Ext. Tracking

Will be using the Mini as a race tracker (secondary emergency use: messaging/SOS if I get stuck), so the aim is to get the most out of the battery between charges (two week event) while using a send interval of 10 minutes to provide a good tracking resolution to organisers/followers.

Using the settings Send Interval = 10min, Log Interval = off, Bluetooth = off, ANT+ = off, Display Brightness = 10%, Display Timeout = 15sec

..is there much further to be gained from enabling the Ext. Tracking mode? From what I can see this disables bluetooth and ANT+ (already done) as well as sleeps the device between send intervals (in this setup will be for <10mins at a time), not sure on how much this sleeping helps? Also will the sleep/wake cycles have any impact on either the send point accuracy or timings?

Finally, I know the Mini automatically detects when you are stationary and reduces send intervals to 4hrs until you start moving again. Presumably this works in both normal and ext. tracking modes? Begs the question: is there much power-saving benefit to manually turning the device off while resting for say 4-6hrs overnight vs. letting it automatically reduce the send intervals, with the obvious risk being I might forget to turn it on again when setting off!

Thanks in advance.

0 twolpert over 3 years ago

Although it varies somewhat by device, I think that the biggest benefit to extended tracking mode is that it stops the normal hourly active mail check. If conditions are not ideal, the mail check can be a big battery suck because the device tries VERY hard to complete the check. I believe it also defers the physical sending of track points - so there would be some "lag" in what other see on MapShare. (I don't think it affects the accuracy, but does affect when the points are sent.)

Yes, the 4 hour fallback when stationary also works in expedition mode.

There is still a battery-saving benefit to turning the device off when not in use for several hours.

0 SpikySimonW over 3 years ago in reply to twolpert

Interesting point on the mail check. I naively thought every time a sat. connection was made it did a full series of data exchange: tracking point send AND message send/receive. So if you had tracking to every 10 minutes, then as a byproduct it would actually check for messages every 10 minutes. If you had tracking set to longer than an hour, or tracking wasn't active, it would automatically check for messages every hour. Similarly when a message is sent, it also sends a tracking point and checks for incoming messages too. Perhaps I'm wrong (rarely use incoming messages, all about tracking points with the odd preset message sends for me).

0 twolpert over 3 years ago in reply to SpikySimonW

You are basically correct, but it's more complicated than that. What happens when you send something (track point, message or whatever), is that the Iridium network acknowledges the send. Until it sees the acknowledgement, the unit continues to retry - which can also be a battery suck in challenging conditions. IF there are messages pending for the unit, the satellite network piggybacks a notification on the acknowledgement. This is just a notification - it's up to the unit to actually request and receive the messages.

Typically, the unit does so immediately on receiving the notification. My understanding is that extended tracking mode defers the actual request/receive of the messages. From a power perspective, the request/receive is equivalent to an active mail check when messages are pending.

Note that I have not systematically tested this. Just my understanding.

0 SpikySimonW over 3 years ago in reply to twolpert

Got it, well explained, thanks.

On the one hand this makes a good case for using the ext. tracking and I can see how deferring the full message request/receive could save power. On the other hand, for someone like me that rarely if ever receives messages, it probably wouldn't make a whole lot of difference!

0 skyeye over 3 years ago in reply to twolpert

I had just some extensive test with mini against 66i last week.

The mini, in extended mode, did indeed receive msg upon sending a trackpoint, but I did miss nay kind of ringing. Either it was just a short beep or absent fully. However next time I opened it manually, the messages were here, listed on the main screen.