The DTV mask specifications are tighter for digital than for analog for out of channel noise. In fact, it takes a special setup to even measure it since spectrum analyzers generally don't have the dynamic range to measure it directly.
Hap Griffin WZ4O VP - Engineering SCETV ----- Original Message ----- From: Ray Brown To: [email protected] Sent: Saturday, January 10, 2009 12:23 AM Subject: Re: [Repeater-Builder] DTV ch 2 vs 6m ----- Original Message ----- From: "Paul N1BUG" <[email protected]> > After transition I will have a "local" channel broadcasting DTV on > their low VHF channel 2 assignment. I'm curious... does anyone know > whether DTV will be more (or less) susceptible to interference from > ham radio transmissions than analog TV? You're going to have a DTV 02 there in Maine? Wow. Anyway, what happened in Dallas a couple of years ago ought to be noteworthy... I think one of the Dallas stations was testing full output DTV on channel 36, and Baylor University's medical telemetry, which is supposed to be in protected spectrum at channel 37, the lower third of their telemetry went "no signal" when the transmitter keyed up. Their biomed techs were in full panic mode most of that day until they figured it out. Seems that the DTV specs allow for the full 6 MHz bandwidth per channel The excess bandwidth overloaded the tele receivers, which I think were only a couple of miles away. Trying to remember the details. But everyone I've talked to says the same thing, the DTV will take up the whole allocated space, and maybe a half meg more each side. For those 6m folks, that means that everything between 53.5 and 54 MHz may become very noisy and unusable. Ray, KB0STN
