Sky HD system - illogical problem?

[dennishoy]

Satellite channels are normally 'polarised'; some horizontal and other vertically to avoid interference between adjacent frequencies. Polarisation is perfomed within the LNB by software in the receiver changing the supply voltage down the coax cable. However, Sky HD boxes are made cheaply for a mass market aimed at the Sky package only, and as far as I know, this feature has been omitted. (I think) all the channels are transmitted with horizontal polarisation.

No, this isn't the case. A couple of randomly chosen links:

http://forums.digitalspy.co.uk/showthread.php?t=1176626

http://free-tv.ie/astra-satellite-frequencies

With the normal mini-dishes, satellite reception is pretty marginal at the best of times, and is affected by all extremes of weather. Anything less than a 100% perfect installation will suffer from occasional channel loss, and obviously cheap plastics where once metal was used might well contribute to this.

I got $ky Digital back in 1999 or 2000 - and back in those days you had to pay a massive(!) £40 for the installation (the boxes had just become free at that point - before they were £200 IIRC). The chap who installed the dish was a local self-employed engineer who did jobs for Sky, and as he wasn't especially busy on the day, he ended up staying for about 90 minutes, drinking tea and chatting about technical stuff (he realised who I worked for, so as you can imagine, we had plenty to discuss!). Nice guy - who did a proper job. I never suffered reception problems in the 5 or 6 years that I lived in that house - but plenty of our neighbours did with their 20 minute free installations!

Haven't had Sky since then. Hardly watch TV these days

Cheers,

Mark

I stand corrected. Thanks, Mark.
Sky must have updated the system over the years because I recall all the channels were 'H' polarisation a few years ago.

I bought my first sateliite kit in 1985 long before Sky existed. It was an analogue system, 1.8m dish, NEC2022 receiver/positioner, C120 mount LNB and separate mechanical polariser and dual band LNB for Ku and the French Telecom bands. Band switching was by changing the LNB power supply from 12V to 18V for the higher Telecom band. There was a Sky channel, encrypted using the Oak Orion system which could be hacked using a few ICs and a tuned circuit. The fun was in decrypting the porn channel Red-Hot Dutch which simply swamped the signal with a fixed frequency carrier. All you had to do was apply the same frequency and amplitude, but 180 degrees out of phase to null the interference. My first phase locked loop using TTL I recall. Other channels were Music Box, Supechannel, Premiere and a few others, uplinked from the UK.

BSB came along using the DMAC encryption system and circular polarisation. You needed a 'squarial' to receive the programmes which were British rather than the Sky American rubbish that fills every channel nowadays.

When BSB went bust, squarials became freely available along with DMC decoders which were considered obsolete. However, the more clever folk changed the crystal to double the frequency and fitted a new EPROM so the box became a D2MAC decoder for hacking the Scandinavian channels that used that format for transmisison. The films were broadcast in the original language and subtitled into Swedish. The 'key' could be found by trial and error and lasted for a few days until the company changed it. Problem for them was that only a certain number of 'keys' could be stored in the decoder so they kept rotating 'keys' usually on a monthly basis. This was not considerd to be piracy as you could not pay for these programs in the UK so were not depriving the channel provider of any income. Some of the channels changed format around 10pm and became very 'interesting' if you know what I mean.....
Happy days indeed. (before Sky came along).