Theo Verelst Local Diary Page 65

I've ditched the usual header for the moment, I think it doesn't help much anyhow.
This page is copyrighted by me, and may be read and transfered by any means only as a whole and including the references to me. I guess thats normal, the writer can chose that of course, maybe I´ll make some creative commons stuff one day, of course I have made Free and Open Source software and even hardware designs available!

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  Feb, 2009

More work still, Theo, isn't there ever an end to it? Donno, I guess some things are still interesting in my opinion.

More waves on the Bwise canvas

This is a 2 times 10 sine/exponent block sound generator algorithm made with bwise, maxima, my own sound program and some tcl helper routines. The sineexp block contains a sine generator with frequency (f) and modulation input (e, maybe I should take the derivative, but that would be easy with maxima!) which is multitplied by a natural 'e' based exponent with exponent -t*e and  two amplitude modulation inputs (a1, a2):

   (download loadable bwise canvas file, note the scope doesn't completely load, the rest will work)

In this example the frequencies of the blocks are per column integer harmonics with a slight , increasing detune for higher harmonics, for both columns the other direction (up/down). The components in the one column are made stronger for softly played notes, and also shorter, the other column is heard when notes are played louder, and has longer decay time.

Also the spectra are different, and there are two cross column FM modulations between the first in the one and between the third in the opposite direction. The resulting sound can be heared in a short musical tryout here:

 wav        24 bit mone wav example, 4MB
 t.mp3     192 kbps
 tl.mp3    48   kbps

The oscilogram in the small window above is accurate for the first 170 samples of notes played at 440 herz with velocity equal to 1/2 (64 in midi code) and was generated by using maxima to compute 170 values based in all non-floating point input! Similarly, the below larger graph is 2000 samples computed and eventually converted to floating point by executing in Bwise :

canvas .g.c
pack .g.c -expand y -fill both
time {set r [domaxima float(makelist(subst(y/44100,x,subst((1/4),v,${mult11.out})),y,0,2000))]}
.g.c create line 0 500 2000 500 -fill green
set o {} ; set n 0 ; foreach i [split [string range $r 1 end-1] ,] { append o "$n [expr 500-3000*$i] " ; incr n}
.g.c create line $o -fill red

The Cuda Profiler on Fedora 10/64

I used the profiler of 2.1 on the 2.1 smokeparticle example:

Radio Controlled HD

I got a 25 euro (really, no joke) RC car model from an electronics store to play with, so that I can put the HD cam on top and make some nice drive-through shots. With the lid and electronics shield of:

The little PCB with small black blob in the circle in the middle is probably the control chip, not much electronics needed around it!

The first day the socket transformer seems to have given up, so for the battery pack (yellow on the right, already worth a part of the 25) I made an improvised current source charger circuit, with a 50 Watts transformer (left) a heavy rectifier and Elco, and a current circuit based on a bike headlight in the source circuit of a power FET (2) with it's gate controlled by potmeter (1). Charges up to 450 mA into any voltage between 0 (actually) and about 25 volts, which works good, it appears, the car runs fine.

In fact it is quite good, I tried it on blacktop and it can go quite  speed, control is reasonable, and it is fairly well built, with suspension (but no parallel guided wheel arms) and a differential.

So I fitted the HD camera on top of the soft pad above, kept the throttle under control and made some film, of which a few small shots here:

In fact al pictures where in not so light and of course quite in motion environment!

Household pictures

A big plant, not too expensive, seems to give off oxygen nicely and makes the corner look more dressed up.

The setup I made the above sounds with:

The pond frozen! Actually it has been frozen for like 10cm or more some weeks ago.

Test pictures:

Actually basically a snapshot, but I found the light effect on top great, that is a fairly expensive 20 Watts (100W equivalent) reflector saving-light, which as only a few lights do gives a nice bundle and complexion of light. and the picture shows a nice 70s style TV spot effect.