Resolution Bandwidth (RBW) Normalization
Convert a level measured with one resolution bandwidth to the RBW the standard requires, with separate handling for noise-like, impulsive and narrowband signals.
Worked example
Input: Measured level 40 dBµV, RBW used for the measurement 9 kHz, Target RBW 120 kHz, Signal type Noise-like (10·log)
Result: Correction ΔL 11.2494 dB, Normalized level 51.2494 dBµV, RBW ratio (B₂/B₁) 13.3333 ×
Result: Correction ΔL 11.2494 dB, Normalized level 51.2494 dBµV, RBW ratio (B₂/B₁) 13.3333 ×
Formula
Noise-like: ΔL = 10·log₁₀(B₂ / B₁)
Impulsive: ΔL = 20·log₁₀(B₂ / B₁)
A narrowband signal does not change with bandwidth (ΔL = 0)
How it works
The measured level of a broadband signal depends on the RBW. Signals whose power scales with bandwidth, such as random noise, are corrected by 10·log₁₀(B₂/B₁); signals whose amplitude scales with bandwidth, such as impulses, by 20·log₁₀(B₂/B₁). A narrowband signal such as a single carrier does not change with bandwidth. For example, noise measured at 9 kHz converted to a 120 kHz reference is +11.25 dB.
Practical tipPre-compliance scans often use a wider RBW for speed and then normalize, but picking the wrong signal type puts an 11 dB error straight into the result. Change the RBW and watch the trace: if the level follows, it is broadband; if it does not, it is narrowband. Figures for a formal test report must be measured at the RBW the standard specifies; this conversion is for pre-compliance review only.
Related calculators
Results and summaries are for reference. For certification and test reports use the latest official standard text and calibrated instrument data. Last updated: 2026-10-10