A spectrum analyzer is an essential tool for measuring and visualizing signals across different frequencies.
One of its most critical settings is Resolution Bandwidth (RBW), which significantly impacts frequency resolution, measurement speed, and signal detection.
In this article, we’ll explore what RBW (Resolution Bandwidth) means in a spectrum analyzer, how it affects signal analysis, and when to adjust it for optimal performance.
Table of Contents
What Is RBW in a Spectrum Analyzer?
Resolution Bandwidth (RBW) is the smallest frequency range a spectrum analyzer can resolve at any given point. It defines how finely the device can separate closely spaced signals and impacts the accuracy and clarity of signal measurements.
RBW in Simple Terms
- Lower RBW = Better frequency resolution, but slower sweep time.
- Higher RBW = Faster measurements, but reduced ability to distinguish nearby signals.
How Does RBW Affect Spectrum Analysis?
Frequency Resolution
- A narrow RBW allows you to distinguish signals that are very close in frequency.
- A wide RBW blends closely spaced signals together, making it harder to analyze them separately.
Noise Floor & Signal Detection
- Lower RBW reduces noise, allowing detection of weaker signals.
- Higher RBW increases the noise floor, potentially hiding weak signals.
Sweep Time
- Lower RBW = Slower scan speeds (more data points collected).
- Higher RBW = Faster scan speeds, useful for quick signal detection.
Choosing the Right RBW for Your Application
| Application | Recommended RBW | Why? |
|---|---|---|
| Broadband signal scanning | Higher RBW (100 kHz – 1 MHz) | Faster scanning speed |
| Narrowband signal analysis | Lower RBW (10 Hz – 1 kHz) | Better frequency resolution |
| Weak signal detection | Lower RBW (1 Hz – 100 Hz) | Reduces noise floor |
| Interference analysis | Variable RBW (adjust as needed) | Helps separate signals clearly |
Final Thoughts
RBW is an important setting in spectrum analyzers, affecting the balance between speed, accuracy, and sensitivity.
- For quick signal scanning, a higher RBW is preferred
- For detailed signal analysis, a lower RBW helps separate closely spaced signals.
Understanding how to adjust RBW properly ensures more accurate and efficient spectrum analysis.
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