Case study # 1.4 Title Emission from telephone equipment affecting an amateur radio Type of trouble Acoustic noise. Source of trouble Host equipment of telephone system. System affected Customer's equipment and office equipment. Location Customer premises, Telecommunication centre. Keywords Emission, amateur radio, common mode choke, filtering. Version date 2004-01-01 System configuration Acoustic noise interference occurred in an amateur radio installed on the second floor of a building (see Figure 1.4-1). The building's first floor is an office and workshop and the second floor is a living space. The affected frequencies were 145.00 and 144.00 MHz. A lot of office equipment and manufacturing equipment was installed on the first floor. The distance between the amateur radio and the noise source (core equipment) was 10 m. Amateur radio Living space Workshop Office Core equipment Miti(08)_F1.4-1 Figure 1.4-1 – System configuration Copyright © ITU 2010 – All Rights Reserved