 For the colour channels and narrow-band luminance, the low-pass filters had a Gaussian shaped pass-band and, although such filters were not ‘sharp-cut’, they were linear phase and gave negligible overshoots on transients.The wide-band luminance channel had its bandwidth defined by a linear phase low pass filter with a 3 dB cut-off at 6.8 MHz.Its design follows the lattice filter methods of Bode.