Accession Number:

ADA193324

Title:

A Notch Filter Instrument for Measuring ELF (Extremely Low Frequency) MSK (Minimum Shift Keying) Signals.

Descriptive Note:

Technical rept.,

Corporate Author:

IIT RESEARCH INST CHICAGO IL

Personal Author(s):

• Drexler, R. G.
• Gauger, J. R.

Report Date:

1988-01-01

Pagination or Media Count:

101.0

Abstract:

This report presents a notch filter technique for measuring extremely low frequency ELF signals in the presence of other higher-level, low frequency voltages, specifically 60 Hz and harmonics, on public utility systems. The report also describes the design, development, and operation of a special-purpose notch filter instrument that allows the practical realization of this measurement technique. The instrument, called the Notch Box III, is compact 2.75 x 10 x 9 in., lightweight less than 4 lb, and battery operated for complete electrical isolation and portability of its electronic circuitry. It features input buffering and selectable attenuation, input overload warning, a narrow-band 60 Hz notch filter with greater than 80 dB of attenuation, a Chebyshev low-pass filter providing sharp roll-off above 100 Hz, output signal buffering, and battery charge status indication. The Notch Box III can operate 150 hours on a single battery charge. Keywords Extremely low frequency Interference mitigation Active filter Notch filter Interference measurement Noise measurement Instrumentation.

Descriptors:

• *EXTREMELY LOW FREQUENCY
• *FREQUENCY SHIFT KEYERS
• *NOISE(RADIO)
• *ELECTROMAGNETIC WAVE FILTERS
• ATTENUATION
• CIRCUITS
• ELECTRICAL INSULATION
• ELECTRONICS
• HARMONICS
• INPUT
• INSTRUMENTATION
• INTERFERENCE
• LOW FREQUENCY
• LOW PASS FILTERS
• LOW VOLTAGE
• MEASUREMENT
• OUTPUT
• OVERLOAD
• PUBLIC UTILITIES
• SIGNALS
• WARNING SYSTEMS
• BANDSTOP FILTERS
• NARROWBAND
• TRANSFER FUNCTIONS

Subject Categories:

• Electricity and Magnetism
• Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE