Reference
Serial Mask Testing & Serial Pattern Trigger User Manual
31
Standards and Bandwidth.
When the instrument system bandwidth (which
includes the instrument, attached probes, and/or cabling) falls into the range of
1.5 to 1.8 (0.8 for optical signals) times the data signal bit rate, the third
harmonic of the data signal is significantly attenuated. The instrument displays
useful qualitative information, but quantitative rise-time measurements under
these conditions may not be accurate.
For example, a 1394b standard signal at the S800b rate has a bit rate of
983.0 Mb/s. 1.5 to 1.8 times this value is a range of 1.47 to 1.77 GHz. Therefore,
you should not use a 1.5 GHz measurement system for making quantitative
rise-time measurements of this standard.
When just the instrument bandwidth falls within 1.5-1.8 (0.8 for optical signals)
times the bit rate of a selected mask standard, the instrument displays the
message “Consider system bandwidth when testing at this bit rate.” in the status
area above the graticule.
There are a number of optical mask test key points to be aware of prior to doing
optical mask testing on the CSA7000 Series instruments.
H
The CSA7000 Series instruments, when equipped with the O/E Electrical
Out-to-Ch1 Input Adapter, are calibrated optical reference receivers. This
means that the instrument optical to electrical converter and instrument input
channel have been tuned to have a fourth-order Bessel-Thompson response,
as well as the correct frequency response for each supported standard by use
of digital filters.
H
When the O/E Electrical Out-to-Ch1 Input Adapter is installed, you select an
optical mask, and the Bessel-Thompson filter mode is On, then only channel
1 is available. Trying to turn on any other channels, or perform certain
functions such as changing the acquisition mode, results in an error message.
Turning the Bessel-Thompson filter mode to off enables access to the other
instrument channels, though channel 1 is no longer in the calibrated ORR
mode.
H
Optical signal mask testing is available for Fibre Channel, InfiniBand,
SONET, 1394
β
, and 1G Ethernet standards.
H
If a listed standard is not available on your instrument, it is because the
bandwidth of your instrument is not high enough to test that standard.
H
You can use O/E Adapters on different CSA7000 instruments without
affecting the optical reference receiver calibration on an instrument.
H
CSA7000 Series instruments provides recovered clock and recovered data
signal outputs on the instrument front panel, as well as using the signals for
internal triggering.
Optical Mask Testing
Key Points
(CSA7000 Series Only)
Summary of Contents for CSA7000 Series
Page 8: ...Preface vi Serial Mask Testing Serial Pattern Trigger User Manual ...
Page 12: ...Getting Started 4 Serial Mask Testing Serial Pattern Trigger User Manual ...
Page 18: ...Operating Basics 10 Serial Mask Testing Serial Pattern Trigger User Manual ...
Page 48: ...Reference 40 Serial Mask Testing Serial Pattern Trigger User Manual ...
Page 62: ...Index 54 Serial Mask Testing Serial Pattern Trigger User Manual ...