(meteorobs) Fwd: Digital TV

[bob71741]

When digital TV (ATSC) replaces analog TV (NTSC), the frequency plan
will remain the same;for example, ch4 will still be 66-72 MHz. What
channels will not be available still appears to be rampant speculation
and rumor at this time. Some say the lower VHF (2-6), and other
sources cite some UHF stations.

If you monitored the TV audio subcarrier on an FM receiver, this will
not be available with ATSC operation. If you monitored the video
carrier with an AM/SSB receiver, then a pilot carrier will be
available to continue the monitoring since the digital video carrier
will be surpressed due to the nature of the digital modulation. The
pilot carrier will  be available on all channels at 60 KHz above the
current video carrier frequency. For the channel 4 example, the pilot
carrier will be at 67.31 MHz, 60KHz above the 67.25 video carrier
frequency.

Hopefully the new converter boxes may provide some handles to monitor
an AGC voltage, or to simply be used an an RF converter to continue
forward scatter monitoring.

Regards
Bob

--- In meteorobs at yahoogroups.com, Ed Majden <epmajden at ...> wrote:
>
> Thomas Ashcraft wrote:
> 
> PS:  The future of tv forward scatter in the US may be coming to an end
> in the next year as the tv broadcast system moves to digital.
> 
> 
> Begin forwarded message:
> 
> > From: Mark Kardos
> > Date: December 13, 2007 2:14:29 PM PST
> > To: Ed Majden <epmajden at ...>
> > Subject: Re: Digital TV
> >
> > Hi Ed,
> >
> >         As far as I know, don't count on the currently used 
> > frequencies. CBC has one Digital TV transmitter in operation, in 
> > Vancouver. It is listed as CH 58VL, at 734.31 Mhz. The equivalent UHF 
> > frequency is CH 58 at 734.25 Mhz. As far as I know, there wont be any 
> > signals broadcast in the current low-band VHF (CH-2 to CH-6).
> >         I haven't seen any paperwork yet on what the new systems will 
> > be like, because Vancouver Island will be getting only one 
> > transmitter, for Victoria, and that project hasn't started yet.
> >         Everything else will be off the air as of August 31, 2011, 
> > according to Industry Canada.
> >         As for the characteristics of the carriers, the current 
> > carrier you are monitoring is just an AM modulated signal. DTV will 
> > look more like the signal you currently get off of Expressvu or 
> > Starchoice, where multiple channels can be multiplexed through the 
> > same transmitter.
> >         The big push in the industry is to get the transmitters on
the 
> > air, as who-ever does it first will then be able to lease space to 
> > other broadcasters. It's cheaper than everyone setting up their own 
> > site.
> >
> >
> > At 12:23 PM 13/12/2007, you wrote:
> >> Hi Mark:
> >>         With my forward scatter meteor detection setup I monitor CH3 
> >> at 61.26 Mhz.  What is going to happen when TV switches to digital 
> >> broadcasting?  Will the carriers remain at the same frequencies with 
> >> the same characteristics or will this render forward scatter systems 
> >> obsolete?
> >> This question came up on meteorobs so I thought I would ask your 
> >> opinion.
> >> Thanks:
> >> Ed
> >
> _______________________________________________
> Mailing list meteorobs: meteorobs at ...
> To UNSUBSCRIBE, email: owner-meteorobs at ...
> http://lists.meteorobs.org/mailman/listinfo/meteorobs
>