Multichannel Systems MC_Rack Manual - Manual (Page 134)

MC_Rack Manual
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Note: Please use first order filters whenever possible. Higher order filters tend to be unstable
and oscillate, especially when using very low or very high cutoff frequencies.
Warning: Please keep an eye on the “Performance” window. The window shows the
percentage of time available between two samples that is needed for real-time feedback
calculations (filtering and feedback logic). It should never exceed 90 %. Real-time feedback is
automatically switched off if more than 90 % of the resources of the Digital Signal Processor
(DSP) are expended. In case of performance problems, decrease sampling rate, if possible.
The “Status” window displays the status of the real-time feedback feature: “Off” immediately
after disabling the “Real-time Feedback” button, “On” after starting the tool and after the first
download.
Signal Detection
In the “Detection” tab, you can define a threshold as detection level for each channel
separately. All events that cross the threshold are detected. Please read chapter “Spike Detection
Methods” under “Spike Sorter” in this manual for more details. As usual, the settings have to be
downloaded to the DSP with the “Download” command.
Individual channels can be selected from the drop down menu. For each channel, a threshold
in μV can be selected from the numeric updown box. All signals crossing the threshold will be
detected as events. The same function can be achieved by dragging the threshold line in the
real-time feedback display.
Important: Changes in the detection settings also have to be downloaded to the DSP with the
“Download” command.
Enable the check box “neg. Slope”. If you select the option “Negative Slope”, the fall of the
signal curve is regarded, otherwise the rise is considered. This setting applies only to the selected
channel. In the “Apply to All” window, click “Slope” button to apply the slope setting to all
channels. Click “Level” button to apply the detection level of the currently selected channel
to all channels.
To modify the threshold level of all channels, please click the buttons of the “Tune all Levels”
numeric updown box. Tuning all channels means, that the different levels of all channels are
modified stepwise up or down by the same factor (+1 μV or -1 μV).The current level is displayed
in the microvolt box “μV” above.
The “Automatic” feature is convenient to automatically assign an individual detection level to
each channel. The standard deviation of the noise of each data trace is used to estimate its signal
threshold.