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Design of the test facility for the measurement of noise silencers

Bolejko Romuald, Plaskota Przemysław, Dobrucki Andrzej B., Pruc Krzysztof

Vibrations in Physical Systems

2022

Vol. 33, nr 3

art. no. 2022309

In the paper, a description of the test facility designed and implemented for noise silencers according to the methodology specified in the PN-EN ISO 7235 standard is presented. It is possible to measure the insertion loss, flow noise, and pressure loss on the test stand. In particular, the following issues were presented: noise protection in the low frequency range, the design of the anechoic termination, and measurements of the sound pressure level in the flow. To obtain a sufficiently high level of noise protection, three noise transmission paths were considered: direct, indirect, and flanking. The design of the anechoic termination was based on the profile of the catenoid tube, which made it possible to obtain strong sound absorption in the low-frequency range while maintaining a limited length of a terminator. A specially designed microphone cap was used to measure the sound pressure level in the flow field. The paper also presents results of selected measurements that illustrate the possibilities of the designed test stand.

Subiektywna ocena multipleksu radiofonii lokalnej DAB+ działającej w Gdańsku i Wrocławiu

Falkowski-Gilski Przemysław, Brachmański Stefan, Dobrucki Andrzej B.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

2020

nr 7-8

316--319, CD

Standard DAB+ (Digital Audio Broadcasting plus) jest wiodącym systemem naziemnej radiofonii cyfrowej. W porównaniu do analogowej radiofonii FM wszystkie usługi, obejmujące tradycyjne programy radiowe oraz usługi transmisji danych, grupowane są w zbiór (ensemble). Praca ta przedstawia proces rekonfiguracji polskiego multipleksu na przykładzie lokalnej radiofonii DAB+ w Gdańsku i Wrocławiu. Opisuje wyniki badań subiektywnych dotyczących jakości programów radiowych nadawanych jednocześnie w technice cyfrowej i analogowej.

The DAB+ (Digital Audio Broadcasting plus) system is one of the leading standards of terrestrial digital broadcasting. Compared with analog FM radio, all services, including traditional audio programs as well as additional data services, are grouped in an ensemble. This paper describes the process of reconfiguring the Polish multiplex on the example of local DAB+ radio in Gdansk and Wroclaw. It presents results of a subjective quality study, concerning broadcasting in both digital and analog techniques.