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Instrument: PASSIVE IONOSPHERIC MONITOR : Passive Ionospheric Monitor (SSI/P)
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Associated Platforms
DMSP 5D-1/F4
DMSP 5D-1/F2

Related Data Sets
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[Source: National Space Science Data Center, ]

The instrument consisted of a high-frequency radio receiver connected to a short antenna that swept from 1.3 to 13.9 MHz in 100-kHz steps. The device was used to monitor the ionospheric breakthrough frequency of noise generated by manmade or natural sources below the f2 layer to obtain the critical frequency of this layer (fof2). The fof2 parameter was used in constructing electron-density profiles used in forecasting the state of the ionosphere. The instrument could detect electric fields down to 10 microvolts/m.

Online Resources

Instrument Logistics
Instrument Owner: United States Air Force