Total RF shows winning wireless ways for coverage of NYC Marathon

By Ken Kerschbaumer

Wireless audio and video technologies took central stage this weekend during TV coverage of the New York City Marathon. And it was up to Total RF to ensure the broadcast went off without a hitch.

This is the granddaddy of them all, says RF Central CTO James P. Malone. This is the marathon all the others look up to.

Total RF s crew has done hundreds of marathons but it s the New York City Marathon, with its mass of humanity and unique geography over five boroughs that shows how big a wireless show can get. The Chicago marathon, for example, requires only two RF transmission sites as the runners run in a circle while the Boston Marathon requires six transmission sites with five located on 120-foot platforms to overcome changes in elevation during the race. But the attention the New York City Marathon grabs around the world requires special attention.

Four motorcycles, two trucks and two helicopters outfitted with Flir gyro-stabilized camera systems grab action on the course and send it back wirelessly to one of three receive and transmission sites: one in Bay Ridge, Brooklyn, another on top of the Citibank building in Queens and a third on the roof of the GE Building in Manhattan.

We have six antennas that collect the signals on the rooftop and a maximum ratio combining diversity systems to reinforce the signal whenever there is loss due to interference, says Malone of the digital systems that are now standard operating procedure for the marathon.

The receivers then multiplex ASI bitstreams into Tandberg multiplexers before sending the signals back to the production truck located near Tavern on the Green in Central Park.

COFDM allows us to spread data over multiple carriers in the same band and interleave them so that one carrier reinforces another, he says. Data is redundant and an echo canceling system cleans up the signals.

The core technical component are Gigawave transmitters, Tandberg and RF Central encoders, Tandberg multiplexers in the truck and a backbone network from Harris, Eurotech and Extranet.

A new technology that was experimented with this weekend was a system that automatically switches from one transmit site to the next. Right now it s up to manual operators to keep on top of the strongest signal.

The next challenge will be going HD. Right now we re around 7 Mbps per carrier so we ll need to step that up to 18 Mbps, says Malone who has begun experimenting with double and triple transmission systems to get enough bandwidth for HD.