Abstract: A disclosed method includes: dividing an signal into a first signal and a second signal; performing frequency multiplication and amplification on the first signal to obtain an intermediate signal of corresponding power and frequency, and using the second signal as a local oscillation signal. The method further includes dividing the intermediate signal into a first intermediate signal and a second intermediate signal, and using the first intermediate signal as a reference signal; performing frequency mixing on the second intermediate signal and the local oscillation signal to obtain a mixed signal, which is a high-frequency millimeter wave signal; transmitting the mixed signal by a transmitting antenna; and performing frequency mixing on the signal received by a receiving antenna and the reference signal to obtain an intermediate-frequency controllable signal having a frequency consistent with that of the output signal of the signal source.

Abstract: A phase-locked loop (PLL) for a radar system includes an oscillator configured to have an output frequency and a multi-modulus divider (MMD) configured to implement successive frequency modulation ramps of the oscillator output frequency, each frequency modulation ramp beginning at a first frequency and ending at a second frequency. The PLL is operated by downmixing an output of the MMD to a frequency above zero Hertz, measuring the downmixed output of the MMD to generate a plurality of MMD output measurements for each frequency modulation ramp, and calculating the frequency of the MMD based on the plurality of MMD output measurements for each frequency modulation ramp.

Abstract: An apparatus includes a selection device to select a spreading profile from a plurality of spreading profiles, and an oscillation device to generate clock signals having different frequencies over time based on the selected spreading profile. A method includes selecting a spreading profile from a plurality of spreading profiles, and generating clock signals having different frequencies over time based on the selected spreading profile.

Abstract: With an oscillator circuit with a frequency sweep function, a first counter counts a reference clock for a number of counts that corresponds to a digital first setting signal, and generates a first count completion signal which is asserted on completion of the count. A D/A converter converts a digital second setting signal into an analog control voltage. A VCO oscillates with a frequency according to the control voltage. When the first count completion signal is asserted, the VCO is reset. An output combining unit receives the output signal of the VCO, generates the output signal of the oscillator circuit, and generates the first setting signal and the second setting signal.

Abstract: A frequency jitter generation circuit having a voltage generator and an oscillator circuit is provided. The voltage generator receives an input voltage and converts the input voltage into an upper reference voltage output to the oscillator circuit. Voltage level of the upper reference voltage is varying. The oscillator circuit is coupled with the voltage generator. Voltage level of a reference voltage in the oscillator circuit is oscillated between the upper reference voltage and a lower reference voltage to generate a frequency signal with a jitter based on the variation of the upper reference voltage.

Abstract: A clock frequency modulator for an oscillator having a digital circuit for the generation of a signal modulating the clock frequency, the digital circuit adapted to obtain, from the signal generated by the oscillator, a first pulse signal having a lower frequency than the clock frequency of the oscillator, a digital counter adapted to count the pulses of the first signal and to produce a digital signal and a digital-to-analog converter adapted to convert the digital signal in the signal for modulating the clock frequency of the oscillator.

Abstract: Noise generation is reduced further. Oscillation control circuit 11 generates a modulation signal modulating oscillation frequency of an oscillation signal generated by oscillation circuit 12 and outputs modulation signal to same. Preferably, the modulation signal fluctuates period of the oscillation signal sequentially. The oscillation circuit 12 is composed of a ring oscillator, for example, and the power supply voltage or power supply current of the ring oscillator is controlled to fluctuate sequentially by the modulation signal output from the oscillation circuit 11. Buffer 14 of charge pump circuit 13 generates signals /? and ? by the oscillation signal and drives capacitors C1 and C2 for supplying a higher voltage than the voltage of the power supply Vcc to gate of N-channel MOSFET Q1.

Abstract: A single chip digital frequency synthesiser (1) for synthesising a frequency swept synthesised output signal of a selectable frequency sweep comprises a direct digital synthesiser (5) which produces the frequency swept synthesised output signal on an output terminal (7) in response to values of a frequency control digital word applied to a frequency control input (8) thereof by an on-chip data processing circuit (25). An on-chip programmable data storing circuit (12) is programmable to store data indicative of a selected mode in which the digital frequency synthesiser (1) is to operate, and to store data indicative of selectable frequency and the time domains of the frequency swept synthesised output signal to be produced.

Abstract: An output cycle of a pulse string generated from a pulse generating section (2) is divided by a pulse dividing section (3) and a signal having a cycle which is plural times as great as the cycle of an output pulse is output from the pulse dividing section (3). This signal is input as an interruption request signal to a CPU (1). Consequently, the CPU (1) can execute an interruption processing in a cycle which is plural times as great as the cycle of the output pulse. By the interruption processing, the number of pulses to be output is controlled.

Abstract: A method of producing a clock signal with reduced electromagnetic interference spectral components includes providing a first clock signal; producing a second clock signal by delaying the first clock signal; and generating a jittered clock signal by switching between the first clock signal and the second clock signal at times selected responsive to a random number generator.

Abstract: This invention provides a voltage controlled oscillator that improves the linearity of frequency variable characteristics and increases the range of frequency that can be varied by a control voltage. A resistor circuit is connected between a piezoelectric resonator X and an oscillator circuit. The resistor circuit includes a plurality of oscillation-amplitude adjusting resistors Rs1 to Rsn and corresponding switches SW1 to SWn. The resistor circuit adjusts the amplitude of oscillation. When a control voltage Vc applied to a varactor Cv is at a low potential, clipping by a forward voltage of the varactor Cv is suppressed, and the frequency is linearly changed by the control voltage Vc within a range of a low potential to a high potential.

Abstract: A method for detecting and correcting non-linearities in radio-frequency, voltage controlled oscillators provides for digitization of the frequency signal by feeding the undelayed frequency signal and a delayed frequency signal generated therefrom into EXOR gates. The digital pulses produced thereform are converted using a low pass filter into a proportional DC voltage value which is proportional to the oscillator frequency and is used as a basis for producing a correction value for the frequency control of the oscillator.

Abstract: An inexpensive numerically-controlled fast frequency-hopping microwave synthesizer. A voltage-controlled oscillator (VCO) output phase remains locked to an internal direct digital synthesizer (DDS) reference signal over the entire output frequency band, which is an order of magnitude larger than the internal sampling clock frequency. A “Nyquist-boundary hopping” scheme compares signals from an alias band of the DDS with signals from an alias band of the sampled VCO output to derive an output phase error signal, which is forced to zero in a manner that locks the VCO output phase to the DDS output phase over a frequency hop-distance greater than the DDS bandwidth. Accordingly, in a single second, the synthesizer can hop phase-continuously in a single clock cycle to each of hundreds of thousands of different microwave output frequencies with relatively low clock rates (up to 100 MHz) commensurate with silicon application-specific integrated circuits (ASICs).

Abstract: A system of spreading the energy of higher harmonic frequencies in digital circuits to lower the interference to bandpass receivers is disclosed. A set of passive, impedance-regulated circuits, preferably housed in a standard enclosure, comprises a power restoring unit, a modulating signal generator, an internal oscillator and an impedance spreading unit. The circuits are equivalent to passive resonators such as crystal resonators used in standard oscillators. Any existing standard oscillator that uses common crystal resonators can be transformed into a spectrum-spread oscillator by replacing the crystal resonator with the disclosed circuit, whereby a tightly controlled small frequency spreading occurs in the fundamental clock frequency. Further an active oscillator is disclosed wherein a spreading circuit spreads the frequency of the clock signal originally generated by the oscillator based on a sequence of processing the original clock signal.

Abstract: The output of a voltage-controlled oscillator (VCO), after being passed through a resonator having a single-peak characteristic, is detected by a detector. The output of the detector is sampled and held at a time instant that the control input voltage to the VCO reaches a maximum and also at a time instant that it reaches a minimum, and the difference between them is fed back to the control input of the VCO. In this way, the center frequency of the VCO is controlled so that it becomes equal to the center frequency of the resonator. In the case of a VCO as an FM modulator in an FM-CW radar, the sample-and-hold timing is derived from a clock signal based on which a triangle wave is generated. In the case of a VCO as an FSK modulator, the sample-and-hold timing is obtained by detecting a 0 and a 1 in input data.

Abstract: A regulating circuit for a quartz crystal oscillator-based timepiece is capable of compensating for large deviations in oscillation frequency of the quartz crystal oscillator. A frequency divider sequentially divides the reference clock by one-half. A regulation data setting circuit sets logical regulation data used to compensate for deviations in the oscillation frequency of the oscillator from a desired value. A regulation circuit adjusts the frequency dividing ratio of the frequency dividing circuit based on the logical regulation data in accordance with a predetermined cycle and controls in such a manner that the frequency of a divided output signal of the frequency divider has a predetermined frequency. When the frequency of the divided output signal cannot coincide with the predetermined frequency using the set logical regulation data, the range of adjustment is shifted using data set in a switch during production of the timepiece.

Abstract: An ultra-linear chirp generator includes a voltage controlled oscillator (VCO) having a tuning characteristic which is naturally nonlinear, a linear ramp generator which generates a linearly ramping output signal having a linear slope characteristic with respect to time, a polynomial correction waveform generator which generates a polynomial correction signal, and a summer which is responsive to and sums the linearly ramping output signal and the polynomial correction signal. The summer generates a VCO tuning signal for tuning the VCO. The tuning signal corresponds to the linearly ramping output signal predistorted with a nonlinearity opposite to the natural nonlinearity of the VCO tuning characteristic. The linear chirp generator also includes a phase locked loop which is responsive to the output signal of the VCO and which has a reference frequency which is related to the repetition rate of the output signal of the VCO.

Abstract: A signal source provides an output signal which can sweep over a broad frequency range in a well-controlled manner. The signal source includes a voltage controlled oscillator (VCO) producing the output signal and a waveform synthesizer producing a reference signal. The VCO output signal is phase locked to the reference signal. To make the VCO signal continuously sweep over a broad frequency range, the reference signal sweeps repeatedly over a narrow frequency range. During each sweep of the reference signal, the VCO frequency tracks an integer harmonic of the reference signal frequency. The frequency and phase of the reference signal for each successive sweep are abruptly reset at the beginning of each sweep selected such that the VCO signal frequency locks to another integer harmonic of the reference signal frequency and does not change.

Abstract: A closed loop linearizer method and apparatus for providing a linear ramp modulation for a voltage controlled oscillator (VCO). A counter is connected to the VCO for calculating two frequency values of the oscillator at one or more time points during a ramp interval. The difference of the two frequency values is then compared with that of a predetermined ideal difference frequency value. A resulting correction value is then generated and used to adjust digital control values upward and downward, thereby causing the VCO to produce a linear modulation ramp output slope over time.

Abstract: A low-frequency low bandwidth Linear Frequency Modulation (LFM) waveform, nominally a 1 MHz to 10 Mz swept frequency analog sinusoid or digital square wave, is produced by direct digital synthesis. This waveform is upconverted in frequency and expanded in bandwidth, nominally to microwave frequencies with bandwidths of nominally 160-360 MHz, in a multiplying offset phase locked loop. The phase locked loop also linearly frequency modulates a X-band carrier with the microwave frequency LFM waveform to produce an output signal suitable for Synthetic Aperture Radar. The phase locked loop induces low phase error, and may be closed around the radar transmitter to remove phase errors induced by that unit.

Abstract: A method and apparatus for a sweep oscillator and a spectrum analyzer containing the sweep oscillator having a precisely determined center frequency includes a sweep circuit having a sawtooth waveform, a reference oscillator, a microprocessor controller and a modified phase-locked loop. The modified phase-locked loop further includes a control signal summer, a voltage controlled oscillator coupled to the control signal summer, a sweep oscillator output, and a sample and hold circuit including a switching circuit.

Abstract: A circuit for generating an output signal having an output frequency that varies linearly with time, and to an FM CW radar system utilizing such a circuit. The circuit includes a voltage controlled oscillator that produces an output signal at its output terminal at an output frequency that corresponds to the voltage of an input tuning signal. A comparison signal circuit receives the output signal and produces a periodic comparison signal such that when the output frequency varies by .DELTA.f, the comparison signal frequency varies by .DELTA.f/N where N is a positive integer. An update counter periodically causes the value of N to change by a predetermined integer amount. A phase detector compares the comparison signal to a periodic reference signal, and produces a correction signal that is filtered to provide the tuning signal for the VCO. The value of N is preferably changed at an update frequency that is equal to the frequency of the reference signal times an integer.

Abstract: An apparatus and method utilizing a sweep-frequency, high voltage generator coupled to an applicator gun for feeding electric power into pest-infested dielectrics, for example termite-infested wood. Utilizing a conventional line frequency of 120 or 60 Hz, the generator produces 140 kilovolts propagated within a spectral band ranging from 15 to 120 kHz and rich in harmonics. Output is discharged through a high-voltage energy storage capacitor charged using an insulated gate bipolar transistor driven by a variable frequency inductively coupled multivibrator. The output voltages penetrate dielectrics and electrocute the pests inside. The invention is effective against insects having hard exoskeletons comprised substantially of cuticulin, chitin, and sclerotin.

Abstract: Linearizing circuitry for an FMCW transmitter (1,2) employing a linear modulation waveform. The output signal is sampled (3,4,5) in successive intervals, small compared to the modulation period, and a cycle count (16) taken in each interval; a reference count is derived for each interval, either by way of a look-up table (21) triggered by a clock count (17) or derived by way of a clock driven processor (18). A comparison (20) is made and any error (22) is used to control (11) the phase of the modulation waveform.

Abstract: A swept synthesizer signal source provides a digital synchronization signal for accurate internal synchronization of events and for external synchronization of data taking and other operations to predetermined frequencies generated by an oscillator during a sweep. The digital synchronization signal includes a predetermined number of digital pulses, regardless of the sweep time. A ramp voltage which controls the oscillator is corrected during a calibration period to sweep between predetermined limits, thereby insuring that the ramp voltage is synchronized to the digital synchronization signal. The slope of the frequency versus time sweep is also corrected to further improve accuracy. A power level correction technique insures precision power leveling regardless of the sweep range. A table of correction/frequency pairs is entered into the instrument, and an interpolation algorithm is employed to determine corrections at frequencies corresponding to each synchronization pulse.

Abstract: A frequency synthesizer is provided in which the output is a truly continuous sweep of frequency, not a staircase of spot frequencies. A programmable frequency divider PD is connected to the output of a voltage-controlled oscillator (VCO) to divide the VCO output by a variable integer N. At each VCO output cycle, the integer N is incremented (or decremented). The output of a phase comparator PC, which compares the divider output with a fixed reference frequency, is connected via an integrator (10) to the VCO frequency control input (2). A constant phase error produces a ramp rise of VCO frequency.

Abstract: In a process and a circuit for exciting an ultrasonic generator the latter is excited by an output signal of a voltage-controlled oscillator, which is controlled by a control device including a triangular wave generator so that its frequency is periodically swept in a range covering the series resonance of the ultrasonic generator. A measured quantity value, which can be voltage or current corresponding to the damping of the ultrasonic generator, is formed and is compared with the maximum permitted damping. If the established damping is smaller than the maximum permitted damping, the oscillator is additionally regulated as a function of the measured quantity. This measured quantity is preferably a function of the exciting current of the ultrasonic generator. An instantaneous measured value and a delayed value are formed and their difference is compared with a threshold value in a comparator. If this difference is the same as the threshold value, the sweep direction in the control device is reversed.

Abstract: An integrated circuit random number generator which uses a triangular output analog oscillator to vary the frequency of a higher frequency voltage controlled oscillator. The output of the voltage controlled oscillator is sampled at a rate much less than the rate of oscillation of the voltage controlled oscillator to produce random digital values.

Abstract: A random number generator designed for use with an electronic key uses a triangular output analog oscillator to vary the frequency of a higher frequency voltage controlled oscillator. The output of the voltage controlled oscillator is sampled at a rate much less than the rate of oscillation of the voltage controlled oscillator to produce random digital values.

Abstract: A PLL frequency synthesizer comprises a voltage controlled oscillator which oscillates in response to a frequency signal corresponding to a control signal to be input and which outputs the frequency signal as an output of said PLL frequency synthesizer; a multiplier means for multiplying a reference frequency signal to be input; a mixer for mixing the frequency signal which is output from the voltage controlled oscillator and the multiplied reference frequency signal which is output from the multiplier, and for outputting a frequency signal representative of a difference therebetween; a variable frequency divider for dividing the difference frequency signal at a variable dividing ratio; a fixed frequency divider for dividing the reference frequency signal at a predetermined dividing ratio; a frequency phase comparator for detecting a phase difference between an output signal from the variable frequency divider and an output signal from the fixed frequency divider and for outputting a phase difference signal t

Abstract: A signal generating device and method of control thereof for producing a desired output frequency, the generator having coarse and fine tuning controls capable of producing frequency changes over a limited range, wherein the output of the device is combined in a mixing device with a multi-component reference signal produced from an oscillatory generator circuit, a beat signal is detected by processing circuitry as the frequency controls are adjusted and the values of the frequencies of the control signals occurring on such detection are stored, and using a look-up table or algorithm the value of a correction signal is determined which, when combined with the stored values, will cause the output frequency of the device to be adjusted to the desired value via the fine tuner.

Abstract: A microwave frequency oscillator capable of being linearly swept over a wide frequency range around a central frequency comprising a field-effect transistor with a high gain, the output of which is fed back to the input from a coupler consisting of two relatively narrow striplines located close together. A wobbulator circuit is fitted in shunt to the feedback network comprises two voltage variable capacitors in series between three line components designed to optimize the frequency modulation linearity in relation to the voltage variable capacitance diode control voltage. The oscillator is useful in equipment requiring extreme linearity such as radio-altimeter sources.

Abstract: An apparatus and method for generating an output signal having portions thereof being linearly swept in frequency. A controller, responsive to external signals, generates a series of control signals. An oscillator, responsive to each one of the control signals, produces an output signal. The output signal includes a series of output waveforms each linearly swept in frequency and corresponding to a respective one of the control signals. A first servo, responsive to each one of the output waveforms, produces a series of first correction signals each dependent upon the linearity error in a corresponding one of the output waveforms. The first correction signals modify a corresponding control signal as applied to the oscillator so as to correct linearity errors occurring in a corresponding one of the output waveforms. A second servo, responsive to each one of the first correction signals, produces a series of second correction signals each dependent upon the correlations in the first correction signals.

Abstract: A frequency-agile source of microwave frequency signals is shown to include: a voltage-controlled oscillator operating within a band of microwave frequencies; a crystal-controlled oscillator operating at a frequency lower than the band of microwave frequencies and producing harmonics within such band; a phase detector having samples of the signals out of the crystal-controlled oscillator and the voltage-controlled oscillator applied as input signals; and a shaping amplifier receiving the output signal of the phase detector to provide a control signal related to the phase difference between the signal out of the voltage-controlled oscillator and the harmonic of the crystal-controlled oscillator nearest to the frequency of the voltage-controlled oscillator.

Abstract: A method and apparatus for generating a sweep signal, the frequency of which is accurately known at all times during the sweep cycle. The beginning and ending frequencies are fixed by a phase-locked loop and the resulting error correction voltages are stored. During the sweep, these error voltages determine the offset and slope of the D.C. voltage ramp signal which governs the frequency of the sweep oscillator.

Abstract: A digital device generating a frequency-modulated signal. The device comprises a programmable divider which divides the frequency f.sub.H of the clock by a variable integer N supplied by a control circuit. The output pulse signal of the frequency divider initiates the supplying of the next value of N by the control circuit. A shaping circuit brings the pulse signal into the form of a signal whose half-cycles successively have a duration equal to an integer multiple N of the clock period 1/f.sub.H. A supplementary circuit makes it possible to improve the precision of the modulation obtained compared with the desired phase by optionally delaying each half-cycle of the modulated signal by a fraction of the block period. The present invention is applicable to radar and telemetry.

Abstract: An electronically tunable solid-state microwave frequency source comprises a transmission-absorption filter incorporated within a magnetic structure. The transmission-absorption filter is employed with a tunable solid-state oscillator and tunable solid-state multiplier to provide a continuously tunable microwave signal source with enhanced spurious signal attenuation over a multiple-octave tuning range. The filter structure comprises a sphere of monocrystalline garnet such as yttrium iron garnet (YIG) and two coupling loops disposed in the field region of an adjustable field DC magnet. The coupling loops are disposed orthogonal to the magnetic field and to each other. In a specific embodiment the first coupling loop is operative to receive at its input the fundamental frequency signal and at its output is grounded, and the second coupling loop is operative to receive a harmonic input signal at its input and to convey a desired output signal at its output.

Abstract: A phase-locked voltage controlled oscillator for generating frequency modulated waveforms having a programmable digital RF phase shifter to determine the phase difference between the output signal and a phase corrected reference signal to thereby generate the desired output waveform.

Abstract: A co-axial magnetron is provided with a cavity whose resonant frequency can be very rapidly altered in a cyclic manner so that the microwave output frequency of the magnetron can be chosen to lie within the available frequency band of the cavity. The cylindrical walls of the co-axial resonant cavity are constituted by or coupled to the inner surfaces of one or more tuning forks which are maintained in vibration by externally mounted electro-magnetic transducers. As the tines of the tuning forks vibrate, the effect is to cyclically increase and decrease the effective diameter of the cavity, thereby changing its resonant frequency. An adjustable end plate can be provided for the cavity so that fine tuning or slow rate tuning can be provided in addition to the frequency agility provided by the tuning fork.

Abstract: A sweep voltage from a sweep voltage generator is provided to sweep start and stop adjusting means, the outputs of which are summed by a summing circuit and, by the summed output, the oscillation frequency of a voltage controller oscillator is controlled. The oscillation frequency of the voltage controlled oscillator and the output frequency of a reference signal generator set to a sweep start frequency are compared by comparing means. The output of the sweep voltage generator is put in a sweep start state and sweep start adjusting means is adjusted in accordance with the output of the comparing means, thereby to cause the oscillation frequency of the voltage controlled oscillator to agree with a set sweep start frequency. The output of the sweep voltage generator is put in a sweep stop state and sweep stop adjusting means is adjusted in accordance with the output of the comparing means, thereby to cause the oscillation frequency of the voltage controlled oscillator to agree with a set sweep stop frequency.

Abstract: Non-linearities in the sweep output of a voltage controlled oscillator are automatically linearized by a scheme that compensates for changes in slope of the variation in frequency with time during a high accuracy calibration mode, prior to placing the VCO into real time operation. During the calibration mode the sweep rate of the VCO is slowed down as the operational frequency range of interest is divided into a prescribed number of subfrequency segments or windows. During each window, an input control code, obtained from a random access memory (RAM) and representative of the intended slope of the VCO frequency sweep (for that window of interest), is applied to a digital-to-analog converter (DAC) whose output is integrated and applied to the voltage control input of the VCO.

Abstract: A phase controlled oscillator comprises a first sweeping oscillator producing an output voltage controlled by a control input signal and a first sweeping signal within a limited output voltage amplitude, a second sweeping oscillator which produces a second sweeping signal having an amplitude smaller than that of the first sweeping signal supplied to a phase locked loop, the phase relation of input and output signals of the second sweeping oscillator being selected such that it stops oscillation when the loop is in a locked state, and a control circuit adapted to hold the output voltage of the first sweeping oscillator.

Abstract: A swept frequency oscillator is capable of providing an output signal whose frequency can be swept over a very wide range at a rate which is not dictated by the period of the lowest frequency in the range. The signal detector monitors the output level of the oscillator so as to generate a control signal to remove variations in the output power level. At frequencies below a particular value, the time constant of the detector is modified progressively so as to be inversely proportional to the frequency being generated. Thus at low frequencies in the swept range, the time constant of the detector is increased.

Abstract: The average frequency and sweep rate of a chirped oscillator are automatically digitally controlled for correction of long term drift. During each of successive swept-frequency chirps, the swept frequency output of a voltage-controlled oscillator is counted and the overflow time of the counter is utilized to control the average frequency. A second counter counts the chirp frequency in a first direction during a first preset period at the beginning of each chirp and counts the chirp frequency in a second and opposite direction during an identical preset period later in the chirp, to provide an underflow transition related to the slope of the chirped frequency signal. Digital circuitry for synthesis of the chirped oscillator frequency ramp signal, and for correction of the average frequency and slope thereof responsive to the first and second counter transitions, is utilized.

Abstract: The starting frequency and sweep rate of a chirped frequency-shift-keyed oscillator are automatically controlled for correction of long-term drift. The substantially linear swept frequency output of the oscillator, during each of a successive multiplicity of swept frequency chirps, is counted and the count converted to an error signal utilized to control an appropriate potential in the oscillator circuit. The initial frequency is monitored, where the swept frequency range is small compared to the initial frequency, by counting the number of cyles during a chirp period in obtaining a first error signal from the total cycle count. The frequency-chirp ramp rate is monitored by counting the number of cycles during an initial portion, e.g.

Abstract: A linear sweep frequency modulator for a varactor tuned transistor microwave oscillator used in an FM/CW radio altimeter where the oscillator-frequency v. varactor bias characteristic is non-linear. A linear triangular wave is converted by means of a function generator to the non-linear wave required for varactor bias to cause linear frequency modulation of the oscillator. Linearity of modulation is tested by measuring variations in the period of a calibration signal derived from a delay line. Variations in the period of the calibration signal are measured by determining the difference between the average and the instantaneous calibration period and sampling the difference during each cycle of the triangular wave, once during the upswing thereof when the oscillator is at low frequency and once during the down swing thereof when the oscillator is at high frequency and separately integrating the up swing and down swing samples.

Abstract: An improved driving signal source for an electrical analog of a reciprocating compressor generates a variable frequency sinusoidal output. The ratio between the electrical frequency used by the analog and the mechanical frequency of the modeled compressor is controlled by a ratio set switch. Upper and lower limits of the mechanical speed are operator determined, and the electrical output frequency is varied between the corresponding upper and lower electrical analog frequencies. The instantaneous output frequency of the improved source is displayed in terms of mechanical compressor speed. The ratio of electrical to mechanical frequency can be changed independently of the upper and lower mechanical speed settings.

Abstract: A circuit for linearizing the oscillator sweep output frequency signal of a oltage controlled oscillator is disclosed. The voltage controlled oscillator is driven by the output of an op amp, which amplifies and filters the output of a D/A converter. The D/A converter responds to preselected 8-bit words, stored in an EPROM, so as to produce a desired output frequency at each memory address. The addresses, in turn, are provided by a combination of gates, counters, input signals and a clock.

Abstract: A device for producing a varying frequency sine wave synthesized so that frequency is swept linearly with time for use in a continuous transmission FM sonar. A crystal clock, divider and a 16 bit digital output sweep counter produce 2.sup.16 counts for each sweep period T.sub.s. The 2.sup.16 counts are applied to a 16 bit digital to analog converter to provide a highly linear voltage ramp (the smoothed result of 2.sup.16 steps). The ramp is converted to a proportional frequency which is applied to a 5 bit digital counter to access a read only memory programmed to provide a digital output representing points along a sine wave. The memory output is applied to a digital to analog converter to produce a voltage output that is a 32 stepped approximation of a sinewave at a frequency which increases betweeen f.sub.1 and f.sub.2 with the linearity of the ramp voltage. A filter smoothes the output.

Abstract: A yelping alarm signal generator has a current controlled audio oscillator with a feedback loop around it that produces a control current that is a direct function of the oscillation frequency so that only one capacitor external to the integrated circuits is required.