Theory of Operation
CSA8000 & TDS8000 Instruments and Sampling Modules
3–5
80C0X and 80C0X-CR optical modules share the same mechanical package and
built with a common circuit board. Different functionality within the modules
(current and future modules) is achieved by installing different O/E modules,
filters and clock recovery boards along with setting the sampler bandwidth as
demanded. The key features supported in the module are:
H
A one channel, low noise, adjustable bandwidth sampler allowing multiple
bandwidth settings for optimizing noise verses bandwidth demands.
H
An amplified or non-amplified O/E converter.
H
Support for a switch module with a straight through path and two filtered
reference receiver paths between the O/E converter and the sampler.
H
An average optical power meter.
H
Integral clock recovery option with internal plumbing connection to the
trigger, front panel clock and data output.
H
I
2
C communication with the mainframe for identification, control and
calibration/compensation storage.
The “system response” depends on all of the components in the signal path from
the front panel to the sampler. Bandwidth and reference receiver responses are
calibrated at the factory with a sub-picosecond optical impulse applied to the
front panel connector. This insures that all components are included, but also
means that components can not be replaced without performing calibration.
Compensation performs a DC transfer curve characterization for each bandwidth/
reference receiver setting. The curve data is stored in the module’s EEPROM and
used to generate a look-up table in the mainframe. This data corrects for
linearity, gain and offset errors in the sampler.
Reference receivers can be created in any of the following ways:
H
A hardware filter inserted between the sampler and O/E.
H
Adjust the sampler’s bandwidth.
H
Adjust the O/E response with the sampler set to a higher bandwidth.
The available bandwidth and reference receiver selections, and the method used
to set the bandwidth for 80C01, 80C02, and 80C03 optical modules:
The power monitor is a second measure of the photodiode current that is
independent of the sampler signal path. Analog circuitry continuously senses the
current flowing into the bias side of the photodiode. The signal is amplified by a
programmable gain amplifier and input to an 8 bit AD converter. The AD
converter and amplifier are controlled through the I
2
C interface. Compensation
performs two functions in the power meter: First, two offset inputs are adjusted
in the amplifier so that the signal stays in range for all of the gain settings. Next,
80C0X and 80C0X-CR
Optical Sampling Modules
Summary of Contents for CSA8000 Series
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Page 18: ...Service Safety Summary xiv CSA8000 TDS8000 Instruments and Sampling Modules ...
Page 22: ...Preface xviii CSA8000 TDS8000 Instruments and Sampling Modules ...
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Page 59: ...80C00 Modules Specifications 1 36 CSA8000 TDS8000 Instruments and Sampling Modules back ...
Page 63: ...80A01 Module Specifications 1 40 CSA8000 TDS8000 Instruments and Sampling Modules ...
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Page 74: ...Installation 2 10 CSA8000 TDS8000 Instruments and Sampling Modules ...
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Page 103: ...Theory of Operation 3 10 CSA8000 TDS8000 Instruments and Sampling Modules ...
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Page 106: ...Performance Verification Procedures 4 2 CSA8000 TDS8000 Instruments and Sampling Modules ...
Page 122: ...Brief Procedures 4 18 CSA8000 TDS8000 Instruments and Sampling Modules ...
Page 126: ...Performance Tests 4 22 CSA8000 TDS8000 Instruments and Sampling Modules ...
Page 218: ...80A01 Trigger Preamplifier Module 4 114 CSA8000 TDS8000 Instruments and Sampling Modules ...
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Page 231: ...Maintenance 6 6 CSA8000 TDS8000 Instruments and Sampling Modules ...
Page 291: ...Removal and Installation Procedures 6 66 CSA8000 TDS8000 Instruments and Sampling Modules ...
Page 307: ...Repackaging Instructions 6 82 CSA8000 TDS8000 Instruments and Sampling Modules ...
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Page 315: ...Electrical Parts List 8 2 CSA8000 TDS8000 Instruments and Sampling Modules ...
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