Charles W. Rhodes

My research into DTV-DTV interference resulted in some interesting spectrum plots concerning third-order intermodulation (IM3) products as a source of such interference.

I have recently written about the hot topic of sharing broadcast spectrum with unlicensed devices.

By all accounts, the IEEE Fall Broadcast Technology Symposium was a success.

With repacking now in the future for many UHF broadcasters, the problems of interference between DTV signals crammed into Channels 14–29 for example, need to be reconsidered.

In 2014 the FCC published details on how it will configure the 600 MHz Band.

If my antenna is on my rooftop, everything is probably OK, but if my antenna is indoors, it may pick up enough signal power from a nearby cellphone to block DTV reception.

All third-order intermodulation products, (IM3 and Triple Beats), occupy three contiguous channels, so there can be interference to reception on Chs. 30, 31, 32, 33, 34, and 35.

It’s a given that there is going to be considerable “channel shuffling” after the upcoming television broadcast spectrum auctions.

This column has used the term “D/U ratio” (desired/ undesired) in describing how the FCC might repack the UHF TV spectrum.

I expect the FCC to soon grant permission for LightSquared to proceed with its build-out.

In addition to DTV sideband splatter into adjacent spectrum, there is another source of noise jamming built into receiving devices that have poor RF selectivity.

So what should the FCC do about Channel 30?

My simulations indicate the spectrum which may be generated in GPS receivers by LightSquared signals.

Additional testing set for January was to involve prototypes of GPS receivers and active GPA antennas for commercial aircraft

FM traps help, but won't solve every problem.

The average field strength of a SFN would have to decrease to permit all incumbent broadcasters to continue to with their very own channel.

It is a little early for ghost stories, but let’s hope single frequency networks don’t come to haunt broadcasters.

Distortion comes in two basic classes: Linear distortion, which is not an oxymoron; and nonlinear distortion, which includes all other distortions except noise.

In the past, I have written about out-of-band (OOB) interference between ATSC signals in different bands: the low VHF band into a high VHF channel and a high VHF band ATSC into a UHF channel.