Harris Broadcast Communications has printed a technical support
paper, "Low Band VHF Television Transmission and Amateur Radio
Operation" in January, which comprehensively analyzes the condition
in which a channel 2 NTSC TV transmitter (one of their models) can
introduce interference in the weak signal portion of 6 meters. The
transmitter is not neccessarily at fault, since it meets the FCC
specifications. However, the Rules and Regs are not sufficient to
ensure that hams don't get clobbered. This is mainly a concern for
folks living within line of sight of the TX tower, where the
sidebands can still present noise above the floor of most ham RX
setups. Some tricks are mentioned, such as adding high power filters
at the TX, or at each receiver, and it presents the optomistic
conclusion that in 2006, NTSC transmitters will cease operation in
North America, while the DTV emission mask is more stringent.
To read a copy:
http://www.broadcast.harris.com/support/white_papers.asp
Then go to Television, and download the big file. It is a well done report.
73
John
K5PRO
--
|