Al Limberg wrote: > Vertical polarised antennas were preferred in the early > days because they were not as good pigeon roosts. So > roofs kept cleaner. But I think now, in the UK and in Italy, vertical and horizontal are used to help in frequency planning. Especially because mountainous regions require so many translators. I guess you can reuse the frequency channel somewhat sooner if you change the polarization. In some parts of Italy, you're expected to use vertical on some channels and horizontal for others. Here's an example: http://www.dgtvi.it/dgtvi/copertura.aspx?TRS_ID=1550000&PROVID=38&CITYID =4779&CS=1 However, this MIMO idea the BBC is attempting to use for doubling its channel capacity is a lot more complicated than just assuming you can double the capacity by sending one stream in v and a totally separate stream in h. This space-time code stuff is still fairly new, but it seems from what I've read that if the transmitter does not have knowledge of the channel properties, which it wouldn't have in a one-way broadcast, you would need more than just two transmit and two receive antennas to hope to double the channel capacity. And not only that, but it helps to be in a Rayleigh channel to get the capacity gains. As the channel goes Ricean and Gaussian, the bit error rates at the high capacity settings start to rise, which means the high capacity setting becomes less robust. In short, if you really want "multipath to be your friend," as the saying goes, then lack of multipath works against you. Bert ---------------------------------------------------------------------- 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.