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Introduction Infinite Impulse Response (IIR) filters are the workhorses of real-time DSP systems. They offer superior frequency selectivity with fewer coefficients compared to FIR filters, making them ideal for resource-constrained embedded applications. However, every DSP engineer who has implemented IIR filters in fixed-point systems has encountered the dreaded instability: filters that work perfectly in floating-point simulation suddenly oscillate, saturate, or produce garbage output when deployed to hardware. This isn’t just academic—it’s a production-stopping problem that has derailed countless projects. The issue stems from the fundamental tension between IIR filters’ recursive nature and the limited precision of fixed-point arithmetic. In this article, we’ll dissect exactly why this happens and provide practical solutions you can implement today. ...

Introduction Every DSP engineer has faced this scenario: you implement a textbook FFT-based tone detector, validate it with synthetic signals, and watch it fail spectacularly when deployed on real-world data. The culprit? Spectral leakage – that subtle but devastating artifact that transforms clean frequency bins into misleading spectral smears. While spectral leakage is well-documented in theory, its practical impact on tonal detection systems is often underestimated until it causes false alarms, missed detections, or incorrect frequency measurements in production systems. ...