Showing papers on "Signal published in 1969"

Transyt: a traffic network study tool

Abstract: THE "TRANSYT" COMPUTER PROGRAM IS DESCRIBED FOR DERIVING OPTIMUM FIXED TIME SIGNAL PLANS. THE MAJOR FEATURES OF TRAFFIC FLOW IN A SIGNAL NETWORK ARE REPRESENTED BUT THE METHOD OF CALCULATION IS SUCH THAT THE SOLUTION TIME IS SHORT. A "HILLCLIMB" TYPE OF OPTIMISATION IS USED WHICH GIVES GOOD CONVERGENCY ON THE OPTIMAL SIGNAL SETTINGS./RRL/

Adaptive digital communication system

Abstract: An adaptive digital multiplexer including a multiplex format computer, a time slot generator, and a combiner. The format computer determines the number of time slots required within a time frame and assigns input signals to time slots according to the information rate and priority of each input signal. Assignments are made such that transmission of lower priority input signals are interleaved between transmission of higher priority signals thereby allowing the multiplexed output to be adapted to a reduced transmission rate of increased bit duration by progressively eliminating transmission of lower priority signals.

Pulse compression by means of linear-period modulation

Abstract: In applications where large time-bandwidth products and high target speeds combine, linear FM pulse-compression systems used in radar or sonar suffer considerable losses in performance. This paper deals with the problem of wide-band signal optimizintion for the purpose of minimizing signal degradation resulting from Doppler distortion effects. The equation for the instantaneous frequency of a Doppler-transformed signal is derived. The optimum frequency-modulation law is then shown to be the linear period modulation (it can be with equal rights called hyperbolic frequency modulation or logarithmic phase modulation). It is interesting to note that some kinds of bats use this type of signal in their "sonar." Exact and approximate expressions for the spectrum of a linear-period-modulated rectangular pulse are given, and the shape of the compressed output pulse is considered. Signal degradation due to Doppler distortion is shown to be negligible in the case of linear-period-modulation pulses. The influence of pulse envelope on the compressed signal waveform is discussed, and envelope-optimization examples are presented. A possibility for active generation of the optimum signal is mentioned. Significant properties of linear FM and linear-period-modulation pulse compression systems are compared.

Implantable bio-data monitoring method and apparatus

Abstract: A system for monitoring a condition of a body function or organ or device implanted within a body includes a sensor or transducer responsive to that condition or a change in it connected to a signal means capable of producing an audible, visual or heat signal of variable intensity indication to control the energization of the signal means from a source of energy. The sensor and signal means and the source of energy may be implanted within the body with the signal means sufficiently near the surface of the skin so that its energized state may be detected from outside the body.

Multiplexing system for selection of notes and voices in an electronic musical instrument

Abstract: In an electric organ, the actuation of keys in accordance with corresponding, audible tones to be reproduced effects the gating of pulses into time slots of a time division multiplex signal, the time slots of the multiplex signal being structured in accordance with a desired assignment sequence to correspond to the keys and to be representative thereof for identifying each note capable of being generated by the organ. A set of note, or tone, generators with availability assignment control means for capturing a pulse in the multiplex signal are each rendered responsive to a given captured pulse for generating the tone represented by that pulse. A second multiplex system having time slot pulse assignments additionally provides for generation of a time division multiplex signal for control of voices and other characteristics to be imparted to the reproduced tones.

The intrinsic dimensionality of signal collections

Abstract: In view of the trend toward the representation of signals as physical observables characterized by vectors in an abstract signal space, rather than as time or frequency functions, it is desirable that dimensionality be defined in a manner independent of the choice of basis on which the vectors are projected. The intrinsic dimensionality of a collection of signals is defined to be equal to the number of free parameters required in a hypothetical signal generator capable of producing a close approximation to each signal in the collection. Thus defined, the dimensionality becomes a relationship between the vectors representing the signals. This relationship need not be a linear one and does not depend on the basis onto which the vectors are projected in the signal-measuring process. A digital computer program for estimating this dimensionality from the signal coefficients on an arbitrary basis has been developed. The program makes use of some results obtained from a multi-dimensional scaling problem in experimental psychology and utilizes an inverse relationship between the variance in interpoint distances within a hypersphere and the dimensionality of the hypersphere. Using this method, the results are believed to be independent of the choice of orthogonal basis, and no prior knowledge of the analytical form of the signals is assumed. The validity of the program is tested and verified by using it to estimate the dimensionality of signals of known structure.

Fast response stepped-wave switching power converter circuit

Abstract: To obtain fast response to a cyclical AC or variable DC input reference signal by a stepped-wave power converter circuit comprising a plurality of equal or unequal inverter modules connected in series or parallel so that the module output voltages add algebraically, the composite instantaneous output stepped-wave voltage is compared with the instantaneous voltage values of the limits of a control band placed about the reference signal. One or more inverter modules are switched to produce a step change whenever the composite output voltage is outside the control band limits. An application is a fast response switching power amplifier for driving sonar transducers.

Process for fabricating a panel array of electromechanical light valves

Abstract: Electromechanical light valves in a panel array are fabricated by a process including several metal patterning steps. Each light valve consists of a housing having grounded conducting walls for shielding the interior thereof from external electrostatic forces produced by surrounding valves in the array or from other external electrostatic forces. These walls are formed in a series of processing steps on a light transparent substrate coated with a conductive coating. Light from a source enters one end of the housing through a light transparent substrate to which is mounted an electrostatically controlled leaf shutter for each valve also formed in a series of processing steps. Upon completion of the processing for forming the individual leaf shutters on the one transparent substrate and the valve housings on the other transparent substrate, the two transparent panels are aligned to form an array of electromechanical light valves. The display state of the individual light valves may be modulated by a video signal in a system that makes use of the capacitance of the individual valve as a storage device for transforming the video signal, which is available only during a writing time of short duration to a display signal. Necessary components for each of the light valves required in a display duration modulation system are fabricated in the process for producing the light valve array.

On the output spectrum of unlocked driven oscillators

Abstract: A method is given to determine the components of the signal of an unlocked driven oscillator. The phase modulation signal, which perturbs the free oscillation, is expanded in a Fourier series.

Surface vehicle fleet command and control system

Abstract: A system for communicating with and locating mobile surface vehicles in a high multipath signal clutter environment such as an urban center. This system seeks to take advantage of the scattering of the CW wave in urban areas for both communication and ranging where line of sight radiation techniques may not properly function. A plurality of remote relay stations are located at fixed points throughout the urban area. Each station receives and transmits wireless coded digital data and tone burst signals, the tone burst signals being used for phase ranging. Additionally, each of the surface vehicles is equipped with a transponder. The vehicle transponder is responsive only to a radio signal having a formatted message. This includes the vehicle identification code and a ranging tone suitably impressed thereon. The formatted signal is transmitted from one of the relay stations and picked up by a preselected number of other relay stations as well as the vehicle transponder. The transponder in turn generates a reply signal containing message data and a tone burst signal in phase with the original transmitted signal.

A new electric field controlled reflective optical storage effect in mixed liquid crystal systems

Abstract: A new electric field controlled reflective optical storage effect has been discovered in mixed nematic-cholesteric liquid crystal systems. Ion motion produced by a dc electric field is used to emulsify the initially transparent mixture and give it a milky white appearance. This state remains after the dc signal is removed. The material can be returned to its initial state by applying an audio-frequency signal. The reflective contrast ratio of 7 to 1, flat construction, low voltage and power writing capability, and storage with continuous readout requiring no maintaining power make the new effect seem attractive for indicator-type applications using solid state addressing circuitry.

Method of and means for gainranging amplification

Abstract: A gain-ranging amplifier is disclosed comprising a plurality of fixed gain amplifier stages connected in cascade and means for taking the output signal from any one of the fixed gain amplifier stages. Control means are described whereby such output signal is taken from the amplifier stage immediately preceding the first such stage which is being overdriven at a particular point in time by the signal which is being amplified. Specific circuits are disclosed for use in seismic geophysical exploration applications and means for generating a signal representative of the amount of gain utilized in amplifying the input signal and for monitoring the input signal are described.

Vehicle location by a signal attenuation method

Abstract: A method of vehicle location is discussed in which the attenuation of the signal from a mobile transmitter is measured. A test system and procedure for obtaining data is described. A series of curves are developed which specify the anticipated error for a four-station grid. The signal strength measurements could be very tedious and time consuming, but a system was devised that makes it possible to automate the procedure. This system, called the signal amplitude sampler and totalization unit (SASTU), is fully described.

Automotive multiplex system

Abstract: A multiplex system for controlling and sensing various component parts such as head lights, engine temperature, fuel level, and turn signal lights is disclosed. The system employs a single twowire cable to communicate both power and signals between such components and a central control and metering console which may be the instrument dash console. Time multiplex is employed using a reverse polarity for clock pulses from that of the information pulses. Both analog and digital data may be accommodated by using pulse-width modulation as well as bi-level modulation. Receiving units employ a N delay one-shot triggered by the clock pulse and an AND circuit driven by the output of the N delay one-shot and the signal present on the single signal wire, to drive a one-shot which controls a switching device. Similar circuitry is employed for the digital transmitting and the analog transmitter and receiver. A socket input unit for tapping into the single cable in parallel to other input units by employing a piercing plug is disclosed.

Field effect transistor switch, particularly for multiplexing

Abstract: In a device for multiplexing plural analog signals, a high impedance switch, wherein the conduction state of a first field effect transistor is controlled by a second field effect transistor, is provided for expeditious switching of an input signal and minimal loading of an input source

Method to control dosage of additive into treatment process and automatic device therefor

Abstract: A METHOD FOR CONTROLLING, BY A NOVEL FEEDFORWARD-FEEDBACK ADAPTIVE SYSTEM, A CONTINUOUS PROCESS OF TREATING A FLUID, CONTAINING AN INGRIEDENT, THAT INCLUDES INCORPORATING A DOSAGE OF ADDITIVE IN THE FLOWING FLUID SO AS TO CHANGE THE INGRIDIENT. DURING THE OPERATION OF THE PROCESS, WITHOUT THE USE OF THE CONTROL METHOD, THERE CAN BE UNPREDICTABLE VARIATIONS AFFECTING THE EFFICIENCY OF THE TREATMENT SO AS TO REQUIRE CORRECTION OF THE DOSAGE OF ADDITIVE TO AN UNPREDICTABLE EXTENT. A DEVICE FOR THIS SYTEM PROVIDES FOR AUTOMATIC CONTROL OF DOSAGE OF THE ADDITIVE. IN THE PROCESS THERE IS A NONLINER RELATIONSHIP BETWEEN THE AMOUNT OF ADDITIVE AND THE DEGREE OF TREATMENT. THIS RELATIONSHIP CAN BE EXPRESSED AS A MONOTONIC CURVE WITHIN THE RANGE OF CONCENTRATION OF THE INGREDIENT IN THE FLUID AND THE RANGE OF DOSAGE REQUIRED FOR THE DESIRED EXTENT OF TREATMENT. THE CONTROL METHOD COMPRISES: A FEEDFORWARD CONTROL PROCESS INCLUDING (1) MONITORING THE FLOWING FLUID TO SENSE A PROPERTY OF THE FLUID RELEVANT TO THE TREATMENT OF THE FLUID BY THE ADDITIVE, AND (2) GENERATING A FIRST SIGNAL PROPORTIONAL TO THE MAGNITUDE OF THE SENSED PROPERTY OF THE FLUID TO BE TREATED, A FEEDBACK CONTROL PROCESS INCLUDING (1) MONITORING A PRODUCT OF THE TREATMENT PROCESS TO SENSE A PROPERTY OF THAT PRODUCT RELEVANT TO THE DESIRED RESULT OF THE TREATMENT PROCESS, (2) GENERATING A SECOND SIGNAL PROPORTIONAL TO THE DESIRED MAGNITUDE OF THE SENSED PROPERTY OF THE PRODUCT, (3) GENERATING A THIRD SIGNAL PROPORTIONAL TO THE MAGNITUDE OF THE ACTUAL SENSED PROPERTY OF THE PRODUCT, AND (4) COMPARING THE SECOND AND THIRD SIGNALS TO PROVIDE AN ERROR SIGNAL INDICATING THE DIFFERENCE BETWEEN THE ACTUAL AND DESIRED SENSED PROPERTY OF THE PRODUCT, AN ADAPTIVE CONTROL PROCESS INCLUDING (1) SUPERIMPOSING THE FIRST SIGNAL ON THE ERROR SIGNAL BY DIVIDING THE LATTER BY THE FORMER TO PROVIDE A FOURTH SIGNAL, (2) INTEGRATING THE FOURTH SIGNAL OVER A LONG PERIOD OF TIME TO PROVIDE A FIFTH SIGNAL, AND (3) MULTIPLYING THE FIRST SIGNAL BY THE FIFTH SIGNAL TO OBTAIN A SIXTH SIGNAL THAT INCLUDES THE VARIABLE GAIN FOR THE FIRST SIGNAL BY THE EXTENT OF THE FIFTH SIGNAL, AND USING THE SIXTH SIGNAL TO ADJUST THE DOSAGE OF ADDITIVE INTO THE FLUID. THE DEVICE FOR AUTOMATICALLY CONTROLLING THE DOSAGE OF ADDITIVE PERFORMS THE THREE BASIC CONTROL FUNCTIONS DESCRIBED ABOVE FOR THE PROCESS. THUS THE PART OF THE DEVICE THAT PROVIDES A SIGNAL REPRESENTING A COMPARISON OF ACTUAL AND DESIRED PROPERTY OF A PRODUCT OF THE TREATMENT IS THE FEEDBACK SYSTEM THAT IS USED TO ADJUST DOSAGE WITH THE ADJUSTMENT TIME BEING MADE THROUGH AN INTERGRATOR TO REDUCE THE STEADY STATE ERROR TO ZERO. THE SIGNAL PROPORTIONAL TO THE MAGNITUDE OF THE PROPERTY OF THE FLUID TO BE TREATED IS THE FEEDFORWARD SIGNAL THAT PROVIDES ESSENTIALLY INSTANTANEOUS CORRECTIVE RESPONSE WHILE THE OTHER SYSTEM IS VERY SLOW. THE CONTROL OF THE FEEDFORWARD SYSTEM TO CHANGE WITH VARIATION IN ONE OR MORE PROCESS CONDITIONS, E.G., EFFICIENCY, IS DETERMINED BY THE FEEDBACK SYSTEM THAT ADJUSTS THE GAIN OF THE FEEDFORWARD SYSTEM.

Quadrasonic sound system

Abstract: A stereophonic sound system is disclosed utilizing a two-channel transmission path yet capable of locating virtual sound sources at any point on a circle around a listener. The two-channel transmission path may consist of conventional stereophonic channels such as records, tapes, broadcasting channels, etc. The recording or transmitting means (as the case may be) of the invention provides two audio signals which may comprise preselected combinations of four (for example) directional inputs. One channel may include the first input plus a signal proportional to the sum of the second and fourth inputs, while the second channel consists of the third input plus a signal proportional to the difference between the second and fourth inputs. The sound reproducing means couples these signals and various combinations thereof to four (for example) loudspeakers which may be arranged on the circumference of a circle around the listener. The first speaker may be responsive to the signal on one channel, the next adjacent speaker is responsive to the sum of the signals on the two channels, the third successive speaker is responsive to the second channel, and the last speaker is responsive to the difference between the signals on the two channels. Means are disclosed for controlling the gain in the signal paths of the voltages coupled to the various speakers relative to the other speakers to increase the audio separation between adjacent speakers and thus enhance the directional effect.

Digital memory area correlation tracker

Abstract: A digital tracker which provides a continuous display of the area tracked mprising a delay line coupled in circuit with a comparator, a video digitizer and a sensor. The digital tracker further comprises circuit means connected between the delay line and the sensor for deriving an error correction signal in response to any mismatch between the present, delayed video scene and the reference scene, stored in the delay line. A staircase raster generator which can be positively synchronized with the delay line through the use of a common master clock is used as the sensor and the delay line is a shift register which enables any desired bit of the stored signal to be available for use at any time.

Multimode cardiac paces with p-wave and r-wave sensing means

Abstract: A cardiac pacer including a pulse generator having an R-C circuit for controlling the generation of stimulating pulses. An electrode surgically placed on or in the ventricle of the heart is coupled to the output of the pulse generator. A reference or indifferent electrode is subcutaneously implanted and coupled to the pacer circuits. When no cardiac electrical activity exists stimulating pulses are provided at a preset rate. The ventricular electrode is coupled to the input of a first signal responsive circuit and to the pulse generator. In response to ventricular electrical signals of either polarity, for example R-waves, the first signal responsive circuit resets the R-C circuit in the pulse generator to a predetermined level inhibiting the subsequent generation of impulses for a suitable time such as one second. Another electrode surgically placed on or in the atrium of the heart is coupled to the input of a second signal responsive circuit which includes timing means and which is connected in controlling relation to the pulse generator. In response to atrial electrical signals, known as P-waves, and in the absence of ventricular electrical signals, the second signal responsive circuit causes the pulse generator to provide time-delayed stimulating pulses synchronized with the atrial beats.

Apparatus for stimulating muscles controlled by the same muscles

Abstract: Apparatus for stimulating a muscle, using an E.M.G. signal sensed in the muscle, is described. The signal sensed is amplified, filtered and rectified before being applied to a monostable circuit which, if the E.M.G. signal is greater than a threshold value, enters its quasi-stable state. A stimulator circuit applies a voltage to electrodes adjacent to the muscle while the monostable circuit is in its quasi-stable state but the apparatus reverts to its sensing mode when the monostable circuit is in its stable state, allowing the E.M.G. signal to initiate further stimulation, if required. The apparatus is particularly useful in overcoming incontinence.

Interference cancellation system

Abstract: This invention relates to radio communication systems and more particularly to systems for minimizing or eliminating interference in radio receivers. The invention is more particularly directed towards the elimination of interference in radio receivers from strong adjacent transmitters having signal levels several orders of magnitude stronger than the wanted signal. This system includes means for sampling the unwanted or interference signal and linearly processing it to develop a signal that is related to the incoming signal as a relatively time invariant ratio. The system includes means for adding the derived signal to the received signal to effectively cancel the interference signal.

Biological cell analyzing system

Abstract: A biological cell analyzing system which is capable of automatically categorizing unstained biological cells as normal or non-normal. The cells are made to flow through a transparent tube in single file and are scanned with a mixture of ultra-violet and visible light. The cytoplasm and nucleus of each cell absorb ultra-violet radiation to different degrees, and the emergent light signal, as modulated by the scanned cells, is detected, amplified, and extended to a data processor which logically analyzes the signal from each cell on a real-time basis. The visible light signal is subtracted from the ultra-violet light signal to improve the signal/noise ratio of the latter, and to automatically cancel out non-biological debris. A number of acceptance tests are electronically performed on each cell, and if any of the tests is failed the cell is categorized as non-normal. Ambiguous conditions, resulting for example from the clumping of cells, are identified and separately counted. The system can process up to several thousand cells from a single sample during a one-minute run.

Skid control system

Abstract: A control system and force motor assembly for controlling the skidding of a vehicle under braked conditions when the control system provides a signal for controlling the position of an armature or fluid pressure controlling device in one of three conditions; the first condition being the ''''dump'''' mode of operation when the force motor is controlled to preclude braking pressure from being supplied to the wheels of the vehicle, the ''''hold'''' mode of operation when the braking force presented at the time the system goes into the ''''hold'''' mode of operation is maintained, and the ''''return'''' mode of operation when full applied braking pressure is returned to the vehicle wheels The control system is effectively responsive to a critical slip signal, the signal being generated in response to a sensed difference between a hypothetical vehicle deceleration, as approximated by a decreasing ramp signal, and the vehicle wheel speed This comparison is made on a differential basis to provide an output signal which is utilized in controlling an output gate The gate is also responsive to the sensing of a positive wheel acceleration signal and a change in sign of the rate of change of wheel acceleration The signal from the output gate is fed to an output logic circuit, the output logic circuit also being rendered responsive to the first derivative of the wheel velocity signal and a combination of first and second derivative of the wheel velocity signal The output signals are utilized in the output logic circuit to generate one of three signal conditions across the solenoid coil of the force motor actuator assembly In the return mode of operation, the polarity of the output signals generated across the solenoid coil are of the same polarity to cause zero current to flow through the solenoid coil In the dump mode of operation, the coil is provided with current flow in a first direction and in the hold mode of operation the solenoid coil is supplied with current flowing in a second direction opposite to the first direction The force motor is fabricated with a three positioned armature which is adapted to be placed either in the return or deactuated position, where no signals are provided from the control circuit; a dump mode of operation which connects the manually actuated brake cylinder hydraulically to the wheel cylinders to provide full braking pressure; and the hold position which maintains the pressure being fed to the wheels at the time the hold position is achieved

Inertial/doppler-satellite navigation system

Abstract: Terrestrial navigation apparatus for a vehicle includes a system of inertial sensors generating signals representative of the position and velocity of the vehicle, a data processor, and a receiver for receiving data from a doppler satellite system including a signal of known frequency as well as signals representative of the satellite''s position. The difference between the doppler frequency shift computed from the information received from the satellite and the doppler frequency shift computed by the inertial system is modeled as an observable in a Kalman filter programmed into the data processor to generate a set of error signals representative of estimates of the errors in the position and velocity signals generated by the inertial sensors. The error estimate signals are then used to correct the errors in the inertial sensors. In one disclosed embodiment, the external, observed parameter is a discrete frequency; whereas in an alternative system, it is a frequency count.

Radiant energy inspection system for rotating objects

Abstract: Radiant energy inspection system for rotating objects including means for directing parallel light beams tangentially along diametrically opposite surface locations of the object, each beam being partially intercepted in accordance with the radial displacements of the object surface relative to the beams. Geometric qualities of the object are determined by producing signals representing the unintercepted beam portions and comparing the signals with one another in a predetermined algebraic frame of reference. Eccentricity is indicated by inphase signal variations while surface irregularities are indicated by phase shifted signal variations. Diameter is indicated by the algebraic difference between the signals.

Recording medium responsive to force fields and apparatus for recording and reproducing signals on the medium

Abstract: A recording medium is shown which is responsive to a magnetic or an electrostatic field for recording an input signal thereon having a continuous web of an encapsulating or entrapping material containing a suspension of highly reflective flakes. Exposure to a magnetic or an electrostatic field reorients the preoriented flakes to provide a contrast between the exposed portions of the recording medium and the unexposed portions thereof.

Laser recording system with both surface defect and data error checking

Abstract: A laser data recording system for storing digital information in the form of digital bits ablated from an energy-absorbing storage medium by an intensity modulated laser beam. The system provides instantaneous reflective readout of the local surface state of the storage medium as the ablative recording process is initiated at selected locations along a scan line, in response to the intensity of the modulated laser beam. This reflective readout simultaneously provides a recording surface continuity verification signal which is monitored to insure that the storage medium surface is free from defects at the point of recording. The proper sequence of levels of this instantaneous reflective signal verifies that the portions of the data record which are to be ablated are actually generated, and that the regions which are not to be ablated are void-free, thus insuring a completely correct recording. The laser beam is scanned in parallel scan lines across the storage surface and during read-out of stored information the intensity of the laser beam is set at a fixed level sufficiently low that ablation cannot occur. Signals are also provided for automatically centering the laser beam on selected scan line and for servo control of laser intensity. In one embodiment removable and replaceable recording strips are mounted around the surface of the drum. A rectangular cross-section is optically imparted to the laser beam.

Apparatus for providing the pilot values of characteristics of an asynchronous three phase machine

Abstract: Multipliers produce a signal having a magnitude proportional to the sum of the squares of the rotary flux vectors and the induced three phase voltage vector of an asynchronous three phase machine by first producing signals having instantaneous magnitudes proportional to flux components of voltages induced in two winding axes spaced from each other by 120*. The multipliers multiply each signal magnitude by itself as well as by the other. The resultant products are then algebraically added.

Method and apparatus for measuring the damping characteristics of a structure

Abstract: APPARATUS FOR MEASURING THE DAMPING CHARACTERICS OF A STRUCTURE OR SYSTEM DURING EXCITATION BY RANDOM FORCES OR INFLUENCES. THE "RANDOMDEC" APPARATUS IS COMPRISED OF AT LEAST TWO PARALLEL SAMPLING CIRCUITS WHICH PERFORM TIME SEQENTIAL SAMPLING OPERATIONS ON PREDETERMINED PORTIONS OF A GIVEN INPUT SIGNAL. THE CORRESPONDING OUTPUTS OF EACH SAMPLING CIRCUIT ARE THAN ADDED TOGETHER AT A PLURALITY OF OUTPUT TERMINALS. FROM EACH OUTPUT TERMINAL A SAMPLING TRANSIENT INDICATIVE OF A POINT ON THE DAMPING CHARACTERISTIC OF THE STRUCTURE CAN BE OBTAINED. IN ACCORDANCE WITH THE INVENTION, A SYSTEM IS ALSO DISCLOSED UTILIZING THIS APPARATUS TO PROVIDE AN ONTHE-LINE DAMPING RATIO AND PERIOD DETECTION AND DISPLAY APPARATUS INCLUDING MEANS FOR INSTANTANEOUSLY OBSERVING THE DAMPING CHARACTERISTICS OF THE MONITORED STRUCTURE AND PROVIDING AN OUTPUT CONTROL SIGNAL WHICH CAN BE USED TO INFLUENCE THE CHARACTERISTICS OF THE STRUCTURE OR THE FORCES APPLIED THERETO IN A SELECTED MANNER.