Incremental encoders from different manufacturers use differing timing for the index pulse. The
index pulse may be aligned to any of the 4 quadrature states and may have a pulse width of
either a full cycle (4 quadrature states), a half cycle (2 quadrature states) or a quarter cycle
(1 quadrature state). Index pulses of a full cycle width or a half cycle width are normally termed
‘ungated’ and index pulses of a quarter cycle width are normally termed ‘gated’.
“The index pulse may be aligned to any of the 4 quadrature states ”———是指Z信号的沿与AB正交信号在一个周期内的状态机的4中状态的对应关系,且未必有什么确定的关系。
“a pulse width of either a full cycle (4 quadrature states), a half cycle (2 quadrature states) or a quarter cycle(1 quadrature state)”———是指Z信号的宽度与AB正交信号周期的关系,即全周期(对应4个四倍频脉冲),半周期(对应2个四倍频脉冲),或1/4周期(对应1个四倍频脉冲)。
“Index pulses of a full cycle width or a half cycle width are normally termed‘ungated’ and index pulses of a quarter cycle width are normally termed ‘gated’”———只有Z信号的宽度只对应一个个四倍频脉冲宽度时,可以称为被AB正交信号的状态机组合“门选”过,也就是对应(对齐于)唯一状态机,而其它的宽度下,其对齐关系都与状态机无关,即可以任意对齐,只保证宽度。