New Delhi: Prasar Bharati has released fresh laboratory and field evaluation reports on Direct-to-Mobile (D2M) broadcasting in the 470-582 MHz spectrum band, stating that the technology did not interfere with mobile voice calls or SMS services under the tested conditions.
The latest tests, conducted using ATSC 3.0-based D2M transmission technology, come amid continuing scrutiny from the telecom industry over possible interference risks with IMT services and concerns related to device heating.
According to the public broadcaster, the evaluations were carried out in collaboration with the Ministry of Information and Broadcasting, Telecommunication Engineering Centre (TEC), the Wireless Planning and Coordination wing of the Department of Telecommunications, MeitY, DST, Indian Institute of Technology Kanpur and its technology partner.
Field Tests Show 100% Call and SMS Success Rates
The field trials were conducted in Delhi on March 25, 2026, to assess whether mobile services retained operational priority during active D2M streaming sessions.
Tests were carried out on both Jio and Airtel networks under 4G, 5G and 2G conditions using devices such as the MarkOne D2M handset and Samsung smartphones equipped with D2M dongles.
The report documented 10 call attempts across four different test scenarios and recorded zero call failures. It reported a 100% call setup success rate and full SMS delivery success across all cases.
According to the findings, incoming voice calls were received successfully while D2M playback either resumed automatically after calls or continued uninterrupted where no pause was required.
The report concluded that D2M operation did not impair the successful handling of voice calls or SMS services during the test conditions.
Lab Evaluation Clears Emission and Leakage Parameters
The laboratory evaluation was conducted on March 13, 2026, at Bengaluru-based Aracion Technology Private Limited, a TEC-recognised testing facility.
The tests focused on measuring base station transmit power, spurious emissions and adjacent-channel leakage for a 40W D2M Broadcast Radio Head operating in the 470-582 MHz range.
According to the report, the equipment satisfied all acceptance criteria for channel power, spurious emissions and adjacent-channel leakage across lower, mid and upper frequency bands.
The broadcaster said the D2M system complied with Category B base station transmitter spurious emission limits specified under 3GPP standards. Testing covered frequency ranges from 9 kHz to 2.910 GHz, including harmonic regions.
Measured transmit power values ranged between 45.75 dBm and 47.24 dBm across 474 MHz, 522 MHz and 578 MHz test frequencies, with all conditions marked as pass.
Adjacent-channel leakage measurements were also found to be within prescribed limits across all tested frequency ranges.
SFN Trials Indicate Improved Coverage Stability
Prasar Bharati also conducted Single Frequency Network (SFN) demonstrations for D2M transmission in Delhi using combinations of High Power High Tower (HPHT) and Low Power Low Tower (LPLT) transmitters operating on 538 MHz near Kartavya Path.
The report stated that synchronised multi-transmitter deployments improved signal quality and reception stability compared to single-transmitter operation, particularly in overlap zones.
At Central Vista Parking 2, baseline conditions using only HPHT infrastructure recorded around -78 dBm RSSI and 4 dB SNR. The addition of synchronised LPLT sites improved readings to approximately -49 dBm to -58 dBm RSSI and 23-30 dB SNR, according to the report.
The field assessment concluded that SFN deployment enhanced reception robustness and coverage continuity for D2M broadcasting under the tested conditions.
Industry Scrutiny Continues
The fresh reports follow earlier D2M tests conducted in November 2025 after telecom stakeholders raised concerns regarding possible interference with telecom networks and handset heating issues.
Industry associations had earlier criticised the government-led testing process as lacking transparency and broader stakeholder participation. Telecom players had sought a technology-neutral evaluation framework involving operators, device manufacturers, chipset vendors, regulators and accredited laboratories.
Prasar Bharati said the updated Terms of Reference for the latest tests were finalised after a March 6, 2026, meeting involving nodal officers from DoT, MeitY, DST, DEA and IIT Kanpur under the chairmanship of the broadcaster’s CEO.
However, the revised framework also clarified that the current phase was limited to laboratory verification of out-of-band emissions and functional validation of voice calls and SMS during active D2M streaming. Broader evaluations, including quality-of-service KPIs and electromagnetic field exposure studies, were excluded at this stage.
Prasar Bharati has been working on D2M broadcasting technology since signing an MoU with IIT Kanpur in 2019 to develop a roadmap for next-generation digital terrestrial broadcasting in India.
Subsequent proof-of-concept trials were conducted in Bengaluru and Delhi using hybrid HPHT and LPLT transmission infrastructure, including the use of the Pitampura television tower as part of the Delhi pilot deployment.
