If a unit has less than one field of memory then it is not in the family of field or frame synchronizers, it is probably a Time Base Corrector. Remember any Time Base Corrector with more than one field of memory is also a synchronizer, but not all synchronizers are Time Base Correctors. There is some confusion as to what a time base corrector is and what they do. Time base error is just like the wow and flutter in the play back of music from a record player or audio tape player. When you play a recording of the Boston Pops holding a high note, the sound will be distorted as the player goes a bit faster or slower than it should.
None can make perfect speed all the time.
Wow is long term speed variations, like going 7.48 ips instead of 7.5000 ips. Flutter is short term time variations in speed. Measure the speed and it is constantly fluctuating from 7.481 and 7.480. Video tape recorders have the same problems, only usually less severe. Time base error is most apparent when trying to mix or wipe from a VTR playback to a camera or another VTR playback.