Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: There is disclosed a method of controlling high-latitude communications by cold plasma injection in the distant magnetosphere, and to thereby control the ionospheric and or magnetospheric medium through which the waves are to be propagated.This application incorporates the substance of the invention disclosed in applicant's application Ser. No. 174,047 filed concurrently herewith and now abandoned.

Abstract: A system for performing wellbore telemetry operations wherein a communication link between a subsurface location in a well and the location substantially at the surface is established and maintained through electromagnetic coupling between two insulated electric conductors. The first conductor is electrically coupled to a transmitter, normally located at the subsurface location, and extends upwardly in the well. The second conductor is electrically coupled to a receiver, normally at the surface location, and extends down into the well. Normally, the two conductors will overlap along a substantial portion of the lengths thereof. As the well is drilled deeper and the drill string is lengthened, the transmitter and the first conductor follow the progression of the wellbore into the earth, thereby reducing the overlap between the first and second conductors. When the two conductors cease to overlap, the second conductor may be lengthened to re-establish the overlap.