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EP0252647A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Aircraft cabin noise control apparatus

Assignee: UK Secretary of State for Trade and Industry
•
Filing: 1987-06-23
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Granted: —
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Expires: 2007-06-23
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Abstract

Abstract In propeller or fan driven aircraft, cabin noise levels may be reduced by adjustment of the phase relationship between a reference propeller or fan and some or all of the other propellers or fans. An aircraft cabin (1) contains four microphones (2,3,4,6) and two loudspeakers (6, 7) which form the active elements of a noise control system. The microphone outputs are fed via amplifiers (12, 13, 14, 16) to a digital signal processor (11) having an adaptation algorithm in a memory store. The processor generates an error signal which is used to adjust the synchrophase angle between the reference propeller (10) and a synchrophased propeller (9), controlled by a synchrophaser (8). Thus the synchrophase angle is varied dynamically during flight to minimise propeller noise in the cabin over a range of flying conditions.

Inventors

  • 👤 Stephen John Elliott
  • 👤 Philip Arthur Nelson

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-31 22:24
CPC Classifications
B; B64; B64C; B64C1/00; B64C1/40; B64C11/00; B64C11/46; B64C11/50; G; G10; G10K; G10K11/00; G10K11/16; G10K11/175; G10K11/178; G10K11/1785; G10K11/17853; G10K11/17854; G10K11/17857; G10K11/1787; G10K11/17879; G10K11/17883; G10K2210/00; G10K2210/10; G10K2210/123; G10K2210/128; G10K2210/1281; G10K2210/30; G10K2210/301; G10K2210/3046

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 80 words
Cabin noise control apparatus for a propeller or fan driven aircraft including a synchrophaser for varying, during flight, the phase relationship between a reference propeller (10) or fan of the aircraft and one, some or all of the other propellers or fans of the aircraft characterised in that the phase relationship is varied in response to the output from a signal processor (11) connected to receive and analyse signals from a plurality of transducers (2-5) located inside the cabin (1).
Claim 2
Dependent Claim 80 words
Cabin noise control apparatus for a propeller or fan driven aircraft including a synchrophaser for varying, during flight, the phase relationship between a reference propeller (10) or fan of the aircraft and one, some or all of the other propellers or fans of the aircraft characterised in that the phase relationship is varied in response to the output from a signal processor (11) connected to receive and analyse signals from a plurality of transducers (2-5) located inside the cabin (1).
Claim 3
Dependent Claim 20 words
Cabin noise control apparatus as claimed in Claim 1 wherein at least one of the transducers (2-5) is a microphone.
Claim 4
Dependent Claim 20 words
Cabin noise control apparatus as claimed in Claim 1 wherein at least one of the transducers (2-5) is an accelerometer.
Claim 5
Dependent Claim 35 words
Cabin noise control apparatus as claimed in any preceding claim characterised in that the signal processor (11) forms part of an active noise control system which generates sound waves in anti-phase with ambient noise waves.
Claim 6
Dependent Claim 85 words
Cabin noise control apparatus as claimed in any preceding claim characterised in that the signal processor (11) computes an estimate of the gradient of the sum of the mean square outputs of the transducers (2-5) with respect to-the phase relationship 6m between a reference propeller (10) or fan and each other propeller or fan and causes the synchrophaser to increment Om by an amount dependent on the value of the gradient in order to minimise the sum of the mean square outputs of the transducers.

References Cited (Backward Citations)

GB2126837A Cited
GB2149614A Cited

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