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(TI-58/59) Digital Filters (II & III)
06-21-2020, 08:45 PM
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(TI-58/59) Digital Filters (II & III)
extract from Digital Filters II, dB Magazine, OCT 1982, pages 12-18

"  Most of the audio engineering community learns the art of design in the laboratory. We all remember our first analog filter as a simple resistor-capacitor low pass filter driven with an oscillator and measured with a meter. The discussions on digital filters have, in contrast, tended to the abstract. Perhaps then, it is time to do a laboratory experiment. Since very few of us have programmable signal processing equipment with the required software development systems, we will choose a programmable calculator as our laboratory tool. Like the signal processor, the calculator can be programmed. The difference is only a matter of speed and input mechanism. Nevertheless, we can build filters with the calculator. This tool also allows us to illustrate the art of programming a signal processor. Any programmable calculator will do for the following examples but the illustrations will be based on the TI-58/59.
The first example will be a ten-point transversal filter …

With a little more experience, we'll find that the program can be improved by taking advantage of another program operation called EX i

The discussion on building a digital filter with a calculator will continue next month. That article will not be comprehensible without this one. It would be a good idea to put this issue away until next month. "

extract from Digital Filters III, dB Magazine, NOV 1982, pages 8-12

"  Last month we began an example of "building" a digital filter on an ordinary programmable calculator. This month we will continue with this project, and I'd recommend that you dig out last month's column to refresh your memory.
  We left off with the idea of implementing a delay line using the ring memory algorithm. The coding of the program steps was based on the idea of using the IND (indirect) function for storing data. The following program segment implements a 10-tap delay function: the program can be defined to begin at a particular location, or we can just name the beginning as "A."

… It should also be noted that the above program does not exactly follow the conventions of the TI-58/59 series of calculators. The changes are for readability …

Next month, we will explore using the filter. In the meantime, happy programming! "


ps:"Users of Hewlett-Packard calculators will have to make some other changes because these calculators use reverse-Polish rather than algebraic notations."
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