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