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Wideband and Narrow-Band Step Frequency VLF Receivers

NSSDCA ID: 1964-054A-08

Mission Name: OGO 1
Principal Investigator:Prof. Robert A. Helliwell


This experiment consisted of four VLF radio receivers to be used for study of natural VLF noise occurrences at orbital altitudes. The receiver systems consisted of an inflatable 2.9-m loop antenna, a preamplifier stage at the end of a long boom, and the receiver electronics packages in the main body of the satellite. Three step-frequency receivers, covering frequency ranges of 0.2 to 1.6 kHz, 1.6 to 12.5 kHz, and 12.5 to 100 kHz, each observed a complete spectrum of 256 signal strength values once every 2.3, 18.4, or 147.2 s depending upon the selected mode of operation. Observations from these three receivers were tape recorded at 1 kbs or observed in real time at 1, 8, or 64 kbs. The tape was read out upon command at the 64 kbs rate. The other receiver was a broadband receiver observing signals from 0.3 to 12.5 kHz. These data were not tape recorded, but observed only in real time on the special purpose telemetry channel. Data from the three receivers (called PCM data) were recorded for over half the time in orbit with high bit rate usually used when the satellite was near perigee, and low bit rate near apogee. Broadband resolution depended upon the spectrum analyzer used to process the tape. This Rayspan equipment could provide up to 10-ms time resolution and up to 30 Hz frequency resolution. The broadband data were available only for relatively short portions of the satellite operating lifetime since they were received only when the satellite was scheduled to transmit within range of a telemetry station. This experiment operated nominally during the active satellite lifetime. Satellite operation was restricted to spring (approximately March, April, and May) and fall (approximately September, October, and November) due to spacecraft power supply limitations. A May 1966, Stanford Research Institute Instrument Report by L. H. Rorden et al. (TRF B01944), gives a complete description of this experiment.

Alternate Names

  • OGO1/WidebandandNarrow-BandStepFrequencyVLFReceivers

Facts in Brief

Mass: 1.7 kg
Power (avg): 0.9 W

Funding Agency

  • National Aeronautics and Space Administration (United States)


  • Space Physics: Ionospheric Studies
  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Mr. L. H. RordenOther InvestigatorDEVLCO Incorporated
Dr. Jacyntho J. AngeramiOther InvestigatorStanford University
Prof. Robert A. HelliwellPrincipal InvestigatorStanford
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