I'd like to know about the DVB-T standard, but I get confused when it
comes to configuring a DVB-T system for a Single Frequency Network
topology. I've read that normally for an 8MHz bandwidth using 2k mode
about 1700 carriers are possible. Does this translate to 1700
individual programs?

I think I can probably answer this question if I find a good tutorial
on COFDM. I've found some on Google, but I haven't found one that
explains simply how it is possible to have multiple carriers in a
single channel.

Thanks!

On 28 nov, 18:53, MRW wrote:
I'd like to know about the DVB-T standard, but I get confused when it
comes to configuring a DVB-T system for a Single Frequency Network
topology. I've read that normally for an 8MHz bandwidth using 2k mode
about 1700 carriers are possible. Does this translate to 1700
individual programs?

I think I can probably answer this question if I find a good tutorial
on COFDM. I've found some on Google, but I haven't found one that
explains simply how it is possible to have multiple carriers in a
single channel.

Thanks!

Hello,

General info on COFDM can be found on the internet. When you want do
dive into details, go the www.etsi.org. They have the nice
standards...... for free. Probably you have to register one time (for
free). More standardization institutes should make the standards
available for free.

Do a search in the "standards download area" on DVB and you will find
all the details. Maybe you can find some tutorial as well.

With regards to the 1700 carriers. They spread the datastream over
very much individual subcarriers, so the datarate per carrier is very
low and you will not suffer from inter symbol interference due to
delayspread. Of course there is frequency selective fading, but the
bandwidth is such that the total signal will not be in a deep fade
completely. Depending on the required image quality, they can put
several streams into one 8 MHz wide channel. All are spread out over
the individual subcarriers to get the best performance in a multipath
propagation environment. The modulation and demodulation goes in a
special way so that there is minimal adjacent subcarrier
interference.

Hope this helps a bit.

Best regards,


Wim
PA3DJS
www.tetech.nl

"MRW" wrote in message
...
I'd like to know about the DVB-T standard, but I get confused when it
comes to configuring a DVB-T system for a Single Frequency Network
topology. I've read that normally for an 8MHz bandwidth using 2k mode
about 1700 carriers are possible. Does this translate to 1700
individual programs?

I think I can probably answer this question if I find a good tutorial
on COFDM. I've found some on Google, but I haven't found one that
explains simply how it is possible to have multiple carriers in a
single channel.

Crossposted for a useful purpose.

The alt.video.digital-tv newsgroup has been home to numerous discussions of
COFDM and the various ways it's being employed. It was a contender for US
broadcast DTV but it lost out to 8VSB in a decision process that some people
said was political -- or worse. One of the leading proponents of COFDM
posted to alt.video.digital-tv as "Bob Miller," although he has nothing
there currently.

Bob Miller may have the material you want, given that he has
been a vocal advocate. The viacel.com web site comes up blank; I hope that
email address isn't a dud. Good luck.

These links might be useful for understanding (C)OFDM

http://www.ebu.ch/trev_278-stott.pdf

http://www.dtg.org.uk/reference/tutorial_transmission.html

http://www.tvtechnology.com/features/On-RF/dl_8VSB_vs_cofdm_part1.shtml

http://www.tvtechnology.com/features/On-RF/dl_8VSB_vs_cofdm_part2.shtml

Kirk Bayne
alt.video.digital-tv Home Page
http://www.geocities.com/lislislislis/avdtv.htm

On Nov 29, 3:54 am, K. B. hotmail.com@lis2lis2 wrote:
These links might be useful for understanding (C)OFDM

http://www.ebu.ch/trev_278-stott.pdf

http://www.dtg.org.uk/reference/tutorial_transmission.html

http://www.tvtechnology.com/features/On-RF/dl_8VSB_vs_cofdm_part1.shtml

http://www.tvtechnology.com/features/On-RF/dl_8VSB_vs_cofdm_part2.shtml

Kirk Bayne
alt.video.digital-tv Home Page
http://www.geocities.com/lislislislis/avdtv.htm

Thank you everyone! I did not realize that there is a digital TV
group.

"MRW" wrote in message
...
I'd like to know about the DVB-T standard, but I get confused when it
comes to configuring a DVB-T system for a Single Frequency Network
topology. I've read that normally for an 8MHz bandwidth using 2k mode
about 1700 carriers are possible. Does this translate to 1700
individual programs?

I think I can probably answer this question if I find a good tutorial
on COFDM. I've found some on Google, but I haven't found one that
explains simply how it is possible to have multiple carriers in a
single channel.


Before contacting viacel for any _useful_ info on this,
just for the heck of it, first google search with these terms:

"bob miller" liar cofdm

"Sal M. Onella" wrote in message
...

"MRW" wrote in message
...
I'd like to know about the DVB-T standard, but I get confused when it
comes to configuring a DVB-T system for a Single Frequency Network
topology. I've read that normally for an 8MHz bandwidth using 2k mode
about 1700 carriers are possible. Does this translate to 1700
individual programs?

I think I can probably answer this question if I find a good tutorial
on COFDM. I've found some on Google, but I haven't found one that
explains simply how it is possible to have multiple carriers in a
single channel.

Crossposted for a useful purpose.

The alt.video.digital-tv newsgroup has been home to numerous discussions
of
COFDM and the various ways it's being employed. It was a contender for US
broadcast DTV but it lost out to 8VSB in a decision process that some
people
said was political -- or worse. One of the leading proponents of COFDM
posted to alt.video.digital-tv as "Bob Miller," although he has nothing
there currently.

COFDM has some disadvantages. For the same quality received signal it
requires more peak power at the transmitter than 8VSB, but TV transmitters
are peak limited. It is more susceptible to impulse noise, and you can't
have a full power COFDM signal on an adjacent channel to an analog NTSC or
PAL signal. My understanding is that the last mentioned is causing
complications in some European countries with the analog to digital
changeover. They will have very little HD until the analog service has been
shut down.

Bob Miller has ulterior motives. His company wants mobile digital TV
transmission to moving cars, which 8VSB has problems with (I think because
of the equalizer which takes several seconds to train. In a moving vehicle
it would be continuously hunting)).

Tam

Bob Miller may have the material you want, given that he
has
been a vocal advocate. The viacel.com web site comes up blank; I hope
that
email address isn't a dud. Good luck.