flee@gnh-applesauce.cts.com (FRANK LEE) (01/22/91)
About writing software in assembly to stretch a machine's abilities, you're right. In days long past, people were able to: achieve four-voice sound on an Apple II+/48k/1.023MHz through assembly alone! do advanced vector animation... etc.... About aliasing as it applies to A/D conversion, there's a rule in information theory (Nyquist Theorem) that your sampling rate must be GREATER than twice the highest frequency you intend to sample, else you'll get bad results. There are two ways of dealing with it. One is to use a low-pass filter with a cut-off at or slightly below 1/2 your sampling frequency. Another is to dither the audio with pink noise (i.e. noise whose intensity decreases as frequency increases). A construction article for just such a device appeared in Popular Elctronics, April 1990, that'll dither any analog input. INET: flee@gnh-applesauce.cts.com UUCP: crash!pnet01!gnh-applesauce!flee ARPA: crash!pnet01!gnh-applesauce!flee@nosc.mil
SHBOUM@MACALSTR.EDU (01/24/91)
Ok, I'd like to thank everyone about the help on informing me what the
concept of aliasing is, but now I've got another question. From the information
concept of aliasing is, but now I've got another question. From the general
concencious, the process of aliasing needs a good filter. Which of the sound
cards for the IIGS have good filters, or better yet, which is the best card
cards for the IIGS have good filters, or better yet, which is the best sound
digitizer card made for the IIGS to date? I know of the add on to the
Supersonic sound card, Future Sound, Sonic Blaster, and Audio Animator
Supersonic sound card, Future Sound, Sonic Blaster, and Audio Animator cards
and can recall there being a few others made so far. However, since I'm
interested in getting one soon, I'd like to know which is the best card to get.
{Yes, I know a couple of the cards are discontinued, or who's supplier has
gone bankrupt...} Thanks...
| Hal Bouma | Send e-mail to: SHBOUM@MACALSTR.EDU
| Macalester College
| Macalester College | GEnie: H.BOUMA