A document that lends some interesting insights into the current DRM+ trial in Edinburgh, Scotland has popped up on the Web, via the European Broadcast Union's (EBU) tech website. The PDF contains graphics and outline notes used by BBC Principal Systems Architect Lindsay Cornell during his presentation preceding the EBU Digital Radio Summit held in Geneva on Feb. 17.

The UK trial, now underway for several weeks, is taking place under BBC supervision using a combined antenna facility and channel formerly assigned to a defunct commercial talk station on 107MHz. A Nautel NV5 transmitter is said to provide sufficient RF drive to produce a 1kW ERP digital signal, apparently making this the highest-power DRM+ trial to date.

According to the document, both the current and previous trials are characterized using two different ODFM service modes delivered on a 100kHz channel -- a more robust 4 QAM, which delivers a data throughput of about 50kb/s, as well as a less-resilient 16 QAM signal with a channel capacity of roughly 150kb/s. The 4 QAM test signal carries a single program stream at 45kb/s, while the 16 QAM carries two audio channels multicasting at 70kb/s each. All audio is compressed using an AAC derived CODEC.

Presentation graphics include screenshots of a spectrum analyzer used in the vehicular test bed, along with a 4 QAM preliminary coverage map.

Testing is expected to continue into the spring. A final report on trial findings will be presented to the ITU by the DRM Consortium.