Hedghog 625-405 standards converter

[Synchrodyne]

The following attachments document some of the changes in the 405-line waveform standard.

First, Wireless World (WW) 1961 April showed the original 1935 specification:

   

Second, WW 1948 December showed the waveform as it then was:

   

Third, WW 1950 March recorded the forthcoming aspect ratio change:

   

Fourth, WW 1952 June showed the waveform as promulgated by the CCIR:

   

Fifth, WW 1956 January recorded changes since 1952:

   

Sixth, the waveform as recorded by Hutson in “Television Receiver Theory, Part 1” of 1966:

           

Additionally, from WW 1948 April, a commentary about the then-new Test Card C as it applied to the 5:4 aspect ratio:

           



Cheers,

Steve