Abstract: The present invention uses digital values of MSK-like waveshapes which can be stored in a storage media such as a ROM and then output in a prescribed fashion such as in phase quadrature through the use of an addressing technique to the ROM. The digital values, each of N bits, are then multiplied in quadrature times a data representative signal which is divided into phase quadrature components. These N+1 bit products are summed to produce a composite digital signal representing analog bipolar values. A digital-to-analog conversion provides the modulated analog output signal.

Abstract: An all digital circuit which operates with an electronic oscillator of the type that receives an input signal and synchronizes its oscillations to transitions in the input signal, comprises: a pulse-generating circuit 20 coupled to the oscillator for digitally forming periodic pulses in synchronization with selected oscillations of the oscillator; a detecting circuit 30 coupled to receive the pulses and the input signal for digitally detecting whether a transition occurs in the input signal in the absence of a pulse; and a counting circuit 40 coupled to the detecting circuit for digitally counting so long as the detecting circuit fails to detect a transition in the absence of a pulse and for indicating the oscillator is synchronized when the count reaches a predetermined number.

Abstract: A frequency time standard monitoring system includes three highly accurate standards of substantially identical frequency. These three standards are compared in pairs by three monitoring apparatus. Each such apparatus includes a fine window detector for determining the phase relationship between the two applied frequency standard clock signals, and a phase shifter responsive to the fine window detector for shifting the phase of one of the signals until the signals are phase aligned. When this occurs, the fine window detector is disabled and a coarse window detector monitors the two clock signals to ensure that the clocks do not drift beyond tolerable limits. The output signal of the coarse window detector is applied, along with the corresponding signals from the other two monitoring apparatus, to a select logic which determines which standard should be on-line in the event of a fault detection.

Abstract: The acquisition of phase lock to a reference frequency by a signal acquisition system is accomplished using a voltage controlled oscillator, a wideband frequency discriminator, a prepositioning circuit, and a phase lock loop. The voltage controlled oscillator is prepositioned within a loop bandwidth of the reference frequency by the prepositioning circuit and the wide band frequency discriminator which provide coarse tuning. The voltage controlled oscillator achieves phase lock with the reference frequency when it receives the fine tune signal from the phase lock loop. Using both the discriminator and the phase lock loop allows fast acquisition without the need to calibrate the voltage controlled oscillator. Since the discriminator pull-in range is much larger than the phase-lock loop bandwidth, the number of bits can be much smaller than in an acquisition circuit using a digital prepositioning circuit alone.

Abstract: An FM signal demodulating circuit which provides accurate drop-out compensation without producing an unnatural sounding output. The period of the receive FM signal is periodically detected for each cycle thereof to produce a signal having a level corresponding to the period of the FM signal. The signal so derived is held for each period of the FM signal, including periods during which drop-out occurs. The reciprocal of the level of the held signal forms the demodulated output signal.

Abstract: Apparatus is depicted which enables the sampling of the phase angle of a modulated signal and manipulates the sample signals to demodulate the same. The apparatus is particularly adaptable for use in demodulating the I and Q channel signals of a zero IF receiver. The system contains an angle sensing circuit which combines the I and Q channel signals in differential form to produce a series of output signals of an angular range indicative of the present value of the instanteous phase. The signals from the angle detector are coupled to an octant decoder which operates to determine the particular octant that the angle is to be included in. In the present system eight octants are used, each comprising 45.degree.. The octant decoder determines which octant the angle belongs in and assigns a predetermined angle value to that angle. In one embodiment, the assigned angle values are 0.degree., 45.degree., 90.degree., 135.degree., 180.degree., 225.degree., 270.degree. or 315.degree..

Abstract: An offset compensator is disclosed. The offset compensator is suitable for use with any antipodal information signal distorted by an offset voltage. The offset compensator measures the positive and negative peak amplitudes, compares the magnitudes thereof, and produces a correction voltage based on that comparison. The correction voltage has a positive sign when the magnitude of the negative peak amplitude exceeds the magnitude of the positive peak amplitude, and the correction voltage has a negative sign when the magnitude of the positive peak amplitude exceeds the magnitude of the negative peak amplitude. The magnitude of the correction voltage represents the difference between the magnitudes of the positive and negative peak amplitudes, and is added to the antipodal information signal to remove the offset voltage.

Abstract: The output signal frequencies of two current controlled oscillators are made to track closely by matching timing currents with a current mirror. A frequency difference between the output signals is obtained by establishing an additional timing current for only one of said oscillators.

Abstract: In order to establish accurate sample timing in a digital demodulator which forms part of an orthogonally multiplexed parallel data transmission system, two second-order PLLs are arranged after a demodulating section of the digital demodulator so as to receive baseband signals of corresponding pilot channels. The two second-order PLLs each includes an integrator. These integrators apply the outputs thereof to a subtracter which applies the subtraction result to a voltage-controlled oscillator in order to establish the accurate sample timing.

Abstract: A quadrature amplitude modulation (QAM) demodulator system has in-phase and quadrature channel detectors receiving local oscillator signals which must be in precise phase quadrature relationship with each other. The in-phase and quadrature channels each have analog-to-digital converters with n output bits, where n is greater than m, the number of bits required for the data output for each channel. The n-m less significant bits in one channel are used to derive a signal indicating the deviation from a true quadrature relationship between the local oscillator signals. The error signal controls an adjustment of the phase of one of the local oscillator signals, to bring about the precise quadrature relationship required for accurate demodulation.

Abstract: Between insulative layers (31-37, 41-44), a multilayer substrate comprises at least one dielectric layer (26-29). It is possible to form capacitors (58), resistors (46), and wiring conductors (61, 62) in the substrate. The at least one dielectric layer should be of at least one dielectric composition which has a perovskite structure. Preferably, each insulative layer is of an insulating material which consists essentially of aluminum oxide and lead borosilicate glass. The substrate is convenient in manufacturing a crystal oscillator by mounting a crystal vibrator (71) and a transistor (72) on the principal surface(s). Examples of the dielectric composition are:Pb[(Fe.sub.2/3.W.sub.1/3).sub.0.33 (Fe.sub.1/2.Nb.sub.1/2).sub.0.67 ]O.sub.3,Pb[(Mn.sub.1/3.Nb.sub.2/3).sub.0.01 (Mg.sub.1/2.W.sub.1/2).sub.0.30 (Ni.sub.1/3.Nb.sub.2/3).sub.0.49 Ti.sub.0.20 ]O.sub.3,andPb[(Mg.sub.1/2.W.sub.1/2).sub.0.66 Ti.sub.0.34 ]O.sub.3.

Abstract: Apparatus to provide calibrated frequency modulation (FM) of frequencies generated in a phase-locked loop is disclosed. A phase-locked loop (PLL) includes a voltage-controlled oscillator (VCO) which is locked to a loop frequence signal frequency. A modulo-10 divider is included which adds integral multiples of two pi radians of phase to the output signal of the VCO whenever the modulus of the divider is reduced by an integer. This forces the PLL to step change the loop frequency by an integral multiple of the reference frequency. A sampling circuit senses and measures the change in the VCO control voltage resulting from the step change in the loop frequency. The change in the control voltage is a measure of the VCO gain at that frequency. The change in the control voltage is converted to a digital number which is loaded into a multiplying digital-to-analog converter (DAC) to adjust the gain of the DAC.

Abstract: A phase locked loop for bringing an oscillator (1) into phase with an incoming signal. In accordance with the invention there are means which on the one hand determine whether the phase difference between the oscillator output signal and the incoming signal is positive or negative and on the other hand in response thereto cause the oscillator (1) to emit either of two output signal frequencies, one of which is predeterminately higher while the other is predeterminately lower than the incoming signal frequency. The oscillator (1) is hereby brought into phase with the incoming signal when the former emits its two output signal frequencies alternatingly.

Abstract: A 16-quadrature amplitude modulation (QAM) modulator for radio links converts a train of data into signals having a phase selected from sixteen predetermined phase values and an amplitude selected from four values. The modulator divides the data train into two data sub-trains. The two data sub-trains are respectively applied to a pair of four-phase modulators that are fed by a carrier source. The 16-QAM modulator also comprises two phase locked loops each including a voltage controlled microwave oscillator and an associated differential phase detector. The differential phase detector responds to the output of the associated four-phase modulator and the output of the associated voltage controlled microwave oscillator. Predetermined parts of the output signals of the two phase locked loops are added.

Abstract: The invention relates to a crystal controllable oscillator circuit. The oscillator includes an amplifier and an oscillation sustaining feed-back loop coupled between an output and an input of the amplifier the loop including two integrators in series for inhibiting oscillation at crystal overtones. Each integrator provides 90.degree. phase shift independently of the oscillators defining RC product which determines only the gain thereby making the oscillator less sensitive to variations in circuit time constants due to temperature and manufacturing tolerance effects. The invention is particularly suitable for incorporating in integrated circuit form where only a single pin connection is required for the controlling crystal.

Abstract: An oscillator includes two transistors or like devices having their emitters connected to a common of a power source. The two transistors or like devices are interconnected with the base of the first connected to the collector of the second and the base of the second connected to the collector of the first. An inductance is placed across the base-collector connectors and a circuit through the oscillator is completed via a lead to one of the base-collector connectors.

Abstract: A quadrature amplitude modulation (QAM) demodulator system derives a local oscillator signal which has the frequency and phase of the suppressed carrier of the QAM signal, so as to permit proper demodulation. In-phase and quadrature channels of the demodulator system each have an analog-to-digital converter with n output bits, where n is greater than m, the number of bits required for the data output for each channel. The n-m less significant bits are used to derive a signal indicating the error in phase alignment between the local oscillator signal and the QAM signal. In a phase locked loop, this error signal drives a voltage-controlled oscillator to phase lock with the suppressed carrier of the QAM signal. To acquire frequency and phase lock, a digital-to-analog converter in the loop is clocked each time the phase alignment of the VCO signal and QAM signal is close.

Abstract: A data demodulator for digital signals in which the times of the zero crossings in hard limited signals in the orthogonal outputs (I and Q) of a direct demodulation receiver are used to recover the carrier and clock signals.

Abstract: For determining the half-cycle durations of the input signal which is presented as a sequence of sampled values, its zero crossings are approximated by lines which interconnect the two sampled values of different signs on both sides of the zero crossing. The half-cycle duration is derived from the number of sampled values within a period, i.e. between two consecutive zero crossings, and from the time intervals at the beginning and end of each half-cycle determined by the intersection of the approximation line with the axis. The time intervals at the beginning and end of each period are corrected for a more accurate determination of the duration and the time intervals during which the values of the individual half-cycle durations are stored, are made to approximate to these half-cycle durations. The instantaneous frequency of the input signal is determined from the values of the half-cycle durations which have thus been shifted in time by forming the reciprocal.

Abstract: In a distributed IMPATT structure, power is coupled out through a side contact. That is, in previously proposed distributed IMPATT structures, the gain medium (the active region of the IMPATT) operates as a transmission line. The prior art has attempted to couple output power from the gain medium through an end contact, i.e., through a contact which is perpendicular to the primary direction of energy propagation (and also to the direction of maximum elongation) of the active medium. In the present invention, a sidewall contact extends in a direction which is parallel to the principal direction of propagation of the energy in the active medium. Thus, the sidewall contact plus the active region together can be considered as a single transmission line. This extended transmission line is also connected to a second distributed semiconductor element which functions as a varactor.