5. Monitor Output
The Monitor Output is provided as a visual aid to assist with parameter setup and ver-
ify operation of the Model 9660 ICB Digital Signal Processor. The Monitor Output
uses a Digital to Analog Converter (DAC) to convert or reconstruct the sampled digi-
tal filtered signal (with trapezoidal weighting function) into the analog time domain
for viewing.
The Monitor Output has 12 bits of resolution and an 8 volts dynamic range which re-
flects full scale for the selected MCA Conversion Gain. It is only intended to drive the
input of an oscilloscope for viewing, as it has limited drive capability. Using the Mon-
itor Output to drive accessories other than an oscilloscope, such as traditional ADC’s,
Mixer Routers, etc. is not recommended.
In addition to the reconstructed Trapezoid signal, a small amount of digital noise may
also be observed mixed in with the signal. This is an artifact of residual noise pickup
associated with the monitor output reconstruction DAC and associated circuitry, and is
normal. The digital filter data being processed does not contain this noise.
Trapezoid Output
The reconstituted trapezoid waveform provided on the monitor output is similar to the
output of a traditional spectroscopy amplifier when verifying operation and setup. Fig-
ure 16 shows a typical trapezoidal waveform as viewed on the Monitor Output when
using a germanium detector and
60
Co source, with the 9660 FILTER set for a Rise
Time of 5.6
µ
s and Flat Top of 0.8
µ
s.
User’s Manual - ICN 9231014G
29
Trapezoid Output
Figure 16 Typical Monitor Output
Scope:
Vertical: 2 V/div
Horizontal 2.5
µ
s/div
