900-mc PTM Over-the-Horizon Radio Link

An experimental over-the-horizon radio link has been installed and tested for several months by the Federal Telecommunication Laboratories. Its chief purpose has not been to study propagation, although several interesting results may appear, nor to establish a commercially usable communication facility, but rather to study the application of this relatively unexploited type of propagation to multi-channel transmission, particularly that using ptm, pulse-time modulation.