ScottAW

I think both you and I need a life... (my post similar to yours, except mechanical-based)

Ron_C

Not too sure why 90% of the answers are relating to television sets, and video games.

James R.

so everything you see is essentially part of a moving average and not the result of X number of discrete samples per'se...the eye is an analog system and there is a time constant or decay time for an image to fully fade away.

This moving average is often called a low pass filter...meaning things which have a low instantaneous rate of change will pass through...but those which vary to quickly will be attenuated. In the digital audio and video world this type of thing is called an anti-aliasing fitler...a device which basically limits the bandwidth of an input signal so that it does not exceed 0.5 times the sampling rate...if you violate this you will have to deal with the aliases. In video this shows up as staircase and other visual anomolies...in audio it shows up as discrete tones which are related to the sampling frequency and how many Hz your input signal was above it...so for a 48kHz sampling rate...if you put in a signal which is 30kHz you should see a nasty alias at 24kHz-((30kHz-(48kHz/2)) or 18kHz it sounds like crap when this happens...you get whistles and birdies.

Regards,

James R.

2001 A4 1.8TQMSXP (Brakes After Feb 10th, AWE Stainless Steel Lines, Oettinger Pedal Set + Dead, Oettinger RE's 17x8, Yoko AVS Sports 225/45/R17, European Xenon Housings, Bailey BPV & RS4 Grill)

EdP

or you figure you'll need to post this at SOME time, and had it in a text file for just such an occasion... :b

James R.

I think I pretty much kicked down the goods on that one Ed...read my post

Bryce

Good post...I'm supposed to be studing for a Physics exam tomorrow. aarugh.

Bobby Kinstle

It's easier to express it in terms we all know without getting into human eye biology

EdP

I did. I responded

Bryce

So Nick- Have we throughly confused you yet?

James R.

it's a total pita to try and draw a schematic from a PCB which you have in hand...thank god it's only a single layer board. I need more info on how to charge the Nokia batteries...they use a switching buck convertor to drop the voltage down from 13.8 to whatever the battery wants...but then you have to vary the duty cycle of the charging pulses as a function of the current drawn...and at some point you need to make the determination that the battery is fully charged and to stop trying to charge it...I've never done a battery charger design other than linear trickle types...which may work for this as well...there would certainly be less noise (read none), but you have lower thermal efficiency as a result...which we can fix with a heatsink...no biggie. Ultimately I'd like to use a switching buck conveter because of the high efficiency...it's far less likely to tax the car battery while you charge / talk with the engine off etc etc, but it must be quiet...which is currently the source of the noise issue you complained about.

Anyhow I'll figure it out...btw - this is not the nokia cark board...but an aftermarket charger...

Regards,

James R.

2001 A4 1.8TQMSXP (Brakes After Feb 10th, AWE Stainless Steel Lines, Oettinger Pedal Set + Dead, Oettinger RE's 17x8, Yoko AVS Sports 225/45/R17, European Xenon Housings, Bailey BPV & RS4 Grill)