Prasar Bharati tests say D2M broadcast won’t heat phones or hurt 4G, 5G networks

IIT Kanpur–Tejas Networks lab study on a 40W D2M transmitter in 470–582 MHz finds no harmful interference on key mobile bands and only a marginal rise in handset temperature, but wider trials still needed. 

Public broadcaster Prasar Bharati has released lab test results indicating that proposed Direct-to-Mobile (D2M) services in the 470–582 MHz band do not overheat phones or interfere with 4G/5G networks under the tested conditions.

The tests were conducted by IIT Kanpur and its partner, Tejas Networks, at Aracion Technology, a NABL-accredited and TEC-designated laboratory in Bengaluru. They used a 40W D2M Broadcast Radio Head based on ATSC 3.0 and a D2M-enabled smartphone that also supports multiple LTE and 5G bands.

In one set of tests, the lab compared phone surface temperature during continuous video playback via D2M versus the same kind of video streamed on YouTube over 4G. After three hours, the D2M mode showed around 35°C on the front and back of the phone, while 4G streaming stayed near 33°C. The lab said this small difference was within normal operating limits and did not indicate overheating.

In the second set, engineers checked if a live 40W D2M signal caused “blocking” or loss of sensitivity on mobile bands n71, n28 and n5. They measured 5G/LTE receiver performance first without D2M and then with the D2M transmitter on at full power, using 3GPP test methods. The phone’s sensitivity and throughput did not drop, giving a desensitisation value of 0 dB and meeting 3GPP blocking requirements.

Spurious emissions from the D2M transmitter were also measured across a wide frequency range and found to be well below 3GPP limits, which means the signal should not leak into other services beyond allowed levels in the tested setup.

The findings strengthen Prasar Bharati and IIT Kanpur’s argument that D2M can technically coexist with existing mobile networks in this UHF band.

However, the report is based on specific equipment and controlled lab conditions. Any large-scale rollout will still need more field trials, regulatory decisions on spectrum, and buy-in from telecom operators who have earlier raised questions on interference and business impact.