Sync/Demod Status Leds - Teledyne T300 Operation Manual

Theory of Operation

13.4.3.2. SYNC/DEMOD STATUS LEDS

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The four sample and hold circuits are designated as follows:
Table 13-2: Sync DEMOD Sample and Hold Circuits
Designation
Measure Gate
Measure Dark Gate
Reference Gate
Reference Dark Gate
Timing for activating the Sample and Hold Circuits is provided by a Phase Lock Loop
(PLL) circuit. Using the segment sensor output as a reference signal the PLL generates
clock signal at ten times that frequency. This faster clock signal is used by the PLD to
make the Sample and Hold Circuits capture the signal during the center portions of the
detected waveform, ignore the rising and falling edges of the detector signal.
The following two status LEDs located on the sync/demod board provide additional
diagnostic tools for checking the GFC Wheel rotation.
Table 13-3: Sync/Demod Status LED Activity
LED Function
D1 M/R Sensor Status
D2 Segment Sensor Status
See Section 12.1.4.2 for more information.
Teledyne API – Model T300/T300M CO Analyzer
Active When:
IR BEAM PASSING THROUGH
MEASUREMENT cell of GFC Wheel
MEASUREMENT Cell of GFC Wheel
REFERENCE cell of GFC Wheel
REFERENCE cell of GFC Wheel
Sample & Hold
Active
Sample & Hold
Inactive
Figure 13-14: Sample & Hold Timing
Status OK
LED flashes approximately
2/second
LED flashes approximately
6/second
Segment Sensor Pulse is:
HIGH
LOW
HIGH
LOW
Detector
Output
Fault Status
LED is stuck
ON or OFF
LED is stuck
ON or OFF
06864B DCN6314