What is PAL?

Like NTSC, PAL is a set of standards for television.

PAL is widely used in Europe while NTSC is used in the Americas and some Asian countries. The crucial difference then between PAL and NTSC is that A PAL set has a DELAY LINE whilest a NTSC set does not.

PAL stands for Phase Alternating Line and is used primarily to correct phase errors that have occured due to to varying propogation conditions such as terrain which is capable of altering the phase of the colour signals R-Y and B-Y ( Green is not transmitted ) The prime principle of correcting the phase errors occur with in the receiver . The colour information is stored in a delay line on alternate lines, the stored line is then compared to the next line and an error signal is produced which is used to "Pull " the subcrrier oscilater to alter its frequency hence the phase and the hue of the colour information . A burst of sub carrier frequency of 4.43 MGHZ, approx 10 cycles is rectified and used to provide a n ident signal which when present switches the chroma amps on , Of course a monochrome TV does not receive the ident signal and continues to show the programme in B?W . This is what is know as reverse compatibility .

PAL does not directly specify the number of lines in the picture. The full system name does however: PAL 625 Line.

In France they use a different system called "SECAM".

In the early days, PAL was certainly a better system to encode the color information. However, the introduction of digital production and far better timing circuitry has virtually eliminated the color variations that Brits would notice when watching NTSC for the first time. A well timed NTSC signal is almost impossible to tell apart from a PAL signal in terms of color quality.

However, The US and other NTSC countries use a 30 Hz frame rate while PAL and the Europeans use 25Hz frame rate. It can be argued that the lower frame rate used by Europe causes more flicker than the US frame rate. My American colleagues in the broadcast industry consistently notice the frame rate difference when they come to Europe (ok, so they are all engineering nerds and maybe others wouldn't notice). For that reason, even in Europe, when demonstrating broadcast production equipment, we often use 30Hz material to get the higher frame rate.