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Making Daisy Chains From Field of Towers

The FCC has shown broadcasters their post-spectrum auction repack future, and it’s all about daisy chains.

Not the child’s flower necklace, but in the engineering sense of the term. In broadcast TV, a daisy chain is a blueprint for towers in contiguous markets, a key part of the ongoing and bold—some might say Byzantine—plan by regulators to redistribute the nation’s airwaves more efficiently.

The process will amount to a second DTV transition requiring thousands of channel changes, tower and antenna moves or tweaks, equipment testing and channel re-tuning by millions of viewers.

While broadcasters had been pitching a regional approach to reallocating new channels after the incentive auction, it proved to be more about physics and geography FCC officials said when unveiling the plan on Sept. 30.

Had it been workable, a regional approach would have been better for deploying resources given what broadcasters point out is a limited number of crews for modifying towers and installing transmission lines. But it turns out that the repacking physics means there will be chains of stations whose moves are interrelated, but not neatly confined to compact geographic areas, said the FCC.

That means a phased approach. It will be regional to the degree that in no DMA will there be more than two phases, which limits consumers’ need to re-scan for channels. (For a glossary of repack terms to know, visit

The number of stations that will have to change channels after the auction is monumental, even if the FCC can’t get wireless companies to pay for the 114 MHz it is clearing—the reverse portion of the auction is likely to be completed by sometime next week.

If the FCC clears 114 MHz, the number of stations that will have to move to new channels is a whopping 1,393, with 799 of those moves dependent on the moves of at least one other station. The largest set of linked moves will involve 105 stations that will need to coordinate.

But even if the FCC only clears 84 MHz, it will still mean 1,274 stations have to switch channels. Of the total, 710 moves are linked in some way, requiring extra coordination.

Scale of Change Prompts Worry

B&C spoke with broadcasters to gauge reactions to the plan, but they all requested anonymity given they are still vetting the complicated design. All pointed to one key detail, which is that even at the 84 MHz clearing target, far more than a thousand stations would be moving, which has them worried about whether the government has set aside enough money and time to accommodate it.

The FCC is trying to limit the number of stations whose moves are connected—“breaking up the daisy chains,” as one broadcaster put it. But there remain complexities within each market’s moves—some stations will have to change towers, others only make minor modifications—that some broadcasters are concerned are not sufficiently addressed in the FCC plan.

“The FCC’s value-add is they are trying to reduce the daisy chains, but what about the 20 different scenarios within those smaller chains?” asked a broadcasting executive who requested anonymity.

Broadcasters want the FCC to finesse the plan to take that into account. Despite its complexity, some say, it may also be an overly simplistic approach. There are still many unknowns in this unprecedented reverse/forward spectrum auction.

FCC Media Bureau chief Bill Lake says a strictly regional approach was impossible because “these daisy chains, we find, don’t really respect geographic areas. It is more a matter of physics and the allocation of channels.” Lake also says that phased approach and staggered transition start times will cut down on interference as stations test equipment on their new channels.

“While some parties have suggested that the Bureau could divide the country into specific regions for the transition,” said the FCC in its public notice of the plan, “it is not possible to create a wholly regionalized plan that will respect interference constraints because the interference constraints create dependencies that may overlap geographic areas.” Those “some parties” included the National Association of Broadcasters, which had sought a regional repack that prioritized the most populous regions first. The NAB was still working through the plan at presstime, and had no comment.

Jean Kiddoo, incentive auction task force deputy chair for the transition, said that they had talked to stakeholders who originally were looking for a geographic approach and “once they started diving into it their view had changed somewhat since they now understand the whole dependency problem.”

Next Steps

Look for the FCC to transition the stations that have to be repacked in the wireless band as early as possible so that those wireless companies can start using the spectrum they have bid billions of dollars for in the forward auction.

Still, the FCC won’t know for weeks or months the number and identity of the stations that will need to move to new channels. But the agency wanted to put out its plan for structuring that move now so stakeholders could see it and comment on it, says the Media Bureau’s Lake.

Once the auction does close, the FCC will send out confidential letters to stations with their final channel assignments so they have more time to prepare.

“Like the many other decisions related to this auction, we find ourselves attempting something for which there is little or no precedent,” Lake said. He adds that the FCC’s plan is just that—a plan—and one he insists can be “improved or altered” following input and insight from stakeholders. As it stands, the proposal is already the result of consultation with broadcasters and wireless operators and tech companies.

All this channel-changing will cost big in equipment fees. For example, an NAB-commissioned study concluded that for stations that move to a lower channel—which is what the transition is primarily all about—each would need new auxiliary and main antennas that could cost up to $450,000 apiece. Congress set aside $1.75 billion, but broadcasters don’t think that will cover it.

Beyond cost, broadcasters are not convinced there will be enough time to make the switch inside the 39-month deadline following the auction. The FCC has a waiver policy for stations that can’t meet that deadline, and chairman Wheeler said he would be at the head of the line to Congress if the money was not enough. (Of course, Wheeler will almost certainly not be at the FCC when the bill comes due, given that he will likely be gone by the middle of next year, if not sooner.)

The logistics of this repack look scary-hard, so it’s apt that the FCC made Halloween (Oct. 31) the deadline for initial stakeholder input on the plan.

Lake says the FCC is willing to make changes to the proposal based on stakeholder responses. Asked the chances the FCC would do that, one broadcaster said: “That’s the $1.75 billion question.”


The FCC is proposing not to let stations park on temporary channels during the transition. That’s good news for broadcasters, who had opposed it.

The bad news for stations is that the FCC is seeking input on whether that was the right decision, or whether it should allow them after all. That worries broadcasters because of the potential added cost and impact on viewers who would have to retune their sets from the old channel to the temporary, then again to the new one.

“Using a temporary channel during the transition could reduce the size of linked-station sets but would also add costs, strain resources, and add more rescans for viewers,” the FCC said in arguing that the liabilities outweighed the benefits.

While the FCC said temporary channels would also make it easier for stations to operate and test new channels, it would also mean a double transition—to the temporary channel and then the new one.

Broadcasters did not want to have to make that double move and opposed the temporary channels.

The FCC said one way that temporary channels might be allowed was if it found other means of reducing the number and size of sets of linked stations.