Earlier this year, in February and March, the DRM Consortium conducted an extensive trial of the DRM standard in the FM band in New Delhi and Jaipur in India at the request of the AIR (All India Radio).
It was a part of an evaluation of two digital radio options for the FM band for the Ministry of Information and Broadcasting to choose from and recommend.
The measurements were done with a professional DRM receiver and a selection of commercial DRM receivers and mobile phones upgraded for DRM reception in the FM band.
The measurements were carried out based on a pure-digital single DRM signal (block) as well as multi-DRM configurations (placing multiple DRM blocks side-by-side from a single transmitter). DRM is a pure digital standard, but a simulcast operation (DRM and analogue FM signals side-by-side from a single transmitter) was also conducted from the same transmitter. DRM was also shown to work in FM white spaces without affecting ongoing analogue FM transmissions.
The measurements demonstrated that DRM can deliver up to 3 audio plus 1 multimedia service per DRM signal block in the given spectrum , while allowing for maximum utilisation of the FM-band spectrum.
During the trial it was confirmed that adding DRM transmissions to the FM band is fully compatible and does not interfere with on-going analogue FM services. Also, DRM as a pure-digital radio standard has the ability to efficiently broadcast multiple DRM signals side-by-side from a single transmitter, and for operating in flexible configurations alongside an analogue FM signal from the same transmitter.
DRM also delivered additional Journaline advanced text service in multiple Indian languages, to be ready for delivering Emergency Warning Functionality, and to efficiently enable traffic, travel and online teaching services over broadcast, without requiring internet connectivity.
It was also proven that existing receiver models, already supporting DRM in the AM bands as adopted by India, can support DRM in all bands by a simple firmware upgrade without hardware modifications.