30 years since the closure of BSB

So, during the transition period, would you have received a better quality picture of Sky's channels if you used a BSB dish and got them in D-MAC than if you had a Sky dish?

Difficult to say. Sky's Osterley facility was a PAL composite site, so everything from there would have had a PAL footprint on there, which would still be present in the D-MAC signals. My memory was there wasn't much to choose between them quality wise

You'd have got the NICAMesque sound from the BSB system (Astra was horribly noisy, until proper PANDA noise reduction launched), and less transmission artefacts due to the D-MAC coding, but with baked in PAL from the Sky chain.

Yes, it didn't take too much mis-tuning, dish mis alignment, or rain fade for 'sparklies' to appear on Astra, and the triangular noise spectrum for FM'd Video (which was the IBA's main technical case for using MAC in the first place) where as RF wise the BSB satellite reception was far more robust.

As others have said - Sky was analogue composite, so the D-MAC component broadcasts would have been decoded PAL (with composite PAL artefacts). However there were two areas where it was potentially a bit better.

1. MAC didn't use a high frequency PAL subcarrier, but carried chroma, like lumninance, at baseband. Both BSB's MAC and Sky's PAL were FM modulated on satellite, but FM has a triangular noise shape, which means you get more noise at higher frequencies. As a result PAL composite (used by Sky on Astra) had higher levels of chroma noise than MAC. Sky's PAL composite stuff was always a bit chroma-noisier than a good terrestrial signal at the time too.

2. Sky used a pretty nasty audio modulation system on Astra, whereas BSB used NICAM digital.

However those differences were probably pretty minor. Sky channels originated composite certainly wouldn't have looked as clean as the BSB channels when playing component content when connected via an RGB SCART connection - but again most people probably wouldn't have really noticed a huge difference.

One annoying thing about Sky's analogue broadcasts, was the field rate flicker that the VideoCrypt encryption seemed to introduce ?

Hmm - wonder what caused that - as the encryption was cut-and-rotate line-based. There was some additional (25Hz?) stuff done on FM satellite modulation wasn't there to do with power efficiency (possibly because of syncs?)

Videocrypt on satellite did nothing for the noise performance of the broadcasts that's for sure.

(The BBC trialled it for BBC Select on terrestrial and because of multi path and other issues it was terrible - which is why the terrestrial version of Videocrypt used line shuffling rather than cut-and-rotate)

Umm. It's all a bit odd. I'm sure the non VC encoded channels (notably the German stuff) didn't suffer the problem ?

And, that's another thing, PAL Plus on Astra analogue looked better than I was expecting

I'd be interested to know what the playout chain was for the post-merger Sky channels on Marcopolo. Looking at how cleanly the Now Channel gives way to Sky News, I imagine that was routed via Now's playout suite - did the Sky Arts opt outs still come from Marcopolo House?

Does anyone know if the satellites are still in orbit?

Marcopolo 1 (now Sirius W): https://www.n2yo.com/satellite/?s=20193

Marcopolo 2 has been in a junk orbit since 2003.

Not after over 30 years!