BSL PRO 4 Manual - Biopac

Part C — Analysis Functions 323Synchronization TipDelay allows for a positive or negative time shift to be introduced between start of graph data and start of thelinked media file, thus compensating for any data/media alignment issues that may arise. Playbacksynchronization is often necessary because there is an unknown delay between the actual start of theacquisition and the start of the first video frame. If precise synchronization is required, the Playbacksynchronization setting allows one to change the timing of the first video frame with respect to the first datasample.As an example to determine synchronization, an LED can be connected to the I/O output of the MP36/MP35device. The Digital Outputs Output Control can then be set up to toggle any digital channel (D1-D8) on/off.With the LED viewable in the video, simply determine when the digital output occurred in the graph and enterthe appropriate Playback synchronization value necessary to correct the alignment. Note that one can neverachieve better than 1/30 of a second synchronization, which is the video frame rate.BIOPAC Digital LED connected to MP3x I/O port1) Note: Because synchronization requires a time scale value, it cannot be applied to graphs displayed inX-Y mode, or for FFT and Histogram windows. Once the LED has illuminated and you can see thesquare wave in the file, you can hide the channel.2) After the recording is complete, use the I-beam selection tool to measure the offset between the LEDillumination and the leading edge of the digital impulse. Use a Delta T measurement to determine thedelay information; Delay may be positive or negative based on camera performance. Delay should beentered in the Linked Media row for each segment—see page 324.BSL PRO Manual