This week BBC News ran a story on how taxi drivers in Japan are hearing the unexpected sounds of cooing babies on their CB radios. The cause: U.S.-purchased baby monitors from nearby U.S. military bases that are interfering with communication frequencies. Why would this happen? It’s likely that the baby monitors were manufactured to work on region two communication frequencies, and while being used in Japan, they’re interfering with communication frequencies allocated to region one.

The International Telecommunication Union (ITU) divides the world into three regions. Each region has its own frequency-band allocations; that is, in each region, each frequency band is allocated to a specific use. Sometimes a local authority like the Federal Communications Commission (FCC) in the United States regulates the use of frequency bands.

Say you want to find out how a specific frequency like 2GHz is allocated. Type “frequency allocation 2GHz” into Wolfram|Alpha.

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