South African TV

[Synchrodyne]

My expert says:

quite simply they wanted to be different* to encourage manufacture in SA. Completely misguided. The 42 to 68MHZ is  or was a military band at the time.

So System I was because of politics.

(* Because if you look at PAL I, EXCLUDING South Africa, hardly anyone used it compared to other PAL versions.)

I am inclined towards circumspection when it comes to accepting as “completely misguided” the South African decision to adopt System I.
 
The relatively small number of countries that used System I reflects the fact that it was a late entry, and that by the time it was available, the majority had already chosen their TV transmission system.  And of those yet to make a choice some were in the Francophone group for which System K’ had been developed.
 
Looked at another way, had South Africa chosen System B/G/H in the 1970s, that could well have been described as being retrograde.  By the late 1950s I think it was generally recognized that the Gerber compromise 7 MHz channel and 5 MHz vision bandwidth was too much of a compromise.  On that basis those major countries that had yet to introduce a 625/50 service, and could support the development and implementation of an improved transmission system were prudent to have done so.  In fact during the 1950s there were UK commentators were quite critical of the Gerber system, and some recommended a 7.4 MHz vision bandwidth, which was a bit unrealistic.  The 1949 UK industry export 625/50 system proposal was predicated on a 6 MHz vision bandwidth.
 
As I recall, manufacture of TV receivers in South Africa with significant local content was mandatory in the early years of TV there.  So there was no need for a technical non-tariff barrier to imports, given that they were prohibited anyway.
 
As to the visible performance of the different transmission systems, here is something I wrote for another forum a while back:
 
I have lived in both System B and System I countries – two of each - and also in a System M country, so I have had on-going exposure to three systems. The sequence was B, I, B, M, I, M, B, B. 

My overall impression was that System I pictures were generally a bit better than System B pictures.  The best way I can describe it is that System I pictures were somehow “cleaner” or “calmer”.  I shouldn’t say that they were obviously of wider bandwidth; rather that there was less distracting stuff going on in the background that shouldn’t have been going on.  That was the impression that I had when I first saw System I pictures, and it didn’t change over many years.  Given that this came from watching a variety of receivers, mostly of the domestic type, and probably few of which took full advantage of the transmitted bandwidth, I’d say that the difference had less to do with the primary effects of receiver vision bandwidth choice, but more with the secondary effects of the bandpass filtering and any baseband peaking, such as phase-shifting, ringing and so on.  Perhaps that kind of picture deterioration should have been reduced as compared with the early days once synchronous demodulation and SAW filters became established, but then the greater part of the above observation period was in the synchronous/SAWF era. 

I should note that System M was no cleaner than System B, and I’d say that, at least as seen on conventional 25-26 inch screen CRT receivers, the vertical definition was only just enough.  But System M had a big advantage in terms of freedom from flicker.  Once you were accustomed to it, then the flicker with 50 Hz pictures encountered when travelling was very noticeable.  After a move from an M area to a 50 Hz area, it was quite a few weeks before one adjusted to the flicker and no longer noticed it so much. I also noticed the difference between B and I when on trips that took in both Singapore (B) and Hong Kong (I), that despite the vagaries of hotel TV systems. 

I have had only passing acquaintance with Systems D/K and L.  But I do remember looking at D/K pictures in a domestic setting in Lanzhou, China back in 1987 and thinking that they were as “clean” as System I pictures.  The same with System L; I recall looking very closely at a B&O receiver in Paris in 1996, in particular to see if I could find any obvious signs that it was a positive modulation transmission, but no luck on that. 

The foregoing is simply one layperson’s observations and perceptions, essentially subjective and mostly with sequential rather than side-by-side comparisons. Naturally it embodies any biases I may have, and perhaps an element of self-suggestion.
 

Cheers, 

Steve