The Standards Committees

NTSC vs PAL vs SECAM

see also  http://www.mastervideo.com/videospecs.htm 

There are three major TV standards used in the world today. These are the American NTSC (National Television Systems Committee) color television system, the European PAL (Phase Alternation Line rate) and the French-Former Soviet Union SECAM (Sequential Couleur avec Memoire).

The largest difference between the three systems is the vertical lines. NTSC uses 525 lines (interlaced) while both PAL and SECAM use 625 lines. NTSC frame rates are slightly less than 1/2 the 60 Hz power line frequency, while PAL and SECAM frame rates are exactly 1/2 the 50 Hz power line frequency.

            lines       active      vertical    aspect      horizontal  frame rate  
                        lines       resolution  ratio       resolution              
NTSC        525         484         242         4/3         427         29.94       
PAL         625         575         290         4/3         425         25          
SECAM       625         575         290         4/3         465         25          

So why is the resolution 427 x 242  and the aspect ratio 4:3 ?  The ratio doesn't even come close !!  The spacing of the horizontal pixels is the identical the vertical spacing of the lines. But more likely, again - the numbers are wrong.  I trust the 242 since that is defined scan lines, but not the 427, since the beam uses an analog waveform to place the "pixels" on the phosphor.