@Pit: Looking forward to your feedback. You need to re-do your calibration so long as you haven't done any of the normal things that might cause you to need to re-do it, e.g. rotate the guide camera sensor, change the weight balance, ...
@John, Great questions, see below:
How would I go about getting this version of the guider
You're asking a more general question, which is "how do I get to use the KStars pre-release experimental/beta software?" Unless you compile the software yourself, the experimental releases are only available on Linux systems using the techniques described in
www.indilib.org/download.html. If you build from source, you can look at the KStars README page at
invent.kde.org/education/kstars#building
Keep in mind that running experimental software always has risk that it will be less reliable than released software. Also note that you'd not only get the new internal guider changes, but also any other changes that have been made since the last release. I, and I'm sure many other experienced forum users, will be happy to help futher if these web pages aren't clear enough, but I'd suggest either started a new forum topic on getting the latest release, or, probably better, finding the last such topic and continuing it.
Also, will I be able to swap back and forward between the guider versions?
I do, but if this is new to you, it may not be straight-forward. Jasem's instructions show you how to do that. If you build from source, you can just run the new binary without installing it. If you are unsure, you should definitely fully back up your system, so that you can restore.
If I understand correctly what you've changed....(procedure for finding the aggressiveness)
Yes, that makes sense. You don't need to re-calibrate, you could look at your current calibration--it's show in the Calibration tag in the guider options. You might want to skip that procedure and just use the default aggressiveness and see how you like it before making changes.
Does the guider respond immediately to parameter changes or do I need to restart it?
It should respond immediately to changes in Aggressiveness and min/max moves.
What's the algorithm for Integral Gain, i.e. how many previous values are averaged and is it a straight average or weighted in some way, e.g. more recent weighted higher? If GPG is used with Integral Gain how do they interact, or is it one or other but not both at the same time?
First, I did not modify nor experiment with integral gain as part of this change. In fact, I don't use it. I welcome someone looking further into and figuring out if it is helpful and how to configure it. I have looked at the code extensively, as part of this, and understand what is done. Integral gain looks at up the previous 50 guider iterations (upto, because there may be fewer available--e.g. on the 25th iteration it looks at the past 24).
It takes a straight, unweighted average of the guide deviation, e.g. it may wind up computing that the mean historical guide deviation is -0.5 arc-seconds. It then weights in that error with the current guiding measurement, using the aggressiveness (for the current measurement) and the integral gain weighting the historical measurement. GPG does not use integral gain. It has its own hardwired mechanism. (Good point, I should grey it out when GPG is enabled.)
You are probably already thinking about this but PHD2 offers suggestions for parameter settings based on the calibration. I think this would be very useful for the internal guider.
Agreed, a wizard for computing the best parameters would be great. I don't have any concrete news on this.
For calibration, the PHD2 folks recommend doing a calibration at a specific telescope orientation and then leaving it alone until the setup is changed. Presumably it would be the same here
Yes, the PHD2 recommendations are good, and in general their advice applies to the Ekos internal guider as well.