Track logs on the 60/76 series

[MajBach]

Finally used my 76CSx on its first real practical trip – boat trip – and after downloading the tracks and going through the manual several times, I am still left with a few questions I need help with.

First, I have the unit set to ‘wrap’ track logs and to also store tracks to the card. Also, before downloading the tracks onto the PC, I removed the memory card. I had already uploaded 19 different track logs recorded on a different GPS and converted to Garmin before the trip commenced so I figured I only had room for one more track log but much to my surprise, 34 tracks appeared in Mapsource when I received the data from the unit. At first, I found it strange that the tracks were broken down into various sizes over the course of a full days travel from point A to B but then I remembered I shut the unit off several times and concluded this was the reason. However, I still didn’t understand why there were 14 active logs (for a total of around 2800 track points) in addition to the 19 tracks already in the unit. I then deleted a couple of the short ones and uploaded the same tracks back into the unit and again downloaded them. Once again I was surprised to see these tracks were duplicated and the ones I had deleted in Mapsource remained in the unit for a total of 50 tracks. I then picked the GPSr and went to the Track screen and it showed only 1 track being active. When I saved the track within the GPSr and then downloaded it onto the PC, ALL the active track logs were STILL there plus one new one (totaling 500 points and named today’s date). This new track was all the active tracks stiched together and whittled down to 500 points.

I then put the memory card in a reader and download the tracks auto stored by the GPSr and saw all the same active track logs that were in the GPSr stored on it but each one was one track point smaller.

So, here is what I cannot understand:

1. How many active track logs can there be stored in the GPSr?

2. Why can they not be seen on the unit as separate tracks since they are stored in the memory that way?

3. What happens when the active track log reaches is maximum (3000 or 10000?)

a. Are the individual track log parts stored in the unit deleted as a whole or individually or overwritten one point at a time

b. Whats the difference with the stored data specifically between ‘wrap’ set to on or off?

4. when the GPSr is set to store track on the memory card, does it store them identically to the way they are stored on the unit (except in a different file format)?

 

A lot to answer so I appreciate the input as well as any other useful info you know that Garmin didn’t cover in the manual.

MajBach

[+apersson850]

1. There can (probably) be as many as there can be track points. As you have already noticed, the ACTIVE LOG gets splitted if you turn the unit off, for example. Then it continues on ACTIVE LOG 001, or similar. Some units always split the log if you start routing somewhere, some split them if you loose satellite reception. Some older units/firmwares even splitted the log if reception went from 3D to 2D, or vice versa. By the GPS, it's still considered to be the active log, even if it's split up in segments. This splitting makes it easier to pick out one single activity, when you have uploaded the whole bunch of them to Mapsource.

 

2. Seems I already answered that above.

 

3. When the active log gets full (something the math geniuses at Garmin think occurs at 99%), then it will either stop recording, or throw away the oldest point when it wants to insert a new one. Which it does depends upon if you've set it to wrap when full or not. For a 76 CSx the max capacity is 10000 points. The figure 3000 may come from that that's the default setting for how many of these 10000 points will be shown on the map display. Frequently, if you show all 10000, the map will be utterly cluttered. I think the default 3000 comes from the original track log capacity in units like the eTrex Vista.

 

3a. In the 76 CSx, the track points are deleted one point at a time, when the log wraps around. In a unit like the Zumo, they are archived, then removed, one individual activity at a time.

 

3b. The data stored in the active log is the same. It just stops recording when you've used the 10000 points, if it's not set to wrap. If you refer to named tracks stored on the unit, then they are reduced in data content by removing time and speed information as well as reducing the number of points to no more than 500. This is done by filtering out small movements, in order to try to keep the large picture intact.

 

4. Tracks stored on the card aren't data reduced. They contain every point that was in the active log, but may have been deleted later due to wrapping of the log. I haven't tried what happens to the log on card if the internal log has stopped due to running out of memory and you've set it not to wrap. Technically, it should be able to continue logging to the card anyway, as long as there's space available there.

[MajBach]

1.

 

4.

EXCELLENT!! Thank you!

[+apersson850]

You're welcome. Interesting quote you made!