[opendtv] NYC SFN test

Here's an excellent short article on the NYC 2-tower SFN test, from this
past November:

http://broadcastengineering.com/infrastructure/ion_single-frequency_netw
ork/

The article explains that the exciters from multiple transmitters are
synchronized, in particular to synchronize the trellis coding of each
tower.

The paragraph that most succinctly describes how this SFN is configured
is:

"Two transmitters were used for the tests. The main transmitter was
located in West Orange, NJ, and a secondary transmitter was located in
Manhattan at Four Times Square. The main transmitter already provides
coverage to most of the market. The secondary transmitter's job was to
improve the coverage in Manhattan and parts of Long Island where the New
York City skyline was acting as a shield to the main signal."

To me, that's why the test was successful. One main transmitter site for
the bulk of coverage, with the supplemental signal expected to be
surrounded by signal from the main site, so that the echo tolerance of
receivers is not exceeded in areas where the supplemental tower's signal
is still strong.

This arrangement is similar to the Paris SFN.

Bert
 
 
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