I’d love to see a map/diagram of what that looked like!
It might be hard to see. The app I used for mapping seems to invert colors when I posted the images. Let me know if you can’t see the map or node positions
1 Like
Took the liberty of fixing this.
3 Likes
Thanks for helping out there.
I take it one is a vertical profile and the second is a horizontal profile?
If so, I can see how it’s working now, but probably somewhat marginal with just 3 hops.
Looks like adding a couple of nodes and then letting the extra hops do the rest should work better. If it was working OK on 3 hops, then this will also likely provide the chance to - if need be for some reason - picking up one of the relays and putting it back into use as a personal unit in a pinch in case the guide’s was broken lost, or needed otherwise as a substitute, so will be a potentially useful option as a backup.
If you are able to cover the underground from the surface in just 5 hops or less, then you could also put the extra hop or two to good use to, say, communicate into the cave from the parking lot, service, or emergency vehicle. That could be useful on busy days, fetching supplies or tools, or when staffing is limited.
2 Likes
Yes, one is vertical the other is horizontal. I hadn’t realized, at the time, that these could only use a couple hops between personal units. I was trying to use with only 2 personal units and 6 relays in between. I had wondered why it kept showing “message sent using 2 relays” even though I continued adding more. This gives me a few ideas and great hopes for extending the range greatly.
I’ve just updated to the 5.0 so hopefully that will give me further range still. I would really like to be able to communicate as far back as the point where we dock our kayaks (.259 miles of sinuous limestone boulder filled passage).
2 Likes
MikeL,
Are you by chance the same Michael I’ve been talking with via email?
May be a different Mike? I am getting emails from the forum here letting me know of your updated replies, but my replies have been here so far as I recall. 
This definitely sounds like a situation that will be improved further by 5.0.
Hey Kevin,
While solar may not work, if there’s any kind of an air current or stream?
this may help - $159.
Best of luck.
2 Likes
This is a very interesting use case. My first thoughts are that he normal voice radios would be best for real emergency use, and their range should be extendable using passive repeater/radiators placed at strategic points in the cave. These are essentially tuned antennas that passively (no power or repeating needed) re-radiate the signal in a different direction, providing a little signal gain from directionality. I think they are commonly used in train tunnels and such.
But the GTM addition would be nice as a secondary means of communication, and one that the participants could even use (I’d guess most keep their phones on them, since folks these days seem to be unable to step away from them for 30 seconds) in the event of a separation or emergency with a cave guide (probably unlikely though).
Of course, that scenario raises the question of whether the participants would know how to use the device, pair it, have the app on-hand already, etc.