=20 -----Original Message----- From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of Doug McDonald Sent: Friday, 17 February 2006 5:35 AM To: opendtv@xxxxxxxxxxxxx Subject: [opendtv] Re: Doug is Missing the Point Ian Mackenzie wrote: > Doug >=20 > You have it wrong as usual. >=20 > The coverage of Sydney uses a SFN on UHF from Multiple transmission=20 > sites which are fed >>From the digital transmission on VHF off air. > No microwaves, no fibres, etc. >=20 Then it's NOT AN SFN. Well, the UHF part micght or might not be depending on whether the transmitters are phase-synchronized. Doug You just don't understand how a SFN works. IT IS A SFN The SFN principle is that you can cover an area with Multiple transmitters from multiple sites with overlap From multiple sites at a receiving location so that There can be multiple "echoes" or even "pre-echoes" Without affecting receivability. The proviso is that they are within the guard interval. In any SFN the transmitters are phase synchronised It wouldn't be a SFN if they weren't. FOR A SFN YOU DO NOT NEED TO HAVE A MODULATOR, SFN ADAPTER GPS REFERENCE, MICROWAVE FEED, (or fibre)TO EACH SITE AS THE FEED CAN BE OFF AIR.=20 This is what is being commonly done with DVB COFDM in=20 Australia and many other countries. >=20 > As to transmitter costs the cost for a DVB Transmitter is identical to > an ATSC transmitter It just uses a different modulator. >=20 What you describe seems not to be a true SFN and if it is just off-channel repeaters, it's no different from what ATSC does trivially. Not exactly trivially but IT IS A TRUE SFN! > The nationwide SFN is ridiculous, just like=3D20 > the thought of covering the USA in ATSC. > In Australia anyone, anywhere can get the=3D20 > networks in digital if not FTA VHF or UHF > Then on satellite. >=20 Ah so you DON'T have universal COFDM OTA coverage! Just what I thought. Doug, What you may not realise is that in Australia we have many huge areas where no-one lives and there is a population of 5 Lizards and 1 Feral cat chasing them=20 per 100 square miles or more. Do you seriously suggest that there should be 5 "Earth Scorchers" to allow the perhaps 5 people in the single homestead within range to be able to=20 select which programme they watch? The populated areas are well served with DVB COFDM without having to run silly powers. =20 =20 ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org=20 - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line. ---------------------------------------------------------------------- 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.