THE SECRET SAUCE
Software is the
secret sauce of the modern oscilloscope.
Pre-installed software analyzes the captured data to measure the amplitude, frequency, pulse width, rise/fall time, and
other specs. These are displayed decimally on the screen along with the waveform. Special software packages are
available to conduct far more detailed
analysis of the signal ().
Some common analysis packages target jitter analysis, analysis of high-speed
serial data streams including clock recovery and eye mask unfolding; Ethernet
testing; power-supply (switching) analysis; DVI and HDMI; low-speed serial
buses like CAN, LIN, I2C, and SPI; and
memory testing (such as fully buffered
DIMM and DDR2 compliance).
A fast Fourier transform option is an
example that provides a frequency spectrum plot of the signal. Other software is
for debugging. You can even program
the scope yourself in some cases where
your special needs can be met.
Always look for a scope that has good
basic software to start. Some of this software can even be pre-installed. Also,
choose your scopes from a manufacturer
that continues to upgrade its products
and offers additional analysis packages.
Most manufacturers provide packages
that let you generate user-defined functions generated by external software such
as Matlab, LabVIEW, Excel, or other
proprietary products.
Third-party software sources are
growing, too. National Instruments'
SignalExpress scope analysis software,
designed for the company's PXI scopes,
is also available for scopes from other
companies like Tektronix. The SignalExpress signal analysis software is programmable in a drag-and-drop environment. Processing includes alignment,
filtering, averaging, and scaling.
Measurements include amplitude, timing, and histogram in the time domain or
power, frequency response, and distortion in the frequency domain. SignalExpress also allows sweep operations for
limit testing. And, it can close the gap
between design and test, which software
providers have neglected up to this point.
Analysis used during design can be more
easily transferred to manufacturing test.
Another third-party software package
for real-time scopes, Amherst Systems
Associates' M1 OT (for oscilloscope
tools), handles sophisticated analysis
software tasks and more. Among the
wide range of analysis features are RjDj
jitter analysis and DDR2 compliance. It
offers greater analysis precision as well as
a TestScript feature that lets you program
automated measurement sequences.
To help familiarize scope users with
the analysis package, ASA's Cirrus Program gives away the M1 OT professional
package (worth almost $8000) to any
organization that is in the process of purchasing or has taken delivery within the
last 30 days of a new Agilent or Yokogawa real-time scope. Check out ASA's
Web site for more details.
The basic oscilloscope hardware has
almost reached the commodity stage.
New innovations will come from better
software. Watch for more third-party
software and stepped-up scope manufacturer software offerings.
For more, see "Jitter—A Scope's Toughest
Challenge."