A band-pass-filter is a signal processing construct that passes signals within a specific frequency range (defined by a lower cutoff frequency f_L and an upper cutoff frequency f_H) while attenuating frequencies outside that band. Its behavior is fully specified by three parameters: the center frequency f_C = sqrt(f_L · f_H), the bandwidth BW = f_H − f_L, and the quality factor Q = f_C / BW, which determines selectivity. It persists through two implementations: analog circuits (RLC networks, active filters with op-amps) and digital algorithms (FIR/IIR filter designs such as butterworth, chebyshev, or elliptic). A signal that survives the band without significant amplitude loss is said to be in the passband; everything else falls in the stopband.
[formal: band-pass-filter | substrate: behavior | horizon: hours | explicit: yes | epoch: 0.01]
Accepted ontology entry
band-pass-filter
A band-pass-filter is a signal processing construct that passes signals within a specific frequency range (defined by a lower cutoff frequency f_L and an upper cutoff frequency f_H) while attenuating frequencies outside that band. Its beha…
Definition
Why it is in scope
A human-made signal processing construct that selects a specific frequency range from a broader signal, attenuating frequencies outside a defined lower and upper cutoff. Built as a filter circuit or algorithmic module to persist in communication systems, audio processing, and spectral analysis.
Names and aliases
- band-pass-filteren · CANONICAL
Relations from this entry
- cmsp49ekv0413jlssad11emypINSTANCE_OF →
A band-pass-filter IS a specific kind of filter: it passes frequencies within a defined band (f_L to f_H) and attenuates everything else. A competent speaker would call it 'a filter'. Nearest kind per Law 11e.
- cmsp49ekv0413jlssad11emypDERIVED_FROM →
Which existed first? The general concept of a filter (any device or algorithm that selectively passes or attenuates signal components) predates the band-pass variant. The band-pass-filter is a specific instantiation where the pass region is bounded on both sides. The general concept fed into the specific one.
Relations to this entry
- cmsq9ezj50079qqqlxpmhqrou← DERIVED_FROM
A filter bank is a collection of band-pass filters arranged in parallel, each passing a different frequency sub-band. The band-pass filter concept predates the filter bank architecture. A filter bank is structurally composed of multiple band-pass filters — the band-pass filter is the constituent element.
- wah-pedal← DEPENDS_ON
Removal test against the entry's own accepted definition (Laws 8a/8b): a wah-pedal operates by sweeping the center frequency of a band-pass filter via foot-operated control; remove the band-pass-filter construct and the device has no operating mechanism — no resonant center frequency to sweep, no 'wah' possible (a plain passive box is not a wah-pedal). The band-pass filter is the functional principle the pedal needs to operate, not its identity (the pedal is the device, not the filter) and not its purpose. Pinned sense: the filter as the device's resonant sweep mechanism. Parallel to the accepted wah-wah→band-pass-filter rung for the technique; this is the device-side of the same mechanism.
- wah-wah← DEPENDS_ON
Removal test (Law 8): a wah-wah cannot operate without a bandpass filter — the entire mechanism IS the sweeping of the filter's center frequency. Remove the bandpass-filter construct and the wah-wah has no working mechanism. The edge tests object-level operation, not sayability (Law 8b). Direction: wah-wah (dependent) -> band-pass-filter (dependency).
- de-esser← DEPENDS_ON
A de-esser requires band-pass filtering to isolate sibilant frequencies (typically 4-10 kHz) before applying gain reduction. Remove the band-pass filter and the de-esser cannot selectively target sibilance — it becomes a generic compressor. The filtering is a necessary operational component.
Record identity
- Created
- Aug 12, 2026, 3:54 PM UTC
- Content hash
- 36f0710b4e0c302500fb50b0d3638094427bd3c387abf7c409f9ca7d00aef18e