INTERFERENCE
DIAGNOSIS: INTERFERENCE Chris Fosten, Manager, Communications Infrastructure, ACMA
Interference diagnosis and management is all in a day’s work for the ACMA and its expert inspectors.
A typical day in the field A mobile phone carrier reported to the ACMA that one of its base stations near Flemington, close to Melbourne’s CBD, was experiencing interference. An ACMA officer travelled to the area to find the source and stop the interference. The information pointed to a transmitter located in a housing area close to the Flemington Racecourse. The ACMA officer scoured the area using a spectrum
6 Critical Comms - Nov/Dec 2017
analyser to gauge the signal strength and find the location of the transmitter. The high-density housing complicated the search because it caused high signal reflections, but the officer used his expertise to quickly narrow the search down to a couple of houses. He then used his 800–900 MHz directional Yagi antenna to pinpoint the exact location of the device on the second floor of a townhouse, near an external wall. With the cooperation of the resident, the inspector quickly identified a malfunctioning
indoor TV antenna booster as the source of the interference. This type of device should not transmit radio signals in the mobile phone band. The inspector explained to the resident why the device couldn’t be used and advised on how TV reception in the townhouse could be improved. The device was disconnected and an advice notice issued to reinforce the information he had provided. With the booster out of action, the carrier’s mobile network was restored to its normal performance.
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Images courtesy ACMA.
T
he ACMA plays an important role in managing Australia’s radiofrequency spectrum. For the general public, this means making sure radiocommunications and broadcasting services work without being affected by interference — we all want to use our smartphones and enjoy TV and radio services uninterrupted. For industry and government, it can mean the difference between providing a reliable mission-critical communications service or one that is compromised by unauthorised and harmful transmissions or interference. Managing interference can be done from behind a desk in some cases, but more often diagnosis and resolution takes ACMA officers into the field and to all parts of Australia — from our major cities to coastal and outback communities. ACMA field staff, who are technically qualified and appointed as inspectors, respond to complaints of interference and work hard to make sure everyone gets the most out of Australia’s radiofrequency spectrum.