Abstract: An arrangement for generating a high power optical radar beam. The arrangement includes first and second laser sources each having a first laser for generating an optical beam of a relatively low frequency F1 and a second laser for generating an optical beam of relatively higher frequency F2. Each laser source provides a first optical beam of frequency F2 and a second optical beam of frequency F1+F2. The arrangement also includes first and second waveform generators each having a modulator and a mixer. A first waveform generator receives the optical beams from the first laser source and a modulation signal for modulating the F1+F2 optical beam. The first waveform generator is operative to provide an output optical beam of frequency F1 having all of the modulation applied to the optical beam of frequency F1+F2.

Abstract: A laser radar system is disclosed. The laser radar system includes a transmitting means that transmits a signal. The transmitted signal is formed by an optical signal that is amplitude modulated with a source signal thereby forming a transmitted signal having light packets at a repetition rate of the source signal. A receiving means that receives the transmitted signal after it is reflected from an object. A Doppler processor determines the Doppler frequency shift of the source signal from signals derived from the reflected signal.

Abstract: A radar exciter including a direct digital synthesis (DDS) wideband waveform generator which performs the frequency synthesis function heretofore performed by a direct analog synthesizer. This is achieved by deriving the DDS frequencies, the exciter RF frequencies, the radar synchronizer clock frequency and receiver analog/digital (A/D) converter clock frequency from a common signal source generating a master frequency. The present invention eliminates the direct analog synthesizer and relies solely on the digital generation of waveforms by a DDS wideband waveform generator which performs a discrete sampling process so as to provide coherent frequency and timing relationships.

Abstract: A T/R module including a multilevel, multichip microwave package having a plurality of gallium arsenide monolithic microwave integrated circuit chips (MMICs) implementing RF switching elements, a variable phase shifter, a plurality of RF amplifiers, and gain trim attenuators and which are located on a planar RF assembly. The module's architecture includes shared or common MMIC circuit elements during both transmit and receive operation modes thus reducing the number of MMICs required while at the same time preloading the supply voltage regulator-modulator which supplies DC power to all the MMIC circuits without degrading T/R module efficiency.

Abstract: A T/R module including a multilevel, multichip microwave package having a plurality of gallium arsenide monolithic microwave integrated circuit chips (MMICs) implementing RF switching elements, a variable phase shifter, a plurality of RF amplifiers, and gain trim attenuators and which are located on a planar RF assembly. The module's architecture includes shared or common MMIC circuit elements during both transmit and receive operation modes thus reducing the number of MMICs required while at the same time preloading the supply voltage regulator-modulator which supplies DC power to all the MMIC circuits without degrading T/R module efficiency.

Abstract: A frequency compensator allows the frequency of a multiple element array to be varied while maintaining a constant separation of the multiple beams output from the array. Since the apparent position of the elements is a function of frequency, by changing the apparent distance in accordance with frequency such that the elements appear to be at desired position, the beamsets may remain relatively aligned as the frequency changes. Both transmitted and received beamsets may be compensated.

Abstract: A dual mode active aperture phased array system for pulsed radar and continuous wave applications. The system may be switched between the two modes without appreciable loss of average effective radiated power. Both the voltage and current of the biasing power to the amplifying transistors is varied to accommodate the difference in peak amplitude power while maintaining the optimum average effective radiated power. The DC power supply is a chopper.

Abstract: A phased array antenna having a first plurality of phase shifters each connected to a solid state transmit module power amplifier. Equal split power combiners, each having a pair of inputs and a pair of outputs, are connected to the power amplifiers and to each other in a corporated tree hierarchal configuration. One of the pair of inputs of each of the power combiners of each higher hierarchy is connected to one of the pair of outputs of the power combiners of a lower hierarchy. A subarray is connected to the other of the pair of outputs of each of the power combiners. A subarray is connected to both outputs of the highest hierarchy. A second plurality of individual phase shifter elements are associated with the individual elements of each subarray. The first plurality of phase shifter elements adjust the illumination and phase of the signal entering each subarray. The second plurality of phase shift elements steer the beam.

Abstract: An oscillator circuit is coupled to receive first and second reference signals and includes a voltage-controlled oscillator for generating an oscillating signal. A difference frequency calculation circuit is coupled to the voltage-controlled oscillator to produce a count signal corresponding to a difference in frequency between the oscillating signal and the first reference signal. A feedback circuit is coupled to the difference frequency calculation circuit and coupled to receive the second reference signal which corresponds to a predetermined frequency for the oscillating signal. The feedback circuit provides a control signal as an input to the voltage-controlled oscillator to control the frequency of the oscillating signal.

Abstract: The present invention includes an apparatus that prebiases a transmitted radar signal. The prebiasing of the transmit signal automatically aligns the return signals in one dimension or dimensionally transforms the return signals thereby removing the need for one of the dimensional processing operations of a conventinal two dimensional return signal interpolator. A map function generator produces small frequency (phase) changes in the transmitted signal during each pulse over the entire integration or exposure period. The map function generator produces a parabolic frequency change control signal applied during the integration period. The control signal is divided into segments where each segment controls a single transmit pulse. The control signal modifies a linear frequency modulation control signal. conventionally produced by high resolution radar systems.

Abstract: An electronically steerable phased array radar antenna system for transmitting and receiving broadband linear FM signals is detailed. The antenna comprises a plurality of subarrays, each of which are connected by circulator means to a transmit-receive module. The highly linearized FM waveform is fed to the transmit-receive module, and a CW waveform is fed to a phase shifter in the module. The phase shifter applies a frequency offset to the CW waveform which is then added to the linear FM wideband signal for each antenna subarray. This frequency offset serves a beam steering function and can be considered a synthetic time delay.

Abstract: A wide-band amplifier apparatus utilizing a low frequency and a high frequency phase lock loop to achieve low phase delay at the loop bandwidth. The bandwidth products of the low and high frequency loop paths are combined and applied to the voltage controlled oscillator to minimize phase delay and to achieve a more stable loop.

Abstract: An electronically agile multi-beam radar including a clutter positioning system for positioning the band of clutter signals in the derived doppler frequency spectrum of each of the individual beams is disclosed. The radar is operative to switchedly transmit a plurality of beams directionally separated by time sharing the illuminating power thereof. Each beam includes at least one transmission of a plurality of R.F. pulses constituting a radar look. The radar is also operative to receive echo R.F. pulses of the look from each transmitted beam dispersed in time with echo R.F. pulses of the looks of the other transmitted beams of the plurality.

Abstract: This invention is directed to a narrow band filter for eliminating out-of-band noise in the oscillator signal of a doppler radar system. It provides a very high Q filter derived from a Bulk Acoustic Resonator's (BAR) high Q, L-Band response and uses thermal feedback to lock the BAR's response band onto the input frequency. The BAR is a very narrow band filter with a Q near 40,000 and a comblike frequency response having passbands occurring every 5 MHz, approximately. The comblike response of the BAR shifts down 60 KHz for every 1.degree. C. rise in temperature. In this invention a frequency sensitive heater is used to move the response comb of the BAR up or down in accordance with changes in the frequency of the incoming signal. The input frequency can be allowed to drift and the heat source will produce more heat or less heat, keeping the response right at the input frequency.

Abstract: A system for comparing the frequency of a voltage controlled oscillator to a stable reference oscillator to generate control signals which maintain the voltage controlled oscillator in phase lock with the reference oscillator. The circuit utilizes a digital frequency comparator to determine whether the output frequency of the voltage controlled oscillator is above or below the reference frequency. When the frequency of the oscillator is either above or below the desired value, pulses are generated which are integrated to produce a DC signal which changes the frequency of the oscillator to achieve the desired value. Additionally, a continuous electrical signal is generated when the output of the voltage controlled oscillator is in phase with the reference signal. When phase lock is achieved the output of the frequency determining circuit goes to zero and phase lock is maintained by the continuous electrical signal.

Abstract: A sampling linearizer including a phase shifter for use in improving the accuracy of an FM generated waveform with respect to a desired frequency rate of change is disclosed. The sampling linearizer comprises an oscillator for generating a reference frequency signal; a mixer governed by the generated FM waveform signal and the reference frequency signal to generate a first signal which is sampled at predetermined sampling times; and a linearizing servo controller which is governed by the sampled signal to reduce the inaccuracies in the genereated FM waveform with respect to the desired frequency rate of change. The sampling linearizer further includes a phase shifter disposed between the oscillator and mixer thereof and operative upon the reference frequency signal to generate another signal, the phase shifter being operative to shift the phase of the another signal with respect to the reference frequency signal as governed by a sequence of control signals representative of predetermined phase shift values.

Abstract: A phase distortion detector is used in a wideband feedback control loop to detect phase distortion on a wideband pulsed linearly frequency modulated waveform (chirped) without the use of excessively long delay lines. The detector mixes two reference signals, each of a predetermined frequency, one frequency higher than the other. A phase lock loop ensures that the two signals are phase coherent. Each signal is then mixed with the chirped waveform, delayed for different time intervals, and mixed again to produce an error signal proportional to the phase distortion on the chirp pulse which distortion is also an indication of the frequency non-linearity of the chirp pulse. The error signal is then used to correct such non-linearity.

Abstract: A digitally controlled microwave phase lock loop for switching rapidly from one lock frequency to another is disclosed. A digital word corresponding to a desired input voltage for a selected frequency is converted to an analog voltage for application to the coarse tuning port of the loop's voltage controlled oscillator. Prior to switching to another frequency, the error voltage for the fine tuning port is compared with a zero error reference voltage. The least significant bit of the digital word for such frequency is increased or decreased by one depending on the direction difference between the compared voltages. This incrementally changed word controls the coarse tuning voltage during the next selection of the particular frequency. The system is initialized by repetitively selecting each of the possible frequencies until the digital word for each selected frequency is within one increment of the zero error reference voltage for the fine tuning port.

Abstract: A vibration noise filtering system for use in airborne radar master oscillator, RMO, systems is disclosed. Master and slave crystal oscillators are used, the slave oscillator being phase locked to the master oscillator governed by a phase locked loop, PLL, having a predetermined low frequency bandwidth. The master oscillator is structurally coupled directly to a source of vibration of the aircraft, while the slave oscillator is isolated and supported from the vibration source by a mechanical passive isolator having a resonant frequency well within the low frequency bandwidth of the PLL. The output of the slave oscillator which is the source of the RMO signal has a phase spectral density within the phase stability requirements of a typical RMO across the operating modulating frequency ranges of both air-to-ground and air-to-air radar modes.

Abstract: An automatic frequency control for causing a local oscillator to track the frequency of a transmitter such that the received echo of a transmitted pulse may be combined with the output of the local oscillator in a mixer to provide an intermediate frequency signal which is suitable for amplification, filtering and detection operations. The automatic frequency control includes an average frequency control loop for determining the average frequency of the local oscillator output signal, an electromechanical frequency transducer cooperating with a sample and hold circuit for providing a modulating signal to modulate the average frequency of the local oscillator output signal in response to the frequency of the next pulse to be provided by the transmitter, and a modulation gain control loop for controlling the gain of the modulating signal to compensate for variations in the transfer functions of the electromechanical frequency transducer and the sample and hold circuit.