SimSmith 7 Release Notes
SimSmith version 7 contains several significant changes and a variety of major and minor enhancements.
Version 7 introduces a feature I tried very hard to avoid: modes of operation. There are only a few, but having opened the door, I’m sure more will follow. These modes can be set by clicking on “file/preferences”. Here you can set a variety of parameters which affect operation. You probably won’t change many, but you should know they are there. Please go take a look. I know the preferences menu is primative…..
NOTE: if you want to write design files which are readable by version 5 and 6 you need to set the “save for version 5 or 6”. This is necessary because previous versions of SimSmith were intolerant of circuit descriptions which contained unrecognized information. Oh… and when you do this, the preferences won’t be saved… sorry! Most of you don’t go backwards so, hopefully, this won’t be much of an issue.
The most significant new feature for SimSmith version 7 is support for drag and click tuning. These features are invoked by using the right mouse button.
There are two modes of operation. The first mode is used when working with the Smith chart when there is no sweeping taking place. If you right click on an arc you can drag the endpoint of that arc to a new location. By default, SimSmith will tune two arcs, the one you clicked and the one ‘just before’ it. This is considered a ‘drag tune depth’ of two. You can change the depth by modifying the “file/Preferences/drag_tune_depth” parameter. Setting it to 0 disables drag tuning.
The second mode of operation occurs during sweeps. In this case, right clicking on a point will set the component parameter values to match those used to create this point during the sweep. The easiest way to see this at work is to sweep a circuit using frequency. Then, you can ‘right click and drag’ the operating point on the curve. You will see the Generator MHz value updated to reflect the cursor’s location.
It might help to know a little about how SimSmith tries to do this drag tuning. It implements a fairly simple algorithm and uses a brute force technique. Starting with the arc you select it makes a list of parameters it can change. It then implements the following algorithm:
start_all_over:
for (i=0;i<numParams;) {
if (canGetCloserAdjusting(parameter[i])) {
doAdjustment(parameter[i]);
gotostart_all_over;
}
++i; // move to next parameter.
}
In English: start with parameter 0 (which is the arc you clicked on). If you can get the endpoint of the arc closer to the mouse, do so. If not, move to the next parameter. If there are no more parameters, you are done. If there is another parameter, try to get closer by adjusting that parameter. If you can, do so and start all over. If not, move to the next parameter…..
The most significant changes were made in the SWR and PGain charts. These charts now work essentially the same as the Smith Chart. Specifically, the cursor in the SWR chart will now snap to actual computed data points on the SWR and PowerGain curves. If the cursor is not near a computed point, no ‘report’ is generated in the lower right hand part of the window. If you don’t see a report… the cursor is not near a computed point.
Another change in the SWR chart is that Power can now be plotted in multi-dimensional sweeps. Power is plotted using dashed lines (or dots), SWR curves are solid.
When you move the cursor around the Smith and SWR charts, SimSmith snaps the cursor to the closest ‘computed datum’. When it does this, it highlights the component which corresponds to the point.