[opendtv] Re: Integrated DTV PSIP

  • From: "John Shutt" <shuttj@xxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 2 Dec 2005 08:52:11 -0500

----- Original Message ----- 
From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>

> I'm not sure how to solve that problem. If you have to
> scan each channel, and it takes some finite waiting time
> to get the data from any given channel, you're going to
> have a long wait. Hopefully, the EPG data is stored in
> non-volatile memory, and updated in the background.

This is not the case for any of the STBs I have used so far.  Each and every 
time you call up the full guide it has to scan all the channels.  The box 
will update the mini guide for just the channel you're tuned to, but will 
forget it as soon as you change to another channel.  Nobody is making this 
stuff properly, because it's too much work.

The only workaround is to have a second tuner scanning the channels for EPG 
data, but we all know how dear a second tuner would be.  I know of DVB boxes 
with two tuners for the PVR, but I don't know of any ATSC equiviliant yet.

> The antenna pointing problem has to be solved even for
> recording devices. Meaning, not solved with rotors, IMO.
> In principle, that also applies to the analog time
> service from PBS. It seems fairly robust, but I'm sure
> it too has its limits.

The ideal situation is to be able to use omnidirectional antenna.  Unless 
you are in a very rare situation where you are way out in the boonies 
between two major markets and can only receive signals with a huge mast 
mounted antenna, an omni antenna with preamp if necessary should suffice. 
Most folks who have outdoor antennas with rotors now are for the most part 
pointing them for minimum ghosting, not maximum signal strength.  Same for 
ATSC to date.

The PBS XDS data is simply encoded in field two of the closed captioning 
vertical interval data.  If you can decode captions, your VCR can decode 
XDS.  It is rather robust and if you have a viewable picture, you will have 
retrievable data.  If you have a V-Chip enabled set, this is also the same 
place where the ratings information is carried.  Most stations just don't 
broadcast the time data.


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