Charles W. Rhodes

You'd be amazed at what stands in the way between the viewer and the broadcast signal

With the end of the FCC’s spectrum auction in January, it’s time to measure its damaging effects on broadcasters.

In its recent Report and Order, the FCC revealed 11 scenarios under consideration for a 600 MHz Band Plan following the spectrum auctions.

By now almost everyone knows the NAB has filed a lawsuit against the FCC over its spectrum auctions TV channel repack.

Such second-order distortion products may be generated by strong local FM radio signals in the front end of DTV receivers and downconvertors.

As many DTV signals are radiated in the UHF band with more than this power, they enjoy some signal level margin within their coverage area.

FMI now has three aspects.

Without any changes to OET-69, the commission could not take up any additional planning criteria such as interference between DTV signals having a channel relationship other that N±1 and N.

What a DTV signal can do that an analog signal such as NTSC could not do is to awaken sleeping persons believed by the local authorities to be threatened.

What is needed is an EAS which can alert the threatened populace while not scaring the entire nation. Our present EAS cannot do this, but a well designed Digital EAS could over our DTV channels.

The January 1954 issue of "Proceedings of the Institute of Electrical and Electronic Engineers" was a special issue devoted entirely to the NTSC compatible color television system adopted by the FCC.

The FCC regulates co-channel and adjacent channel interference by its channel allotment plan. It does not regulate “taboo channel interference,” a term left over from analog television.

Tests demonstrated that DTV-DTV interference will happen.

The first time I received an e-mail about DTV reception only during daylight hours, I was dubious.

We found that the maximum undesired signal at which these units could perform was between –22.2 dBm for the best box, to –28.7 dBm for the worst.

The FCC has a spectrum utilization committee, which is now studying all the test data. When they will finish these studies is not yet known.

The simplest scheme is to employ a much higher gain antenna.

The FCC suggests that by adopting a Single Frequency Network topology, the present minimum distances allowed between DTV transmitters could be substantially reduced.

Could an SFN support our ATSC standard, or would we have to change our DTV standard to embrace COFDM and thereby obsolete millions of receivers?

Ghosts of DTV signals could easily be seen on analog TV screens, but with DTV, they are invisible on the TV screen.

Lagging echoes are more the serious problem

There are no minimum performance specs in the FCC rules, and in fact, the FCC does not have authority to set them.

Reducing the distances between transmitters on the same channel would increase DTV-DTV interference if each transmitter continued to operate at its present power and height of its antenna.