KRON-TV's big race

The situation

To provide fluid television coverage of the race, the station had to conquer microwave transmission hurdles, such as tall buildings in the downtown financial district and the many trees in Golden Gate Park. Improvising to the best of its abilities in years past, the station compensated for such issues by relying on multiple ENG vehicles and equipment, requiring more preparation, manpower, receiver sites and use of telco fiber lines. Additionally, years of experimenting with various methods to provide motion capture of the runners had yet to yield an adequate visual signal for the producers of the show. This resulted in more work among studio producers, directors, engineers and on-air talent who were not on location, but were left sifting through limited live options.

The solution

Equipping the broadcast crew with the technology needed to capture footage from above the buildings and trees, RF Central employed maximum ratio combining, a diversity combining method in which signals from each channel are added together.

Making typical obstacles a thing of the past, two RFX-RMR-X6 six-way diversity receivers with fan-beam antennas were installed, and digital channel filters for channels 1 and 3 were mounted 640ft up the Mt. Sutro Television Tower. (See Figure 1.) Three fan-beamed antennas were placed on the east face of Sutro Tower, and the other three were placed on the west face for optimum reception for the diversity receivers. For the first time, KRON was in a position to provide coverage of both women's and men's leaders during the race, instead of having to limit coverage to only the men as it did in prior years.

While runners seek the optimum speed during the annual “ING Bay to Breakers” 12K race, KRON-TV station engineers confront a similar challenge as they strive to provide live, continuous coverage of the race from start to finish. For past races, the station used various equipment and services to determine the most effective way for delivering uninterrupted coverage of the three-hour trek through the streets of San Francisco, CA. During the May 2007 run, the station discovered key solutions using digital microwave technology provided by RF Central.

A Chevrolet Heritage High Roof (HHR) vehicle was custom built to outfit an ENG transmission package for televising the women's leaders. The men were captured with a portable high-power transmitter, RFX-PHT, which was attached to a custom motorcycle equipped with two antennas mounted onto a pole. (See Figure 2.) The bike was driven by one person, while a second rider operated the camera and talent rode in the motorcycle side car to give an up-to-the-second progress of the race.

The footage acquired by the motorcycle team was fed through a directional coupler to provide 1W power to an uplink pancake antenna for the helicopter receiver and 7W of power to an omni antenna for direct reception at Sutro Tower. The motorcycle transmitted on digital channel 1 to the two locations, streaming footage to the helicopter while simultaneously shooting to Mt. Sutro. Offering the motorcycle shots to both locations, the dual transmission gave the station more options in that it could have the helicopter get a shot from the onboard Flir camera system and also have the motorcycle shot from Sutro Tower, which had its own dedicated intercity relay to the studio. This enabled the technical director to have motorcycle and helicopter overview shot in double boxes.

The HHR car transmitted on digital channel 3 to Sutro Tower, which was sent back to the station via its own intercity relay. This supplied the studio director with instant and full access to all on-site coverage and more camera options.

The station's helicopter was outfitted with two down-looking pancaked antennas mounted on the skids of the Bell 206. The antennas' cables were run into the RF Extreme RMRTD dual-diversity receiver with its analog output feeding the aircraft switcher into the analog channel 10 helicopter transmitter which was received at Mt. Diablo receive site and then via an intercity relay feed to the studio.


While usage of RF Central equipment and services afforded KRON 4 the means to finally achieve the type of comprehensive race coverage it had been seeking, the station also maximized cost- and time-efficiency along the way. Combining high-quality with portability and simplicity cut down assembly time and the number of engineers needed for operating gear. Additionally, the equipment was lighter compared with that of prior systems used by the broadcast team, presenting a more tolerable experience in equipment and resulting in more productivity among engineers. Serving as an extension to the KRON team, several members of RF Central's professional staff were dispatched on-location the Tuesday prior to the Sunday race — where they remained throughout the week, assisting with equipment setup and demonstrating equipment applications.

Sharing its expertise with KRON, RF Central served as broadcast forecaster, evaluating the coverage location and identifying issues of concern, which included potential risks for interference. Rather than being reactive, the support staff implemented proactive measures, bringing in reinforcements by adding superpower filters to avoid issues with audio signal obstruction sparked by unknown, outside sources.

Final results

When the three hours of live continual racing action came to a close, viewers were afforded an all encompassing perspective of the “ING Bay to Breakers” 12K race like never before. In bringing the experience along the bay home, RF Central empowered KRON to reach its goals without missing a step, uncovering the hidden tools and methods necessary for achieving comprehensive race coverage.

Bill Rinker is assistant chief engineer for KRON.