2013

Beer Fridge Disrupts Mobile Networks in Australia

Technicians from Australian mobile service provider Telstra track interference to a defective beer fridge using handheld antennas and a new “software robot.”

An Australian man’s defective beer fridge is being blamed for mobile network disruptions in several nearby neighborhoods.

Technicians from mobile service provider Telstra determined that the motor of a beer fridge located in the garage of Craig Reynolds of Wangaratta, Australia was generating an electric spark that created enough RF noise to affect the 850mHz band, after complaints of a network “black spot” arose.

“I’m amazed something like that could knock out part of the network,” Reynolds told the Herald Sun. “You’re certainly going to stop and wonder. I’m going to run and see if my fridge is all right next time there’s a problem with the network”.

While the beer fridge is one of the more unusual pieces of equipment that has interfered with Telstra’s mobile networks, it is one example of “hundreds and hundreds of investigative interference jobs that are done each year across the country,” Richard Henderson, Telstra’s area team manager for mobile coverage delivery in the Victorian metropolitan area, told iTnews.

2003

Baby alarm interferes with aircraft communications

A well-known make of wireless baby alarm is known to cause occasional interference with aircraft communication at some U.K. airports. It is not the wireless technology in the baby alarm that is the problem, it is their plug-top power supply, which uses a switch-mode converter. A faulty batch of power supplies was shipped with the baby alarms, and although they function well enough they emit powerfully on VHF radio channels used by National Air Traffic Services (NATS).

The interference is particularly difficult to detect on the ground but when NATS is informed of problems of this sort, they are able to overfly the troubled area with a specially equipped aircraft, partly funded by the Radiocommunications Agency (RA). When the aircraft has located the source of the interference, NATS will send in a specially equipped road vehicle which identifies the house concerned.

Officers from the RA then exchange the faulty plug-top power supply and send it back to the baby alarm manufacturer, who ship a (non-VHF-transmitting) replacement. It is a lot of trouble to go to for a low-cost electronic item, but flight safety requires us to do it.

Gov't warns U.S. forces over radio waves from baby monitors

(Japan Today, 16th August 2010)

The Internal Affairs and Communications Ministry has warned the U.S. forces in Japan over unauthorized radio waves emitted by baby monitors used in the homes of military personnel, as they are disrupting radio transmissions nearby for taxi and trucking services, according to ministry officials.

Some foreign-made baby monitors, often used by families of U.S. military and civilian personnel stationed in Japan, emit radio waves stronger than the stipulated level or of similar frequency as mobile phone and radio contact base stations close by, resulting in communication interference in violation of the radio law. A public relations officer of the U.S. forces in Japan said they are striving to curb illegal radio transmissions and discouraging the use of baby monitors bought in the United States through broadcasting and newspapers for military personnel.

A baby monitor uses a radio system to allow people to check on infants at a distance, such as in separate rooms in a house, by setting a transmitter equipped with a microphone and sometimes a camera near the baby and listening to them or watching them on portable receivers.

Since 2008, there have been increasing cases of detection of illegal radio waves from U.S. military-related residential areas in Okinawa Prefecture, which hosts the bulk of U.S. military bases and facilities in Japan. The communications ministry’s local telecommunications office investigated the cases and determined that the radio waves were emitted by foreign-made baby monitors, according to the officials. Similar cases have also been reported at residences of U.S. military personnel in Tokyo, Kanagawa, Yamaguchi and Nagasaki prefectures. As emissions of illegal radio waves continue sporadically in various areas, a ministry official said, ‘‘There are also situations in which they could affect important radio communication such as among firefighters. We hope people will not use products that do not comply with Japan’s standards.’‘  

The problem is not unique to U.S. military-related families in Japan, however, as there have also been cases of Japanese people using foreign-made baby monitors and other devices such as transceivers that do not meet Japanese technical standards, leading experts to caution against the use of such foreign-made products. For example, a Japanese family in Toyama city was found to have disrupted mobile phone communications in September 2009 using a baby monitor purchased in the United States, while in April this year in Nagoya, a Chinese-made baby monitor caused interference in radio communications by trucks. 

2000

Thermostats interfering with TV and radio reception

Faulty thermostats can cause annoying interference to television and radio broadcast reception – normally in short bursts, which may recur at intervals. Thermostats switching on and off in central heating systems, refrigerators or freezers can all cause interference problems but, generally, thermostats installed in central heating systems are the most common cause.

Sometimes the offending thermostat is found in the house that is suffering from the interference, although there have been cases where the source of the interference has been found some distance away.

In one example (above), the interference signal is generated from a boiler gas control valve and its associated thermostat switching from stand-by to ON and vice versa. These systems have a typical power consumption of 3kW and can generate a low power single-phase arc when switched. This causes a short burst of radiation. When the thermostat is malfunctioning this burst of radiation can be heard as a rough rasping noise which typically lasts for a few seconds but may last for 20 seconds or more. It repeats typically every 10 minutes but in some cases, a faulty thermostat may arc several times per minute. In the first figure, the stand-by to ON case is shown, while in the second the ON to OFF case is presented. This kind of interference which is intermittent in nature is mostly noticed in relation to the reception of analogue TV signal at 500 to 850 MHz and sometimes on FM radio at 88-108 MHz.

Note: the implementation of digital TV hasn't made the problem go away: it's just harder to recognise as interference, as the effect is usually of pixellation or blocking of the picture.

2006

Digital box interference triggers 'SOS' alert and helicopter search

(Taken from BBC News / Scotland, Sunday, 15th January 2006)

A faulty TV digital box sparked a rescue mission from RAF Kinloss by sending out a signal identical to those transmitted by vessels in distress. The Kinloss site in Moray, which co-ordinates rescue operations across the UK, detected an "SOS" call from the Portsmouth area on 5th January.

A coastguard helicopter spent two hours searching the harbour area before the signal was traced to dry land. An RAF spokesman said the signal had been a "complete freak". Telecoms regulator Ofcom was asked to look into the signal and confirmed the source.

RAF spokesman Michael Mulford said the Aeronautical Rescue Co-ordination Centre at the airbase had picked up the beacon from one of five orbiting satellites. He said it was transmitting on the major emergency frequency. "We traced it to Portsmouth Harbour, checked and found out there were no vessels in the area or missing planes." The rescue centre then contacted Ofcom, which was able to establish it was coming from a household.

Mr Mulford added: "This is very very unusual, it's a complete freak and the odds of a digibox sending out such a signal must be astronomical. The guy who owns it really should do the lottery because the chances of sending out a signal from a digibox and sending out precisely and exactly on a major emergency channel are far more than 14 million to one."

Ofcom has since removed the £50 Freeview box for tests. An Ofcom spokesman said: "This is a real one-off as digital boxes only receive signals. They shouldn't be sending out signals, let alone maydays. The householder was happy to hand it over to our engineers who are trying to get to the bottom of the defect."

[Note: if the quote attributed to the Ofcom spokesman above is correct, he must have been quite new in the job. See next story.]

TV box launches sea rescue search

(BBC News, Devon, 14 February 2006)

A Devon pensioner's digital television box started a sea search operation when it sent out a distress signal.

The emergency signal was picked up in Scotland at RAF Kinloss. The base alerted coastguards at Falmouth who sent out two lifeboat rescue teams. Mary Donaldson, 67, from Wembury near Plymouth, said she had no idea her Freeview box sent the signal until her home was traced by Ofcom. A similar incident in Portsmouth in January also started a sea search.

Mrs Donaldson was confronted by two officials at her front door on 24 January after Falmouth Coastguard had sent out two lifeboat rescue teams. A spokesman for RAF Kinloss said: "We received the 121.5 signal and posted it to Falmouth - they launched and tasked the RNLI boat to this lady's house." It is not known how the boxes sent out the signal, but both incidents are being investigated by broadcasting regulator Ofcom.

An Ofcom spokesman said that after RAF Kinloss reported the mayday signals, detector equipment was used to trace the boxes. They were then taken away for testing. He added that both cases were rare instances. He said: "Any box that is capable of receiving is capable of transmitting, and they somehow flipped from receiving to sending. These are two instances in the millions of boxes being used. It's a very small number, and we don't believe it is a widespread problem."

The results of the investigation are expected back within two weeks. A Freeview spokesman said it was believed the fault was with the boxes manufacturers and the organisation would wait for the Ofcom results before putting together any contingency plan to recall Freeview boxes. The spokesman said: "Freeview is just the service, anything to do with the signal would be the manufacturer's territory. It is not a big issue for us at the moment - it is two boxes out of 10 million we have in the country. Therefore we are not putting together a contingency plan yet."

CR/CD/DVC combo TV sends out false distress signals

(Taken from Conformity magazine, 21st January 2005; the original article was entitled: "TV Interference Triggers Aircraft Rescue Satellite Response", and published in the Corvallis Gazette-Times, 17th October 2004.)

This October, Chris van Rossman of Corvallis, Oregon turned on his do-everything combo TV and got a big surprise - the police, the Civil Air Patrol, and the County Search and Rescue Officers knocked on his door. Apparently, Mr. van Rossman's flat screen, VCR/CD/DVC combo TV had developed some sort of strong emission at 121.5MHz, which is a rescue frequency used by aircraft and boat distress transponders and monitored by orbiting satellites. This service uses an uncoded analog carrier detection system, and is therefore rather sensitive to unauthorized transmissions.

When the distress signal was picked up from the satellite, the information was picked up by the Air Force Coordination Center at Langley Air Force Base in Virginia. Langley in turn called the volunteer Civil Air Patrol in Oregon, which in turn contacted Benton Country Search and Rescue for help in locating the signal. Using radio direction finding equipment, the officers were able to narrow the source down to a few possible units in Mr. Rossman's apartment building. When they knocked on his door and he turned off his set to answer, the signal disappeared.

David Mandrell, the CAP squad leader had heard of similar inadvertent interference from consumer equipment, but often it was weak enough to be ignored. This particular instance of interference was unusual because it was abnormally strong. Mr. Rossman was simply warned to keep his TV turned off or face fines of potentially up to $10,000 per day for emitting a false distress signal. He has contacted the set's manufacturer, whose technicians had never heard of a case like this, and has agreed to send him a free replacement.

Plane madness: Schoolboy has TV aerial confiscated by Government officials for interfering with aircraft signals

(Daily Mail, 28th October 2009)

A schoolboy was stunned when Government officials swooped on his bedroom and confiscated his TV aerial - because it was interfering with planes landing at a nearby airport. Nickie Chamberlain, 12, had used the booster device for two years to watch cartoons, music channels and Big Brother on his 14-inch television. But three weeks ago an official from the Office of Communications (Ofcom) turned up at his home claiming the £15 aerial was affecting planes landing at Luton Airport. According to Ofcom, pilots coming in to land at the airport had lost contact with the control tower because the faulty aerial was transmitting on the same frequency as the cockpit radios.

The communication problems meant pilots landing their aircraft had to scramble to change the frequency so they could continue to communicate with the control tower. Air traffic controllers first noticed the communication problems on the flight path into Luton, which is directly over Nickie's house in Linslade, Bedfordshire, on October 6. An Ofcom engineer was sent to the house and he used a handheld device to trace the signal to the small booster aerial sitting on top of Nickie's television.

His father, DHL operations manager Dave Chamberlain, 46, spoke of his shock and said he could not believe a tiny aerial could affect aeroplanes flying over his house. He said: 'We were told pilots flying over the house were losing contact with the control tower as they came into land. The engineer was waiting outside the house when I came home from work and told me pilots had been complaining and they had traced the signal to our house. I couldn't believe it and at first I thought the engineer was some sort of conman so I had to carefully check his identification and make sure he was for real. Then we went inside and he followed the signal using a special reader to my son's bedroom and his booster aerial - I was absolutely gobsmacked.'

Nickie, who lives in the three bedroom semi-detached house with his dad, brother Glenn, 14, and mother Erika, 42, said he was amazed he had caused so much trouble. He said: 'When I found out what happened I was upset because I couldn't watch cartoons or the television for a while - but it's better than causing a plane crash.'

The Ofcom representative ordered Mr Chamberlain to dispose of the aerial in the bin. A spokesman said they had been asked to trace the signal by National Air Traffic Control after complaints from pilots. According to the spokesman the problem occurred because the faulty aerial started to malfunction and 'self-oscillate' - sending out a range of different frequencies.

The spokesman said: 'You essentially get a sound much like the screeching you get when you put a microphone too close to a loud speaker. The booster aerial was, at different stages, giving off the same frequency as the aeroplane radio and that is why the pilots were losing contact. Our field engineers regularly work with National Air Traffic control and were able to trace the signal back to this little boys bedroom. This is obviously quite unusual.'

A spokeswoman for the NATS said they were aware of the incident but added no passengers or pilots were in danger at any stage. She said:  'The planes have multiple back-up communication systems and this is not something where any passengers were in any danger. Obviously safety is our major concern.' Luton Airport declined to comment.