[opendtv] Re: DTV Delay Bill

House failed to pass the Delay bill. June 12th delay looks dead.

http://www.broadcastingcable.com/article/162898-DTV_Delay_Bill_Fails_To_Pass_In_House.php

Bob Miller

On Wed, Jan 28, 2009 at 12:08 PM, John Shutt <shuttj@xxxxxxxxx> wrote:
> If the change is relatively small, it is easy to change frequencies.  An
> agile exciter can be tuned to another channel as easily as a television
> changes channels.  If the final output stage is solid state, there's not
> much else needed.  If the output stage is an IOT or MSDC Klystron, then the
> cavities also have to be tuned for the new frequency.
>
> Then there is the harmonic filter and the ATSC mask filter that either needs
> to be retuned or replaced.  That's not such an easy task.
>
> And finally there is the waveguide and transmitting antenna.  Certain
> waveguide segment lengths aren't compatible with certain frequencies, and if
> you have a slot antenna it is tuned for a single frequency and must be
> replaced.  If you have a wideband panel antenna, then you can reuse it.
>
> In our case the jump from 23 to 40 required gutting of everything from the
> IOT to the feedline.  The old NTSC harmonic filter had to go, the switchless
> combiner had to go, even the waveguide from the output cavities had to be
> changed out.
>
> Also, since we're going from NTSC to ATSC on this transmitter, the exciter
> and upconverter had to be changed out as well.  I think our IPAs are
> staying.
>
> John
> ----- Original Message ----- From: <dan.grimes@xxxxxxxx>
> To: <opendtv@xxxxxxxxxxxxx>
> Sent: Wednesday, January 28, 2009 11:37 AM
> Subject: [opendtv] Re: DTV Delay Bill
>
>
>> How easy is it to change frequencies?  I thought that transmitters were
>> pretty much designed for one channel and weren't easily manipulated.  But
>> it sounds like they can be changed in a day these days.  I imagine with
>> new synthesized frequency generators, it is now programmable.  How do they
>> work these days?  Is the RF processing and transmission path able to
>> handle a wide spectrum?
>>
>> Dan
>>
>
>
>
>
>
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
> - Using the UNSUBSCRIBE command in your user configuration settings at
> FreeLists.org
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
> unsubscribe in the subject line.
>
>
 
 
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 
FreeLists.org 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts: