Hopping across country

#1

We purchased two sets for Christmas presents. We had three reasons for purchasing these from my understanding.

  1. To be able to communicate with our son in law and daughter during a hurricane. Though we are normally together, we couldn’t communicate with our cells when we were in two different cars. So I thought this would work since we were following them.
  2. To be able to communicate with our granddaughter in CA if there is an earthquake. So it would be FL to CA. My understanding was that the message would hop from one node to another. Also to communicate with husband if we had a hurricane here while he travels.
  3. To be able to communicate when we go overseas back to the US as well as between each other if we got separated from each other.

Can someone please comment on how these will work for each one.

Thanks!

#2

1 and 3 should work for you. Lower your expectations and it’s possible for 2 to work, sort of.

Keep in mind, the goTenna Mesh is a tiny radio with 1 watt of power. Direct messaging (DM) range from a single unit to another tends to be around a half mile. If inside a car, it may be less unless there’s lot of glass.

For overseas use, the goTenna Mesh is approved for use in some 40 countries. It automatically adjusts it’s power to fit each nation’s commercial radio band plan in the 900 mHz band.

For #2, with the goTenna Plus subscription (you get 30 days free when you first start using the GTM) you get a SMS relay service. How it works is that you send your SMS messages via the mesh. If they fail, you can try the network again to reach someone with goTenna on their phone who also has cell data service. The message gets sent to a server in New York, which forwards it via the internet to its destination. Thus it’s dependent on both ends of the message path having cell service - which may not work in an earthquake.

That aside, there is no national mesh network yet. There are local and regional networks. However, the maximum hop count (using goTenna Mesh relays) is currently 6 hops. That max hop count will likely go up in the future, but it’s going to be some time before the network is thick enough and the hop count high enough to reach across country.

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#3

Bets51,

Good questions. I’ll give you my view on each use case in turn:

  1. Paraphrasing, the first use case is: “Communicate while in two separate cars following each other in close proximity.”

This is viable, as long as there is a passenger doing the messaging! :wink: Be aware that radio transmission and reception from inside one vehicle to inside another is poor because of the surrounding metal cage that is the frame and body of the car. Thus, the viable distance for highly reliable radio-messaging is short because you are in a structure that interferes with radio transmission. In my experience, you’ll want to be within a few tenths of a mile of each other for good results. Also be aware that it will be problematic if you don’t have a good line of sight (through the glass car windows) from one goTenna Mesh device to the other. The obvious way to improve the effective range is to mount the goTenna Mesh devices securely on the outside of the vehicles, but that will require preplanning to have a secure way to mount it, and it still may not be viable in hurricane storm conditions that you mentioned for this use case.

  1. The second use case is: “To be able to communicate with our granddaughter in CA if there is an earthquake. So it would be FL to CA.”

This is not viable. Why not? …

Simply put, the goTenna Mesh protocol puts a limitation on the number of “hops” that will be executed for a message, and the viable distance per hop is nowhere close to the distance needed to permit communication between Florida and California.

A more thorough explanation is:

Long term, the basic capability planned has been established as a maximum of (3) node hops for a message. Users who opt to subscribe to the goTenna “Plus” service will be granted an additional (3) hops, for a maximum capability of (6) node hops for a message. Currently (and only temporarily) the goTenna team has enabled a maximum of (6) hops per message for all users, even if they don’t subscribe to the “Plus” service. This has been explained on this community forum as a means to thoroughly beta-test the (6) hop functionality.

Without getting too technical, there is a practical limit to the number of node hops that can be supported on the finite radio band available to the goTenna Mesh product. Increasing the maximum number of hops permitted decreases the performance of the Mesh and its delivery success rate.

The shortest distance between Florida and California is approximately 2000 miles. Thus, the (6) hop limit would mean that each node hop would need to cover a distance of just over 333 miles - that isn’t feasible for 1-watt radio signals on the 900 MHz frequency band used by the goTenna Mesh. The maximum reported distance for a successful 1-hop (point to point, line of sight) goTenna Mesh transmission is approximately 50 miles, and under varying environmental conditions and topography it is usually much less. (Usually, it’s between 0.5 and 5.0 miles). Thus a more reasonable expectation for the effective communication distance in wide open spaces with flat topography and good line of sight is perhaps a maximum of 5 miles per hop x 6 hops = 30 miles. This also assumes that there is adequate node density across the area from the point of origin to the destination - a condition that won’t exist in most places today. (That’s why we need to mesh the world!)

  1. The third use case is: “To be able to communicate when we go overseas back to the US as well as between each other if we got separated from each other.”

While overseas communication back to the US is not viable for the reasons explained above, it is viable to communicate between separated travelers in the same vicinity - this is a very practical application of these devices.

So in summary, a practical expectation for the day-to-day communication distance using all 6 available node hops in optimal conditions is (arguably) around 30 miles. Under poor conditions, 6 node hops might only get you 3 miles, and under wildly optimistic ideal conditions, 6 node hops might get you 300 miles - but I wouldn’t count on it!

  • JT
#4

There’s another potential problem with car windows and, increasingly, building windows. As a way to conserve energy, many windows now have a metallic film deposited on them to limit the thermal transmission through the glass. This also blocks radio signals from a goTenna Mesh, so even having lots of glass doesn’t necessarily make things better.

I’ll second the caution about texting while driving. While these laws were originally targeted at cellphones, as far as the police are concerned if you’re using it to pair with your goTenna, it’s the same thing as using a cellphone without a GTM. It’s just unsafe, too.

However, if you can locate your goTenna on the roof of your vehicle, it works quite well. Here’s a couple of pics showing the unit installed in a pickle jar modified with a magnet.

What looks like coax going into the truck is actually the USB power cord. It’s on 24/7 as a relay. However, for a temp install, the battery in the GTM could be taken out of the pickle jar and recharged inside overnight, keeping things simpler.

Like this, you will find yourself with ranges longer than would be possible from inside the vehicle. The Bluetooth link works fine for standard vehicles, but if you’ve got something big like a motor home you might have to get closer to the pickle jar up top to have that work consistently.

#5

Mike,

I suggest you get one of these bad boys and paint it the same colour as your roof to complete your slick setup.

#6

That would be pretty slick and would look great – if it was only longer. The one I’m using now is a 10 footer and it’s got just a little slack in it. The closest place to get power is at the bottom back of the center console.

Of course, this is a Land Cruiser and aerodynamics areb’t exactly it’s strong suit.