File:Arduino-based wow-and-flutter meter as-built.jpg

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Arduino-based wow-and-flutter meter - as-built photo

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Description
English: Arduino-based wow-and-flutter meter - as-built photo. Testing DSP procedures. The input is connected to an internal oscillator that modulates 3120 Hz carrier with a square 4Hz clock with +/- 1.25% modulation spread. Which is exactly what shows on the LCD owing to the robustness of DSP math (W-number is for wideband, N-number for narrowband chaneels per DIN 45507; with this test signal they must almost match). The odd values of F and delta-F result from the use of a crude 8-bit timer. The only 16-bit timer is busy measuring the input signal period. The Arduino has more than enough speed to calculate the DSP filters, however, its clock speed and the resolution of its 16-bit timer are barely sufficient for the job. Ideally, it needs 24-bit or better timer with much higher clock speed than the stock 16 MHz.
Русский: Измеритель детонации (магнитофонов и ЭПУ) на основе ардуино. Внешний вид. На этом фото измерительный вход подключен к выходу генератора, несущая которого (примерно 3120 Гц) модулируется меандром частотой 4 Гц (опорная по DIN45507) с девиацией частоты +/- 1.25% - что и отображается на экране (для широкополосного W и узкополосного N каналов измерения). Странные значения несущей и девиации - следствие использования в качестве генератора 8-битного таймера (единственный 16-битный таймер занят измерениями). Производительность 16-мегагерцовой ардуины более чем достаточна для задач простейшего DSP, но тактовая частота и разрешение 16-битного таймера еле-еле пригодны для измерений. Приходится решать непростой компромисс между разрешением и качеством АЧХ, высокочастотная ветвь которой так или иначе будет значительно отклоняться от ГОСТа 11948-78 (он же DIN 45507).
Date
Source Own work
Author Retired electrician
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Schematic
DSP flowchart

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I, the copyright holder of this work, hereby publish it under the following license:
Creative Commons CC-Zero This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
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current12:38, 1 June 2023Thumbnail for version as of 12:38, 1 June 20234,173 × 3,365 (2.92 MB)Retired electrician (talk | contribs)Uploaded own work with UploadWizard

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