Ofcom extends deadline for interferers, those who fear them

4G vs granny-alarm deathmatch rumbles on

Ofcom is extending the deadline for feedback on potential interference from, and to, 4G services ahead of next year's mega auction.

Ofcom has been speaking to manufacturers and retailers of kit using nearby frequencies, including personal alarms and monitoring keyfobs, and has now extended the window for their comment to match the 11 August deadline set for those concerned 4G is going to interfere with Digital TV broadcasts.

The scale of digital television, and potential impact of any interruption to service, pushed Ofcom to separate DTT interference into its own consultation, which established that 4G services will indeed knock out TV viewing for a significant number of people. But Ofcom has also published research (PDF, very technical) showing that other radio users nearby could also see problems, and extended the deadline for them to let the regulator know.

Those radio users come under the heading of Short range Radio Devices (SRDs), which includes a variety of audio equipment and radio frequency identity tags (RFIDs), as well as the wireless alarms of the type often used by the elderly, either fixed around the house or worn for easy access. All these devices operate, licence-free, between 863 and 870MHz. The 4G space tops out at 862MHz, which is close enough to generate significant interference to the low-power transmissions of SRDs.

The study does highlight some potential problems, though the fact that there are, as yet, no 4G handsets able to use the allocated band makes testing a rather theoretical affair. Modelling suggests that alarm systems won't be impacted; unsurprising given the simplicity of the signalling, but audio systems could see significant interference.

Anyone interested in mitigating such interference now has until August 11 to let Ofcom know, sharing a deadline with those who want to keep DTT on the air. ®