Pseudo-atmospheric noise generator with control of temporal characteristics

• US 4,375,620 A
• Filed: 12/15/1980
• Issued: 03/01/1983
• Est. Priority Date: 12/15/1980
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Singer, Paul A., Cernius, Roger K.
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US06/216,715
• Time in Patent Office: 806 Days
• Field of Search: 331/78, 364/717
• US Class Current: 331/78
• CPC Class Codes: H03K 3/84 Generating pulses having a predetermined statistical distribution of a parameter, e.g. random pulse generators

Abstract

An improved pseudo-atmospheric noise generator includes the capability forroducing 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.

Claims

1. An improved pseudo-atmospheric noise generator for producing noise in the VLF/LF spectrum with known amplitude probability distributions while controlling the temporal characteristics of the impulses comprising:

a plurality of pseudo-random bit generators having amplitude probability distribution outputs;

means coupled to receive the outputs from the pseudo-random bit generators for storing and selecting the outputs from the pseudo-random bit generators;

means coupled to the storing and selecting means for providing distribution of bursts of pulses representative of geographical temporal probability distributions for regional storms;

means coupled to the distribution providing means for converting digital pulses to analog signals of the random amplitude and distribution as determined by the distribution providing means;

a Gaussian noise source; and

means coupled to the analog signal converting means and the Gaussian noise source for summing the Gaussian noise signals and the analog signals in a selective ratio to provide the desired pseudo-random atmospheric noise signal.

2. An improved pseudo-atmospheric noise generator according to claim 1 in which the distribution providing means is a microprocessor suitably interconnected to provide bursts of pulses representative of geographical temporal probability distributions for regional storms.

3. An improved pseudo-atmospheric noise generator according to claim 2 in which the summing means includes a pair of summing resistors selected to adjust the relative amplitudes of the output of the converting means and the output of the Gaussian noise source.

4. An improved pseudo-atmospheric noise generator according to claim 2 in which the summing means further includes a resistor ladder receiving the Gaussian noise signals and coupled to an adjustable analog multiplexer coupled to the analog signal converting means.

5. An improved pseudo-atmospheric noise generator according to claim 4 in which the magnitude of the output of the analog multiplexer is selected under control of the microprocessor.

6. An improved pseudo-atmospheric noise generator according to claim 2 in which the pseudo-random bit generators are driven by a common clock oscillator.

7. An improved pseudo-atmospheric noise generator according to claim 5 in which the pseudo-random bit generators are driven by a common clock oscillator.

8. An improved pseudo-atmospheric noise generator according to claim 6 in which the storing and selecting means is a buffer/multiplexer unit and the converting means is a digital-to-analog converter and the Gaussian noise source is a pseudo-random bit generator.

9. An improved pseudo-atmospheric noise generator according to claim 5 in which the storing and selecting means is a buffer/multiplexer unit and the converting means is a digital-to-analog converter and the Gaussian noise source is a pseudo-random bit generator.

10. A method of creating a reference noise level signal for test purposes comprising:

attenuating a predetermined Gaussian noise pattern at a preselected amplitude;

passing the attenuated Gaussian noise pattern through a low pass filter and a wide dynamic range amplifier; and

feeding the resultant signal through a bandpass filter having a known equivalent noise band width so that the Gaussian noise then establishes for the user a simulated atmospheric noise RMS level.