robmx
04-03-2004, 03:37 PM
(On another forum a poster had intermittent reception problems and had a large oak tree at 100 ft in the direct line of sight of all broadcast stations. My comment follows.)
I would bet that you have issues with that oak tree. How is the reception on a breezy day? That would account for your having a good signal some times and multipath interference other times.
This multipath problem if that is what it is, the possible need for multiple antennas with rotors for more than one HDTV set and the need for rotors at all come compliments of 8-VSB.
None of this would be true with other modulaiotons used by the rest of the world including DVB-T COFDM, ISDB-T(Japan) and, if the adopt it, DMB in China.
Any of these modulations would receive multiple stations on a simple omni antenna that would proablaly be installed in your HDTV set without even being visible. You would buy the set and plug it in and only if you had problems with signal strength would you even have to deal with an antenna issue at all.
Here is an example of a TV set that will work in the rest of the world sans S. Korea, the US and Canada.
http://www.followmedia-tv.com/
Note that four diversity internal antennas are incorporated into the set.
Or you could receive television on your cell phone like in Japan and soon in Europe. Before you even think it Japan does this while delivering HDTV. The cell phone actually incorporates a DTV receiver and diversity antenna.
http://www.itmedia.co.jp/mobile/0308/08/sanyo.html
HDTV can be received on PCMCIA cards with 3 inch non directional antennas while moving at 100 mph. Think about this as you fiddle with rotorized antennas for each DTV set that can be interfered with by a breeze and a tree.
All this compliments of your Congress and FCC which is supposed to have your (consumer) best interest at heart.
You might want to see how robust HDTV reception in Australia is while you are at it. 120 kph at up to 40 km from a station broadcasting at 30 kW they had good reception mobile with omni monopole antenna.
This was with a broadcast signal that was SPECIFICALLY not set up for mobile. This was set up for FIXED reception. Understand that a modulation like COFDM DVB-T (used in Australia) normally would trade robustness (mobile reception) for datarate. Not in this case. They are receiving a high datarate HDTV signal (1080i) while mobile in a 7 MHz channel (one more than our 6 MHZ) that is also broadcasting an SDTV signal. They have less than 6 MHz for the HD signal in OZ.
Go to page 13 in this PDF
http://www.dvb.org/documents/newsletters/DVB-SCENE-08.pdf
So the equation is less bandwidth, HDTV mobile with simple antenna (like the one on the cell phone in the Sanyo URL).
The equation is NOT rotorized antennas like in the US that cannot handle trees.
Just another cost associated with our current bought and paid for government. It doesn't take much to buy this government but it sure cost the citizens a lot in consequences and money. 0]
I would bet that you have issues with that oak tree. How is the reception on a breezy day? That would account for your having a good signal some times and multipath interference other times.
This multipath problem if that is what it is, the possible need for multiple antennas with rotors for more than one HDTV set and the need for rotors at all come compliments of 8-VSB.
None of this would be true with other modulaiotons used by the rest of the world including DVB-T COFDM, ISDB-T(Japan) and, if the adopt it, DMB in China.
Any of these modulations would receive multiple stations on a simple omni antenna that would proablaly be installed in your HDTV set without even being visible. You would buy the set and plug it in and only if you had problems with signal strength would you even have to deal with an antenna issue at all.
Here is an example of a TV set that will work in the rest of the world sans S. Korea, the US and Canada.
http://www.followmedia-tv.com/
Note that four diversity internal antennas are incorporated into the set.
Or you could receive television on your cell phone like in Japan and soon in Europe. Before you even think it Japan does this while delivering HDTV. The cell phone actually incorporates a DTV receiver and diversity antenna.
http://www.itmedia.co.jp/mobile/0308/08/sanyo.html
HDTV can be received on PCMCIA cards with 3 inch non directional antennas while moving at 100 mph. Think about this as you fiddle with rotorized antennas for each DTV set that can be interfered with by a breeze and a tree.
All this compliments of your Congress and FCC which is supposed to have your (consumer) best interest at heart.
You might want to see how robust HDTV reception in Australia is while you are at it. 120 kph at up to 40 km from a station broadcasting at 30 kW they had good reception mobile with omni monopole antenna.
This was with a broadcast signal that was SPECIFICALLY not set up for mobile. This was set up for FIXED reception. Understand that a modulation like COFDM DVB-T (used in Australia) normally would trade robustness (mobile reception) for datarate. Not in this case. They are receiving a high datarate HDTV signal (1080i) while mobile in a 7 MHz channel (one more than our 6 MHZ) that is also broadcasting an SDTV signal. They have less than 6 MHz for the HD signal in OZ.
Go to page 13 in this PDF
http://www.dvb.org/documents/newsletters/DVB-SCENE-08.pdf
So the equation is less bandwidth, HDTV mobile with simple antenna (like the one on the cell phone in the Sanyo URL).
The equation is NOT rotorized antennas like in the US that cannot handle trees.
Just another cost associated with our current bought and paid for government. It doesn't take much to buy this government but it sure cost the citizens a lot in consequences and money. 0]
