You are doing fantastic work. Both the preservation of old equipment, as well as of course the fantastic in-depth videos. It is very much appreciated (and I’m saying that as someone who neither is nor ever was even near the broadcast industry in any way)!
Hi Matt. In 1990 I worked for a company in Melbourne Australia supporting re 140Mbps Video CODECs(8:00). I spent some time in Copenhagen training at re. They were great folks. You're right, their documentation was outstanding as was their engineering. I do remember learning about their SIS but never used it in Australia. They had broadcast quality audio coders (15kHz?) that would interleave data into slots in the 140Mbps stream and I believe there was room for 2Mbps data as well. The 10 bit video sample rate was locked to 3 times the colour subcarrier and there was some very clever padding and frame size manipulation to sync with the 140Mbps data stream. Varying the SIS data rate as you mentioned would be consistent. Pseudo random encryption was not primarily for security but rather to prevent dc offsets occuring as a result of repeating bit patterns during static video scenes. I'd love to get hold of a TxRx pair. Thanks for the video. Was a real nostalgia trip.
Glad you enjoyed it. Would love to get a pair of those codecs on the channel. That particular coder is surviving but all of the decoders had been scrapped unfortunately.
2001 me learning tv repair would've loved this video. 2024 me that has forgotten more about tv systems than most people ever learn thoroughly enjoyed watching
The EBU, European Broadcasting Union used SIS on their satellite feeds till mid 1999 when they changed to digital.Various 'pirate' decoders were on the market for audio which worked well. Without one the line lock would 'wobble' in time with the audio which of course couldn't be heard.
I believe both C4 and TV-am made use of the NICAM spare data capacity for a low-quality talkback channel to outside broadcasts. This makes sense as TV-am was routed directly to the transmitters during their broadcasting hours I believe - and so if the data had been in the SiS distribution it would have reached every transmitter (irrespective of whether the local company had any support for NICAM data talkback?). I have heard reference to it being used for C4 racing - presumably after 1992 when C4 took over advertising playout from the local ITV companies and added their own distribution to transmitters. However I believe C4 moved to 34Mbs compressed distribution around this time too - so it may not have been fully end-to-end SiS? (Was it ETSI compression they used? It was a major reason for them choosing D5 over Digital Betacam as they were concerned about compression concatenation at the time I seem to remember?)
Hi Matt. Very interesting video . I'm always amazed by the sheer amounts of hacks and improvement to analog tv, usually in the VBE. I've been messing around with hacktv and it's become quiet apparent just how much analog tv sucks with weak signals and multipath. Really gives you a clear understating of the enormous output power and the many repeater station the big station had. The end-to-end setup with NICAM is pretty neat but I can't help but think that the biggest home market adoption problem is that FM was usually good enough, especially though small and cheap tv speakers. I'm glad I came across you channel, keep it up! :) Jelle
Hii Matt We had those RE encoders and decoders in our OB vans and RF link vans all over here at DR, we used this in the beginning of the 90s, before we moved to satelitte contrib. I actually work together with one of the guys that worked at RE and he was one of the developer of the RE system. He worked there until Barco closed down the Danish division. They also made encoder/decoders that could handle DSIS with other data in the signal such as teletext. When in use the monitoring in the contrib RF link was a bit problematic, since you wasnt able to monitor the regular ITS signals in the signal without a decoder in the RF Link van, because the raw signal hasnt any sync for the monitoring equipment to lock into. But the system encoding was quite robust, even on a bad RF link with noice.
Yes I had that problem with syncs. If you need syncs to monitor the input of the decoder, the other problem is the propagation delay of the decoder, in which case you also need an SPG to generate syncs subtracting the decoder delay!
I remember equalising video links at the start of my career, and on a marginal signal we'd often have to tweak the eq to such an extent that by the time the SIS could be decoded, there was usually a load of ringing on all luminance transitions in the picture. The studio would often complain, so you'd offer them the choice of ringing on the picture but usable audio (the subcarrier audio would often be unusable in these sorts of situations, as well), or a decent picture but with no audio.
I would have loved to hear more about the shenanigans in DR/DK. They have such a rich history on satellite with PAL, MAC, Nicam, cable, satellite and terrestrial distribution. I suspect, just like everyone else, all the 'old' equipment has been thrown out.
Sound-in-Sync started off gating part analog waveform and therefore had limited audio frequency response, this was well before digital was a thing. The other area from memory, it was used with FMVSB transmissions, to fit into an 8 MHz UHF channel for outside broadcast work.
25:50 - This rings a very vague bell; is it possible that the low-quality audio feed was some sort of comms circuit? As a Cameraman I was never involved with TX/RX hardware; but I recall seeing feeds with tinny telephonic-sounding gallery audio on them which was (I recall being told) sent 'SIS'.
Information on the BBC Decoder is on the bbceng info site, under the equipment name CD3/504. Further information can then be found for each sub-module, eg AM1/38, UN16/515, FL1/31 etc. This may not exactly match the Varian unit that you have, but it should be close to the BBC Design.
Thanks for that. Just had a quick look. This appears to be for the old mono system, which actually I have yet to come across such detailed information about! Very interesting...
It's times like this I wish I'd paid more attention to the RE DSIS kit I got given for an old work project about 15 years ago. When we determined we wouldn't be able to use it, I think it went into offsite storage and never came back. It's a shame as I think I had at least two encoders and a single decoder. Great video BTW.
hi,enjoyed your video, .Back i early 1990's i hunted satellite feeds,one saturday night i came across Noel Edmonds show using SiS on their satellite OB, live at a birthday party somewhere in the uk, Noel was in studio dressed as leatherman from the village people, his feed was then fed via Sat and recieved at OB site, mixed with the YMCA video being shown at the birthday party,,Thus, when the man whos birthday it was, got up on stage to do the YMCA carriokee, the screen behind him, then showed Noel joining in......... this was the suprise, when revealed... all done in SIS, i did record all this show using SIS inserter decoder,, its on Vhs somewhere..... must look.for it..👍
I have a copy of the user manual as a PDF that you can have. You will be able to do more experiments and even get into the monitoring software that drives the error LEDs. I have a Harris badged coder and a TVT decoder saved from the skip. The open frame construction always made me nervous when working in racks with this gear in.
Brilliant. I look forward to seeing it. I think the open frame construction made sense in terms of how it was deployed. Very good for airflow, just a bit fragile when used standalone. I believe there was an official ruggedised case for the equipment for cases where it had to be used standalone!
Just wondered if you had seen the response I sent to your email on Tuesday? On my end I had noticed that your message ended up in my junk folder for some reason!
Very interesting fun! Shows again the robustness of Nicam! There’s an interesting BBC R&D report from 1966 comparing the relative goodness of using various pulse techniques to carry sound in sync (1966/58). They compare PCM (which obviously won) with PAM, PWM and PPM. There doesn’t seem to be any indication that any of these other SiS techniques were actually in use though. In the references there are references to a paper about the French 819 line system muxing sound. Has anyone ever seen this fabled HD system from the 1960s?
Very nice! Some of the SiS kit we have in Belfast has the Harris branding. Almost all the kit that's still languishing upstairs was used for contribution feeds rather than transmission, and it's all wired for analogue audio! We also have a system for sending NICAM-3 over microwave... but that's another story.
~15:20 "sounds exactly the same" -- not here, at least to me it seems the frequency jumps up almost a half-tone. And you can hear that quite clearly when it's switching. Why is that?
I assume the low bitrate speech you mention is the 9.5kbps CELP codec developed for the AUDETEL project. I don't know whether the NICAM additional data version was ever actually used anywhere - the UK audio description trial broadcasts used the even lower bitrate (7.5kbps) teletext transmission version. I would be *very* interested if any of your viewers ever turn up one of those coders, but I fear they're another thing that only existed in single digit numbers of units and have long since been scrapped.
It was developed by the University of Surrey as "Speka Ltd". It seems like the BBC had at least two encoders as they generated audio streams live (frequently we find programme audio from TV or radio channels being routed out). ITV's signals were pre-prepared for playout like subtitles. One of the decoders still exists in Peter Weitzel's collection. Decoding was mostly reverse engineered before we learnt that.
End-to-end digital audio in the days of analog TV does sound rad indeed! What kind of link would such a signal be transmitted through? Coaxial cable? Microwave? ...fiber optic...? I can't really get the appeal of the original SiS for mono, though. Why not just modulate a 5.5/6/6.5 MHz subcarrier as for public broadcasts? In fact I'm mildly surprised that such a "baseband video with modulated audio subcarrier" signal was never really a thing - it would allow passing the entire TV signal down a single cable ;) - but I digress. I just don't fully get it - if the problem was avoiding a second cable, why engineer this elaborate sound-in-sync setup instead of just slapping on an FM or AM subcarrier? The fidelity wouldn't even be that far off considering that the original system was just 10-bit, what's that, 60 dB SNR? But of course, in the NICAM era it makes much more sense.
@@kFY514 the problem was the enormous proliferation of technologies for carrying the video signal. Consider for example a 140mbps FOTs link. Not going to get any subcarriers over that. There was a system called sound over subcarrier in the UK. It put an FM mono carrier right at the end of the video spectrum but it was mono and not very good.
IIRC 'original' SiS was analogue samples, two per sync pulse. So they could be created and recovered with sample and hold analogue technology, no need for AD/DA or way back then.
@@mattstvbarn I can't answer that precisely.... I worked for the BBC for a while in the mid-80s and we had to go to Evesham to be taught stuff. One of things was SiS, the system we played with was analogue samples at twice line rate. As I never saw this stuff again it's entirely possible memory is faulty... But that aspect has remained clear. I presume this was what the BBC standardised on for distribution prior to the introduction of Nicam and I'm pretty sure it was Designs Department originated.
@@paulranson6973 was that system not VIMCAS or maybe VISCAS? It used to carry a waveform on a couple of lines in the VBS. ISTR OB's used it on contribution feeds for 4 wires/talkback etc. I don't think it was good enough for programme sound.
