USA As Represented by Secretary of the Navy

Other

Paul A Singer

Roger K Cernius

James W Bond

James L Conrath

Donald J Adrian

Don M French

Donald I Parsons

Lynn K Thomas

A visual display system provides patterns for visually aiding an operator determining the nature and noise environment of the incoming signal. A conventional signal receiver and an oscilloscope are coupled to a phase detector, a clock circuit and a frequency synthesizer. The clock circuit synchronizes the operation of the receiver, phase detector and frequency synthesizer. The phase detector includes a digital delay means for imparting a digital time delay between two signals and has two outputs connected to the X and Y deflection terminals of the oscilloscope screen for effecting a display in a lissajous form and another, third output connected to the Z terminal to vary the intensity of a part of the screen such that patterns are generated on the oscilloscope that might represent the inherent nature of the incoming signal which might include, the type of noise, the presence of doppler shift or CW interference, or drift of a component.

Visual aid for VLF MSK signals

A message expansion decoder for a communication channel includes decoder and address read-only memories (ROMs). The decoder ROM has storage locations storing fixed-length code words representing characters of messages carried by the communication channel and integers of a first set representing partial addresses of storage locations in the decoder memory of the fixed-length code words. The address ROM has storage locations storing integers of a second set representing variable-length code words which, in turn, represent the same characters as represented by the fixed-length code words. The decoder further includes a detector, counters and an adder. The detector and counters are coupled with the address ROM and receive a concatenated string of variable-length comma-free code words and identify individual variable-length code words therefrom to generate addresses of storage locations of the address ROM for addressing the same to output integers from the second set. The adder is coupled between the address and decoder ROMs and receives integers outputted from the address ROM and adds thereto integers from the first set stored in the decoder ROM to generate complete addresses of storage locations of the decoder ROM for addressing same to output fixed-length code words stored at the addressed storage locations and to output stored integers of the first set.

Message expansion decoder and decoding method for a communication channel

An apparatus provides patterns for visually aiding an operator in determig the nature and noise environment of the incoming signal. A conventional signal receiver and an oscilloscope are coupled to a pair of phase detectors, a clock circuit, a reference circuit, and a timing circuit. The clock circuit synchronizes the operation of the receiver, reference circuit, and timing circuit. The phase detectors have pair of inputs and an output with the inputs of one detector being connected to the receiver and the reference circuit, and its output is connected to the Y deflection axis of the oscilloscope screen. The inputs of the other detector are connected to the receiver and the output of the reference circuit via a preselected analog time delay, and its output is connected to the X deflection axis of the oscilloscope screen. The output of the timing circuit is connected to the Z intensity axis of the oscilloscope screen for a preselected time duration to provide the capability to vary the intensity of a part of the screen such that patterns are generated on the oscilloscope screen representing the presence of some constituents and the inherent nature of the incoming signal which might include, the type of noise, the presence of doppler shift or CW interference, or drift of a component.

Apparatus for visually aiding MSK detection and interference recognition

A message compression encoder for a communication channel carrying messages onstructed of characters from a predetermined character set includes a read-only memory (ROM) and input and output temporary storage buffers respectively connected to input address ports and output data ports of the memory. The ROM has storage locations storing comma-free code words representing characters of the character set in accordance with predetermined probabilities of occurrence in messages carried by the communication channel. The input buffer receives fixed-length code words representing characters of messages carried by the communication channel and arranges them to generate addresses of the ROM storage locations for addressing the same. The ROM is operable in response to addressing of its storage locations to output stored fixed-length comma-free code words. These stored code words contain variable-length code words representing the same characters represented by the fixed-length code words but are composed of fewer bits than compose the fixed-length code words. The output buffer receives the stored code words from the ROM and a detector connected to the output buffer separates and outputs the variable-length code words. The ROM also is operable upon addressing of a predetermined code word stored therein of outputting such code word to the input buffer to cause resetting of the buffer.

Message compression encoder and encoding method for a communication

A receiver test apparatus that injects a plurality of attenuated test sigs into a receiver under test is improved by contemporaneously injecting a test message to identify the level of the attenuation test signals so that an operator may easily identify the level at which receiver anomalies occur. The test signals and messages are programmed so that testing may be easily reproduced.

Receiver test apparatus with test message injector

A signal generator includes a pseudo-random bit generator that feeds bits three screening gates and three interconnected counters to simulate the electronic interference noise source attributed to three 400 hertz motors. The electronic interference effect includes fluctuations of frequencies to represent the slight variations in motor-generator speeds attributed to the 400 hertz motors so that a more realistic evaluation can be made on nearby communications and navigation equipments.

400 Hertz harmonic generator

A programmable time varying attenuator has a reprogrammable digital circuit or impressing an analog attenuation signal on a continuous wave noise signal. This signal is fed to the input of a receiver and since the digital circuitry can be reprogrammed with a known sequence to effect a desired analog attenuation, a receiver's performance can be monitored and evaluated when the attenuated signal or error signal is simultaneously received with information signals. A desired time relationship between the information signals and the time varying attenuating test signal or error signal is maintained since both are slaved to a common standard. The programmable time varying attenuator is programmable independent of the information signal source and, therefore, is adaptable with different sources while being a highly reliable and cost effect device for system testing.

Programmable time varying attenuator

A reliable, repeatable and stable VLF/LF atmospheric noise generator is cble of producing noise with known or given amplitude probability distributions and temporal characteristics such as pulse duration, pulse spacing, pulses per unit time and the discharge fine structure between pulses. A pseudo random noise carrier signal is multiplied in a plurality of digital-to-analog converters with the discharge envelopes created in a plurality of interconnected discharge envelope generators. The discharges are representative of cloud-to-ground discharges, intercloud discharges, the discharge rate, strokes per discharge and the discharge fine structure. All of the discharges are readily modifiable by suitably reprogramming operatively coupled memories and microprocessors in accordance with selected loading instructions.

Pseudo atmospheric noise generator having variable amplitude probability

An improved pseudo-atmospheric noise generator includes the capability for roducing noise in the VLF/LF spectrum with known amplitude probability distributions while controlling the temporal characteristics of the simulated impulses. The outputs from a number of pseudo-random bit generators are selected by a microprocessor in accordance with expected or anticipated atmospheric disturbances from a number of geographical regions. The microprocessor selected outputs are fed to a digital-to-analog converter which feeds the converted signals to a summer. An independent Gaussian noise source is coupled to the summer and the outputs from the Gaussian noise source and the digital-to-analog converter are combined to create a composite pseudo-atmospheric noise signal. The improvement also includes capability for self-testing and set up.

Pseudo-atmospheric noise generator with control of temporal

A reliable, repeatable and stable generator capable of producing noise with nown or given amplitude probability distributions up to 96 dB dynamic range, commonly found in atmospheric noise VLF/LF frequency bands. A continuous impulse noise amplitude probability distribution is digitally synthesized in a piece-wise fashion in 6 dB amplitude increments. These increments are linearly combined with a digitally generated Gaussian noise component for simulation of VLF and LF atmospheric noise.

Growing community of inventors

San Diego, CA, United States of America

Paul A Singer