Why are some radio broadcasts undetectable by triangulation?

[GiTS]

I read an article on these radio broadcasts whose location is undetectable. The thing is, I thought there was no such thing as an undetectable radio station. Is it because they are broadcasting from so far away that the signal bounces around? I know people can use a signal strength detector to track down tagged animals in the woods. It usually takes no longer than a day to find them. So how can the locating these stations be any different. I read that a retired Naval intelligence officer found one in West Palm by driving hundreds of miles, using a radio signal direction finder. But why did he have to drive so far? Shouldn't a mile distance between receivers be more than enough distance to triangulate a position.

 

[Baluncore]

There is no problem locating or identifying the nationality of number or letter stations. The people doing it are government employees, who for security reasons do not publish the information. The first rule of radio surveillance is; Never transmit. Obviously the second and third rules are the same as the first.

As a high power international broadcast, it is not possible to tell who any embedded code message might be addressed to, or where the recipient might be. It is also not possible to tell if or when a coded message is inserted into the pseudo-random stream. That is an example of steganography. https://en.wikipedia.org/wiki/Steganography

It takes less than one person to maintain and operate a numbers station. It takes the opposition several persons to monitor it. A numbers station is a decoy that can waste the time of the enemy, as it is not possible to cryptanalyse a cipher that is used only once for a short message.

One important thing to realize is that a numbers station is a placeholder, it keeps equipment and a radio frequency available in case it is ever needed. As you look more deeply into the radio spectrum you will find there are many other less powerful, but more interesting placeholders masquerading as legitimate international data links. They attract attention away from real clandestine stations.

You can waste a lifetime looking for patterns in the numbers, doing jigsaw puzzles, or locating radio stations.