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The new WuTech
H-469TV photodiode array (PDA) performance is very similar
to the previous PDA used in Neuroplex. However, using surface mount
technology and low power consumption components the entire circuitry
of the H-469III (The diode array, first and second stage amplifiers
and multiplexer) now fits inside one box. This new arrangement eliminates
the need for an amplifier rack and the heavy cable bundles used with
NeuroPlex. Thus the new system is much more compact, much lighter
and easier to handle and ship. Moreover, it is much more reliable
and easier to operate as problems like 60 Hz line noise, oscillations
and ground loops are eliminated.
Dynamic Range
Up to 17 bits (100 db); the system can record signals as small as
10-5 of the resting light level.
Frame Rate
The phototdiode array system was designed for high speed data acquisition:
0.9 msec per frame (including 464 diodes and 8 electrodes). The
user can sample a subset of the array to further increase the frame
rate.
Dark Noise
Low, close to the Johnson noise of a 1 G-ohm resistor.
Signal-To-Noise Ratio
Near optimal signal-to-noise ratio for a broad range of light levels.
Silicon diodes have quantum efficiencies near 1.0. Unlike a CCD
camera, the photodiodes do not saturate at light intensities achieved
in neurobiological experiments. Base-line subtraction (AC coupling)
in individual channels offers an effective A-to-D resolution of
more than 20 bits with the 12 bit A-to-D converter.
Comprehensive
Software Designed With Neurobiology and Physiology In Mind
Neurobiologists typically analyze voltages using electrodes. The
software includes the data format that neurobiologists are used
to analyzing - wave forms over time for each photodiode input. NeuroPlex
also creates pseudo-color images and "movies". Further,
the system provides 8 BNC inputs that are sampled and displayed
with the photodiode data. A mouse driven point-and-click interface
is provided which shows multiple views of the data for clarity and
simplicity. Reasonably comprehensive analysis capability is provided.
Integrated System
Includes all the necessary components from the photodiode array
through the data acquisition and processing unit (diode array, amplifiers,
multiplexers, analogue-to-digital converter, computer, and output
control panel).
Experimental Control
The system can control a shutter and a stimulator. Three kinds of
triggering for data acquisition/averaging are available:
1. Triggered by user/computer.
2. Triggered by an external event.
3. Triggered by an event recorded on one of
the 472 channels.
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