Molecular Devices Digidata 1550B, User Manual

Page: 16 / 40

Digidata 1550B Low-Noise Data Acquisition System User Start Guide
16 5040237 B
HumSilencer Adaptive Noise Cancellation System
The HumSilencer Adaptive Noise Cancellation System (ANC) is integrated into Analog Input
Channels #0, #2, #4, and #6 of the Digidata 1550B digitizer, depending on the model, so no
additional hardware installation is required. When it is in use, it eliminates electrical hum
interference at 50 Hz or 60 Hz and the associated high
‐
frequency harmonics. The ON/OFF
switch for ANC is software
‐
controlled. ANC works by learning the noise
‐
patterns that are
synchronous with the AC power, known as hum, caching a signal
‐
averaged replica of the hum,
and subtracting the noise replica from the signal in real time. It adapts to noise changes in
about 1 second, within 50 power
‐
cycles at 50 Hz or 60 Hz. It is designed to work with
peak-to-peak hum amplitudes that, when combined with the signal of interest and other
non-line-synchronous noise sources, are within the
‐
10 to +10V range of the Digidata 1550B
digitizer analog inputs. It is not a filter and does not have a filtering effect on acquired signals;
nor does it cause waveform distortion, such as, frequency change, amplitude attenuation,
phase shift, or DC-voltage shift.
Note: The HumSilencer system controls do not display in the AxoScope software or the
Clampex software Demo configuration, nor do they display without a connection to and
configuration with a Digidata 1550B digitizer that has an installed HumSilencer module.
The HumSilencer system control-enabling check box is part of the AxoScope software version
11.2 and the Clampex software version 11.2, located in the Edit Protocol > Inputs dialog tab
(
Figure 3-2 ). A blank check box indicates that the Real Time Controls panel items for ANC are
disabled. The HumSilencer check boxes correspond to the type of ANC channels module with
which your instrument is equipped (0, 1, or 4).
Figure 3-2: Edit Protocol > Input dialog tab check boxes used to enable the Real Time
Controls panel items for the HumSilencer system
CAUTION! The Real Time Controls panel items under HumSilencer do nothing if an
enabling Edit Protocol > Inputs > HumSilencer dialog tab check box is not selected for
an available Analog IN Channel (
Figure 3-2 ).