Broadcasters Have a Full-Power Problem


Emerging technology is being developed to enable a mobile broadcast component to the ATSC standard. This may be the source of badly needed additional future revenue for broadcast stations.

The upcoming NAB show will feature two system modifications to the ATSC Standard, along with live rolling demonstrations by two proponents.

While the possibility of mobile broadcast reception by cellphones, cars, trucks and personal digital appliances is exciting and may represent a new and welcome revenue stream, it remains to be seen if broadcasters will have the facilities to implement a wide area of coverage.

The wireless reception of broadcaster's transmitted signals will, by the very nature of personal devices, have to rely on small, inefficient antennas. A typical antenna on a cellphone today may only provide 10% of the signal that a full-size antenna would provide on our UHF frequencies.

In the VHF band, the signal received may only be 1% of what a full-size antenna would provide.

High transmitted power is the way to reach these small, inefficient receive antennas. Digital stations that operate in the VHF band may find it very difficult to provide robust mobile or portable service at current authorized power levels. This is not true for the UHF band.

The FCC has provided for the maximization of a broadcaster's output power. Maximization provides the means to reach small portable devices over a large market area, thus compensating for the poor antenna performance.

Stations that do not transmit at the highest legal power may find that they will not be able to effectively compete in the mobile and portable business.

How the new revenue stream develops remains to be seen, but low transmitted power in digital surely will preclude a station's effectiveness in the mobile and portable future.