Firework detection system: localising a bang in 10 seconds

4 min reading time

Damage caused around New Year’s Eve in 2015/2016 in the Netherlands came to some eleven million euros. This year seven local authorities hope to keep this damage down to within their limits using the Munisense firework detection system developed by TNO.

“Can you people at TNO not make a crystal ball for us to see where illegal fireworks are being stored?” The question asked by the police in November 2012 was tongue-in-cheek. “Well, we can’t do that but we can create a firework detection system that helps you see when and where fireworks are being set off. If a lot of fireworks regularly go off at a particular address, then there will probably be fireworks stored somewhere there,” says mechanical engineer and TNO medior scientist Peter Wessels.

Linking up

The police force was enthusiastic and Wessels got started. “We have all the components for such a system in house within our ‘Acoustics & Sonar’ department. We know how noise moves through the urban environment. We have expertise in noise recognition and in unmanned acoustic monitoring and via synchronous meter boxes. In fact, all I had to do was link it all up.” Within a month the first prototype of the detection system was tested successfully in a neighbourhood in Voorschoten.

“You can also filter the data by, for instance, day, time and force. Make the loudest bangs visible”

Bang on the map

For a standard area of 2 km2 you need four noise meters. In principle, a noise meter or bang sensor comprises a microphone and a box of electronics. The bangs are recognised and this information goes to a central server. The nose meters are located on rooftops or high buildings, which allows the four microphones to register a firework bang without any interference. The source of the bang is automatically calculated by the difference in the arrival times in the bang sensors, and you can then see where it is on a map of the area. All the data are collected centrally. Moreover, the officer on the beat or the special investigating officer in that area receives a mail with a link to his or her mobile phone. If they click on the link, they see the map with the bang located. This all takes a minute.

Knowledge transfer

At the end of 2014 an improved version of the TNO detection was tried out with success, this time in Hilversum. TNO already had regular contact for a couple of years with the real-time metering company Munisense, which measures not only noise pollution caused by events but also groundwater levels. Wessels: “Munisense also became interested in our firework detection system at the end of 2015. They were able to incorporate and modify our software on their own hardware. I transferred our knowledge to the people at Munisense in record time.” And so in December 2015 the detection went on trial in five local authorities: Amersfoort, Hilversum, Leeuwarden, Rotterdam and Utrecht. Wessels: “In the evening I regularly accompanied the police on their rounds or even walked through neighbourhoods myself to check them out. I went through the entire process: invent, build, apply, consult the users and incorporate their feedback. A couple of years ago, December was by far my busiest working month!”

“In the evening I regularly accompanied the police on their rounds or even walked through neighbourhoods myself to check them out. I went through the entire process”

Licence

In the meantime Munisense has agreed an exclusive ten-year licence agreement for the use of the TNO firework detection technology. Munisense director George Boersma is full of praise for the collaboration with TNO. “The transfer was excellent and on the basis of their knowledge we will continue with the development of the detection system. The system has already become faster and more sophisticated, and we have developed an app where the law enforcers can see the bang together with the address within ten seconds.” This makes the chance of catching those setting off the fireworks much greater. Since the beginning of December firework bangs have been detected in seven local authorities. Boersma: “While there had been a lot more interest, many local authorities were unable to arrange participation this year. I expect the number of participating local authorities to double at the end of 2017.”

Filter by day, time and force

Apart from boosting the chance of catching the perpetrators and finding the illegal fireworks, the detection system also gives the users quite a bit of insight that they can use for the law enforcement, for more effective deployment of the special investigating officers and to develop a policy in the longer term. Boersma: “From last year’s data we know that the fireworks are set off mostly between seven and ten in the evening. You can, for instance, also filter the data by day, time and force. Make the loudest bangs visible: the cobra and other illegal, dangerous fireworks. In the future the system may well be able to recognise the type of firework by the bang.” A standard system for an area of 2 km2 costs a local authority 7,000 to 8,000 euros a year for a three-year contract.

Smart city

The firework detection system can also be modified for use to detect poachers, shooting incidents or to measure building noise. Boersma thinks that ultimately it will become an integrated element in a real-time metrology system for smart cities. Boersma: “This will allow you to recognise all kinds of events in your local authority and take policy measures to respond or enforce the law.”

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Peter Wessels MSc Locatie Leiden - Sch + Page 1 Location: Location The Hague - Oude Waalsdorperweg
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