methods are presented for adjusting trigger threshold values to compensate for drift in the quiescent level of a signal monitored for initiating a data recording event , thereby avoiding false triggering conditions . initial threshold values are periodically adjusted by re - measuring the quiescent signal level , and adjusting the threshold values by an offset computation based upon the measured quiescent signal level drift . re - computation of the trigger threshold values can be implemented on time based or counter based criteria . additionally , a qualification width counter can be utilized to implement a requirement that a trigger threshold criterion be met a given number of times prior to initiating a data recording event , further reducing the possibility of a false triggering situation .