The truck had finally come to a stop, after miles of travel along a mostly-forgotten dirt road, it had snaked up the side of something higher than a hill, but less than a mountain. The door opened, and the Driver exited, carrying a small pelican case, and what looked like an ammo can. He stood quiet, looking this way and that, listening.. Nobody would be up here, but this was an old habit, convinced now that no others were nearby, he started up a very old footpath, towards the top of the hill. Arriving, he opened the pelican case and removed a length of wire that had been wrapped into a small circle. The loop of wire, which was about 2 feet in diameter was then hung from a nearby tree branch. He connected the antenna to a small plastic box, about the size of a pack of cigarettes. From the small box, another connection was made to a similar-sized box he produced from the case. Finally, he plugged this last box into the ammo can, which in fact, just contained a cheap lead-acid battery, that had a variety of electrical connectors that were mounted on the lid of the can.
He looked around once again and waited for everything to finish powering up.
He switched on the small tablet that had been in the pelican case, opened an app, and checked his watch. 7:12AM, today was the 15th, which meant the broadcast should start in 8 minutes. He lit a cigarette and waited, watching the small screen until just a bit after the expected time, he saw the following:
He switched off the tablet and began unplugging the remaining devices, putting everything back into the pelican case, and headed back to his truck parked below.
This can be considered a modern-day example of asynchronous communications. Or communications that either don’t expect a response or don’t expect an immediate response. A great historic example of asynchronous communication would be the BBC radio transmissions that were broadcast to the French Underground, and various covert teams operating behind German-occupied lines. I’m sure you’ve all heard the coded phrases such as ‘The chair is against the wall.’ and ‘John has a brown mustache’. Those phrases had very specific meanings, and there was no acknowledgment if the message had been received, ie: no response was expected.
In my example above, the Truck Driver used a very portable solution to receive a low-power signal. His group had decided on which days, and times the broadcast would occur, the signal would be transmitted using a common digital mode that Radio Amateurs use to test their Antennas, this mode typically uses very low power transmitters, and includes only the station’s callsign, and their maidenhead grid location.
The idea is, if you can receive that signal, you have the option of uploading your successful reception onto a website.
But you don’t have to.
Let’s take a step back tho. Radio Amateur callsign? maidenhead grid location?
In the US, like nearly every other country, if you take and pass the needed exam you will be assigned an Amateur Radio Callsign that is tied directly to your identity. The whole shebang.. First & Last Name, and physical address. You’ll be required to regularly identify your station via your callsign when communicating with others on the radio. Each country assigned a unique prefix to licenses Amateurs, in the example above ‘XE2999‘, the ‘XE’ portion of the callsign references a Mexican callsign. But do you want a direct link back to your identity when communicating?
A maidenhead grid location is a system that breaks the earth into a map of grids, these grids are used to determine where the stations are located in the world. A normal grid, such as in the example above references Toronto, Canada.
Okay, so in our sample above, we can now determine that someone with the Mexican Amateur Radio callsign ‘XE2999’ has just sent a transmission from Grid ‘FN03HP‘
You may be asking ‘How is a guy with a Mexican callsign transmitting from Toronto, Canada?’
What if I told you there was no ‘XE2999’ and there was no transmission originating from Toronto, Canada?
It’s all faked.
And there’s no way to verify the callsign or the grid location.
[DISCLAIMER] I am NOT suggesting you break any laws, the following is informational only.. YOU are responsible for YOUR actions..
In our story above, let’s make a few assumptions:
- There’s a group of folks, located all across the country.
- They all have similar, very lightweight, portable radio equipment that allows them to receive these transmissions.
- They all have a list of ‘callsigns’ to listen for, on specific dates, and times, and those transmissions grid location, which is actually a message.
As a quick example, callsigns may translate to people that are known to the group. ie: Xe2999 may actually be someone named Frank how lives in Florida, and Frank doesn’t even have an Amateur Radio License. There can be as few, or as many ‘XE2999’s’ as a group needs, each using a callsign that can be translated to a member of the group that needs to transmit information.
Finally, the grid location, we can do the same. In long format, you may have something like this
FN03HP = Status: All clear at location
IN80DK = Status: Zombies present at location (lol!)
DM04VB = Status: Out of Food/Supplies, moving to new location.
etc, etc, etc…
The group would just need a list of when to listen, and then translate the ‘callsigns‘ to members of their group, and the ‘grid locations‘ to their current statuses.
Remember, the idea here is to send a message and just expect it will be received by the (typically group of) people that need to receive it.
Hopefully, this explanation gives you a basic idea of the ‘what’ and the ‘why’ in the next post, I’ll explain the ‘how’.