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Sweep-Frequency Sounder

NSSDCA ID: 1965-098A-01

Mission Name: Alouette 2
Principal Investigators:Mr. Donald B. Muldrew
Principal Investigators:Dr. Eldon S. Warren


The purpose of the sweep-frequency sounder experiment was to extend the Alouette 1 measurements to higher altitudes (3000 km) and to a different period of the solar cycle. The Alouette 2 sounder was also designed to provide greatly improved observations of plasma resonances. The sweep-frequency ionosonde was a radio transmitter/receiver that recorded the time delay between a transmitted and returned radio frequency pulse. A continuum of frequencies between 0.12 and 14.5 MHz were sampled once every 32 s. A multiplicity of delay times was usually observed due to birefringence of the ionosphere, nonvertical propagation, ground echoes, plasma resonances, etc. Delay time was primarily a function of distance traversed by the signal, electron density along the propagation path, and mode of propagation. The standard data form is an ionogram (graph) showing delay time (virtual distance of signal reflection from the satellite) versus frequency. Two other common forms of data were prepared from the ionograms. They are digital frequency and/or virtual height values of characteristic ionospheric features and computations of electron density profiles.

Alternate Names

  • Alouette2/Sweep-FrequencySounder
  • Sweep Frequency Sounder

Facts in Brief

Mass: 27 kg
Power (avg): 25 W

Funding Agency

  • Defence Research Board-Defence Research Telecommunications Establishme (Canada)


  • Space Physics: Ionospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Charley TaiebOther InvestigatorCentre National d'Etudes des Telecommunications
Dr. Yoshiharu OgataOther InvestigatorRadio Research Laboratory
Mr. John E. JacksonOther InvestigatorNASA Goddard Space Flight Center
Dr. Lawrence ColinOther InvestigatorNASA Ames Research Center
Dr. George Leroy NelmsOther InvestigatorDepartment of Communications/Communications Research Centre
Dr. J. H. WhittekerOther InvestigatorDepartment of Communications/Communications Research Centre
Dr. Joseph W. KingOther InvestigatorRutherford Appleton Laboratory
Dr. Ravipati RaghavaraoOther InvestigatorPhysical Research
Mr. J. F. TurnerOther InvestigatorIonospheric Prediction Service
Dr. Olav HoltOther InvestigatorAuroral Observatory
Dr. Glen E.K. LockwoodOther InvestigatorDepartment of Communications/Communications Research Centre
Dr. Eldon S. WarrenPrincipal InvestigatorDepartment of Communications/Communications Research Centre
Mr. Donald B. MuldrewPrincipal InvestigatorDepartment of Communications/Communications Research
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