listen for massages

I have 'old' original Delorme Explorer.

I can operate it with tracking OFF.

I can set an interval of listening for mew messages to let say 10min

On the display of the check messages icon it says listening for new messages, next listen 12.23 and there is down counter running and saying how many min it takes to next listen.

The device is outside, I have sent message to it (from portal) but after hours it still does not receive anything.

If I go to to push the check now, I will receive the message.

What exactly I have to set up with the listen for messages to actually also receive a message when no active mail check and no tracking is going on?

Does this listen have any function at all?

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  • I'm going by memory here because I no longer have an active legacy device.

    In the beginning (when the number of iR devices in the world was small), transmission and "listens" at the device were synchronized. Devices listened at intervals (20 minutes sticks in my head). Based on IMEI, different devices listened at different times. For example, your device might listen at 17, 37 and 57 minutes past the hour, while mine might listen at 10, 30 and 50 minutes past. These were passive listens - radio on and listening, but not actively asking the Iridium network if there was traffic waiting. The messages were timed to be "broadcast" by the appropriate Iridium satellite when the target device was listening. This was inherently unreliable for a number of reasons, including the fact that the device might not be on, might not have a good sky view, etc. at the appointed time. In addition, there was no "feedback" to the device - if the device didn't see a message, it might be because there was no message waiting. But it might also be that the device had a poor sky view.

    Eventually, this was replaced by a combination of passive listens and active checks. Passive listens behave (mostly) like the original scheme, but without the timed synchronization of send and listen. (There is also a special "ring" message involved in this, but it's not worth discussing in detail.) This is still unreliable to the point of being useless. The active check actually interrogates the Iridium network to see if there are messages waiting. If so, the device retrieves them. If not, the device knows that there is nothing waiting.

    Note that passive listens don't consume a lot of power since they involve only the receiver. Active listens involve transmission and consume a lot more power. This is compounded by the fact that the active listen will retry if it does not receive an acknowledgement to its query. Can be a real power hog in poor conditions.

    On newer devices, active checks occur at power on, whenever the device sends anything (sent track point, message, or whatever), once an hour, and on demand. After sending a message, there is also a 10-minute interval of more frequent active checks in order to facilitate "conversational" message exchange.

    I am not sure how this carries back to the original SE and Explorer models. Based on you description of the result, I would guess that the "listen interval" control passive listens. And that "check now" is an active listen. I also do not know if these older devices do active listens hourly, in conjunction with sends, or anything else.

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  • I'm going by memory here because I no longer have an active legacy device.

    In the beginning (when the number of iR devices in the world was small), transmission and "listens" at the device were synchronized. Devices listened at intervals (20 minutes sticks in my head). Based on IMEI, different devices listened at different times. For example, your device might listen at 17, 37 and 57 minutes past the hour, while mine might listen at 10, 30 and 50 minutes past. These were passive listens - radio on and listening, but not actively asking the Iridium network if there was traffic waiting. The messages were timed to be "broadcast" by the appropriate Iridium satellite when the target device was listening. This was inherently unreliable for a number of reasons, including the fact that the device might not be on, might not have a good sky view, etc. at the appointed time. In addition, there was no "feedback" to the device - if the device didn't see a message, it might be because there was no message waiting. But it might also be that the device had a poor sky view.

    Eventually, this was replaced by a combination of passive listens and active checks. Passive listens behave (mostly) like the original scheme, but without the timed synchronization of send and listen. (There is also a special "ring" message involved in this, but it's not worth discussing in detail.) This is still unreliable to the point of being useless. The active check actually interrogates the Iridium network to see if there are messages waiting. If so, the device retrieves them. If not, the device knows that there is nothing waiting.

    Note that passive listens don't consume a lot of power since they involve only the receiver. Active listens involve transmission and consume a lot more power. This is compounded by the fact that the active listen will retry if it does not receive an acknowledgement to its query. Can be a real power hog in poor conditions.

    On newer devices, active checks occur at power on, whenever the device sends anything (sent track point, message, or whatever), once an hour, and on demand. After sending a message, there is also a 10-minute interval of more frequent active checks in order to facilitate "conversational" message exchange.

    I am not sure how this carries back to the original SE and Explorer models. Based on you description of the result, I would guess that the "listen interval" control passive listens. And that "check now" is an active listen. I also do not know if these older devices do active listens hourly, in conjunction with sends, or anything else.

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