[kismac] Re: 0.2 new GPS engine?

  • From: Robin L Darroch <robin@xxxxxxxxxxxxx>
  • To: kismac@xxxxxxxxxxxxx
  • Date: Sun, 16 Jan 2005 21:20:03 +0800

Having built 0.2, it stuck me that the GPS position is way off once the unit is getting a fix after having lost sight to the sats. There is a long list of text appearing rather than (x,y) coordinates as I used to have. Is there a complete new engine, and if so, is there a link to a place where the text is explained?

Since I wrote most of the new GPS code, I'll have a go at explaining it. I wrote it mostly for my own interest, but it seemed to me having written it that other people might like the extra info to.

As far as your position is concerned, nothing in the new code will change that. It shows the coordinates your GPS reports, without any kind of translation or modification. If the position shown is way off, then that's what your GPS reported.

Anyway, here's an explanation of what you could see with the new code:

Position: {Latitude} {Longitude}
Elevation: {GPS Altitude in metres/feet}
Velocity: {Speed in km/h} ({Speed in kt}) [MAX]|[PEAK]|[peak: {peak speed}, max: {max speed}]
Track: {GPS track in degrees true}
Sector: {distance travelled since last stopped, average speed since stopped}
Total: {total distance travelled since KisMAC started}
Time: {time reported by GPS}

After the position, it may show


which means that the GPS is not returning a positive fix at this point in time (many GPS units will tell you where they *think* you are, even when they can't say for sure. Naturally, such information has to be flagged as suspect, and this is the way KisMAC shows it.)

If it hasn't received any information from the GPS unit (or GPSD), although it is connected, then you will see:

GPS subsystem works, but there is no data.
If you are using gpsd, there may be no GPS connected.
Otherwise, your GPS is probably connected but not yet reporting a position.

Then there are self-explanatory messages such as "GPS not working" or "GPS disabled".

The idea is that you can see all kinds of information about your driving while using it, and afterwards - how far you've gone (actual track distance travelled - not distance from starting point), how fast you've been driving, etc. I think the terms that might need explanation are "MAX", "PEAK" and "Sector"

MAX is your overall maximum speed - the highest speed reported by the GPS since KisMAC started ([MAX] displays after your speed if you are currently at your maximum speed since starting KisMAC).
PEAK is your maximum speed since the last time you stopped moving (or the second-last time, if you are currently stopped) ([PEAK] displays if you are currently travelling at your fastest speed since the last time you stopped).
Sector is since you last stopped (or the second-last time, if you are currently stopped), and your average speed is reported over that sector (any other average speed would be meaningless, since it would include all time not moving, including at the beginning and end of the journey).

Hopefully once I sort out where I'm living, I'll actually write this up in some properly documented form. In the mean time, feel free to ask if you need anything clarified!

Oh... and if you'd like any *other* information from the GPS, let me know that too!


 Robin L. Darroch - PO Box 2715, South Hedland WA 6722 - +61 421 503 966
      robin@xxxxxxxxxxxxx - robin@xxxxxxxxxxx - robin@xxxxxxxxxxxxx

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