Point source equalised by inverse filtering for measuring ground impedance
Authors: Pedro Cobo, Santiago Ortiz, David Ibarra, Carlos de la Colina
Abstract:
A point source for measuring ground impedance which complies with the omnidirectionality requirements of the ANSI S1.18 standard is presented. The source consists of a small aperture connected to a conventional loudspeaker through a cone. Whilst this source radiates with deviations lesser than ±1 dB within ±45, its frequency response exhibits strong peaks arising from resonances of air inside the cone. To equalise these resonances, inverse filtering is applied. Inverse filters pre-emphasise the electrical signal driving the sound source so that zero-phase (or minimum-phase) cosine-magnitude signals are radiated. Equalisation by inverse filtering has two main advantages in the ground impedance measurement. On the one hand, flattening the frequency response avoids large fluctuations of the excess attenuation curve, which can make difficult its inversion to ground impedance data. On the other hand, inverse filtering shorten the time response of the sound source, this in turn making easier the positioning of a time window to separate ground reflection from reflections/diffractions coming from nearby objects usually present in the acoustic scenario.
Keywords:
Point source
Inverse filtering
Ground impedance
Published in: Applied Acoustics (Volume 74, Issue 4, April 2013)
Publisher: Elsevier
ISSN Information: 0003-682X
Point source equalised by inverse filtering for measuring ground impedance
- Vòng Sơ Khảo Cuộc Thi Đại Sứ Văn Hóa Đọc Năm 2024
- Hoạt động chào mừng "Ngày sách Việt Nam 21/4/2024"
- Ngày hội văn hóa đọc lần V
- Cuộc Thi Ảnh “Khoảnh Khắc VNUHCM Libraries”
- Ngày hội văn hóa đọc lần II
- Ngày hội văn hóa đọc lần IV
- Ngày hội văn hóa đọc lần III
- Tiếp GS Omer Mert Denizci, Trường ĐH Marmara Thổ Nhĩ Kỳ
- Tiếp Cô Claudia Tarzariol Từ The University Of Trento, Italy (Unitrento)
- Tiến sĩ kiều bào Mỹ tặng sách trị giá 150.000 USD cho sinh viên bách khoa
- Khảo sát ý kiến bạn đọc
-
Trực tuyến:9
-
Hôm nay:5479
-
Tuần này:32457
-
Tuần trước:28342
-
Tháng trước:57891
-
Tất cả:4021560