Abstract: Communications link using the ionized trail of a meteor entering the atmosphere at an altitude of approximately 100 kilometers as reflectors to relay radio frequency energy beyond the horizon using a retrodirective adaptive loop. The retrodirective adaptive loop includes a plurality of conjugate antenna elements, with each conjugate antenna element having a spatial servo-loop circuit. At least two stations having antennas with conjugate elements are required for generating a retrodirective oscillating or phase locked loop.

Abstract: The spread spectrum communication system terminal comprises a first subsystem including a first arrangement to encode a locally generally digital data with an error correcting code, a second arrangement for spectrum spreading of the encoded locally generated digital data in at least one mode of operation of the communication system terminal, a third arrangement to receive remotely generated error correcting code encoded digitla data spectrum spread in the one mode of operation and a fourth arrangement to recover the remotely generated digital data. In addition, a second subsystem includes a fifth arrangement frequency hopping the encoded locally generated digital data prior to transmission to a remote location and a sixth arrangement frequency dehopping the encoded remotely generated digital data received from the remote location.

Abstract: A frequency synthesizer circuit operates in a time shared mode. Thus the frequency synthesizer circuit operates to transmit and/or receive a particular frequency for a chosen small amount of time and then sequentially transmits and/or receives the other frequencies for chosen small amounts of time. After all the chosen frequencies have been transmitted and/or received the synthesizer circuit will return to the first of frequency and begin to repeat the process in cyclical fashion.

Abstract: A frequency hopping data communication system for a bidirectional communication system is described in which improved operation in a jamming and/or fading environment is provided. A pseudo-noise code generator is utilized to provide a random sequence of ON-OFF pulses representative of binary numbers which cause a microprocessor to select data at a desired frequency which is then coupled to a frequency synthesizer to provide a controllable frequency and an improved anti-jam capability in both a receiver and transmitter.

Abstract: An improved frequency hopped data communication system with a random transmission of mark and space frequency over the transmission bandwidth to provide independent frequency hopping of the mark and space frequency is provided in the system which is particularly immune to repeater jamming. Only one frequency is transmitted at a time upon selection on a bit instant by a pseudo-noise code generator. The location of the mark and space frequency is randomly chosen, however, the location is known at the transmitter and the repeater by appropriate synchronization equipment.

Abstract: A frequency hopping data communication system which provides reliable communication in a fading environment and also which is jam resistant is described, in which an improved frequency hopping data communication system provides reliable communication in a fading environment such as in a mobile, satellite or scatter communication systems. Pseudo-noise code streams are time displaced with respect to each other, and provide a frequency hopping rate equal to n times the rate of repeated binary data being transmitted, and wherein the pseudo-noise codes are used to directly derive a hopped frequency from a selected code sequence.

Abstract: The frequency hopping data communications system comprises a first circuit arrangement to produce identical first and second pseudo-noise code streams time displaced with respect to each other, each of the first and second code streams producing a frequency hopping rate equal to n times the rate of binary data being transmitted, where n is an integer; a second circuit arrangement coupled to the first circuit arrangement, the second circuit arrangement being responsive to the data and the first and second code streams to provide a modulated signal for conveying the data, the modulated signal having different randomly occurring frequencies representing both binary conditions of the data and random spacing between the randomly occurring frequencies representing each of the binary conditions of the data, each bit of the data being represented by n of the randomly occurring frequencies; a third circuit arrangement coupled to the second circuit arrangement to receive the modulated signal and to separate the randoml

Abstract: A voltage controlled oscillator has coupled thereto N capacitors in different permutation under control of an N stage binary counter and a counter drive signal enabling the generation of signals having 2.sup.N discrete frequencies. A phase locked loop is employed to stabilize each of the 2.sup.N frequencies. This loop includes a mixer coupled to a harmonic generator and the output of the oscillator. The mixer output is applied to a crystal filter whose output is phase compared with a reference signal and the resultant output is employed to stabilize the oscillator.