Crystal-controlled Oscillator Research Articles

TSM-AW Sensors Based on Miller XCOs for Microgravimetric Measurements in Liquid Media

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Up to now, the success of the design of quartz crystal-controlled oscillators (XCOs) based on high-stability classical configurations for uses as microgravimetric thickness-shear-mode acoustic-wave (TSM-AW) sensors in damping media has strongly depended on the ability and experience of the designer. The conditions of strong damping that quartz experiences imply the necessity to adapt the designs so that the oscillation stays in spite of the reduction of its quality factor. Despite all the efforts developed by various authors, a methodology of the design of electronic circuit oscillators for their use in damping media does not exist yet. This is due to the difficulty of the study of the oscillation condition and its possible optimization as a function of the application. In this paper, we propose a methodology to aid designers in developing TSM-AW sensors for high-resolution microgravimetrical applications in liquid media, such as detection of chemical species, biosensors for molecular recognition, etc. Approaches are presented to carry out sensor oscillators based on the Miller topology. </para>

Quartz crystal oscillator circuit for high resolution microgravimetric sensors in fluids

A simple oscillator circuit for high resolution quartz crystal microbalance sensors is proposed for fluid media. It can solve the working problems of standard crystal controlled oscillators in damping media. The design is adapted to the conditions of strong damping that the quartz experiences, so that the oscillation stays in spite of the reduction of the resonator quality factor. The conditions for obtaining a stable frequency according to the resonator damping and the static capacity are studied. Experimental results confirming the success ot the circuit are reported.

Automatic thermal frequency control of microwave oscillator with dielectric disk resonator

Microwave oscillators that are stabilized by sapphire disk resonators have good short-term relative frequency stability (σ(τ)=10−10 over averaging time τ∼1 sec) but inadequate long-term stability. This is mainly due to the high temperature coefficient of frequency of the disk resonator. An automatic frequency-control system based on thermal control of the frequency of the disk resonator was developed to improve the long-term frequency stability of the oscillators. The parameters of the automatic frequency-control system were optimized by computer, which involved solution of the nonstationary problem of the temperature distribution in the disk resonator and examination of the stability of the automatic control system for diffuse propagation of the control signal. Recommendations are given for selection of the heater geometry and frequency-control method. An oscillator with the thermal frequencecy-control system had a long-term relative frequency instability of (0.3–1)·10−8 per day, which was determined by the stability of the crystal-controlled reference oscillator. The automatic frequency-control system did not appreciably change the noise characteristics of the oscillator.

電磁界による下顎頭動態記録装置の開発 第１報 装置の概要と特性について

It is very important for clinical diagnosis to record and analyze condylar movement in cranio-mandibular disorders. Recently, many devices have been developed for this purpose. These devices can measure precisely condylar movements, but are difficult to manipulate. We have developed a simple device which substitute a palpation of the posterior aspect of the TMJ. We modified the Cardiokymograph which use electro-magnetic field. The characteristics of this device are the use of a frequency-variable crystal-controlled oscillator, and the application of the coil itself which is a part of the oscillator as a probe. We tested many electrical characteristics of this device and assured the effectiveness, that is, sensitivity, directivity, frequency response characteristic, transient response characteristic, and temperature response characteristic. We tried to insert a probe into the external auditory meatus, and record condylar movement as a positional change of the skin. It seems to suggest that our device can record a feature of condylar movement.

Simulation of the Steady-State Behavior of Crystal-Controlled Oscillators Using the WATAND Computer-Aided Design Program

The WATAND computer-aided design package has been used to successfully simulate the steady-state response of crystal-controlled oscillators. The WATAND program contains a routine that allows the steady-state response of a nonlinear dynamic circuit with slow transients to be found without the lengthy and uneconomical process of integrating in the time from t = 0. Oscillators simulated were the following: an LC oscillator with discrete components; and three crystal-controlled oscillators, one with silicon integrated circuits and two with discrete components, one having an external tank. To simulate some of these oscillator circuits, some of the algorithms in WATAND had to be modified. Suggestions for further improvements in oscillator simulation are also made.

Crystal-controlled telemetry system for long-term acquisition of physiological data.

A crystal-controlled telemetry system was developed for long-term high-reliability recording of blood pressure in unrestrained animals. The miniaturized transducer-transmitter system is powered by two lithium batteries that allow for more than 200 h of continuous recording of blood pressure before battery replacement. The total system has a flat frequency response of 0-25 Hz and a time stability of +/- 1 mmHg/day. Linearity is better than 0.5%. The high degree of dependability of the system permits us to perform continuous, unattended, around-the-clock recordings of pressure and heart rate in unrestrained animals. Very high dependability is achieved by the use of a novel piezoresistive blood pressure transducer and by the inherent stability of the crystal-controlled radio-frequency oscillator of the transmitter. The receiver is also crystal tuned to the measured transmitter frequency. This transmitter-receiver frequency locking ensures very reliable reception of the telemetered signal.

Piezoelectric devices

The history of the discovery of piezoelectricity and its application in practical devices is traced from the late 19th century. The origin of the piezoelectric effect is outlined in terms of the symmetry of the materials, and Tables are given in which the electroelastic properties are listed for single crystals, ferroelectric ceramics and polymers which show the phenomenon. The applications of both the direct and inverse piezoelectric effect are considered in devices operating at frequencies from DC to greater than 100 GHz. Particular attention is paid to signal processing using piezoelectric substrates for surface acoustic waves, and to the use of quartz in crystal-controlled oscillators, but the whole range of devices from low frequency transducers, through acoustic and ultrasonic devices to VHF filters is discussed.

Musical instrument tuner with incremental scale shift

Instant scale shifting by predetermined increments is provided in a musical instrument tuning device by means of a programmable phase locked loop and crystal-controlled oscillator combination. The incremental scale steps are extremely accurate without need for recalibration and with no change in the tone intervals.

Design of microcomputer-based data acquisition system for the time-of-flight ion scattering spectrometer

A microcomputer-based data acquisition system used on a time-of-flight ion scattering spectrometer is described. The flight time of 90°-scattered ions from target atom determined directly with a 30 MHz crystal-controlled oscillator and its associated circuit. The ion intensity is detected by a channel multiplier, and its output signal pulse is converted from the analog form into digital form by an ADC. Both flight time and ion intensity are stored in the microcomputer.

Use of transistor heavy biasing for a novel method of generation of quartz crystal overtones and mixed-frequency oscillations

A new method, involving increased dc biasing in transistor crystal-controlled oscillators has been used for generating, apart from the fundamental, overtones and mixed adjoining modes of quartz crystal oscillations.

New system for microwave Q-factor measurement

A new system has been developed for determining precisely the Q-factor of an X-band open resonator. The new system differs from previous systems in its use of an injection-locked phase-shifting technique to provide electronically a ± π/4 phase shift for Q-factor measurement. The ± π/4 phase change is produced at an i.f. frequency with a total uncertainy that is an order of magnitude lower than is possible with conventional phase shifters. The phase-shifting technique employs a crystal-controlled reference oscillator and a second oscillator whose free running frequency is close to that of the reference oscillator. The output of the second oscillator is injection-locked to the 8th harmonic of the reference-oscillator signal. A π/4 phase shift on the output of the second locked oscillator is achieved by unlocking it from one cycle of the 8th harmonic of the reference oscillator and relocking it to an adjacent cycle. The new system uses single-sideband homodyne detection. Single-sideband modulation is achieved by using the open resonator as a high-Q filter to remove all but the required sideband from the output of a double-sideband modulator. The new system incorporates the injection-locked phase-shifting technique and the homodyne detection system in a phase-locked loop to provide rapid Q-factor measurements.

The Automatic Liquid Level Monitor for Pumping Wells

The Automatic Liquid Level Monitor digitally measures and records the depth to the liquid, the time of the measurement, and the casing pressure of a well at preselected time intervals. These data are used to calculate the bottom-hole pressure to obtain the buildup and drawdown characteristics of a pumping well. Introduction Pressure measurements in producing wells have been Pressure measurements in producing wells have been performed since the early 1920's. Since that time, much performed since the early 1920's. Since that time, much has been published on the importance of pressure tests and methods of analysis in oil and gas wells. Detailed analyses of pressure buildup and drawdown tests are used primarily to determine pump efficiency, formation primarily to determine pump efficiency, formation permeability, reservoir pressure, productivity index, and permeability, reservoir pressure, productivity index, and skin factor. The bottom-hole pressure in flowing wells is relatively easy to obtain with the use of a wireline bottom-hole pressure gauge. However, it is much more difficult to obtain accurate bottom-hole pressure data on pumping wells because of the production tubing and pumping wells because of the production tubing and pump in the well. In an attempt to overcome this pump in the well. In an attempt to overcome this problem, pressure gauges have been developed that mount on problem, pressure gauges have been developed that mount on the bottom of the production tubing. The pressure then is recorded on the surface by means of a cable that is clamped to the tubing. These gauges yield accurate data, but their expense for obtaining information on only one well at a time has limited their use. Some effort also has been made to lower a wireline bottom-hole pressure gauge through the casing annulus, but this, too, generally has proved to be impractical Acoustic well sounding of the liquid level in producing wells has received wide acceptance in the field and can be used to calculate the actual bottom-hole pressure. Several different types of manually operated well sounders presently are available. Each of these devices requires the presently are available. Each of these devices requires the operator to initiate the acoustic pulse into the well casing and to interpret a resultant strip chart, which records the reflections from the tubing collars and the liquid interface. The distances between the collar reflections are measured and are used to determine the depth to the liquid level. To define the shape of a buildup curve, it is necessary to obtain a large number of soundings over a long period of time. Because of the excessive operator time period of time. Because of the excessive operator time required to obtain these readings, the manually operated sounder seldom is used in this way. The Automatic Liquid Level Monitor, developed by Mobil Research and Development Corp., overcomes this difficulty so that the liquid level during buildup and drawdown tests can be measured automatically often enough and long enough to provide an accurate measure of the shape of the bottom-hole pressure curves. This is a digital system that prints out not only the actual depth to the liquid level in feet, but also the time of the sounding and the casing pressure, These measurements are made automatically on a preselected schedule without having an operator in attendance. Description of the Automatic Liquid Level Monitor The Automatic Liquid Level Monitor uses the same method of acoustic well sounding as do the manually operated devices. However, instead of determining the liquid depth by counting tubing collars, the travel time of the acoustic pulse is measured accurately by counting the number of pulses from a very precise 1-MHz crystal-controlled oscillator. This system yields a high degree of sensitivity to the liquid movement in a well with a precision limited only by the initial calibration of the monitor and the stability of the oscillator. JPT P. 1019

Crystal-controlled pump signal source for an experimental parametric acoustic receiving array

In the Parametric Acoustic Receiving Array (PARRAY), a locally generated, high-frequency carrier (or pump) wave is modulated in the water by a low-frequency acoustic wave. The information in the low-frequency signal appears as low-level modulation side bands of the pump wave; therefore, the side-band noise of the pump-signal source is an important PARRAY system parameter. Since commercial oscillators with adequate spectral purity were not available, a program was initiated to develop a 65-kHz crystal-controlled oscillator with sufficient spectral purity for use as the pump-signal source in an experimental PARRAY. Application of state-of-the-art techniques and components has enabled the design and construction of a crystal-controlled oscillator with spectral purity previously unattainable in this frequency region. Spectral purity of this oscillator is approximately four orders of magnitude better than commercially available oscillators in the 65-kHz frequency region. Measurements performed on the oscillator show that the spectrum level side-band noise referenced to the carrier level is better than −170 dB for frequencies greater than 100 Hz away from the carrier. The oscillator design is described in detail and side-band noise test data are presented and discussed. [This research was supported by the Advanced Research Projects Agency of the Department of Defense and was monitored by the Naval Electronics Systems Command under Contract NO0039-76-C-0231.]

Electronic speed control for the analytical ultracentrifuge

An electronic speed control for the Spinco model E analytical ultracentrifuge is described. An accuracy of better than 1:104 is obtained, using digital circuits and a crystal-controlled reference oscillator. Acceleration is automatic and the circuitry is provided with several safety devices.

Transmitter for radiotelemetry of intra-arterial pressure in man.

A radiotelemetry transmitter conforming to British Governmental specifications for biomedical telemetry has been devised for either intermittent or continuous recording of intra-arterial pressure in fully ambulant subjects. A1 kHz subcarrier is frequency modulated by the pressure waveform, the subcarrier being in turn frequency modulated on to a crystal-controlled oscillator at 17·060 MHz which, after frequency multiplication, produces an output to drive an integral halfwave aerial at 102·360 MHz. The apparatus has been successfully used for monitoring for periods of 3 to 36 h.

Analysis of the frequency and sensitivity of crystal-controlled oscillators

The equations for the frequency of a crystal oscillator, and the sensitivity of frequency to the circuit parameters are here extended to consider: (1) the effects of motional capacitance, tuning capacitance, circuit capacitors, and the active element impedance; and (2) the Z-type oscillator. A precise normalized frequency difference between the frequency of oscillation and the series resonant frequency of the crystal is defined and derived for both the Y-oscillator and Z-oscillator. A precise normalized frequency difference is likewise derived for the parallel resonant frequency of the crystal. From these, the sensitivity of oscillation frequency to various parameters of the crystal and the circuit is derived. The conditions of validity and practical significance of the expressions are discussed. Experimental results obtained with the Pierce oscillator verify the applicable equations.

Measurement of the Short-Term Stability of Quartz Crystal Resonators and the Implications for Crystal Oscillator Design and Applications

A new technique is presented which makes it possible to measure the inherent short-term stability of quartz crystal resonators in a passive circuit. Comparisons with stability measurements made on crystal controlled oscillators indicate that noise in the electronics of the oscillators very seriously degrades the inherent stability of the quartz resonators for times less than 1 s. A simple model appears to describe the noise mechanism in crystal controlled oscillators and points the way to design changes which should improve their short-term stability by two orders of magnitude. Calculations are outlined which show that with this improved short-term stability it should be feasible to multiply a crystal controlled source to 1 THz and obtain a linewidth of less than 1 Hz. In many cases, this improved short-term stability should also permit a factor of 100 reduction in the length of time necessary to achieve a given level of accuracy in frequency measurements.

Crystal controlled oscillators for radiation environments

Abstract Crystal controlled oscillators have usually been designed to obtain optimum frequency stability; however, in some applications reliability in adverse operating environments is more important than frequency stability. This paper discusses some design tradeoffs between frequency stability and operational reliability as applied to oscillators used in a transient radiation environment. Experimental results have confirmed that design margins have been realized, and observed performance of crystal-controlled oscillators during exposure to transient ionizing radiation has led to new insight into the short-term effects of radiation on quartz crystals.

An ultrastable Mössbauer spectrometer using integrated circuits

An ultrastable Mössbauer spectrometer using integrated circuits has been designed and tested. The system is designed to operate at velocities up to 100 cm/sec. Frequency stabilization of the order of 1 in 105 is obtained using a crystal-controlled oscillator. With the help of an automatic gain control circuit very good amplitude stability of the drive signal is obtained. The electronic system is designed to produce a sinusoidal velocity. The drive is capable of taking reasonably heavy loads so that the drive system can be kept at room temperature and the source is mounted at one end of a long stainless steel tube which goes into a helium Dewar.

Very Long Baseline Interferometry in the Southern Hemisphere

Phase coherent interferometers with intercontinental baselines became possible because of the development of stable frequency standards. With sufficiently stable frequency standards, no connection is necessary between the two ends of an interferometer. The first VLBI experiments were conducted by a group at the University of Florida who used an intensity interferometer with independent tape recorders for observations of Jupiter. Later, they changed to a coherent system using crystal-controlled oscillators. Since then, several interferometer systems have been developed. A Canadian group developed a system using video tape recorders at each end of the interferometer. They recorded the data in analogue form and managed to bring the two tapes together and to synchronize them to an accuracy of better than a microsecond. After synchronization, the outputs were combined and fringes extracted. Their system has a bandwidth of about 4 MHz. No-one else has attempted a wide-band analogue system.