Adam

OK, I understand that a wrong timestamp on the AIS data causes a wrong CPA, but ignoring the timestamp (by implicitly assuming it to be =now) is also wrong, because...

>Not sure what your comment should tell me. I just want to discuss and understand it. - I think, the age should always be included in the CPA calculation, which...

This is maybe interesting in this context. I looked at how `monotonic()` behaves when the system time is changed. I ran this loop and changes the system time, this was...

>At the end you would need the UTC base it is computed from. Yes, but if the machine gets time from GPS, this should actually be easy and already the...

But if you do not write missing values to the data store, they time out and get removed, then it is like as if they have never been there in...

side question: When looking into this I stumbled upon this; COG, course over ground, has the key [`track`](https://github.com/wellenvogel/avnav/blob/bcb1e4322d6013a4defc4cf94f926be4490b3436/server/avnav_nmea.py#L78) but in the GUI, in the widgets and int the data store...

Values in the data store should expire after a certain time if they are not updated. `nav.gps.course` does expire and gets removed from the store and becomes `undefined` in the...

Hmm, OK. - But a field becoming undefined (times out) can happen (sender goes offline or leaves the field blank). Could you help me to understand why `nav.gps.course` becomes `undefined`...

Fields that have expired on the server are no longer present in the data returned by a request to `/viewer/avnav_navi.php?request=gps`. The field `course` is explicitly set to be `undefined` in...

> some ideas how to show course vector/boat direction... If COG/HDT is undefined - do not display a course vector and - display the boat icon as circle/dot (no orientation)