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Roadmap 2024-DRM digital radio services in FM band in India

All India Radio (AIR), the public service broadcaster in India, is providing terrestrial radio services in all the radio broadcast bands – MW, SW, and FM. Commercial broadcasting in FM band is licensed to private radio stations, and community radio stations are also permitted for non-commercial use.

At present, most of the terrestrial radio services in India are in analogue, except for some services of AIR in MW and SW bands, which are in DRM digital.

Keeping in view the advantages of digital radio broadcasting, the Telecom Regulatory Authority of India (TRAI), the regulator for broadcasting, on Feb 1, 2018, had recommended to the Ministry of Information and Broadcasting (M/o I&B), Government of India, that digital broadcasting in FM band (VHF band II) should also be allowed, without disturbing the existing analogue transmissions.

The regulator on Sep 21, 2023, has further recommended to the M/o I&B that the commercial use of low-power terrestrial FM broadcasting for small range coverage by residential complexes, industrial exhibitions, and small businesses may also be permitted and the licensee should be allowed to deploy any type of transmission technologies (analogue/digital/any other).

DRM digital radio standard – About

DRM digital radio

  • Is the most modern, non-proprietary, open digital radio standard. It is recognized and endorsed by relevant organizations, namely ITU and ETSI, and is currently in use in India
  • Is the only digital radio standard that works in all the radio broadcast bands (Fig. 1) – enabling local and regional coverage scenarios as well as large-area and international services with a single standard.

Fig. 1: DRM is the only digital radio standard for all bands, and AM/FM successor.

  • Goes beyond just audio transmission. Not only does DRM provide high-quality audio, but it also offers a range of additional services, such as Journaline, a text and Unicode-based service that presents content in several Indian languages, in a structured format. DRM also supports the transmission of multimedia content like images, graphics, and slideshows, as well as interactive applications that allow listeners to actively participate and engage with the radio broadcast (Fig. 2)

Fig. 2: Multiple services in DRM within an allocated frequency spectrum of 100 kHz.

  • Is scalable both in terms of service offering and spectrum usage. It offers up to four services (3 audio, 1 data) on a single transmission frequency (one DRM block) and allows for multiple DRM blocks side-by-side. This scalability makes DRM digital radio a highly spectrum-optimal and energy-efficient system
  • Delivers improved coverage with minimal interference. DRM digital radio utilizes digital modulation and sophisticated error-correction techniques and incorporates efficient audio coding with xHE-AAC. These mechanisms ensure robust and reliable reception. xHE-AAC is natively supported on Android and iOS and is available on modern mobile phones as a default.
  • In India has seen the fastest market penetration for digital radio technology with over 60 lakh cars with line-fit DRM radio as of mid-2023.
  • Includes emergency warning functionality (EWF) to provide timely and much more effective dissemination of emergency alerts and warnings to the public which cannot be missed by radio listeners irrespective of whether their radio devices are in standby mode and/or tuned to any other frequency. DRM’s EWF is capable of multilingual audio alerts complemented by Journaline text-based service providing detailed information
  • Is on-air broadcasting, delivering one-to-many services and serving equally well an unlimited number of listeners in the given coverage area. Therefore, DRM broadcast does not suffer from point-to-point connection technologies, such as Wi-Fi, Bluetooth, or even mobile phone networks that easily over-saturate in crowded hotspot places, such as stadiums, gathering places, or events

DRM digital radio standard for FM broadcasting too – Justifications
DRM digital broadcast in FM band can benefit from the myriad of services and broadcasting features made possible by DRM digital radio. The following justifications are furnished in support of DRM digital radio over analogue FM:

  1. State-of-the-art future-proof technology. Analogue FM gives reasonably good-quality audio service, but it is a 20th-century technology with limited innovation scope. It is both spectrum- and power-hungry, offering only a single audio service per frequency. Digital broadcasting in the FM band provides multiple services, within the same allocated frequency band, at much-reduced power, along with a host of other value-added services. Due to the inherent advantages of digital transmission, broadcasters the world over are adopting high-quality digital delivery systems.
  2. Half the frequency spectrum required. One audio channel in analogue FM requires a 200-kHz frequency spectrum, whereas one block of DRM digital (which enables the broadcast of up to 3 audio programs and additional multimedia services like Journaline) requires only 100 kHz, i.e., half the spectrum that is required for an analogue FM transmission.
  • Multiple single audio channels and value-added services. In analogue FM, only one audio program can be broadcast in the allocated 200 kHz bandwidth, whereas DRM digital enables to broadcast up to three audio programs (and additional multimedia services like Journaline), within just 100 kHz bandwidth. The availability of two additional audio channels is very important to provide 24-hour news, entertainment, commentaries in multiple languages, etc. It is observed that movies are being carried today on TVs in as many as 20 languages simultaneously. Since multiple DRM blocks (up to 8 blocks) can be carried by a single FM transmitter, a broadcaster can take permission for multiple adjacent channels to broadcast programs in more than three languages, whereas in the case of analogue FM, several transmitters will have to be installed by giving larger frequency offsets and the use of additional combiners.
  1. Seamless incorporation into the national CAP-integrated alert system. In keeping with the plan of the Government of India to provide emergency warnings on all types of platforms, the National Disaster Management Authority (NDMA) is considering the possibility of using the AIR DRM transmitter network also for the dissemination of emergency warning signals. Once the AIR DRM transmitter network starts broadcasting the emergency signals, all types of DRM receivers in use (irrespective of whether they are ON, in standby mode, or tuned to any frequency) will also be able to receive emergency warning signals automatically. As this feature is not available in analogue FM receivers, reception of emergency warning signals will be a very important added reason to provide radio services in the FM band in DRM digital mode only.
  2. No additional spectrum required and efficient use of white spaces. Large white space exists between the already operational (in analogue) large power FM transmitters; it cannot be used for transmission in analogue FM but can be very well utilized for transmissions in digital DRM. For a DRM digital operation, frequencies can be allocated to at least three users in one white space of 600 kHz between two analogue FM transmitters. Thus, a large number of radio channels are possible in DRM digital in all these white spaces in the FM band.
  3. Much lower frequency offset required. In India, center-to-center spacing of 800 kHz is kept between the two analogue FM transmitters (i.e., 600 kHz frequency gap) but a DRM digital transmitter can be installed at a spacing of only a 50-kHz frequency gap from an analogue FM transmission and/or another digital transmitter (Fig. 3). Thus, DRM digital permits the operation of many more FM-band radio services, which in any case would be required, particularly in major cities, where the available spectrum is limited.

Fig. 3: Insertion of a DRM block from a separate transmitter in the white space between existing FM transmissions, showcasing an exemplary frequency gap of 50 kHz.

  • Better cut-off in DRM digital receivers. Analogue FM receivers are required to receive signals within the selected 200 kHz bandwidth only; but it has been observed that FM receivers that do not use digital tuners, do not have a sharp cut-off of 200 kHz. As a result, these receivers get interference from the adjacent analogue FM stations. DRM digital receivers have a much better cut-off response.
  • While analogue FM offers little in terms of innovation and servicing all types of audiences, DRM digital radio is the newest, most complete, and internationally recognized standard for digital broadcasting in all frequency bands (MW, SW, and VHF). DRM digital radio offers three audio services and additional data services, such as Journaline, SlideShow, etc., which fits use cases where each audio service can be of a different language while complementing the audio with text and graphics (subtitles, additional info, ads, etc.) on Journaline. Yet another innovative prospect of DRM digital radio is public signage. A limited broadcast can make use of such public signage.
  1. Reception in mobile phones. DRM standard is supported natively on all mobile phones based on the already available tuners for analogue FM reception. No additional hardware and, therefore, no additional design or component cost is required to enable DRM digital FM support on those phones. The DRM app for mobile phones has already been developed. A consumer version of this app is now available for downloading from the Google Play Store and the Amazon Appstore under the brand name “STARWAVES DRM SoftRadio.” The App can also be installed on Windows, Linux, MacOS, and Android tablets, laptops as well as desktop computers. The mobile phone manufacturers need to provide access of the base band digital output to enable reception of DRM digital signals. The mobile phone industry is also expecting a clear policy announcement for the country to start incorporating this functionality in future phone models. For legacy phone models, external FM front-end dongles have been developed. These dongles along with the already developed DRM radio app can be used to receive full DRM FM functions.
  2. Timing is right. It is the perfect time to introduce DRM digital in the FM band for the large benefits of the DRM standard. This will be fully in line with the TRAI’s recommendation to introduce digital in FM band to digitize and to introduce the advantages of digital radio over analogue to both broadcasters and the audience. With innovative solutions, such as a single DRM receiver serving a large local audience on existing phones, and public signage using the DRM FM transmission, users will be quickly introduced to DRM digital radio giving a boost to the receiver market and Indian industry.

DRM digital radio broadcasting in the FM band – Successful trial in India
On the directions of the M/o I&B, Prasar Bharati had constituted a committee to test the ITU-approved digital radio standards in the FM band and to recommend the most suitable one for India.

As requested by the Committee, the DRM Consortium had carried out a trial in Feb/Mar 2021 and demonstrated all the features of DRM in FM band.

The first phase of the DRM trial was in Delhi wherein the key features of DRM, its efficient coverage potential and flexibility in on-air signal configurations were demonstrated from a standalone transmitter. The second phase was in Jaipur wherein the compatibility of DRM with the FM band channelization in India, where DRM fills the gaps between existing analogue FM services that are not otherwise usable, as well as its compliance with the existing CTI (shared FM transmitter infrastructure) sites was demonstrated by transmitting DRM signals between the white spaces between two analogue FM stations.

It was demonstrated that the DRM standard in the FM band occupies a fixed amount of spectrum – bandwidth of 100 kHz per block (i.e., DRM transmission signal) wherein it can carry up to four services – typically, up to 3 DRM audio services including PAD (program associated data) and one DRM data service (such as Journaline).

In addition to the basic features of carrying service labels, service description, graphical station logo, text messages, Journaline advanced text application and online hybrid interactivity, the capabilities of EWF, 5.1 surround sound, distance learning, traffic and travel information, public signage and slide show were also demonstrated.

Coverage measurement has shown that the 100W low-power DRM signal provided perfect DRM coverage for at least 25 km. Uninterrupted excellent reception was observed on the Mobis car receiver fitted in a Hyundai Verna car, which went around Delhi.

Pure digital operation for single DRM signal as well as multi-DRM configuration, simulcast (DRM and analogue FM) operation and multi-DRM in FM white spaces were also demonstrated (Fig. 4).

Fig. 4: 5-Block multi-DRM transmission in white space between 2 analogue FM stations.

It was demonstrated that all the Android phones could receive (Fig. 5) DRM in FM band, using off-the-shelf dongles and the Starwaves DRM radio app.

Fig. 5: DRM reception on mobile phone.

An efficient DRM rollout approach in the FM band
For digital rollout in FM band, there are different scenarios that could be considered. The following three are the best options:

Option A – Install a single new multi-block DRM transmitter in white space per locality. The cheapest and the easiest way to rollout digital radio services in the FM band is to add a single new broadband transmitter in the unused white space between two analogue FM transmitters to carry multiple DRM blocks. The output of this transmitter can be fed to a separate antenna. As mentioned above, in the white space of 600 kHz between two high-power analogue FM transmitters, it is possible to transmit up to 5 DRM blocks (Fig. 6) successfully from a single transmitter. This has been successfully demonstrated.

Fig. 6: 5 DRM blocks in white space of 600 kHz between 2 analogue FM transmitters.

Option B – Use of existing analogue FM transmitter for DRM digital transmission on time shared basis. As detailed above, in the 200 kHz bandwidth available to a broadcaster for an analogue channel, two DRM blocks can be transmitted, thereby providing up to six audio services and additional multimedia services like Journaline, DRM text message, etc. (provided the existing transmitter is capable to work in linear mode for digital signal transmission).

After the DRM services are available in the country and digital reception devices are available in sufficient quantity, by adopting option A outlined above. However, the broadcaster may be motivated to use this option initially on time-shared basis to transmit DRM digital services.

Option C – Operation of the existing analogue FM transmitter in simulcast mode to carry analogue as well as digital services. If the adjacent unused white space, to the one and/or either side of the analogue signal, is allocated to a licensed broadcaster, he would be able to broadcast one, two, or up to six DRM blocks (Fig. 7), in addition to the service in analogue, from a single transmitter.

Fig. 7: Simulcast of analogue & DRM blocks from a single transmitter.

To sum up, The DRM digital radio broadcasting standard has been designed by the broadcasters, for the broadcasters, with the active assistance and participation of both the transmitter and the receiver manufacturers and other interested parties (such as regulatory bodies). DRM is a high-quality and feature-enhanced digital replacement for the former analogue radio broadcasting standards AM and FM; as such it can be operated with the same channeling and spectrum allocations as currently employed. At the same time, DRM is the only standard which works in all the broadcast bands and can operate smoothly alongside ongoing analogue services in all the broadcast bands.

DRM is on-air in India and expanding in Asia – with Indonesia, China, and Pakistan adopting DRM. Over the past years, DRM receiver, chipset, and automotive manufacturers have invested significantly to bring down the cost of new receiver models, and to increase the sensitivity and feature completeness on those receivers. New chipsets and modules are now available, which will enable the production of low-cost Make in India DRM receivers. India today is the global center of DRM technology and know-how. Indian industry sees a lot of opportunities for export too.

For substantial power saving, excellent sound, efficient use of spectrum, multi-channel provisions, e-learning options, emergency warning functionality, and win-win situation for all the stakeholders, it is requested that the Government of India may announce at the earliest the policy by the Indian government for the use of DRM in FM band by the public service broadcaster (AIR/Prasar Bharati), private broadcasters, community radio stations (CRS), and for small-range low-power FM broadcasting.

The government may also make it mandatory for all mobile phone manufacturers to provide FM reception, including DRM digital facility in all mobile phones and all entertainment systems installed in cars. This will enable the availability of DRM digital radio reception in mobile phones without any additional hardware. Some of the mobile manufacturers have stopped incorporating the FM radio reception facility in their phones. In this connection, Indian IT Ministry, had recently issued an advisory to mobile phone manufacturers in India to continue to provide this feature in their models. TRAI has recommended that M/o I&B may constitute a committee to oversee its implementation by the mobile phone manufacturers.

In the transition period, the cheapest and the easiest way to rollout digital radio services in the FM band is that in every town/city a single new broadband transmitter, to carry multiple DRM blocks, is added in the unused white space between two analogue FM transmitters, without disturbing the existing infrastructure. The transmitter may be installed by the government or by an agency and the digital services leased out to the broadcasters on rental or cost-share basis.

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