T3N wrote on Jul 19th, 2010, 12:41am:If a zero-IF or low-IF has I and Q path, does it require a phase synchronization to avoid the start-up phase uncertainty of the oscillator?
No.
T3N wrote on Jul 19th, 2010, 12:41am:And in the case it requires a phase synchronization, will it be classified as a coherent receiver as well?
Yes.
Whether it is Coherent-scheme or Noncoherent-scheme is a matter of signal detection.
It is no relation to frequency conversion scheme such as zero-IF, low-If and heterodyne.
Note : low-IF is no more than heterodyne and zero-IF is homodyne.
But sometimes there is a case where homodyne means zero-IF with coherent detection.