dsp-collection/signal/InstFreq.js

A collection of JavaScript modules for digital signal processing (written in TypeScript)

import * as AdaptiveStft from "./AdaptiveStft.js";
export function instFreqSingle_relWindow(samples, position, roughtMeasuringFrequency, shiftFactor, relWindowWidth, windowFunction) {
    const shiftDistance = Math.max(1, shiftFactor / roughtMeasuringFrequency);
    const pos1 = position - shiftDistance / 2;
    const pos2 = position + shiftDistance / 2;
    const r1 = AdaptiveStft.getSingle_relWindow(samples, roughtMeasuringFrequency, pos1, relWindowWidth, windowFunction);
    const r2 = AdaptiveStft.getSingle_relWindow(samples, roughtMeasuringFrequency, pos2, relWindowWidth, windowFunction);
    if (!r1 || !r2) {
        return;
    }
    if (r1.frequency != r2.frequency || r1.windowStartPosition >= r2.windowStartPosition || r1.windowWidth != r2.windowWidth) {
        throw new Error();
    }
    const measuringFrequency = r1.frequency;
    const realShiftDistance = r2.windowStartPosition - r1.windowStartPosition;
    const phase1 = r1.component.arg();
    const phase2 = r2.component.arg();
    const phaseDelta = (phase2 + 2 * Math.PI - phase1) % (2 * Math.PI);
    const instFrequency = phaseDelta / (2 * Math.PI) / realShiftDistance;
    const amplitude = (r1.component.abs() + r2.component.abs()) / 2;
    return { instFrequency, measuringFrequency, amplitude };
}
export function instFreqSingle_maxWindow(samples, position, roughtMeasuringFrequency, shiftFactor, maxWindowWidth, windowFunction) {
    const relWindowWidth = Math.floor(maxWindowWidth * roughtMeasuringFrequency);
    return instFreqSingle_relWindow(samples, position, roughtMeasuringFrequency, shiftFactor, relWindowWidth, windowFunction);
}
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