DVB Basics discussion thread

I have just completed a lenghty article on DVB. I spend the entire day looking for info and I hope I didn't commit too many blunders, but it isn't a really scientific work so I'd appreciate comments and corrections. I chose to have a separate thread in order not to have the sticky too cluttered. I'll collect info from this thread to adapt the sticky in due time.

It is a very good article. Your guide states that internet access can only be gained through the satellite cards though but here in the uk AIUI the cable cards can act as a broadband modem.

Nice and really informative. Could use some more details on LNB access however. A few bits that I know: Some of the stuff said about multiple satelites also applies to single satelites. For example, the european ASTRA's at 19.2E transmit in two bands (high band and low band) and with horizontal/vertical polarization. Astra transmits at 10.6-11.6GHz (low band) and 11.6-12.7GHz (high band). The LNB maps the signal down to 950-2050MHz for cable distribution, lowering the frequency by the LOF (local oscillator frequency) which is usally 9.75GHz for low band and 10.6GHz for high band. On one cable, only one of the 4 combinations (hor/low, vert/low, hor/high, vert/high) can be transmitted, selected by LNB power supply level (14/18V) for H/V switching and a modulated 22KHz tone for selecting the high band. Because of that, using the loop-through of a receiver usally doesnt work and may be even dangerous, if the 14V and 18V power supplies collide. There are different LNB's available for ASTRA reception: Old analogue-only and newer high-band capable 'digital' one's. Simple 1, 2, 4 or 8 port LNB's (Single, Twin, Quad and Octo) have a built-in switching matrix (multiswitch) and can serve one receiver per connector. And there are 2 or 4 ported LNB's (Dual and Quattro) that output the 2 (lowband) or 4 (low+high) signals directly. These require a multiswitch connected to them, direct receiver connections wont work.

@psycrow: I've added audio bitrates and a lot of info regarding frame sizes, framerates and aspect ratios both for SDTV and HDTV. @Joe Fenton: Do you know of any receiver / card where you can actually flick a switch that makes it work with another DVB standard? @chipsugar: You have a link to such a card and a cable provider offering these services? I thought cable providers used the DocSIS standard for broadband Internet access... I'd suppose that a standard uniquely created for data transmission is more suitable than DVB (I read something about a 3mbit/s maximum.. and I know cable providers may want to go higher than that so another standard seems to be more suitable). @no_operation: thanks for the info.. I've already added it.

Great article :) I thought I'd just throw a few more points in about Australian DVB-T It operates on a 7Mhz band, I think this is due to historical reasons (ie the old analogue system was 7Mhz too) Also, I believe 576p is a valid 'HDTV' resolultion 720x576x50 progressive I think. A Question, is low band/high band (in satellite terms) the same as Ku-Band and C-Band?

@stux: 720x576p @ 50 fps is already in my document, so it is indeed supported. Is there a specs addendum describing terrestrial transmission in a 7 MHz band? I've not found anything about larger bands so far (except for the Japanese standard). Also, what's the most commonly used DVB standard down under? I keep hearing about DVB-T, but in most other parts of the world, DVB-S is the most widely used DVB standard and DVB-T is just making an entrance.