Harry Jessell’s column on the troubles of digital VHF missed the mark. It can work as well as UHF transmission if it is allowed enough transmission power, receiver performance improves and indoor and outdoor antennas are designed to receive both spectrum bands properly.
Editor: Harry Jessell’s column, “VHF: Now Everything You Know Is Wrong,” missed the point of why so many folks are having problems with VHF DTV reception.
First, the FCC disregarded much of the early research done during the ACATS and Grand Alliance process that recommended power levels nearly 10 db higher than were ultimately adopted in VHF DTV service. It would appear that the incentive for lower signal levels was to accommodate tighter packing of coverage areas to insure all stations in the U.S. at the time had a DTV simulcast station. Getting the table of allocations to work at higher signal levels just became too problematic.
Next is the lack of minimum DTV receiver performance standards. This is particularly true of VHF DTV receiver performance. The receivers’ input preamps, adaptive equalizers (ghost cancelers) and ability to reject unwanted signal rejection (as in FM signals) seem to be poor and add to the issues of good VHF DTV reception in most markets.
Last, and maybe most important, is the poor quality and VHF performance of consumer receiving antennas, both indoor and outdoor types. Many, if not most, indoor and outdoor antennas advertised for DTV use have little or no VHF performance.
I recently saw an advertisement on a major antenna company Web site that appears to be a conventional, multi-element bow-tie style UHF antenna. Yet, it states: “Reception Range: Channels 7 thru 13, up to 45 miles and HD, and channels 14 thru 69 up to 60 miles in HD.” I would be shocked if this antenna had any VHF performance at all and would bet it has instead negative performance.
I am not picking on just this one company. All of the major antenna manufacturers are guilty of misleading consumers and are allowed to continue to selling these useless VHF antennas to consumers.
If the FCC wants to do something about VHF DTV reception, this is a good place to start. At the very least the FCC needs to clean up the antenna advertising and packaging claims. The viewers just do not have the sophisticated knowledge to understand what they are purchasing.
VHF DTV transmission can work as well as UHF transmission if it is allowed enough transmission power, receiver performance improves and indoor and outdoor antennas are designed to receive both spectrum bands properly. — Dave Folsom, vice president and CTO, Raycom Media Inc.