mobile receiver screen capabilities, then compressed in AVC through the Dektec DTC- 315 DtEncode software package.


The Harmonic device muxes


the three HD content (T2 Base) with the mobile content (T2 Lite) and adds the references for SFN operation, generating the T2-MI stream. Through radio link connections, the T2-MI stream is delivered to the transmitting sites in St. Vincent (Salirod transmit site) and in Aosta (Gerdaz transmit site). At each of these sites, the


data stream is routed to a Screen Service modulator. This device is still a prototype, and it’s made of two separate units. The Base and Lite PLPs are time sliced, so the Slave modulator takes care of the Base and sends it to the Master; whereas the Lite PLP is handled and the final RF output is synthetised. The subsequent Screen Service amplifier boosts the output up to 50 W (Aosta) or 100 W (St. Vincent) RMS, which is aired through dedicated antennas. The modulators of the two transmitting sites get the relevant time and frequency reference signals from the GPS receiver card hosted in the


modulator chassis. Building the receiver was a


bit more complicated. Since no commercial T2 Lite capable receiver is available, Sony supplied RAI specialists with a sample board based on the company’s CXD2861 silicon tuner and a prototype receiver that can output T2 Lite content as a parallel data stream, which is then decoded into baseband video.


The receiving system fits


into a light van. It is also equipped with a position tracking device and a data recorder to track the RF parameters and receiving conditions during mobile reception. Tests were conduced under these modulation parameters: T2 Base: 256 QAM Rotated, FEC 3/4, FFT 32k, GI 1/128, PP7, with 28.2 Mbps payload T2 Lite: QPSK Rotated, FEC 1/2, FFT 8k, GI 1/32, PP4, with of 2.2 Mbps payload.


Screenshot from Sony receiving board during mobile test


RESULTS We were really impressed during the T2 Lite mobile test. Even on the typical curving roads you find on the mountains, with frequent 180 degree turns, almost no problem was detected in receiving both the audio and video signals.


On the A5 motorway, while driving up to the 130 km/h


The T2 Lite measurement campaign affirmed the success of two transmitters working as an SFN.


speed limit, as well as in the narrow roads of downtown Aosta, everything performed far ahead of any reasonable expectation; based on past experiences with other systems. Overall, the T2 Lite


measurement campaign affirmed the success of the two transmitters working as an SFN . Together, they provided an effective coverage of the entire Aosta valley floor, with some good coverage zones along side valleys when the relevant geography allowed RF waves to pass through. ///


April 2014 I TV Technology Europe


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