VLF Transmitter Grid laid out in the form of a Six pointed star (Star of David), with the Main Transmitter Station (MTS) at the center and transmission towers at the points.
There are 13 Transmission towers totally.
The grid is composed of a central mast and two concentric circles of six masts each. The radius of inner circle is 730 Meters and that of the outer circle is 1200 Meters
Call Sign : VTX
16 KHz (VTX1) / 17 KHz (VTX2) / 18.2 KHz (VTX3) / 19.4 KHz (VTX4)
Locator : MJ88vj
Whereas a submarine on the surface can transmit and receive wireless messages just like a ship can, submerged submarines can only receive wireless messages on Very Low Frequency (VLF). VLF transmitters require huge antennae suspended high above the ground.
The initial discussions were solely with the Russian side, from whom the submarines had been acquired. Inquiries with western manufacturers indicated that better technology might be available from America. Parallel discussions were therefore pursued, both with Russia and with America.
Between 1979 and 1984, modalities were worked out for American company in collaboration with an Indian company to assume responsibility for the detailed design, manufacture, site installation and commissioning of the VLF transmitting station.
During the same period, the Defence Research and Development Organisation designed the antennae to be fitted in the submarine for receiving VLF transmissions.
Installation of the VLF Transmitter commenced in 1987. Trials completed in 1989. On 20 Oct 90, the VLF Transmitting Station was commissioned as INS KATTABOMMAN. Wikipedia article: http://en.wikipedia.org/wiki/Vijayanarayanam