Abstract: A predistortion linearizer (20) is operative with a microwave signal, as may be provided by signal source (62) to linearize the gain of a power amplifier, such as a traveling-wave-tube power amplifier (74), by introduction of an amplitude and/or a phase distortion to the microwave signal wherein the distortion is inverse to a distortion introduced by the power amplifier, thereby to compensate for the distortion of the power amplifier. The linearizer is constructed of two channels (22, 24) which are operated in parallel but approximately 180 degrees out of phase, with an additional phase increment provided by delay lines (46, 56) to offset one channel from the other channel by a phase difference in a range of approximately 160-200 degrees.

Abstract: A spectral line selector for a laser comprises a diffraction grating that images a waveguide exit plane back into the waveguide with an essentially exact reproduction of the waveguide output intensity and phase distribution and with a predetermined wavelength. The selector also comprises lenses disposed between the waveguide exit at a point between the exit opening and the grating, the lenses providing a magnification and a phase compensation to the beam passing therethrough such that the phase of the beam returned to the waveguide matches that of the exiting beam. Thus, coupling losses due to clipping of the returned beam at the entrance to the waveguide bore and coupling losses due to a mismatch of the returning field phase to that of the waveguide mode are made essentially zero.

Abstract: A receiver for use in digital cellular communication systems determines the type of data transmitted without having to decode the data. Digital cellular communication systems typically use convolutional forward error correction (FEC) coding to allow for error detection and correction at the receiver. The type of encoding is different depending on whether voice data or control data is transmitted. In general, FEC coding is a redundant coding of the encoded data so that for a given encoding algorithm with FEC coding, there will be a limited number of valid code sequences less than the total possible number of code sequences for a transmission of the same number of bits. This characteristic is used to identify the type of encoding without decoding the received information. Consequently, decoding requirements are reduced to those corresponding to the active transmitting encoder, resulting in receiver complexity reduction.

Abstract: A propellant immobilizing system and method in which propellant motion in the propellant storage tanks (22) is reduced or eliminated during velocity change maneuvers to reduce disturbance torques acting upon the spacecraft (10) and improving the spacecraft attitude pointing performance. The thrusters (14, 16, 18 or 20) are fired to produce a small impulse in the direction of the desired Velocity change to begin motion of the propellant within the fuel tank in the opposite direction. After the fuel has moved within the tank to a location in which the propellant center of mass is aligned with the propellant tank (22) center of curvature in the direction of the desired velocity change, thrusters (14, 16, 18 or 20) are again fired to produce a force in the direction of the current velocity of the propellant center of mass to stop the propellant center of mass relative to the propellant tank (22).

Abstract: A flat cavity RF power divider wherein a flat cavity and an input waveguide share a common wall, coupling slots being disposed in the common wall offset from the centerline of the input waveguide for exciting a dominant TE.sub.4,0 mode in the flat cavity, the power divider also including short circuit means for exciting the transverse axis column of the flat cavity, and RF absorber means in the cavity to improve the frequency response of the divider, output coupling means also being provided for providing an RF power output.

Abstract: A temperature-compensated junction isolator (28) is used with a waveguide junction (20) in a hollow microwave waveguide system (22). The junction isolator (28) includes a ferrite cylinder (34) within the waveguide walls (30 and 32) at the junction with its cylinder axis (36) perpendicular to the waveguide walls (30 and 32). A pair of temperature-compensation washers (38) are aligned with the cylinder axis (36) of the ferrite cylinder (34) and are positioned external to the waveguide walls (30 and 32). Each washer (38) has a central opening (40) smaller in diameter than the diameter of the ferrite cylinder (34) and is made of a material whose permeability decreases with increasing temperature, preferably a nickel-iron alloy with about 30 percent iron. A pair of magnets (42) are aligned with the cylinder axis (36) of the ferrite cylinder (34), one of the magnets (42) being located exterior to each of the temperature-compensation washers (38 ).

Abstract: A waveguide coupler for coupling electromagnetic power between a first rectangular waveguide and a second rectangular waveguide includes a one-dimensional intermediate waveguide formed of two plates spaced apart by a distance equal to a common height of the two waveguides. This enables a wave emanating from the first waveguide to spread apart transversely so as to equal the width of the second waveguide, the width of the second waveguide being greater than the width of the first waveguide. A cylindrical lens is located between the intermediate waveguide and the second waveguide to provide for a conversion between a cylindrical wavefront and a planar wavefront. The coupler is operative in reciprocal fashion such that a wave emanating from the first waveguide spreads out in width and is then converted to a planar waveguide prior to entering the second waveguide; and a wave emanating from the second waveguide is converted to a wave of contracting width for entry into the first waveguide.

Abstract: The present invention provides various embodiments of laser systems for generating "chirp" signals. In the broadest sense, a diffraction grating is placed within a laser cavity on the face of a carrier and the motion of the carrier in its own plane causes the laser to chirp. Typically, the diffraction grating is placed in the end-reflector position of the optical path of the resonant cavity associated with the laser. By putting the diffraction grating on the outer peripheral rim of a wheel and rotating the wheel, a sequence of either up-chirp or down-chirp signals can be generated continuously. Similarly, the desired "chirped" signals can be generated by using a diffraction grating oriented radially on the face of a rotating wheel.

Abstract: Frequency modulated radar transmitters with a repetitive linear increase in frequency with time, referred to as "frequency chirps", are required for many radar applications. The present invention provides a simple way of obtaining such a chirped frequency modulation for a laser radar transmitter or the like. The principle is to translate an optical wedge in the direction of its wedge gradient at constant velocity across the optical path of a laser resonator. The resulting increase or decrease in the effective optical length of the resonator causes frequency chips. In a first embodiment of the present invention, a rotating phase plate on the face of a rotating wheel with the added phase varying linearly with angular position around the wheel is placed within a laser's resonator cavity to tune the optical pathlength of the cavity and thereby the longitudinal mode of the resonator to produce the chirp. This embodiment can be used in either a reflective or a transmissive mode.

Abstract: A data router for receiving input data, having a timing characteristic, and transmitting output data that is either bursted or non-bursted. The non-bursted data comprises frames of data with each frame comprising slots of data, each slot having a position and a number. The invention (200) provides translation between bursted and non-bursted formats and includes an input buffer circuit (104) for receiving input data from an input channel and storing the input data as the input data is received from the input channel. An output buffer circuit (210) is included for formatting the stored input data, translating between bursted and non-bursted data formats and outputting the formatted and translated data to an output channel. A sequencer (105) routing controller circuit controls the operation of the input buffer circuit (104) and output buffer circuit (210).

Abstract: A mobile station cellular telephone transmitting system having a digital data source, waveform map, FIR filter with eight taps, a zero force circuit, start/end burst detection circuit, quadrature modulator, upconverter, and power amplifier. The ramping of the power output at the beginning and end of each frame slot or burst is controlled by forcing the first and last symbol of the burst's FIR filter output to zero.

Abstract: A satellite wide area communications network (10) includes a remote transmitter/receiver (28A) that is coupled through a modem unit (30A) to multiple card readers (12A-1 to 12A-n). A master transmitter/receiver (26) is satellite linked to the remote transmitter/receiver and is coupled through a central packet network (16) to multiple host computers (18-1 to 18-j). A network host computer address is determined for each transaction card inserted in the card readers, and the network address is processed to establish a direct link to the host computer for the card through the modem unit, the satellite link (22A, 20, 24), and the central packet network.

Abstract: An autotuning combiner particularly for use in combining signals for radio telephony transmission. The combiner has a series of filter cavities each with an adjuster for fine-tuning the cavity to an input carrier signal. The combiner cavities are stabilized from positional drift in the absence of a carrier signal by means of a mechanical brake which holds the adjuster or a pilot signal generator which simulates the absent carrier signal.

Abstract: A system and method for frequency acquisition by a mobile receiver 14 in a cellular communication system. Data for part of a frame 10 is sampled. Synchronization pattern 36 is rotated by a pattern rotator 37 to simulate fixed frequency offsets. The known sync pattern 36 is correlated with the sampled data by correlator 30 for a number of phase advances corresponding to the simulated fixed frequency offsets. The peak outputs 54 and 58 of the correlator 30 for the number of fixed frequency offsets is interpolated by parabolic interpolator 46 to adjust the receivers voltage controlled crystal oscillator 49 to reduce the offset.

Abstract: A method and apparatus for frequency shifting an optical beam where the frequency shifted beam remains both spatially and temporally coherent with no spread in frequency and can be continually tuned in frequency shift over a wide range without any change in beam pointing or beam quality with time. This is achieved by changing the effective optical path length of the resonant cavity of a laser by translating an optical wedge, such as a prism, across the optical path in the direction of the wedge gradient. In a first embodiment, a rotating helical phase plate is used to linearly increase the optical path of a transmitted or reflected beam with time, thereby frequency shifting the exiting beam. In another embodiment, the rim of a wheel with a spirally increasing or decreasing radius is used in which the outer periphery of the wheel is a mirror.

Abstract: This invention discloses a method for maintaining a desirable orientation of the solar wings of an orbiting satellite (10) relative to the sun. A dual array of sun sensors (26,28) is positioned on a body (12) of the satellite (10) in order to get a measurement of the position of the sun relative to the body (12) once per every orbit of the satellite (10). In addition, an estimate of the position of the solar wings (16,17) relative to the body (12) of the satellite (10) is attained. The sun-to-body angle is then subtracted from the body-to-wing angle to drive an error signal which is applied to a wing driver mechanism in order to maintain the solar wings (16,17) of the satellite (10) in a proper orientation relative to the sun.

Abstract: High reflectance mirror 40 for multiple wavelengths has substrate 42 which carries first reflector stack 46 for reflection of the principal, longer wavelength and a stack 66 which reflects shorter wavelength in an alignment beam. Semiconductor layer 64 separates passes the longer wavelength but reflects and/or absorbs the alignment beam of shorter wavelength. Layer 64 thus effectively optically decouples stacks 46 and 66. Each of the layers in the longer wave first reflecting stack 46 is of an optical thickness equal to an odd number of quarter wavelengths of the principal beam. The semiconductor layer 64 and the shorter wavelength reflecting an optical thickness equal to an even number of quarter wavelengths of the principal beam.

Abstract: Disclosed is a method and apparatus for calibrating phased array receiving antennas that includes circuitry for generating a pair of calibration signals separable one from the other. The signals are injected into the delay elements of the antenna from opposite ends of a complementary calibration cable. The delay produced in the calibration signals is individually measured, and the delays summed and averaged to produce a delay measurement independent of delays produced by the calibration cable and accordingly delay measurement variations caused by environmental effects on the calibration cable.

Abstract: An improved antenna beam forming system 10 for generating a set of directed beams wherein each beam may include carrier signals of more than one frequency is disclosed herein. The improved beam forming system of the present invention includes a first beam forming network 20 for providing a first set of signals. The first beam forming network 20 includes a plurality of phase shifting elements 22 for providing a first phase relationship among the first set of signals in response to first carrier signal of a first frequency. The system 10 of the present invention further includes a second beam forming network 30 for providing a second set of signals. The second beam forming network includes a plurality of phase shifting elements 32 for again providing the first phase relationship among the second set of signals in response to a second carrier signal of a second frequency.

Abstract: An improved high speed word generator (30) which includes a white noise generator (12) for providing first and second bits and exclusive or (XOR) means (32) for providing an output signal which is the exclusive or of said first and second bits. In an alternative embodiment, the invention provides an improved N-bit high speed word generator including noise generator means for providing N bits, either through N one bit noise generators or one one bit noise generator and means for storing the output thereof, and exclusive or (XOR) means for providing M stages of N output signals the first stage of which provides N output signals each of which is the exclusive or of two of said bits and the subsequent stages of which provide N output signals each of which is the exclusive or of the output of the previous stage and an output of said noise generator means.