Signal Processing Functions; Analog Input Circuit Board; Analogoutput Circuit Board - Teledyne 3060E Instruction Manual

Model 3060E Model 3060E Model 3060E
Model 3060E Model 3060E

Signal Processing Functions

Analog signal processing is accomplished in two plug-in circuit cards operating
under control of the microcomputer. One card processes analog input signals
and the other processes analog output signals. Digital signal processing is
accomplished directly by the microcomputer. All analog signals are converted
to digital early in the processing cycle to minimize analog processing and assure
maximum system accuracy, since digital processing is much more accurate than
analog and immune to many parameters such as drift and aging.

Analog Input Circuit Board

The analog input printed circuit board (PCB) is actually a plug-in module
consisting of a main board and a daughter board. Two analog signals are
connected to the inputs of this module for processing. They are:
• Ultra Trace Sensor Current Output
• Mass Flow Controller Output
The circuitry on the daughter board converts the Ultra Trace sensor current to
a corresponding voltage, provides range control, isolates system grounds, and
filters high frequencies from the signal.
The circuitry on the main board processes the filtered output signal from the
daughter board and the signal outputs from the flow controller. All signals are
eventually connected through an analog multiplexer (electronic switch) to the
input of an analog-to-digital converter, where they are converted to digital
signals for use by the microcomputer.
This circuit board also contains a voltage measuring circuit to monitor the
voltage outputs of the system power supply, and a gas selector switch circuit
to adjust the mass flow controller for the background gas selected.
Analog Output Circuit Board
The analog output printed circuit board (PCB) generates the two 0-1 volt and
the two 4-20 mA analog signal outputs available on the rear panel of the
analyzer. These signals, generated in digital format by the microcomputer, are
converted into analog signals by the circuitry on this PCB. The output signals
represent the following:
• 0-1V Signal (Oxygen Measurement)
This output goes from 0 to 1, representing 0 to 100% of the scale
that has been set; i.e., 0.6 volt is equal to 60% of the full scale, or 30
PPB when on the 50 PPB scale. It is possible that the signal may go
past zero into the negative range up to -0.25, especially if the ana-
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Analytical Instruments
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