There are several possible reasons for this. The most common is that the cursor has been positioned after the last cycle in the graph window. “Find All Cycles” does not necessarily search the entire data file. It finds cycles from the current cursor position (as set by the I-beam tool) to the end of the file. Under the “Selection” tab of the cycle detector in versions of AcqKnowledge more recent than 4.2, there is a button labeled “Move Cursor to Origin”. Clicking this button may resolve the issue. For older versions of AcqKnowledge, the user should click “OK” to close the cycle detector window without erasing any applied settings, move the cursor to the beginning of the file or select all data (typing control-a – command-a on a Mac – is an efficient way to select all data), re-open the cycle detector, and choose “Find All Cycles” again. If this does not resolve the issue, then there is likely a problem with the parameters used for searching the data file. If searching for peaks in the data, the threshold may be set too high or too low such that data never cross the threshold. Ensure also that the correct channel is being searched for peaks. If searching for events, make sure that the cycle detector is searching for event marks of a type and location that exist in the file.
Page last modified 19Jan2015
Electrodermal Activity (EDA) is an objective index for understanding emotional states. Researchers measure EDA to gain insights on psychological or physiological response, leading them down the path of scientific discovery. Because EDA is so important to research, BIOPAC has created tools to optimize event-related EDA analysis. Topics include: how to identify skin conductance responses, convert stim events from E-Prime SuperLab, Presentation, Vizard, etc., into AcqKnowledge events that can used for analysis, and score skin conductance responses using the AcqKnowledge automated EDA analysis tool. Register Now
NIRS and CNAP—Pairing great tools for great data Cerebral hemoglobin concentration (blood mass in the brain) is frequently measured in the prefrontal cortex, and systemic arterial blood pressure is known to be a variable factor based on the hemoglobin concentration. A leg pressure cuff was used to constrict and release blood flow to create a […]
BIOPAC’s just released Introductory ECG Guide addresses fundamental to advanced concerns to optimize electrocardiography data recording and analysis. Topics include: ECG Complex; Electrical and Mechanical Sequence of a Heartbeat; Systole and Diastole; Configurations for Lead I, Lead II, Lead III, 6-lead ECG, 12-lead ECG, precordial leads; Ventricular Late Potentials (VLPs); ECG Measurement Tools; Automated Analysis Routines […] Read All