Alpha Hyperbolic Navigational System
Russia.
RSDN-20 (Radioteknicheskaya Systema Dalyokoiy Navigatsii)
The method is known as hyperbolic navigation. Each station transmits alternately on each frequency, giving a distinctive sound sequence.
The receiver recognizes a phase coherent condition (two stations on one frequency at one time)
and knows it is on one LOP (line of position). By evaluating the phase of other two stations the receiver obtains a second LOP. The receiver's position is where the two LOP hyperbolas intersect.

Locations:
Novosibirsk 55:45:22.0 N  84:26:52.4 E
Krasnodar   45:24:17.9 N  38:09:29.0 E (East of  Crimea)
El'Ban      50:04:23.9 N 136:36:24.1 E (Near Komsomolsk on Amur – Far East)
Revda       68:02:07.8 N  34:41:00.0 E (Near Murmansk)
Seyda       39:28:16.0 N  62:43:07.3 E  (Uzbekistan south of Aral sea)

It has been common for Alpha to be off air for shorter and longer periods since 1970.
The 5th Alpha station Seydi has been off air completely but even Revda has been on from time to time.

I only hear the stations at Krasnodar (strongest) and Novosibirsk. The far east stations are not heard. The others are mostly off air.

On frequency 11.905 kHz
Heard: dash, long pause, dit, short pause, dit, short pause, dit, long pause

On frequency 12.5 kHz. Nothing heard.

On frequency 12.6490625
Heard: dash, extra long pause, dit, long pause

On frequency 13.281 kHz. Nothing heard.

On frequency 14.88125 kHz
Heard: dash, long pause, dit, short pause, dit, long pause