U.S. Patent No. 3,714,464. The external strobe should be given within 10 s of the linear input. At the end of this period, the Model 552 resets its internal logic without producing an output signal. For internal strobe, the outputs occur at the selected fraction point of the linear input trailing edge plus the output Delay as selected by the front-panel control. For external strobe the outputs occur at the time of the strobe signal.
Output occurs as leading edge of linear input crosses the lower-level threshold.
Output occurs as leading edge of linear output crosses the upper-level threshold. When the LL REF mode switch is in the EXT position, this control is ineffective. In the BI mode, zero-crossing timing is performed on bipolar inputs. The normal operating mode is the X1 position. The Model 552 input is compatible with all amplifiers having a 0 to 10-V positive linear output range.