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New Delhi: Prasar Bharati has published fresh test reports on the impact of Direct-to-Mobile transmission on IMT services during the operation of D2M technologies in the 470-582 MHz frequency range.
The reports cover laboratory and field evaluations of ATSC 3.0-based D2M technology. The tests examined whether D2M transmission in the 470-582 MHz band met emission limits and whether mobile voice calls and SMS retained priority during active D2M playback.
The public broadcaster said the exercise was carried out in association with the Ministry of Information and Broadcasting, Telecommunication Engineering Centre, the Wireless Planning and Coordination wing of the Department of Telecommunications, MeitY, DST, IIT Kanpur and its technology partner.
The laboratory tests were conducted on March 13, 2026, at Aracion Technology Private Limited in Bengaluru, a TEC-recognised laboratory. The field tests were conducted on March 25, 2026, in Delhi.
The lab evaluation focused on base station transmit power measurement, spurious emission measurement of the Broadcast Radio Head and adjacent channel leakage assessment.
According to the test report, the 40W D2M Broadcast Radio Head operating in the 470-582 MHz band satisfied the acceptance criteria for channel power, spurious emissions and adjacent-channel leakage under the laboratory evaluation.
The report said the D2M Broadcast Radio Head passed the general base station transmitter spurious emission limit lines of Category B specified by 3GPP. The tests covered frequency ranges from 9 kHz to 2.910 GHz, including harmonic regions.
For power measurements, the D2M transmitter was tested at lower, mid and upper bands. The measured values ranged from 45.75 dBm to 47.24 dBm across 474 MHz, 522 MHz and 578 MHz, and all test conditions were marked as pass.
The adjacent-channel leakage assessment was also marked as pass across lower, mid and upper bands. The report said measured adjacent-channel power levels and equivalent ACLR remained within the defined acceptance limits.
The field test examined whether incoming mobile voice calls and SMS messages were prioritised during active D2M playback. Tests were conducted on Jio and Airtel networks across 4G, 5G and 2G conditions using devices including a MarkOne D2M handset and Samsung smartphones with a D2M dongle.
The field report recorded 10 call attempts each across four test cases. It reported zero call blocks, a 100 per cent call setup success rate and a 100 per cent SMS send success rate in all four cases.
The report said incoming voice calls were successfully received and handled, SMS messages were delivered correctly, and D2M playback either resumed after the call or continued normally where no interruption was required.
The field verification concluded that D2M service did not impair the successful receipt and handling of voice calls or SMS messages under the tested conditions.
Prasar Bharati also tested Single Frequency Network functionality for D2M transmission in Delhi. The demonstration used combinations of High Power High Tower and Low Power Low Tower transmitters operating on 538 MHz in the Kartavya Path area.
The report said synchronised multi-transmitter configurations showed improved signal-to-noise ratio and more stable audio-video reception compared with single-transmitter operation, particularly in overlap areas.
At Central Vista Parking 2 on Kartavya Path, the test recorded a weak baseline condition of about -78 dBm RSSI and 4 dB SNR with only HPHT. This improved to about -63 dBm and 22 dB SNR with HPHT plus one LPLT. With HPHT and additional synchronised LPLT sites, the report recorded around -49 dBm to -58 dBm and 23-30 dB SNR.
The report concluded that SFN operation enhanced reception robustness and coverage continuity for D2M service under the tested field conditions.
The latest report follows earlier tests conducted on November 14, 2025, after some stakeholders raised concerns over possible interference with telecom services and heating of mobile devices. Those results were published by Prasar Bharati on November 21, 2025.
The D2M issue has been closely watched because telecom industry bodies had earlier objected to the government’s technical testing process, saying it was not inclusive and lacked transparency.
The industry had sought a broader, technology-neutral evaluation with telecom operators, device makers, chipset vendors, regulators and accredited laboratories involved.
The latest ToR says the updated evaluation framework was prepared after a March 6, 2026, meeting of nominated nodal officers from DoT, MeitY, DST, DEA and IIT Kanpur under the chairmanship of the CEO of Prasar Bharati.
However, the ToR also states that the scope at this stage was limited to laboratory verification of out-of-band emissions and functional verification of IMT voice calls and SMS during active D2M streaming. Other field performance tests, including QoS KPIs and EMF exposure measurements, were excluded at this stage.
Prasar Bharati had entered into an MoU with IIT Kanpur in 2019 to develop a next-generation broadcast roadmap for digital terrestrial broadcasting. IIT Kanpur later conducted a small-scale proof of concept on D2M Next Gen Broadcasting in Bengaluru with its technology partner.
A hybrid proof of concept involving HPHT and LPLT infrastructure was later conducted in Delhi, using a television transmitter at Pitampura as HPHT and several LPLT transmitters around Kartavya Path.
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