POLAR Plasma Wave Investigation (PWI) SFR-Sweep Frequency Receiver-A (SFR-A) Daily Dynamic Spectrograms

The Polar Sweep Frequency Receiver-A (SFR-A) made use of either the Eu (130 m, spin-plane) or Ez (14 m, spin axis) two-sphere electric dipole antennas. Between March 25, 1996 and May 26, 1996, the Eu antenna was the default antenna, from May 27, 1996 through February 9, 1997 the Ez antenna was used and from February 10, 1997 until September 17, 1997 the SFR-A returned to using the Eu antenna. The SFR-A receiver spanned the frequency range from 26 Hz to 808 kHz in 5 bands: 26-200 Hz, 0.2 - 1.6 kHz, 1.7 - 12.6 kHz, 13-100 kHz, 100-808 kHz. Each image is a daily plot of the power spectral density (V^2 m^-2 Hz^-1) of received signal (color scale) as a function of operating frequency (in a logarithmic scale on vertical axis) and time (horizontal axis). At the top of each plot is a title indicating the Instrument, Receiver and Antenna used followed by the time span for the spectrogram. Beneath the time labels on the horizontal axis are ephemeris data: position of the spacecraft in radial distance (Earth radii), geomagnetic latitude, magnetic local time, and McIlwain L-shell. Overlaid on each image is a trace of the electron gyrofrequency.