Satellite-TV

OK. This post should not surprise anyone following my blog.

I'm elaborating on my knowledge of geostationary communication devices.

i.e. satellites

First off, satellites orbit a space-region known as the "Clarke Belt", approx. 22.300 miles (35.888 km) above the equator. Each satellite has a number of 'transponders' (transmitter-responder), and each of these transponders carry a signal back to earth. These signals are carried either on "C band", "Ku Band" or "Ka Band" which signifes what frequency is used to transmit the signal. After travelling through our atmosphere, over 20.000 miles, a dish is able to recieve them.

A satellite-dish can be everything from 18" (inches) to 9' (feet) across. It's main purpose is to be a collector/reflector to catch a microwave-satellite-signal, and aim it towards the 'feedhorn'. The feedhorn recieves the signal and sends it to the 'LNB' (Low Noise Block). The LNB amplifies the signal, and converts it to a frequency more suitable for transmission over a cable, also known as an 'IFL' (Intra-Facility Link). The IFL then carries the signal to the satellite reciever/decoder.

In cases where the signal is digital video broadcasting (DVB), it is usually digitally encoded, and the reciever/decoder has to decode the signal before it can be viewed/used. This also enables satellite-feed vendors to offer more channels over the same bandwidth as used in analogue systems where the channel-capacity is limited by actual transmission-capacity.

The standard audio/visual encoding used in DVB is one of either MPEG2 or MPEG4.

Links:

http://www.tech-faq.com

Just a little side-note on the 'smartcards' used in DVB-transmission and decoding. Smartcards have always, since the beginning of satellite-TV, been the authentication-token used to retrieve encryption-keys for encrypted streams, or simply as an identification-device to identify the recieving party as a valid customer.

Early in the race, these cards were merely electronic storage-chips used for ID information. But after years of development, they incorporate a range of security technologies of which the card-vendors have licensed as  proprietary intellectual property.

Canal Digital

Oh yeah ;-) I am now a proud consumer of satellite-tv streams. I figured since broadcasts in Scandinavia are all DVB-based, a dish-setup would be the way to go. I chose the vendor Canal Digital because I've watched, and favoured their channel-content and service quality since the mid-90s (when they were known as "Filmnet", and thanks for that reference Olti, I had totally forgotten about them ;).

Our local electro-company distributes fiber-based DVB (Digital Video Broadcasting), but they limit every household to just 4 DVB set-top boxes (because of transmission capacity issues, and the fact they deliver fiber-Internet through the same cable-system). This did not favour me much, since I am household member No.5 (typical). So, I basically had to research alternative tv-broadcasting access solutions.

I have always been a fan of satellite-tv, but then again, I didn't like the broadcast quality because it varied quite much from vendor to vendor a few years ago. But the recent introduction of DVB on a national scale (Norway) led me to believe satellite-tv would have gained enormous capabilities because of their wide broadcasting bands, they would not suffer from cable-fatigue, wiring errors or general network failures. AND, Canal Digital was the first satellite-vendor to introduce DVB-based content via satellite in Europe.

Satellite technology only suffer from environmental variables (fog, rain, snow), and this can even be prevented (somewhat) with supplemental satellite-dish equipment. But there is also a more simplified solution to DVB-access here in Norway, which is more intended for non-technical individuals, and it centers around normal tv-antennas with the addition of a smartcard-based DVB set-top box. But this solution has it's own kind of limitations over both satellite-tv and fiber. It relies on normal tv-broadcasting technology (modulated transmissions) with encrypted, encapsulated DVB-streams (MPEG). Thereby, this technology has very limited channel capacity. Whereas fiber+satellite has enormous channel capacity because they have limited signal-compression and stream-encryption.

To sum up my post a little better without all the technical mumbo-jumbo. I really love satellite-tv. Instead of having just the selected big-name channels provided through land-based vendors, I have a plethora of national and international high-def, high quality channel ranges.

Or, seen from another perspective: I have over 117 120* standard channels in my EPG (Electronic Program Guide), compared to fiber (50+) or the modulated transmission solution (10+), without any significant drops in performance and/or quality.

* = Corrected 11.05.2009 10:35 GMT+1