[SAC-HELP] how to use sac function synchronize effectively

[Shutian Ma]

Dear colleagues,

Recently we transferred some waveform records from IRIS. These records generated by the same earthquake do not have the same start time. As we need all the records generated by the same earthquake have the same start time to make measurement we tried to use sac2000 function synchronize. After we used the function and used lh we found all the ktime? are same. When we display those waveform records processed by the function synchronize, we found the original start times are still kept.
Could you tell me how to use the synchronize function effectively?
Do you have another way to make all the records generated by the same earthquake have the same start time?
Thanks in advance,
Shutian