Signalintegrity

Features
Schematic Variables
This is a long awaited and hugely valuable feature, especially for hierarchical projects and scripted applications. Now, a schematic has 'variables'. Devices within the schematic can derive their settings from these variables. Devices which access other projects can also have variables and these variables are passed down into the nested project. In the future, schematic equations will be added that can compute new variables.
The UI handling of these variables will be improved in the future, but for now, is good enough.
Calculation properties in nested projects
Devices that reference other projects can now pass the calculation properties along so that the nested projects inherit these calculation properties.
Eye Diagrams
Sampled Waveforms
Now it is possible to view the sampled waveform containing only the samples taken at the eye diagram alignment point. This is useful for qualitatively viewing the goodness of the communications from the waveform perspective and for generating residual errors in the sampling.
Eye Diagram Measurements
Signal power, noise, residual error, SDR, SNR, and SNDR are now calculated and displayed.
Eye Waveforms (and Regular Waveforms) Added to Simulation Results
Eye waveforms and regular waveforms can now be dropped into a schematic whereby they are added to the waveform and eye diagram results without any simulation -- the waveforms are simply read from the disk and processed. Closes 22.
Optical Measurements
Optical measurements are added to the eye diagram measurements. These are measurements of input and output power, transmission penalty, insertion loss, extinction ratio, etc.
Archiving
An archiving feature has been added for dealing with deeply hierarchical projects. When projects are archived, all of the elements and projects referenced by a schematic are gathered into a directory structure, with the schematics changed to point to these newly located elements and zipped. In this manner, projects can be archived and moved easily.
Headers in S-parameter Files
Headers can now be displayed, edited, and written in post-processing steps.
Lossy Ideal Transmission Line
Ideal transmission lines with skin-effect and dielectric loss can now be used.
PDN Analysis Features
I've been using the tool a lot for analyzing PDNs, and have added a number of features, mostly to speed up these analyses that require typically very high frequency resolution
Multi-port Tees
Every area in a schematic that contains a multiple device port connection was previously implemented as a three-port tee per three port connection, followed by an additional three-port tee connected per extra device connection. This could be a lot of three-port tees, and therefore very large matrices. Now, at the parser level, if I know that there are many device connections, all device connections are made with a very large tee element connecting to all of the device ports. This greatly speeds up the calculation of these types of systems.
Parallel devices
In PDN analysis, it might often occur that many pins of a connector are placed in parallel, and many on-die capacitances might be put in parallel. This could bog down the simulator. Now, there is a specific parallel device that can put any two port device in parallel. This also greatly speeds up the calculation.
Resampling Errors
This is an enormous fix for a problem that mostly only occurs with PDNs. Inside the simulator, all calculations are performed using 50 ohm s-parameters. The ideal reference impedance for a PDN is something like one ohm. The reference impedance itself is not much of a problem, but resampling the s-parameters in the wrong reference impedance could be disastrous. This is a complicated topic, so I'll not completely explain it here, but now, all s-parameters are resampled in their reference impedance prior to conversion to 50 ohms. This means that in sub-schematics, you can set the reference impedance and make sure that the impulse and step response settles in that reference impedance, and rest assured that they will be resampled in that reference impedance. This allows PDN elements to be sampled sufficiently and analyzed for sufficiency of sampling with as few frequency points as possible, and know that it will operate properly in the simulation.
Source waveforms in results
Now, a voltage or current source can be placed raw in to the resulting simulation without having to add a probe. This eliminates the need for a transfer characteristic calculation, which is superfluous and takes unneccesary time.
Minor Features
S-parameter postprocessing
Offset Removal
offset can be removed from the impulse responses of s-parameters. This helps remove any tilt that occurs in the step response due to various problems with s-parameters (including DC point restoration).
Writing Waveforms as .csv
Waveforms can now be saved in .csv format as time, value. Closes 60
Speedups
Probe Calculation Control
To speed things up, probes can now be turned on and off. This allows probes to be placed into a schematic, but disabled until they are really needed for diagnosis or debugging.
Caching
Cached results have been trimmed to use less disk space and to open more quickly.
S-parameter Calculation
These are sped up using some more intricate linear algebra. It turns out that, at the time of my book writing, this simplification feature was already present in symbolic results, but was not carried over to numeric results. It was relatively easy to drop this optimization in. Basically the speedup is to essentially trim away parts of the network that are not interacting with ports at all, thus simplifying the computation.
Schematic Output
Schematics can now be saved as .png files.
Bug Fixes
Two-port Current Sources
A bug that caused the current direction to be invariant to the orientation of the part has been fixed.
Eye Diagrams
Jitter and Noise
Jitter and/or noise is now applied to eye diagrams, even when some (but not all) of the values are zero.
SI units
Engineering notation is no longer used with dB or dB-like units.
Reference Impedance Errors
These are now shown with an error message.
Calibration Standards Documentation
Updated to correctly document units for standards.
Opening S-Parameter Files
Previously, when opening an s-parameter file directly, if a project file was similarly named, it opened the project file. This is now fixed.
Caching fixes
Caching has been improved, especially when moving projects between Linux and Windows machines by properly sorting the netlist prior to generating the hash, and by maintaining the Linux style directory structure. In some projects, cached results were being constantly recalculated.

See [Installation](https://github.com/TeledyneLeCroy/SignalIntegrity/wiki/Installation) for installation instructions.

Features
This release, feature-wise, is all about eye diagrams, eye measurements, and bathtub curves

Eye Diagram Improvements and Annotations


Many eye diagram improvements were made in this release:
* The drawing of the eye diagrams are improved through the use of an enhanced precision mode. (see the [User's Manual](http://teledynelecroy.github.io/SignalIntegrity/SignalIntegrity/App/Help/Help.html.LyXconv/Help.html) for more information.)
* The eye diagrams can now be _annotated_ with measurements made on the eye.
* Previously, the eye diagram configuration was handled globally, which made it very difficult to deal with schematics containing multiple eye probes. Now, the configuration is unique to each eye probe.
* Eyes can now be resized easily just by resizing the window.
* Eyes can now be auto-aligned through a fairly complex algorithm that allows for alignment using vertical and horizontal criterion.


Eye Measurements
Eye measurements come in two forms:
* Horizontal/Vertical -- measures things like eye height, eye width, linearity, RLM.
* Error Rates -- measures SER, BER, etc. on both uncoded and Gray coded symbols.

<p float="left">
<img src="https://user-images.githubusercontent.com/16583311/147608158-04a9468f-dbae-41dd-a382-6ef93aeff388.png" width="400"/>
<img src="https://user-images.githubusercontent.com/16583311/147608169-26ea066f-5ae4-4087-be2b-b0fe15c0011d.png" width="400"/>
</p>

Bathtub Curves

Bug Fixes
Capacitor Devices with ESR
This was really screwed up, and is now fixed.

Dialog Issues
This was not perfectly fixed, but large attempts were made to make dialogs modal, when they needed to be, and to not be resizable, if it didn't make sense, and especially not minimizable, when other dialogs were waiting for them to close. It's not perfect, but much better.

Minor Features
Post Processing
A post processing command is now supplied to change the reference impedance to whatever is desired. This makes it so that the result of the calculation immediately pops up in the desired reference impedance.

Frequency Log Scale
Frequency response and content can now be viewed on a logarithmic scale.

Converting Parts
By selecting a part in the schematic, you can now right-click on it, and convert it to another part. All of the common fields are copied over and the missing fields are set to default -- but it's still easier than placing another part down and entering everything.

Open S-parameter Viewer Standalone
Now, s-parameter files can be opened with _SignalIntegrity_ and they open the viewer directly, without the underlying project. Windows machines can even be configured such that double-clicking on an s-parameter file can open in _SignalIntegrity_.

Caching of Eye Diagrams
The caching mechanism has been extended so that eye diagrams are cached. This means that when changing various eye diagram properties usually does not require recalculation of the underlying eye diagram bitmap (which takes most of the time).

Help System and Unit Tests
The help system was completely updated with the documentation, especially for the eye diagrams and all unit tests were run and passed.

See [Installation](https://github.com/TeledyneLeCroy/SignalIntegrity/wiki/Installation) for installation instructions.

Features

Eye Diagrams
Added the Eye Probe which produces very nice eye diagrams


This capability will be enhanced in the future towards items like clock recovery and measurements made on eye diagrams. For now, it assumes a single specified baud rate, and you must control the delay to center the eye in the diagram automatically -- but it does make beautiful pictures.

Impulse Response Filters
A type of filter has been added that allows for a filter to be described by the impulse (or step response of a waveform).

LeCroy Waveforms
Up to now, the only format for waveforms usable with SignalIntegrity was the SignalIntegrity text based waveform format. Now, LeCroy waveform format (the kind used in LeCroy scopes is available). These waveforms have the .trc extension and are automatically read in properly and a preference has been added to allow saving in this format as the preferred format. This is useful when using SignalIntegrity along with the oscilloscope.
Closes 5.

Transfer Matrices
The SignalIntegrityAppHeadless API that is used for driving project calculations from other Python scripts has been enhanced to allow Simulation projects and Virtual Probe projects to supply only the transfer parameters (or transfer matrices). These, as you might know, are the banks of filters to which the waveforms are applied. Also, the main application allows for calculation and viewing of only the transfer matrices (this was previously possible only after an entire simulation was performed).

Other Small, Miscellaneous Things
Upper case file names are now allowed in s-parameter files. This was not really a problem on Windows machines, but was problematic for Linux machines. Plus, some old VNAs would automatically write wave forms with upper case extensions. This is now handled properly.
The default preferences have been updated so that on new installations, The preferences are the preferred ones (previously, these were the safest ones). This means that SinX interpolation, calculation caching, and grids on plots is now preferred, along with the experimental "Try SVD" in calculations that has been around for a long time and seems to work very well.
The Laplace function filter has been updated to allow for z-domain waveforms (in addition to functions based on f, jw, and s, previously).

Bug Fixes
Waveform Adaption
During waveform adaption, there was a bug that was rarely encountered that caused the fractional delay to not be applied. This is fixed.

Documentation Fixes
Some documentation used with the online software documentation that is automatically generated from the decorated code was repaired.

Skin-effect Resistor
This feature released in the last release was very broken, and is now fixed.

Performance Improvements
It was discovered that the impedance peeling capability added awhile ago for port peeling and de-embedding was running all the time, even when peeling was not being asked for. This did not result in a wrong answer, but added a large amount of work to s-parameter generation and de-embedding, especially for large amounts of frequency points. Now, this is optimized to do as little work as possible when impedance peeling is not desired.

Help System and Unit Tests
The help system was completely updated with the documentation, especially for the eye diagrams and all unit tests were run and passed.


See [Installation](https://github.com/TeledyneLeCroy/SignalIntegrity/wiki/Installation) for installation instructions.

Features
Linear Vertical Scale in S-parameters
S-parameters can now be viewed on a linear vertical scale. The usefulness of this feature is primarily evident when viewing transfer parameters in PDN analyses. For example, if you drive a PDN with a current source and probe the PDN voltage rail, the transfer characteristic is one of V/A = ohms. Therefore, when viewing the transfer characteristic on a linear vertical scale, the readout is in PDN impedance in ohms.

Headless Simulations and S-parameter Calculation Callbacks
Now, when performing a simulation or s-parameter calculation in a "headless" mode (when opening a project and running the project from a script), a callback function can be provided. This is useful to track the progress of the calculation from a script.

Relay contacts increased to 17
so that a 16 contact relay with a common can be used.

Skin-effect Resistor
A resistor device has been added where all of the resistance is due to skin effect (i.e. has a resistance specified in ohms/sqrt(Hz)).

SOLR calibration with no thru provided
Previously, a thru standard estimate was required for SOLR calibrations. Now, it is possible to let the algorithm determine the thru with no estimate provided. This should only be used with highly sampled s-parameters.

Bugs
Resampling in VNA Calibrations
When performing VNA calibrations, the measurements were not being resampled, which is a bug. This meant that the measurements provided must be on the exact same frequency scale as specified in the project in order to work. This has now been corrected and the measurements are resampled onto the project frequency scale.

See [Installation](https://github.com/TeledyneLeCroy/SignalIntegrity/wiki/Installation) for installation instructions.

New Devices
DC Voltage and Current Sources
These are much needed devices that enhance the capability of setting DC points. Previously, this was a cumbersome exercise involving creating a step source that starts at some distant time in the past, requiring the simulation to start only after these DC waveforms stabilized. Now, DC voltage and current sources are not waveforms, but just numbers representing their values. During processing, the DC (number) waveforms are processed by taking the DC frequency response of the filter they are passing through, as opposed to convolution with the impulse response. In addition to these simplifications, DC sources do not require time length, sample rate, etc. They are just always there.
Laplace Device
This is a device that allows the user to directly enter an equation for the S21 in s, w, or f. The remainder of the device performs like an amplifier with infinite input impedance, zero output impedance, and perfect reverse isolation. This device is useful for generating flexible DSP building blocks when the desired function is not available.
Xtalk Calibration Measurement
Previously, for VNA calibrations, two types of calibration measurements were supported: Thru and Reflect. Now, the less often used cross-talk measurement has been added. This had been usable through scripted applications, but it has now been added to the GUI.
Bug Fixes
Honoring 12458 sequence preference in s-parameter property changes
In a previous release, this was added as a preference for the calculation properties, but was missed for s-parameter properties. This is now fixed.

All documentation is up to date with this release. See [Installation](https://github.com/TeledyneLeCroy/SignalIntegrity/wiki/Installation) for installation instructions.

A number of new, useful devices have been added
Filters
A few filters have been added. These filters all have high input impedance, low output impedance, perfect reverse isolation, and a filter in between. Of course, they have s-parameters.
Bessel low pass filter
A Bessel filter can be instantiated in the GUI and in netlists. The filter takes an order and a cutoff frequency.
Butterworth low pass filter
A Butterworth filter can be instantiated in the GUI and in netlists. The filter takes an order and a cutoff frequency.
Equalizers
Two equalizers have been added that are pertinent to the COM specifications for many channels.
CTLE
The continuous time linear equalizer (CTLE) has been added whose parameters are defined according to COM.
FFE
A feed-forward linear tapped delay line equalizer has been added. It takes a tap delay, a list of tap weights, and the number of precursor taps.
Transmission Lines
W element
The W element, useful for dealing with distributed, coupled transmission lines has been added. For more information on this element, see: http://www2.ece.rochester.edu/courses/ECE222/hspice/hspice_devmod.pdf
Waveform Generators
Multi-level Waveform
This is a true PAM-N waveform generator that can output PAM waveforms with any number of (power of two) levels.
Miscellaneous
Ideal Relay
The ideal relay is really useful in scripted applications using projects. Any SPXT relay can be instantiated with a position specifying which port is connected to the common. This way, schematics can be drawn with alternate circuit configurations based on relay position and the relay position can be controlled from within a script (instead of having to use a different project with a different schematic).

See [Installation](https://github.com/TeledyneLeCroy/SignalIntegrity/wiki/Installation) for installation instructions.