1) color of the oupost, that will be wirelessly transmitted for demonstration
2) single decider combinator per outpost , allowing the color to be passed to the radar when the condition is met
3) single constant combinator per outpost, storing the "name" / "ID" of the outpost, under the form of a signal "info" with a value of 1 2 3 4 5 or 6 in the demo map, it also store a quantity of iron, to show another quantity wirelessly transmitted for demonstration
4) lamp indicating that currently this particular outpost is broadcasting to the network its color and its quantity of iron
5) single decider combinator in the main base, this is used to continously call 1 oupost
6) show which outpost is called, currently 3rd lamp from the left, which correspond to the 3rd outpost
7) color of the outpost being called wirelessly transmitted
8) The button to press by pressing F when hovering over it , this is modded , it's used to call the next outpost, pressing several time call each outpost successively and then none, and then restart, it works with the decider (5) to generate a 1tick signal, that will then be stored.
9) nixies tube showing the quantity of iron from the outpost being called, it reads 3000 because there is written 3000 iron ore in the combinator under the lamp in (4).
It's just a way to generate a pulse, the pushbutton, but any belt or inserter in "pulse" mode could do, when thinking about the simplest. It need to generate a "1" for 1/60th second.
Then this pulse is stored, but this is just to make it more visible for demonstration, such combinator isn't even required. In real use, it could be multiplied by any number to call a specific place like outpost 14 or outpost 423 765 432 . It is a "green signal V" so as to leave all material possible transmission.
On the oupost side they have a manually given number 1 2 3 ... 423 765 432 ... in their constant combinator, on the signal "info", and a single decider that read if the amount of "green V signal" generated previously is the same as their given number.
Pushing the button makes the combinator (5) store 1 pulse, and thus call the oupost one, until pressed again, then there are 2 pulses in memory, so it shows the second oupost and when it reaches 7 it reset.
Blueprint contain what's visible on the screenshot which is the "base" and 3 outpost, but the map has 6 outpost total but there was no more color available then.
Edit: fixed