Showing papers on "Frequency drift published in 1995"

Miniature optical scanner for a two axis scanning system

Abstract: A miniature optical scanner includes an electromagnetic drive having stationary magnets and stationary drive coils to minimize the rotational inertia of the scanner and increase the scanner's resonant frequency. The scanner is such that the resonant frequency is manually tunable as well as automatically adjustable to compensate for variables causing frequency drift. The optical scan angle is increased by employing a multiplying mirror with the optical scanner. For a two axis scanning system, the multiplying mirror may be formed of a second optical scanner to increase the optical scan angle relative to both of the axes.

Relating the Hadamard Variance to MCS Kalman Filter Clock Estimation

Abstract: The Global Positioning System (GPS) Master Control Station (MCS) currently makes significant use of the Allan Variance. This two-sample variance equation has proven excellent as a handy, understandable tool, both for time domain analysis of GPS cesium frequency standards, and for fine tuning the MCS's state estimation of these atomic clocks. The Allan Variance does not explicitly converge for the nose types of alpha less than or equal to minus 3 and can be greatly affected by frequency drift. Because GPS rubidium frequency standards exhibit non-trivial aging and aging noise characteristics, the basic Allan Variance analysis must be augmented in order to (a) compensate for a dynamic frequency drift, and (b) characterize two additional noise types, specifically alpha = minus 3, and alpha = minus 4. As the GPS program progresses, we will utilize a larger percentage of rubidium frequency standards than ever before. Hence, GPS rubidium clock characterization will require more attention than ever before. The three sample variance, commonly referred to as a renormalized Hadamard Variance, is unaffected by linear frequency drift, converges for alpha is greater than minus 5, and thus has utility for modeling noise in GPS rubidium frequency standards. This paper demonstrates the potential of Hadamard Variance analysis in GPS operations, and presents an equation that relates the Hadamard Variance to the MCS's Kalman filter process noises.

Subscriber frequency control system and method in point-to-multipoint RF communication system

Abstract: A point-to-multipoint star configured terrestrial radio communication system having at least one base station transmitting to and receiving RF communication signals from a plurality of associated subscriber stations in the 0.3-300 GigaHertz (GHz) range. The system includes means for reducing frequency uncertainty, drift or error of the RF transmissions from each of the subscriber stations to the base station. Each subscriber station has a low cost local reference oscillator, and the system incorporates a reference broadcast signal of high frequency precision from the base station and at each subscriber station there is means for measuring frequency error and compensating for frequency drift/error in the low-cost oscillator at the subscriber station. Moreover, the system can provide an estimate obtained from measuring each subscriber frequency drift or error in the base station and relaying the measured error to the corresponding subscriber station to compensate for that subscriber's transmitter's local oscillator be out of frequency.

Micro-receiver for receiving a high frequency frequency-modulated or phase-modulated signal

Abstract: A micro-receiver for receiving a high frequency frequency modulated or phase modulated signal, including a single integrated circuit in BiCMOS technology and on which is integrated a high frequency amplifier, an oscillator, a modulator, an intermediate frequency filter, an intermediate frequency amplifier, a demodulator, a low pass filter and a low frequency amplifier. The integrated circuit includes in addition a muting or squelch circuit, a voltage multiplier as well as a standby circuit. The circuits working in a lower frequency range are implemented in CMOS technology, and operated in a very energy-saving way with a single-cell battery with a low battery voltage of 1.3 V. The voltage multiplier provides a higher operating voltage for the circuits working in a higher frequency range. Because of the high degree of integration made possible by implementing the intermediate frequency and low frequency circuits in CMOS technology, it is possible to dispose the receiver, including a battery and earphone, in a housing which can be inserted into the external auditory canal of a person.

Power stabilized cryogenic sapphire oscillator

Abstract: Microwave oscillators of exceptional short-term stability have been realized from cryogenic sapphire resonators with loaded Q factors in excess of 10/sup 9/ at 11.9 GHz and 6 K. This has been achieved by a power stabilized loop oscillator with active Pound frequency stabilization. These oscillators have exhibited a fractional frequency stability of 3-4/spl times/10/sup -15/ for integration times from 0.3 to 100 s. The relative drift of these two oscillators over one day is a few times 10/sup -13/. To reduce the long-term drift, which is principally due to excessive room temperature sensitivity, we have added cryogenic sensors for the power and frequency stabilization servos to one of these oscillators. We have also implemented a servo to reduce the room temperature sensitivity of our phase modulators. Testing of this oscillator against a Shanghai Observatory H-maser has shown an Allan deviation of 4/spl times/10/sup -15/ from 600 to 2000 s. >

Low noise 9-GHz sapphire resonator-oscillator with thermoelectric temperature stabilization at 300 Kelvin

Abstract: The authors report on an X-band microwave oscillator incorporating a room temperature thermoelectric stabilized sapphire resonator operating at 9.00000 GHz. With a Galani type stabilization scheme they have measured a reduced single sideband phase noise of about -124 dBc/Hz at 1 kHz with a f/sup -3/ dependence. The measurement was limited by the flicker noise of the phase detector in the feedback electronics. The frequency stability was also measured; at an integration time of 0.1 seconds a /spl delta/f/f of about 10/sup -11/ with a /spl tau//sup 0.7/ dependence was measured. The frequency drift strongly correlated with ambient temperature fluctuations. >

A 3.3 volt high-frequency capacitorless electronically-tunable log-domain oscillator

Abstract: A new type of electronically tunable oscillator using a cascade of two capacitorless first order log-domain all-pass filters as the frequency and the gain controlling element is proposed, where it is shown that the log-domain circuit technique is ideally suited for implementation of electronically tunable oscillators, The resulting oscillator enjoys several attractive properties, namely, low supply voltage, high oscillation frequencies, wide tuning range and relatively large oscillation levels can be obtained without excessive distortions, as oppose to previously reported forward-biased diode based electronically tunable oscillators.

Frequency standard generator synchronized with satellite or other communication network reference clocks

Abstract: A frequency standard generator includes a voltage controlled crystal oscillator for generating high stability output signal to be used as a standard frequency signal, a satellite wave receiver which receives a radio wave from a satellite which includes a highly accurate satellite time signal and reproduces the satellite time signal to be used as a reference for the voltage controlled crystal oscillator, a frequency divider which divides the output signal of the voltage controlled crystal oscillator by a dividing ratio arranged to generate a crystal time signal which is identical in frequency to the satellite time signal, a time interval measuring circuit which measures a time interval which is a phase difference between the satellite time signal and the crystal time signal and generates a digital signal indicating the phase difference, a frequency control processor which arithmetically determines control data based on the digital signal from the time interval measuring circuit such that the phase difference maintains a constant value through an operation of a phase lock loop, and a D/A converter which converts the control data from the frequency control processor to an analog voltage which is used to control the output frequency of the voltage controlled crystal oscillator.

Frequency scanning capaciflector for capacitively determining the material properties

Abstract: A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.

Hardware arrangement and method of driving a piezoelectric transformer

Abstract: An apparatus for controlling a piezoelectric transformer is disclosed. A transformer driver (12) supplies the transformer with a driving voltage the frequency of which is controlled by a frequency oscillator (18). A load current monitor (20, 22, 24, 26) observes a load current flowing through a load such as a fluorescent which is powered by said transformer. A frequency sweep controller (16) controls the frequently oscillator, when the transformer is initially energized, so as to execute a downward frequency sweep wherein the frequency of the driving voltage is swept from a predetermined upper frequency to a predetermined lower frequency. The frequency sweep controller further controls the frequency oscillator, after the transformer has been brought into stable operation, so as to execute the downward frequency sweep when the load current reduces to a second preset level lower than the first preset level.

Frequency synthesizer with controllable loop filter

Abstract: In accordance with a loop open/close control signal, an analog switch closes or opens a loop including a voltage controlled oscillator, a variable frequency divider, a phase comparator, and a first loop filter, the analog switch, and a second loop filter. In order to reduce the change of frequency caused when the open loop state is set immediately after the output frequency is changed, the second loop filter uses a capacitor which shows properties of a small change of capacitance in response to an applied voltage and a small hysteresis. In another embodiment, the voltage controlled oscillator includes a second diode, one terminal of which is grounded, connected in reverses parallel to a first diode switch which switches the output oscillation frequency ranges of the voltage controlled oscillator.

Apparatus and method for maximizing frequency offset tracking performance in a digital receiver

Abstract: An automatic frequency control loop structure utilizes a dual selection automatic frequency control unit which is coupled to a differential phase unit and a coherent phase unit to provide a frequency corrected received signal output for efficient tracking of frequency offset drift and a much lower probability of loss of automatic frequency control loop lock. Thus, a signal from a coherent carrier recovery process provides additional benefit by utilization in adjusting frequency offset tracking performance.

Resonator-based touch-sensitive probe

Abstract: This paper presents a design of a simple low-cost resonator-based touch-sensitive probe. The design exploits the fact that when a stiff element (probe) oscillating near the resonance frequency comes into physical contact with the surface of another body (workpiece), the frequency of vibrational resonance of the probe changes depending on the latter's stiffness. This change can be detected by monitoring the variations in the phase shift between the probe driving force and the resulting strain, which consequently prompts the trigger signal. Standard phase-lock-loop oscillator circuitry is used to adjust the drive frequency to maintain a pre-set phase difference between the input and output signals, thus ensuring that the oscillator remains locked at the probe resonance frequency as contact takes place. A prototype probe has been designed and tested. The probe is excited to resonate at its fundamental frequency by employing piezoelectric drive and pick-up arrangements. The operating frequency of the probe is set at 25.179 kHz (second-mode frequency), which seems to be an adequate choice for excellent static and dynamic characteristics. The shift in the natural frequency as the contact force progresses follows a non-linear trend before it saturates. The maximum frequency shift measured is about 2 kHz, which corresponds to 140 mN contact force in the axial direction, whilst the minimum detectable trigger force is 3.8 mN.

Satellite receiver system having doppler frequency shift tracking

Abstract: A satellite receiver system (400) provides acquisition and frequency tracking of a Doppler-shifted radio signal received from an orbiting satellite. The satellite receiver system (400) includes a Costas phase-lock loop (100) that receives the radio signal and provides an error signal at an error signal output (134) for controlling a conversion frequency generated by a voltage controlled oscillator (200). The voltage controlled oscillator (200) is coupled to the Costas phase-lock loop (100) and generates the conversion frequency for down-converting the radio signal in the Costas phase-lock loop (100). The satellite receiver system (400) further includes a Doppler frequency acquisition and tracking element (300) coupled to the voltage controlled oscillator (200). The Doppler frequency acquisition and tracking element (300) adjusts the conversion frequency to compensate for a Doppler frequency shift occuring in the radio signal due to orbital motion of the orbiting satellite.

Random carrier frequency modulation of PWM waveforms to ease EMC problems in switched mode power supplies

Abstract: Electromagnetic compatibility (EMC) remains an issue which can present many problems to designers of high frequency power converter circuits. Usual techniques for alleviating the problems of interference generation by power converters involve the use of screening materials and filters. However, the effectiveness of such measures depends on the frequency of the interference and the power density at each frequency of interest. As pulse width modulation (PWM) generates high frequency harmonics at multiples of the switching frequency, modulation of the switching frequency may be used to spread the spectral power density present at these harmonic frequencies. This paper presents a technique of frequency-hopping spread-spectrum modulation which may be applied to switched-mode power converters to reduce the spectral power density at harmonics of the switching frequency. The influence of the peak frequency deviation and the modulation sequence length on the resultant spectrum are discussed. These predictions have been broadly confirmed in practice. >

System with automatic compensation for aging and temperature of a crystal oscillator

Abstract: A method and an apparatus for compensating for aging and temperature of the crystal in a crystal oscillator. An RF signal which is transmitted by a mobile telephone switching office (MTSO) (108) and received by the antenna (118). The signal transmitted by the MTSO (108) serves as an external reference. A crystal-controlled main oscillator/time base generator (134) provides a local reference frequency to the converters (120) and provides a time base signal to a counter (136). A controller (112) reads an aging correction value from a memory and provides a frequency control signal to the main oscillator (134). The converters (120) convert the received RF signal to an IF frequency. A limiter (122) provides a limited IF signal to the counter (136). Counter (136) counts the number of cycles of the limited IF signal that appear in a cycle of the time base signal. A controller (112) compares this measured count to a reference count and the count error is determined. The count error is compared to an allowable count error. If the count error is excessive then the controller (112) adjusts the frequency control signal provided to the main oscillator (134) so as to change the frequency of the main oscillator (134). Once the controller (112) has shifted the frequency so that the count error is not excessive then the controller (112) stores the new aging correction value. The measured count is therefore depends upon the frequency of the main oscillator (134) and the frequency of the received signal. This process automatically compensates for the frequency of the main oscillator (134) and, therefore, for aging of the crystal. The frequency of oscillation of the main oscillator (134) is therefore as accurate as the external reference, typically the highly accurate MTSO (108). A high precision oscillator (134) has thus been obtained using an external reference (MTSO 108) and an aging correction value.

Method and circuit for creating frequencies for a radio telephone

Abstract: In the frequency synthesizer described in the present invention, the stable transmission frequency required by the digital operating mode is created from a frequency produced by a free running oscillator and which includes frequency errors. A local frequency (f1) and an intermediate frequency (fIF) including frequency errors are input to a mixer (105) located in the signal path of the transmitter. A transmission frequency transmission signal (fTX) is input to a phase-lock loop with a voltage-controlled oscillator (103) that produces the local frequency (f1). Thereby the frequency error caused by the intermediate frequency (fIF) can be corrected with the local frequency (f1) by adjusting the voltage-controlled oscillator (103) of the loop with a voltage (VD) that is proportional to the phase difference between the transmission frequency signal and a reference signal (VREF) input to a phase comparator. This is implemented by connecting the mixer (105) to the loop during the transmission time period with a controllable switch (104), for example. The local frequency (f1) of the receiver is produced with the frequency synthesizer described in the present invention by disconnecting the mixer (105) from the loop. The invention can be applied in producing frequencies for radio telephones that include dual-mode operating modes and exclusively digital operating modes.

Frequency stabilized laser diode

Abstract: A laser diode has its frequency locked to the frequency of an absorption line of rubidium (water and oxides of nitrogen are also disclosed). The level of absorption, and hence the frequency relationship of the laser light with respect to the absorption line is detected by a photodetector. The absolute frequency of the laser light is guaranteed by initially adjusting the temperature of the diode until the frequency of the light is brought into coincidence with a first absorption line, subsequently maintaining the temperature at a constant level, and adjusting the drive current of the diode until the frequency of laser light achieves coincidence with an adjacent transition line. This ensures that the diode frequency is locked to the same absorption line each occasion the diode is switched on. Additionally, the change in drive current between coincidence with the two adjacent absorption lines is monitored as a further check that the correct transition line has been selected. An error signal for a current servo, which drives the diode, is generated from the photodetector output. An oscillating magnetic field, causing cyclic Zeeman splitting of the absorption lines, and hence cyclic modulation of their frequency, causes a corresponding modulation in the photodetector output. Successive half cycles of the photodetector output are integrated and subtracted from each other in order to generate the error signal; the sign of the error signal thus being indicative of the direction of frequency drift in the laser light.

Multiple crystal non-linear frequency conversion apparatus

Abstract: A non-linear frequency conversion device is tunable over a wide tuning range. An input source provides a first input beam with a frequency μl. A first frequency conversion crystal has an input beam face that is cut at a phase matching angle υ1 and is positioned on a first stage at a stage angle α1. The first frequency conversion crystal provides frequency conversion of the input beam of frequency μ1 to a selected frequency μ2 of a first portion of the selected tuning range. A second frequency conversion crystal has an input beam face that is cut at a phase matching angle υ2 and is positioned on a second stage at a stage angle α2. The second frequency conversion crystal provides frequency conversion of the input beam from a frequency μ1 to a selected frequency μ3 of a second portion of the selected tuning range. Only one of the frequency conversion crystals provides frequency conversion in the range for a particular input wavelength while the other crystal is inactive, and serves as a beam displacement compensator. The non-linear frequency conversion device can be used for second harmonic generation, sum frequency mixing, difference frequency mixing, or optical parametric generation.

Satellite radio receiver

Abstract: A satellite radio receiver obtains signals from a satellite receiving installation comprising one or more frequency converters which may, for example, undergo a frequency drift as a result of temperature variations which cannot be compensated for by an AFC circuit which is located in the satellite radio receiver and which controls a carrier oscillator for carrier regeneration in a demodulator circuit. A local oscillator for a mixer is designed as a PLL local oscillator (44) which can be tuned in large or small increments. The AFC circuit (1) and a synchronizing signal evaluation circuit (40) are coupled to a control circuit (34) so that the PLL local oscillator (44) is tuned: 1) outside the control range of the AFC circuit (1), with a large tuning increment in the case of undetected synchronizing signals, and 2) with a small tuning increment in the case of detected synchronizing signals, until the control range of the AFC circuit (1) is reached. The satellite radio receiver is suitable for connection to satellite receiving installations which comprise a plurality of frequency converters and therefore deviate the nominal receiving frequency in a summary fashion, and for private individual installations which, for economic reasons, possess low frequency stability.

Time correction of an electronic clock.

Abstract: An electronic clock comprises a usual oscillator (4) and a more accurate oscillator (1). The usual oscillator (4) generates a first frequency (Fx) which causes the electronic clock to operate and the more accurate oscillator (1) generates a second frequency (Fo) which is used as a reference frequency. Referring to the second frequency, the first frequency (Fx) is measured by a frequency measurement circuit (3) and a deviation (D) of the first frequency from a design frequency (F D ) is calculated by a processor (6). According to the deviation, time correction of the electronic clock is performed. Therefore, even if an actual oscillation frequency of the usual oscillator (4) is not stable precisely, the accurate time correction can be achieved.

Ring oscillator with frequency control loop

Abstract: An oscillator system (12) and method in which a time period (inverse of frequency) of a multi-stage ring oscillator (ROSC) (16) is adjusted by a bias current (I-BIAS) which controls the charging and discharging times of respective capacitors (e.g., interelectrode capacities) (70, 329) within each stage (60, 300). The time periods of the unadjusted oscillator are counted along with the time periods of a reference clock (46) over a same period of time and a count difference between the two counts is determined. The count difference is applied by a logic circuit in accordance with an algorithm (Tables I and II) relating count differences to incremental bias current levels to adjust the frequency of the oscillator. The logic circuit generates digital gate signals (SP1X to SP8X, SM1X to SM8X) corresponding to the count difference and these signals automatically select the bias current level needed to bring the oscillator frequency into close agreement with the reference clock frequency. The digital gate signals are stored in a non-volatile memory (24) so that the oscillator will continue to operate at the adjusted frequency (i.e., that of the reference clock) even if the reference clock is no longer present and power is temporarily removed. The oscillator system is well suited for implementation by complementary metal oxide semiconductor (CMOS) technology as part of an integrated circuit (IC).

Digital radio system capable of high-speed frequency changing at low power consumption

Abstract: The output frequency of a PLL frequency synthesizer and the output frequency of a fixed oscillator are mixed together in a mixer to produce sum and difference frequencies. The sum frequency is used as a local frequency, and the difference frequency is fed back to the PLL frequency synthesizer. In addition, the output frequency of the fixed oscillator is divided in a predetermined ratio to use it as a local frequency for the second or other subsequent frequency converting stage on the receiver or transmitter side.

Wide frequency range VCO with low jitter

Abstract: Each starved-inverter of a voltage controlled ring oscillator has an output transfer gate associated therewith. The pair of complementary switches composing a transfer gate being controlled in common with the relative current generators of the starved-inverter stage, by a frequency control voltage and by a voltage difference between a supply voltage and the control voltage, respectively. The frequency produced by the oscillator is linearly proportional to the control voltage and inversely proportional to the square root of the supply voltage, for an enhanced noise immunity and improved frequency stability.

Method for driving actuator and ink-jet recording apparatus

Abstract: PROBLEM TO BE SOLVED: To displace an actuator at a speed higher than the intrinsic frequency of the basic mode of the actuator while controlling ringing and overshoot. SOLUTION: During a time shorter than 30μs which is the intrinsic frequency of the basic (primary) mode which is the first oscillation mode of a piezoelectric oscillator, after the addition of a pulse wave form 30 consisting of the rise and fall of voltage, the voltage is again raised. A time from the first voltage rise PO to voltage fall P1 and a time from the voltage fall P1 to the second voltage rise P2 are about 6μs, which is about a half of the intrinsic frequency of the secondary mode to be the second oscillation mode of the piezoelectric oscillator.

Voltage controlled oscillator with improved tuning linearity

Abstract: The object of the invention is a voltage controlled oscillator with improved tuning linearity, which comprises an oscillating transistor (T, 1), a resonator circuit (C11, C12, 11, 12, 19, 20) formed by a capacitance diode (D, 20) and an inductance (L1, 19), whereby the resonator circuit is connected to one of the transistor's (T, 1) electrodes and defines together with the transistor's internal capacitance and external capacitances the oscillator output frequency provided by the transistor. The output frequency can be changed with an external control voltage (V cntrl ) supplied to the cathode of the capacitance diode (D, 20), the control voltage having minimum and maximum values, whereby the oscillator output frequency (f vco ) is arranged to change within a certain frequency band in accordance with the control voltage (V cntrl ). The resonance circuit (RES) is arranged at the current draining electrode (collector) of the transistor to have an effect on the linearity between the control voltage (V cntrl ) and the output frequency (f vco ). The resonance circuit according to the invention provides an approximately linear tuning sensitivity also at low control voltages.

Wide bandwidth loop in a frequency shift keying (FSK) system

Abstract: A digital frequency shift keying (FSK) transmitter provides direct frequency modulation in a wide bandwidth loop. In one embodiment, a discriminator circuit recovers from the output signal of the transmitter a base band signal, which is then compared with the input base band signal to provide an error signal for controlling the output oscillator circuit. In another embodiment, the output oscillator is controlled by a phase detector detecting the phase difference between the base band modulating signal and the output signal of the transmitter. An additional narrow bandwidth loop can be added to compensate for frequency drift in the output oscillator due to temperature or other environmental changes.

Automatic frequency control device for tuning an intermediate frequency signal to a target frequency

Abstract: In an automatic frequency control device for tuning the frequency of an intermediate frequency (IF) signal to a desired or target frequency, a frequency mixer subtracts the frequency of a received signal coming in through an antenna from the frequency of a local oscillation signal output from a voltage controlled oscillator. A reference oscillator outputs a reference oscillation signal on the basis of a control voltage from a digital/analog converter. The local oscillation signal from the voltage controlled oscillator is synchronous in phase to the reference oscillation signal. A frequency measurement circuit measures the frequency of the IF signal. A subtracter subtracts the frequency of the IF signal from the target frequency and thereby produces a frequency error. A multiplier multiplies the frequency error by, in a proportional relation between the frequency of the IF signal and a voltage represented by a control voltage signal, the reciprocal of a gradient of the voltage of the control voltage signal to the frequency of the IF signal. An adder adds the control voltage signal to the output of the multiplier, thereby correcting the control voltage signal. The digital/analog converter converts the control voltage signal to an analog signal and thereby outputs the control voltage.

Temperature-compensated piezoelectric oscillator

Abstract: A temperature-compensated piezoelectric oscillator includes a voltage-controlled piezoelectric oscillator, a first frequency divider, a second frequency divider, and a controller. The voltage-controlled piezoelectric oscillator has an output frequency controlled by a control voltage and oscillates the output frequency having a center frequency f 0 at an ambient temperature of t 0 . The first frequency divider frequency-divides the output frequency from the voltage-controlled piezoelectric oscillator by N to output a first divided output frequency. The second frequency divider frequency-divides the output frequency from the voltage-controlled piezoelectric oscillator by M to output a second divided output frequency. The controller controls the control voltage to be applied to the voltage-controlled piezoelectric oscillator on the basis of a frequency difference between the first and second divided output frequencies upon a variation in ambient temperature of t 0 to keep the output frequency of the voltage-controlled piezoelectric oscillator at the center frequency f 0 .

Advanced technology oscillator for small spacecraft

Abstract: A small, low-mass, ultrastable oscillator with excellent frequency stability (1/spl times/10/sup -13/ at 100 s) is being developed for use in small spacecraft. The very nature of a small spacecraft places a very high premium on mass, size, and power of all instruments. Therefore, the primary task of this design was to reduce by 50% the mass and size of a flight-proven ultrastable oscillator design without seriously degrading the oscillator's frequency stability or immunity to environmental stress-a very challenging design problem. The mass of key components of an oscillator fabricated to test new design ideas was reduced by over 78%. A series of tests, including vibration testing, met or exceeded our expectations. On the basis of the results of the vibration tests, a vibration isolation system will not be used for this oscillator. A second thrust of this development is to optimize the oscillator electronics. Phase noise has been improved by 6 dBc to -159 dBc 1 kHz from the carrier. An oscillator configured to permit easy circuit changes is being used for this work. With the data and knowledge gained from this development, the probability of fulfilling the design goals are very high.