Before Astra Satellite

D2-MAC was a version of D-MAC (different audio).

D/D2-MAC can also have sparklies - the main difference is D2-MAC pictures can provide better quality than PAL. People didn't (many still don't) realise that you still had to have a good tv and SCART leads to make the most of the better quality transmission.

The Marco Polo satellite were stronger than the (then) Astra satellites - hence smaller dishes. But the engineers got it wrong and the very mall dishes for BSB had to be dropped.

For the benefit of that rare bread of Plymouth-bound squarial spotters, above the Costcutter on Mutley Plain there remains to this day a BSB squarial in excellent condition. This building was a Boxclever shop until they pulled out of shops, and of course before that was Granada Rentals (still had the Granada sign right to the end). Presumably the squarial was installed in 1990 to demonstrate BSB.

It used a slightly higher bandwith than PAL - but used the space more effectively.

PAL was never really suited to analogue FM transmission (as used by analogue satellites like Astra and Marcopolo) - as the colour was encoded on a high frequency subcarrier and thus exposed to greater amounts of noise than would be the case with analogue AM VSB transmission used for terrestrial transmisssion. As a result Astra PAL was quite noisy - and the chroma performance was not exactly great. A good terrestrial picture was streets ahead of a satellite broadcast in those days - ignoring the horrors of videocrypt (which massacred the picture)

D/D2-MAC got round this by broadcasting both the luma and chroma at baseband - so with nowhere near as much noise on the chroma. This also had the benefit, as you say, of component picture quality.

I'd argue that there were plenty of RGB SCART equipped TVs in the late 80s and early 90s though...


Fewer than now - but not very few...


I could tell the difference between satellite PAL and terrestrial PAL all too easily... Early Sky was really quite dreadful...

Or more accurately - lower data rate data. (The audio was broadcast as NICAM digital data that made up part of the D/D2 MAC data stream - but other data, like teletext, and private data channels, as well as HD-MAC DATV assistance data could also be carried in the same capacity)

D-MAC and D2-MAC were the same in video terms, but D2-MAC ran at half the data rate of D-MAC to allow the signal to occupy a smaller bandwith channel and potentially fit into European cable slots, that D-MAC would have been too bandwith hungry to cope with.

Though D/D2-MAC didn't have the issues of subcarrier - and sparklies on FM transmission normally hit the high frequencies first, so you would get sparklies on saturated colours using PAL analogue ahead of sparklies on D/D2-MAC analogue transmission.

D/D2-MAC encoding was just a better system for FM encoded transponders than PAL.

Arguably it delivered, in good situations, better quality pictures than most MPEG2 stuff today... Certainly the compression artefacts we see now are probably worse than the D/D2-MAC artefacts then.

On the other hand MPEG2 is MUCH better at coping with HD than HD-MAC was...

> Arguably it delivered, in good situations, better quality pictures than most MPEG2 stuff today... Certainly the compression artefacts we see now are probably worse than the D/D2-MAC artefacts then.

Very true -- this can be demonstrated even now with the remaining D2MAC Danish channels still broadcasting on the successors to the Marcopolo satellites at 5E and 1W. With a strong signal, and a high quality analogue setup, the pictures through analogue are better than the digital feeds of these channels by some margin. Admittedly a large part of the reason for this is overcompression by the broadcasters, but still, MAC was, and is, a very capable system, and it is a shame that it never caught on in most European countries. As you say, Videocrypt was a horror story, even in VC's latter years the picture was still inferior, whereas the PAL analogue signals could be very respectable -- not quite up to terrestrial's standards, but then terrestrial still isn't as good as MAC.

Indeed - though MAC is very bandwith hungry...

You can broadcast quite a number of high-quality standard definition, and at least one high-definition (if not two or three) in the space taken by a single MAC service if you use digital compression.