BIOPAC® Systems, Inc. Logo

How come when I try to record data all I see is a flat line?

There are many possible reasons for a flat signal. It is important to make a distinction between the data (the numbers that the computer is actually recording) and the display of the data (how the numbers are shown in the graph window). The two channels shown in the image below contain the exact same data; the lower channel is a duplicate of the upper. However, the lower channel is displayed with a much coarser scale (zoomed out).

vertical autosclae toolbutton

The first troubleshooting step is to re-scale the display of the data. There are multiple ways to do this, but one is to select the channel and click the vertical autoscale button in the toolbar.

If scaling is not the issue, the next step is to ensure that channel setup is correct.

If neither channel scaling nor channel setup is the cause of the flatline, verify that all equipment is securely connected.

Also make sure that all relevant switches are in the “On” position.

If the system has not been used before, make certain that a signal is expected under the present conditions.

If answers to all of those questions are “yes”, only then is it time to entertain the possibility of a hardware failure.

Spotlight On
free BIOPAC webinar

Evoked Potentials Part II: Event-related or Endogenous Evoked Potentials (ERP)

Learn how to record event-related or endogenous evoked potentials (ERP).

You will learn about:
– Introduction to ERPs
– Theory and guidelines for recording ERPs
– How to record great ERPs data
– Wired and wireless wearable EEG-fNIRS bimodal response to oddball paradigm
– How to mismatch negativity in a virtual world
– How to prepare data for analysis
– Workflow Automation Tools

On Demand Playback

Register Now
Latest News

New Citations | BIOPAC in Psychophysiology Research

The mind and body work together in many ways and psychophysiology research provides insight to these connections. BIOPAC has a variety of systems to power your emotion, arousal, stress, cognitive assessment, group interaction, startle, and other psychophysiology research. Here are some recent studies that have used BIOPAC systems for psychophysiological research… Skin conductance, facial EMG, […]

Seenel Imaging and BIOPAC Systems, Inc. Announce a Global Partnership

           For immediate release: January 4, 2023 Amiens, France and GOLETA, California, USA Seenel Imaging SAS and BIOPAC Systems, Inc. have formed a long-term global partnership to distribute MedelOpt®, Seenel Imaging’s groundbreaking wearable neuroimaging device for the neuroscience research market. Seenel Imaging, based in France, continues its international expansion by partnering with BIOPAC Systems, […]

Read All
Request a Demonstration
Request a Demonstration