Abstract: Particular embodiments relate generally to infrared focal plane arrays and methods thereof. According to one embodiment, an infrared focal plane comprises an array of pixels configured to detect optical radiation in a predetermined radiation band are positioned on a support substrate. The pixels are connected to pixel contacts on a read-out integrated circuit via pixel interconnects comprising bonding bumps. According to some embodiments, indium migration is blocked by a patterned electrical insulator comprising a plurality of intersecting walls defining a plurality of cells that surround each pixel interconnect. The patterned electrical insulator may be dimensioned such that it does not physically contact the support substrate, the array of pixels or pixel interconnects. In this manner, pixel-pair defects due to indium migration resulting from cryogenic thermal-cycling may be prevented, thereby extending the thermal-cycling lifetime of the focal plane array.

Abstract: A modulation/demodulation system and method comprising transmitting structure having first and second PN generators which produce distinct, synchronized, first and second PN sequences. A tapped delay line generates a plurality of symbols from the second PN sequence, each symbol corresponding to an offset of the second PN sequence by one or more chips from the epoch of the first PN sequence. A plurality of output taps are associated with the tapped delay line, with each tap corresponding to one of the symbols. A symbol selection device associated with the output taps selects from amongst the symbols based upon one or more message signal bits. The selected symbols and first PN sequence are applied to separate channels of a modulator to modulate a carrier signal. At a destination, first and second local PN generators generate first and second PN sequences which correspond to the first and second PN sequences in the transmitting structure.

Abstract: A system and method for transmitting one or more range safety commands to a launch vehicle which includes transmitting structure having a pilot code generator and at least one additional code generator for generating at least one transmitter command code corresponding to a range safety command. A PN clock continuously locks the one or more transmitter command codes with the transmitter pilot code. Sequence selection structure selectively applies the one or more transmitter command codes to a modulator which combines the transmitter pilot code and the applied transmitter command codes with a carrier signal, and transmits the pilot and command codes through a relay satellite to the vehicle. Receiving structure in the vehicle recovers the pilot and command codes, and aligns a locally generated pilot code with the recovered pilot code.

Abstract: A receiver is synchronized to a signal and the presence of data in the signal is detected by responding to the signal to derive indications of the amount of time shift necessary to achieve synchronization between the receiver and signal. The receiver is adjusted to be in synchronization with the signal in response to the time shift indications. A measure of the spread of values of the time shift indications is derived. The presence of data in the signal is flagged in response to the spread of values being less than a threshold value.

Abstract: Each diode of an indium antimonide electro-optical detector array on a dielectric backing transparent to optical energy to be detected includes a junction that less than about a half micron from the diode surface on which the energy is initially incident. The optical energy is incident on a P-type doped region prior to being incident on a bulk N-type doped region. Both P-and N-type doped regions of adjacent diodes are spaced from each other. Metal electrically connects the P-type doped regions together without interfering substantially with the incident optical energy. A multiplexer integrated circuit substrate extends parallel to the backing and includes an array of elements for selective readout of the electric property of the diodes. The elements and diodes have approximately the same topographical arrangement so that corresponding ones of the elements and diodes are aligned. An array of indium columns or bumps connects the corresponding aligned elements and diodes.

Abstract: A unit having differing thermal emissivities at differing regions thereof is monitored with an infrared camera for deriving a signal having magnitudes representing infrared emission from multiple pixels in the camera field of view. A computer responsive to the signal (a) stores data representing emissivity and standard temperature of the unit at each of the pixels, (b) combines indications of the infrared emission from each pixel and the stored data representing emissivity of each pixel to derive an indication of monitored temperature of each pixel, (c) compares the stored data representing standard temperature of each pixel and the indications of monitored temperature of each pixel, and (d) derives an indication of the deviation between the magnitude of the standard temperature and monitored temperature at each pixel. In response to the indication of the deviation at each pixel, a property of the unit related to the deviations at the pixels is derived.

Abstract: Each diode of an indium antimonide electro-optical detector array on a dielectric backing transparent to optical energy to be detected includes a junction that less than about a half micron from the diode surface on which the energy is initially incident. The optical energy is incident on a P-type doped region prior to being incident on a bulk N-type doped region. Both P- and N-type doped regions of adjacent diodes are spaced from each other. Metal electrically connects the P-type doped regions together without interfering substantially with the incident optical energy. A multiplexer integrated circuit substrate extends parallel to the backing and includes an array of elements for selective readout of the electric property of the diodes. The elements and diodes have approximately the same topographical arrangement so that corresponding ones of the elements and diodes are aligned. An array of indium columns or bumps connects the corresponding aligned elements and diodes.

Abstract: An indication of the noise content of data bits on a signal line is derived by sampling the amplitude of a signal on the line several times during each of the data bits to derive for each data bit a several bit binary word. Each bit of the several bit word has a value dependent on the amplitude of the signal on the signal line at the time the sample is taken. In response to the number of binary value transitions in each several bit binary word an indication of the noise content of each data bit is derived.

Abstract: A radiometric standard detector responsive to infrared energy comprises an indium antimonide photovoltaic generator, a first mirror and a vacuum dewar including a cold finger and a window. The first mirror and photovoltaic generator are positioned in the dewar to form an optical energy trap. The generator is on the cold finger. A second mirror is external to the dewar. The window, both mirrors and the generator are positioned so a beam of the infrared energy is incident on the window and a portion of the infrared energy incident on the window is reflected from the window to the second mirror, then back to the window.

Abstract: An output of a local oscillator is synchronized to received bits of a digital bit stream by sampling the binary value of each of the received bits several times during each of the received bits, to derive for each received bit a several bit binary word representing the sampled values. A memory is addressed in response to the binary value of the several bit binary word to control the local oscillator synchronization. The synchronized local oscillator controls the sampling times of the plural samples of each of the received bits so that the binary value of the word controls the oscillator synchronization and the sampling times. The addressed word in the memory determines the value of the received bit, controls the oscillator synchronization, and provides indications of sync lock and unit content of each received data bit.

Abstract: A receiver responsive to a noise laden phase modulated signal on a carrier hard limits the signal to derive a constant amplitude phase modulated r.f. signal. The constant amplitude phase modulated r.f. signal is supplied to processing circuitry to derive a digital signal having a value representing the phase of the noise laden carrier. A phase locked loop, including a minimum variance Kalman predictor filter, responds to the noise laden carrier to derive a relatively noise free indication of carrier phase. The noise laden indication of phase and the relatively noise free indication of carrier phase are combined to indicate the phase of the phase modulated signal to which the receiver is responsive.

Abstract: Current derived from an indium arsenide current generating photodetector is determined accurately, despite the presence of a variable resistance between terminals of the photodetector and the photodetector having leads with appreciable resistance connected to the detector terminals. Two leads are connected to each detector terminal. The two leads connected to one of the detector terminals are respectively connected to an inverting input terminal of an operational amplifier and to one terminal of a feedback resistor of the amplifier; the other terminal of the feedback resistor is connected to the amplifier output terminal. The two leads connected to the other terminal of the photodetector are respectively connected to the operational amplifier non-inverting input terminal and to ground. The operational amplifier derives an output voltage that accurately represents the output current of the photodetector, independently of the photodetector resistance and the lead wire resistance.

Abstract: A short monopole RF antenna tuned over a predetermined RF frequency band in response to binary control signals includes a conductive tubular radiating element extending generally at right angles to a ground plane on which the antenna is mounted. A conductive top load inductively coupled to the element extends approximately parallel to the ground plane so that stray capacitance subsists between the ground plane and top load. The antenna is tuned in response to the control signals to a frequency in the band by selectively short-circuiting different plural series-connected inductors in proximity with the top load. Plural leads extend through the interior of the tubular element between a source of the control signals and switches for selectively short circuiting the inductors. The inductors are electrical conductors in a tube-like structure. The leads extend through the interior of the tube-like structure. Electrical conductors in the tube-like structure are in a return path to the control signal source.

Abstract: A voltage controlled oscillator of a phase lock loop responds to a phase error signal having a value commensurate with the phase difference between input and output signals of the loop, wherein the phase difference extends over more than a one cycle difference of the loop input and output signals. The phase error signal is derived by mixing the loop input and output signals to derive a pair of signals having amplitudes representing orthogonal components of the difference frequency of the loop input and output signals. In response to the signals representing the orthogonal components, signals are derived indicative of the whole number cycle difference of the input and output signals, fractional cycle difference of the input and output signals, and a combination of the amplitudes of the signals representing the whole number cycle difference and the fractional cycle difference of the input and output signals.

Abstract: An FM receiver is self tested by connecting a positive feedback network in circuit with a wideband, front end r.f. amplifier of the receiver, so that the amplifier is converted into an oscillator. R.f. and i.f. characteristics of the receiver are determined by comparing the amplitude of an i.f. signal with a predetermined reference value while the amplifier is converted to an oscillator. Noise characteristics of the receiver are determined by comparing the amplitude of an audio frequency signal of the receiver with a predetermined value while the amplifier is converted to an oscillator and the amplifier derives an unmodulated r.f. output. Baseband characteristics of the receiver are determined by varying a reactance in the positive feedback path to impose FM on r.f. oscillations derived by the amplifier and by comparing the amplitude of the output of the audio frequency amplifier with a predetermined value.

Abstract: A carrier is modulated with binary coded data to produce a suppressed carrier constant amplitude wave by shaping modulation for the carrier so the carrier phase changes gradually between predetermined values without cumulative errors, in response to adjacent bits having different values.

Abstract: Data signals are transmitted at a variable information rate with variable power so the transmitted information rate and transmitted power level increase and decrease together to simulate high frequency fading and enable the data transmission to be disguised. The information rate and power vary in response to a predictable noise-like function generator.

Abstract: Variations, due to aging, of resonant frequency characteristics of electromechanical resonators are compensated by an oscillator including the resonantor. An indication of the amount of time that the oscillator is operating addresses a table of values indicative of the manner in which the oscillator changes frequency as the resonator ages. From the table of values a signal having a value indicative of a correction factor for the resonator aging is derived. The frequency of the oscillator is controlled in response to the value of the correction factor. The table of values is stored in a re-programmable memory. The values stored in the memory are corrected by comparing the oscillator frequency with a standard frequency.

Abstract: A carrier wave is frequency modulated to one of M different output frequencies that deviate from the carrier wave frequency by .+-.k.sub.1, .+-.k.sub.2 . . . .+-.k.sub.q. The carrier is modulated in response to a clocked digital signal having n data bits forming a data word, where M=2.sup.n. In response to the digital signal an n bit control signal is derived. M/2 clock frequencies synchronized with the clock data signal are simultaneously derived. An up-down counter responds to the control signal so that one bit of the control signal controls the counting direction of the counter and (n-1) of the bits control which one of the M/2 frequencies is applied to a clock input of the counter. In response to the count in the counter, orthogonal sinusoidal like waves at one of the frequencies k.sub.1, k.sub.2 . . . k.sub.q are derived. The M/2 clock frequencies are equal to k.sub.1 2.sup.P, k.sub.2 2.sup.P . . . k.sub.q 2.sup.P, where P is the number of clock frequency bits in the counter.

Abstract: A clock wave is synchronized to the frequency of serial binary data bits. Digital circuitry derives a clock wave by responding to the data bits to selectively (a) increment a reference frequency, (b) decrement the reference frequency, and (c) not change the reference frequency. The digital circuitry divides each data bit into an even number of sub-bits. The binary value associated with a first half of the divided sub-bits of a particular data bit is compared with the binary value associated with a second half of the divided sub-bits of the particular data bit. In response to the derived clock wave and the comparison, the reference frequency is derived, incremented or decremented. The frequency of the source is respectively incremented and decremented in response to first and second relations of the binary value associated with the first half relative to the binary value associated with the second half.