Radio Frequency Interference (RFI)

in San Clemente, CA

Strong (S-9) wideband "Hiss" observed on 20 meter and 17 meter amateur bands

Continuous "Hiss" from well below 14 MHz to well above 18 MHz - little variation

Always present, day and night,

Unchanged when the house circuit-breaker is switched off and receiver is battery-operated

"Hiss" is due to repeating short sinusoidal bursts

Burst Frequency about 16 MHz, Burst duration 5-6 cycles, Repeating every 8.8 microseconds

Little or no phase correlation between bursts,

giving a continuous spectrum rather than a line spectrum

Peak antenna voltage: 2-4 milliVolts - stronger than Short-Wave Broadcast Stations!

Similar (but slightly different in details) around the neighborhood - local "hot spots"

Data shown below taken with SDR-14 Software Defined Radio and SpectraVue

Click on picture for a larger image, and for more information

Single Burst, 1 microsecond record

100 microsecond record

1 millisecond record

Spectrum: 0 - 30 MHz

Vertical Scale in dB

Waterfall Spectrum: 0 - 30 MHz

Mobile Operation

What is it?

* a neighbor's household appliance ?

* from one of the utility systems (power, cable, telephone) ?

(Note: all utilities are underground, bursts unchanged when house circuit-breaker is switched off)


To Be Updated

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