US Government As Represented by the Secretary of the Army

Thomas A Barley

Gustaf J Rast, Jr

James R Ashley

Raiford L Hammond

Tony D Hodgens

Pierre M Alexander

This method can be used either as an independent radar system or as an adct to an existing radar system, after suitably modifying the existing system, and will provide a cooperative, Radio Frequency passive, identification system for either stationary or moving targets. The system uses suitable devices that will mechanically vibrate as a transponder mechanism as an attachment to stationary or moving targets. A sideband analyzer is used to identify the viberation pattern in the radar return, and therefore, identifies the target.

Cooperative passive identification system for moving or stationary

This radar system can be used as an independent entity or as an addition to n operating radar system for acquiring additional data from a radar target's returned signal that is not currently being utilized. The system is to separate the amplitude modulation and frequency modulation sidebands created by the target's surface motion or vibration into independently useable entities. The system measures near carrier AM and FM noises, together with techniques for integrating these elements into a working radar system.

Detection of vibrating target signatures

A single hybrid junction discriminator is described for operation over a wide operating frequency range. The single hybrid discriminator uses a transmission line, phase shifters and fixed short circuits in providing a resonant cavity in the discriminator element to form a device that will measure near carrier frequency modulated noise on a carrier frequency. Only a minimum exchange of circuit components is required for changed carrier frequencies. With the phase shifter located in the signal channel, operation is a direct and easy process for quadrature detection. Component arrangement is critical to the operation of the single hybrid discriminator. The single hybrid discriminator is more sensitive than either the two hybrid or one hybrid and a directional coupler type discriminator because better usage is made of the available signal power.

Single hybrid junction frequency discriminator

The resonator is formed with a primary line which is slightly less than a ltiple of a half wavelength long, a tee, and a matching stub. The primary line and the stub are adjustable to make the total length a multiple of one half wavelength. A mechanical link can be connected across the two adjustable lengths so as to maintain a total length of a multiple integral of one half wavelength.

Matched high Q, high frequency resonators

An apparatus and method for extending the frequency range of a synthesizer r signal generator upward by several orders of multiplication. The basic stability of the synthesizer or generator is maintained at the higher frequency output. The output band of frequencies from a frequency synthesizer is processed through a homodyne multiplier and multiplied. The multiplied output is coupled to a power divider. The divider output is coupled to bandpass filters allowing selection of harmonic multiples from overlapping frequency bands to be made. A low pass filter in the circuit allows reduction in harmonics and higher order frequencies.

Frequency synthesizer extending method and apparatus

Calibration technique comprises the production of a calibration signal hag a single sideband of modulation which is locked to an incoming carrier. The sideband may be on either side of the carrier and is phase adjusted to be amplitude modulated, frequency modulated or a combination of the two modulation forms.

Near carrier AM-FM calibration technique

A light pipe is used between the ground voltage and the extremely high voge end of a system whereby a pulse can be transmitted from the ground potential end to the high voltage end with safety and without distortion.

Light pipe technique for grid pulsing

It is desirable to be able to measure the FM noise spectra of signals whose arrier power is less than the minimum power level at which a direct non-amplified analyzer can operate satisfactorily. Generally a carrier less than approximately + 2 dbm would require analysis by a very low power measuring system. In the superheterodyne analyzer the discrimination process for a high frequency input signal is accomplished at a suitable intermediate frequency. A single set of discrimination equipment is utilized in the measurement of a wide carrier frequency range of input signals using relatively narrow band intermediate frequency hardware to optimize the analysis function. This provides a means for measuring frequencies from 4 GHz to 8 GHz or from 2 MHz to 2 GHz for example, with high accuracy and sensitivity, while using the same intermediate frequency hardware limited to operational bandwidths of a few MHz. A balanced phase detector, power dividers, attenuators coupled with an optimum length transmission line and balanced mixing of signal and reference signals at an IF level coupled with frequency translation provide frequency discrimination over a wide carrier frequency range.

Wide operating frequency range superheterodyne FM noise analyzer

A superheterodyne noise measuring discriminator uses an optimum length trmission line which permits near carrier frequency modulation to be measured on a carrier frequency in a broad range from approximately two megahertz to two gigahertz with one set of components. A balanced phase detector, power dividers, attenuators coupled with the optimum length transmission line and balanced mixing of signal and reference signals at an IF level provide wide frequency range discrimination. This noise measuring discriminator operates over a wide frequency range with the only component changes being an input bandpass filter, the optimum length transmission line, adjustable phase shift device, and variable frequency local oscillator. The transmission line sections are easily changed by simply selecting proper line lengths which may be previously established. The optimum length transmission line can operate over several octaves of frequency range with analyzer degradation of less than three decibels. In measuring frequency modulation noise, carrier nulling in excess of 60 decibels is accomplished. After this carrier null has been accomplished, the discriminator circuit rejects incidental amplitude modulation on the test signal.

Superheterodyne noise measuring discriminators

Measurement apparatus using an optimum length transmission line discriminr is disclosed which allows near carrier frequency modulation to be measured in the very high and ultra high frequency regions without the use of a microwave type cavity resonator or a tuned resonant circuit. Amplitude modulation rejection through direct current biasing of a quadrature detector enhances near carrier FM measurement. Signal energy is routed through two channels to the quadrature detector. A reference channel provides attenuation and phase shifting, and a signal channel comprising the optimum length line provides FM discrimination. The phase detector is direct current biased to separate amplitude modulation noise from near carrier frequency modulation noise.

Optimum length transmission line discriminator with low noise detector

An optimum length transmission line discriminator circuit is disclosed wh provides for measurement of near carrier frequency modulation in the microwave region. An optimum length of transmission line within the discriminator is instrumental in providing the discrimination function. The transmission line discriminator possesses the same basic circuit properties required to provide measurement and affords a broader range of operation than established microwave cavity methods can feasibly provide. The optimized transmission line length provides for maximum efficiency from the transmission line parameters over a wide frequency range. In measuring frequency modulation noise, carrier nulling in excess of 60 decibels is accomplished with a slide screw tuner in conjunction with the optimized length line. This null is relatively insensitive to environmental effects. After this carrier null has been accomplished, the discriminator circuit rejects incidental amplitude modulation on the test signal, and is not restricted by burnout power ratings of crystals within the phase detector.

Optimum threshold transmission line discriminator

A wide operating frequency range transmission line discriminator uses an imum length transmission line which permits near carrier frequency modulation to be measured on a carrier frequency in a broad range from approximately two megahertz to one gigahertz. A hybrid junction, balanced phase detector, power dividers, attenuators and a variable transmission line coupled with the optimum length transmission line provide a wide frequency range discriminator with only a minimum exchange in selected components being necessary for changes in carrier frequency. This near carrier analyzer operates over the wide frequency range with the only component changes being an input bandpass filter, the optimum length transmission line, and the variable length transmission line used as a variable or adjustable phase shift device. The transmission line sections are easily changed by simply selecting proper line lengths which may be previously established. When optimum detection is not essential in a particular measurement, the optimum length transmission line can effectively operate and accomplish its function over several octaves of frequency range with minimal analyzer degradation, on the order of three decibels. In measuring frequency modulation noise, carrier nulling in excess of 60 decibels is accomplished. After this carrier null has been accomplished, the discriminator circuit rejects incidental amplitude modulation on the test signal, and is not restricted by burnout power ratings of crystals within the phase detector.

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Huntsville, AL, United States of America

Thomas A Barley