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CTV The early days of NTSC colour television.

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Till Eulenspiegel
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From a 1955 book titled "Color Television Engineering". 

 The attachment shows how the colour sub-carrier and sync pulses were generated during the times when valves were used for all electronic circuits.

The master oscillator generates the 3.57Mc/s sub-carrier and also supplies the divider chains to produce the 2H sync. The 31.5Kc/s signal is supplied to the sync pulse divider circuits to produce the sync pulse train in the usual manner, that is divide by 21 and divide by 25 for the 60c/s frame sync. The line sync 15.570c/s from the divide-by-two circuit.

System M Sub Carrier

Till Eulenspiegel.

 
Posted : 23/02/2024 3:16 pm
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Nuvistor
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@till The dividers and multipliers are only shown as blocks, probably quite a few valves in each unit.

Frank

 
Posted : 23/02/2024 3:58 pm
Till Eulenspiegel
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Hi Frank,  from the same book pictures of the sub carrier and burst flag generators.

System M Sub Carrier Gen
System M Sub Burst Flag Gen

Twenty years later this equipment could be replaced with much smaller units employing TTL and transistors and offering better stability and easier adjustments.

Till Eulenspiegel.

 

 

 
Posted : 23/02/2024 4:31 pm
irob2345
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And then there was the SAA1043. A very complete implementation, in one chip, compatible with all standards, by the 1970s.

This part meant that a station's master sync generator was now a 1RU box, with mostly fresh air inside it!

I have the PDF but it's not allowed here.

 
Posted : 24/02/2024 5:01 am
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irob2345
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All this in one chip! Amazing - well it was at the time.

SAA1043 block
 
Posted : 24/02/2024 8:15 am
Cathovisor
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I'll see your SAA1043 and raise you the SAA1101. Which does colour as well.

One of the favourites at work amongst colleagues who built SPGs and PAL coders for 'fun' or self-learning was the Ferranti ZNA134E, also used in the Link 125 camera viewfinder. The ZNA134E pre-dated the SAA1043 by several years.

There was also a single chip PAL pattern generator made by Ferranti, the ZNA234. As a very good colleague of mine said when I blew up said (quite expensive) chip in my pattern generator project: "Now you've smoked the most expensive chip on the board, son, you can truly call yourself an engineer."

He'd not long himself blown up a ZNA134E... which I seem to recall were about GBP22 each in the early 80s.

 
Posted : 24/02/2024 11:57 am
Till Eulenspiegel
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Simplified block diagram of an NTSC 405 line sub-carrier and sync pulse generator.   This circuit is easy enough to realise using TTL but how was it  done during the valve era is a different matter.

System A Sub Carrier Gen

A pair of 405 line sub-carrier crystals. These are for 2,657812.5c/s and were probably made for a receiver rather than an encoder.  To use the crystals in a encoder would require frequency multiplying circuits. X2 and a 525 divider would produce the 10,125c/s line sync pulses but not the 2H pulses. For the frame sync it would have to be X4.

System A Sub Carrier Crystals

Till Eulenspiegel.

 
Posted : 24/02/2024 12:57 pm
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