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Track Management 101
Hopefully, this page will give you an understanding of how the PN-40 uses the memory set aside for track logs. Currently, the PN-40 stores track log data in a private area of internal memory. This means it's not directly accessible to the user and also does not use any of the internal user memory used for storage of maps. The PN-40 has one Active Track Log and 10 Saved Track Logs. Each of these 11 track logs can hold up to 10,000 points.
The Active Track Log
This is the track log where the PN-40 records new points. New track points are added to the log based on either time or distance (See Edit Track Settings for details).
Record points by Time
When set to time, the PN-40 will add a new point at a fixed time interval. The time interval can be set from 1 second to 99 seconds. The following table shows how long it will take to full the 10,000 track log at various Time Interval settings:
| Time Interval | Time to Fill Log |
| 1 second | 2.78 hours |
| 5 seconds | 13.89 hours |
| 15 seconds | 41.67 hours (1.73 days) |
| 60 seconds | 166.67 hours (6.94 days) |
| 99 seconds | 275 hours (11.46 days) |
Record points by Distance
When set to distance, the PN-40 will add a new log point based on distance traveled. The distance interval can be set from 10 ft to 999 ft. The following table shows how far you can travel before filling the 10,000 track log at various Distance Interval settings:
| Distance Interval | Total Distance |
| 10 ft | 18.94 miles |
| 40 ft | 75.76 miles |
| 100 ft | 189.4 miles |
| 400 ft | 757.6 miles |
| 999 ft | 1892 miles |
Actually, recording by distance is a combination of distance and time. This is due to the fact the PN-40 only checks if a point should be recorded at a 1 second interval.
The following table shows when a point is recorded at various speeds of travel. For this example, the Distance Interval is 40 ft.
| Seconds | 4 ft/sec (2.7mph) | 10 ft/sec (6.8 mph) | 35 ft/sec (23.9 mph) | 100 ft/sec (68.2 mph) |
| 1 | 4 | 10 | 35 | 100 - Record |
| 2 | 8 | 20 | 70 - Record | 100 - Record |
| 3 | 12 | 30 | 35 | 100 - Record |
| 4 | 16 | 40 - Record | 70 - Record | 100 - Record |
| 5 | 20 | 10 | 35 | 100 - Record |
| 6 | 24 | 20 | 70 - Record | 100 - Record |
| 7 | 28 | 30 | 35 | 100 - Record |
| 8 | 32 | 40 - Record | 70 - Record | 100 - Record |
| 9 | 36 | 10 | 35 | 100 - Record |
| 10 | 40 - Record | 20 | 70 - Record | 100 - Record |
| 11 | 4 | 30 | 35 | 100 - Record |
| 12 | 8 | 40 - Record | 70 - Record | 100 - Record |
| 13 | 12 | 10 | 35 | 100 - Record |
| 14 | 16 | 20 | 70 - Record | 100 - Record |
| 15 | 20 | 30 | 35 | 100 - Record |
At 4 ft/sec, a point is recorded every 10 seconds, as expected (40 / 4 = 10). At 10 ft/sec, a point is recorded every 4 seconds, again, as expected (40 / 10 = 4), But, at 35 ft/sec, a point is being recorded every 2 seconds, not every 1.14 seconds (40 / 35 = 1.14). Why?
Every second, the PN-40 checks to see how far you've traveled since the last point was recorded, once the distance is greater than or equal to the Distance Interval, a track point is recorded and the process is started all over again. So, at 35 ft/sec, you will have traveled 35 ft after one second, but this is less than 40 ft (the Distance Interval in this example), so no point is recorded. After another second, you will have now traveled 70 ft, which is greater than or equal to 40 ft, so a point is recorded.
What does all this mean? First, if you need an exact distance per point, then you're out of luck. Second, once your ft/sec exceeds the Distance Interval you've set, the PN-40 just records a point every second. Third, the total distance of the track log will never be less than expected (Distance Interval times 10,000), but can be significantly greater than expected.
Example: Distance Interval set to 10 ft. Actual speed of 60 mph (88 ft/sec)
Because you are traveling at 88 ft/sec, which is greater than the Distance Interval of 10 ft, the PN-40 will be recording a point once every second. Therefore, it will take 10,000 seconds to fill up the log, during which time you will have traveled 880,000 ft or 166.7 miles (88 ft/sec * 10,000 seconds). This is almost 9 times farther than would be expected with a Distance Interval of 10 ft (10 ft *10,000 = 100,000 ft or 18.9 miles).
What happens when the Active Track Log fills up?
This depends on the "When track is full" setting (See Edit Track Settings for details). This value has 3 options:
- Stop Recording
- Overwrite Points
- Start Recording New Track
Stop Recording
With this option selected, once the Active Track Log fills up, recording will stop until you manually save the track log. This basically means you get the first 10,000 points of a trip. Once you have manually saved the track log, it is automatically cleared and the PN-40 will start recording again.
Overwrite Points
This option causes the PN-40 to start overwriting the beginning of the Active Track log with new points once the end of the log has been reached. This sets up the Active Track log into an endless loop. What this means is the PN-40 will only have the last 10,000 pointed of a trip. Once you have manually saved the track log, it is automatically cleared and the PN-40 will start recording from the beginning again.
Start Recording New Track
With this option selected, the PN-40 will automatically save the Active Track log once it fills up, then clear it and continue logging. With this option, the PN-40 can record 110,000 points without any input from the user.
NOTE: Once all 10 Saved Track log entries have been filled, the PN-40 will stop recording once the Active Track log fills up.
Manually saving the Active Track Log
At any time, you can go to the Tracks page and select Save (provided there is an empty entry). This will transfer (or save) the track points currently in the Active Track Log into one of the 10 Saved Track logs and then automatically clear the Active Track log. But, by manually saving the Active Track log, you can severely limit the total number of track points that can be saved by the PN-40.
Example: All 10 Saved Track logs are empty and the Active Track log is at 25% after hiking one of your favorite trails.
Before hiking your next trail, you want to save the track log of the trail you just hiked, so you go to the Track page, select Save, and press ENTER. This transfers the Active Track log into one of the Saved Track log entries and then clears the Active Track log. You now hike your next trail. Again, you save the Active Track log when you reach the end of the trail. Lets say after a long day, you have hiked 5 trails and saved each one as shown below:
Normally, each Saved Track log can store up to 10,000 points, therefore 5 of them could save up to 50,000 points. But, in this example, only 15,849 points of the 50,000 possible were used. The remaining 34,151 points can not be used and are basically being wasted. The worst case waste occurs when you save the Active Track log when it only contains a few track points! What this means is you can only save 10 tracks logs, regardless of whether there is 1 point in the log or 10,000 points in a log. But, there are ways to get more out of your available track logs, see the next section for how..
Getting the most from your Track logs
Let's say we're going on a 14 day hiking trip and won't have access to a computer to download any of our track logs. We also want to save each day's hike (or hikes) as a separate track log. There are only 10 Saved Track log entries plus the Active Track log, so how can we store 14 (or more) hikes into 11 entries?
Well, the short answer is we can't! There's just no way to store 14 or more hikes into 11 entries. So, this means if we still want a record of every hike, we're going to have to combine some of the hikes into one Saved Track log entry. Turns out, this is actually a very good solution to the problem!
While we can only have a total of 11 track logs (10 Saved plus the Active), each track log can have multiple "segments" within the log. A segment is like a mini track log. A segment is created when you either Turn off Tracking (See Edit Track Settings for details) or Turn off the power to the PN-40. Once we get home and can download the track logs, Topo USA can be used to easily separate the segments back into individual track logs.
Example: On our first 3 days, we go on the following 5 hikes. We also setup the PN-40 to record track log points based on Distance with a Distance Interval of 20 ft. At the end of each hike we also turn off the PN-40, which causes each hike to be stored as a separate segment within the Active Track log.
So, after the 5 hikes, we will have used 6,737 track log points of a possible 10,000.
At this point, we could manually save the 5 hikes onto one of the Saved Track Log entries, leaving 9 entries for the remaining 11 days of our trip. But this would waste 3,263 track log points (10,000 - 6,737) in the Saved Track log.
With 3,263 track log points still unused in the Active Log, we can still hike another 65,260 ft or 12.36 miles. So, to get the maximum efficiency from our track logs, lets go on some more hikes before storing the Active Track log. In fact, there is a way to setup the PN-40 so we don't even need to worry about the track logs!
Back on the Track Log Settings page (See Edit Track Settings for details), there is a "When track is full" setting. If we set this to "Start Recording New Track", then the PN-40 will automatically save the Active Track log once it fills up, clear it, and then continue recording track log points. The only thing we have to remember is to either turn Track Recording off and then on again, or to turn off the PN-40 at the end of each hike so a separate segment is created.
Example: To finish our example above, lets say with have gone on the following hikes during our 14 day trip:
If we setup track logging as follows:
- Record Points By Distance.
- Recording Interval 20 ft.
- When Track is full, Start Recording New Track.
Then this is how our hikes would be saved:
| Active Track Log
840 - Last 840 points of Day #13 1162 - Day #14 |
| Saved Track Log Entry #1
1162 - Day #1 Hike #1 929 - Day #1, Hike #2 2468 - Day #2 1859 - Day #3, Hike #1 319 - Day #3, Hike #2 1830 - Day #4, Hike #1 726 - Day #4, Hike #2 707 - First 707 points Day #5, Hike #1 |
| Saved Track Log Entry #2
1674 - Last 1674 points of Day #5, Hike #1 900 - Day #5, Hike #2 668 - Day #6, Hike #1 987 - Day #7, Hike #1 1045 - Day #7, Hike #2 3601 - Day #8 319 - Day #9, Hike #1 726 - Day #9, Hike #2 79 - First 79 points of Day #10 |
| Saved Track Log Entry #3
1606 - Last 1606 points of Day #10 1568 - Day #11, Hike #1 668 - Day #11, Hike #2 2149 - Day #12, Hike #1 1539 - Day #12, Hike #2 2470 - First 2470 points of Day #13 |
So, by creating segments, we are able to hike 110.2 miles over 14 days and only use 3 of our 10 Saved Track logs and 20% of the Active Track Log.
Once you get home and download the 3 Saved Tracks and the Active Track log, you can easily save the individual segments to their own files.
Re-Joining Track Segments
If you look at the table above, you will see that the following tracks were recorded across more than one Track Log entry:
- Day #5, Hike #1
- Day #10
- Day #13
Once you have downloaded and saved the individual segments, you will need to "join" these three tracks back together into one segment.
