(meteorobs) Fwd: Digital TV

[Thomas Ashcraft]

Hi Bob, Ed and all,

Thanks for the informations.

I wonder if the "pilot carrier" is available now? If so, I wonder how 
strong of a signal it puts out?

For those in western North America there is a transmitter in Boise, 
Idaho, at 40.530 MHz that is accessible if you have a radio that can get 
USB/SSB or CW at that frequency. It is an odd frequency and many radios 
don't cover that part of the spectrum.

Thomas

bob71741 wrote:
> 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
>>>>         
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