!

Anyhow, all those mpeg hunters or napster adapts should also realize that at least in certain ways they may not know what they are missing, I tried with the Nero mp3PRO encoder to make some versions of the above song, and quite frankly even higher quality mpeg simply suck to f* much to do anything much with. No detailing, no stereo image worth mentioning (except the sickening 'listen to this, it actually has 45 degrees left and right components which chorus along a bit' mpeg fashion), no impules left of any fun, no serious high frequency content, a music impression, that all you can decently get from it, not a decent hifi experience.

Here are the various versions I made, IF some queen guy drops a mail or leaves a server message, I guess I'll gladly take them down.

  queen_39hq.mp3  (3.2 MByte) High Quality variable bit rate encoding
  queen_39lq.mp3   (1.5 MByte) Low Q idem
  queen_39vlq.mp3  (1.4 MByte) real time analog modem quality, fixed bitrate

It all sucks. Nothing fun. Don't know what I'm talking about? Hook up your stereo (the bigger the better, modern usually is better, too) to you soundcard (a AC '97 sound chip will do for the impression) put it up sort of loud (not distorting), place your speaker in a 60 degree angle in front of you, a bit off the ground, at least some space away from back and side walls, sit in the one corner of the equal sided triange (just as far away from either speaker as the speakers are placed apart, possible even make sure the front panel of the speaker is straightly perpendicular with lines to your both ears, and play this piece, which is dubbed (double) acoustical guitar from the last part of the song, without compression ( a wav file, you could even burn it on a CD RW for trying in a CD player), you probably would have to download it first (right mouse button, save as on the link) because I don't think the server in upload direction is up to the full speed data rate.

  queen_39end_nocompr.wav (1.7 MByte) 16 bits 44.1 kHz uncompressed CD quality

Now that is something else.

Are there technical / scientific reasons why such experiments sound better? Hah! Of course! Hundreds, probably.
Which I migh go into in due time.
And of course I'm not suggesting there is no fun in hearing a mpeg on headphones or completely misplaced multimedia speakers, absolutely not. But you don't want mother in? Try it the way I wrote.

If you want the last example to subside without getting cut-off more neatly and pleasantly, and the next song (sweet lady in more than moderately heavy rock form) to kick in nicely: buy the album. I'm sure some antiquariate has it. Just joking, all normal record stores run fair amounts of copies of this kind of music. Belief me, not all new is better.

More electronics hardware work

It's worth it. The USB based AD DA converter (16 bits 44.1 - 96 at least kHz) of good quality of the previous diary page needs to be fitted with a anti-aliasing filter (and a little signal boost) to become what it should be, so I added another piece of circuit board on which I placed a modern opamp with the necessary filters:




Looks nice and not in straight-jacket, its just a first try prototype, and as it goes with sensitive/ accurate / fast electronics, it isn't yet perfect: it hums a bit (easy: it needs shielding), it noises in one channel (it might at the momen even, ehr, oscilate), and it has to much disturbance in the signal (noise, clearly feeding through from the digital parts of the chip, which normally must be stopped by electronic means missing from this setup).

But as far as it does work it is of course taking the sampling frequency (super sonic) out, deminishing the audio range distortion form the interference products with high frequency oversampling digital filter residues.



The above is the filter print with a OPA2353 in this case from Texas Instruments:

   

The components are for a prepared PCB and project for this USB DA and this filter, for which some high quality components were picked, such as the block capacitors. The filter must filter out mainly a near comb filter shaped spectrum of noise shaping products at -60dB I seem to remember quite a bit above 20 kHz, which the 3d order filter should do up to the point of 90 dB overall signal to noise ratio, when this output signal is fed back into the AD and analyzed. That is not bad. Not bad at all.

Maybe I need to just add a better supply de-coupling capacitor, for the first time in my life last year I read Elco capacitor specifications. Usually that's just a value and a max voltage, size and radial/axial, but no, there is of course a major inductance, which is the reason for the need for a small parallel non-electrolitical capacitor, a internal resistance, a measure for its quality, and even a life span, it can take so much charge/current going in and out for instance in a rectifier, and then it starts to wear out. It could even explode, as I know from experience, though usually that is the result of some error, for instance connecting it up the wrong way around.

Computer internals

I was doing a little job on a computer, and thought I'd take some pictures, nothing was broken before, during, or after the operation, I wanted to check some things out, and basically clean the machine up, because it gathers dust after some time.

  
         The inside after lifting the top
         with the keyboard connect cable still connected

  
         The lid with the display taken apart and disconnected
         but with the wireless antenna still holding pieces linked
         double fans and copper heat conductors clearly visible

  
        A very strange (for me as electronicist) device
       completely on top of the lid at the end of
       the wireless antenna wires

Wireless adventures ?

Well, in the sense that I got the chance to play around with some well functioning wireless parts, in the 802 sense that is, 11 megabits per second works fine over a number of tens of meters with not too much obstruction with standard available materials / cards.

Kind of fun to link downstairs to inside a car and find things still work. I even made lights go on and off over a tcl web server (using the parallel port stuff I'll describe, and in that case a power FET 12Volt halogen drive), from outside. The metal can get in the way of course, I think in that case the connection speed suffers.

It is not so easy to make the wireless connection thing work, even on XP which should make such things easy for normal consumers. Pretty impossible, I'd say, without some aid or good (usually absent) manual pages or guidelines, to get two random wireless parties talking together decently.

But then again, getting a local ether or firewire net practically operational isn't that straightforward either. I guess the firewire inter-machine link is in practice maybe even the simples. And the fastest. Kind of fun to blaze tens of megabytes per second effectively over such a single small wire.

Ethernet with at least 100Mb/s is practically usefull. I didn't use much window file sharing, but my own pcom, and I tested X window remote sessions on top of a normal home windows XP with cygwin added, which works fine enough when you know what you're doing, also to a (free !) linux (Redhat 9.0 is the latest I made tick). And a web server works easy, too. Of course the eternal internet connection being usually the main reason for wanting network connectivity, before I could set that up reliably and remove it again., and adapt to different circumstances, some time was wasted.

In short, the non-server machine must at times cycle through their startup to make connections setup automatically smoothly, while reconnecting is possible, and the switching between wire and wireless local networks is not smoothly possible, though with care, one only needs to switch the unused one off at the server, and then reastablish a 'sharing' option for the internet connection, directed to the right subnet. That also makes the local IP names reasonable, starting with 192.168 . Most other hopes for flexibility are useless. Not exactly 'put it on and it all works' no sir. Though that situation can be achieved after setting all up right, is my experience, than the non-server can simply be switched on and: voila, a wireless and internet connection work straight away, which is in itself cool when that works.

Be carefull with the 30milliwatts I'd say, I don't like taking a computer on my lap where right at a very strategical position those 2.4 Gigaherz electromagnetical radiation patterns start their journey to find the base station or other station... And of course there is direction sensitivity of the communicating parts.

Adventure isn't realy the word I'd use for the whole things' operation in general as I could test it, making a connection set up is doable enough, but not when you don't know the various options enough and need to search them out yourself. Also the reestablishing of a connection and the picking up after errors, also for multimedia (heavy bandwidth, like megabytes per seconds effectively) is not always good, the various layers in the connection tend to make it slow and the measurements for instance of signal strength a là windows: not exactly reliable at all times. When you know the various ins and out of a system and XP (mater of not having all drivers for Linux, unfortunately) it seems possible to repeatably set things up and let them work.

The other day I was reading about what are called cantennas, wireless directional antennas based on tin cans or pringles containers, and even juice packages with conducting aluminiom foil. That a fun adventure to try, though I must admit I'm still trying to read in on (cheap ?) parabolic (dish) antennas to do the most decent (and possibly dangerous or illegal) job of directing a wireless lan signal and its reception. I've read about tens of miles and more of possible free air distance that way, which is interesting: go to a nice spot in the woods or park, direct some dishes: and work on the internet and such. Probably illegal, at least in the US the fcc in principle forbids unofficially admitted antennas. But fun, no doubt, and the amount of power from the lan cards normally at least isn't extreme.

On fosdem, there is also a lightning talk about wireless mesh routing, with some cantenna's (AND DRIVERS FOR THE CORRECT OPERATING SYSTEMS... oops, got a bit carried awat here, it just happens to be true that I can't use wireless and adsl materials on linux for that reason at certain essential points) and some (a)dsl's here and there a whole neighbourhood can be available for wireless internet access at low price, and even larger distances could be covered for free and quite efficiently as long as there are some people with 'on' computers and lan cards. Fun. Worth it. Get rid of the stupid phone company fees and overhead and closedness. 1 Mega sms per second, please, preferably for almost free. Yeah, right.

I saw some fun and also some cool pictures on the web (for instance a 'slot' aluminium antenna for microwaves) but I don't have them here, maybe I'll have them later. It would seem fun to try out a directional antenna, at some point, for instance to create a medium distance link, and to once again (I had a (very low power) 3 meter transmitter hobby already in highschool) have more hands on experience with high frequency use when opportunity is available.

I guess I'll be reading here:

   http://www.qsl.net/n1bwt/contents.htm

after all, I scored a straight A (A+) for a not so basic physics course on EM fields during my study...

My wave simulator might even come in handy, but currently it more supposed to be fun enough.

The antenna signal path in the photos above is strange, 2 wires come from the wireless card in the bottom part of the machine, the bend through a 5 mm diameter bended arc in metal, pass to the lid, are buried in conduction foil to the upper rim, where the are connected with the strange devices. Huh? Two unshielded wires next to eachother? Beats me.