By employing different independent polarity codes to polarity-modulate respective quads of averaged values in the vertical-temporal plane of luma, chroma, sidepanel and enhanced-luma components in the mid-frequency and/or high-frequency split-bands of a 4.2 MHz baseband television-type signal, the encoded components can be combined into successive composite quads of an encoded single channel, NTSC compatible, enhanced-definition 4.2 Mhz bandwidth television signal. The successive composite quads of the encoded signal can be decoded by a widescreen receiver without crosstalk taking place among the components, while such an encoded signal does not noticeably affect the display of a standard NTSC receiver.