The Plasma Wave Instrument (PWI) measured ac electric fields
over the frequency range from 1 Hz to 2 MHz, and an amplitude
range of 0.03 microvolt per meter to 100 mV per meter. Magnetic
fields were measured from 1 Hz to 400 kHz over an approximately
100-dB range.

    The objectives of this investigation were to
    measure the spatial, temporal, spectral, and wave
    characteristics (particularly the Poynting vector component
    along the magnetic field line) and the wave polarization for
    extremely-low-frequency (ELF), very-low-frequency (VLF), and
    high-frequency (HF) noise phenomena. Of special interest were
    the auroral kilometric radiation and VLF hiss, and a variety of
    electrostatic waves that may cause field-aligned acceleration of
    particles.
   
    The investigation made use of the long dipole
    antennas in the spin plane and along the Z axis, and a magnetic
    loop antenna. A single-axis search coil magnetometer and a short
    electric antenna were included for low-frequency measurements
    and electrostatic noise measurements at short wavelengths.
   
    The electronics consisted of
   
    * (1) a wideband/long baseline receiver
    with a bandwidth of 10 or 40 kHz in the range 0-2 MHz;
    * (2) a step-frequency correlator, containing two sweep-frequency
    receivers and phase detectors, sweeping 100 Hz to 400 kHz in 32
    s, and giving the phase between magnetic and electric components
    of the field;
    * (3) a low-frequency correlator containing two
    filter receivers and phase detectors (eight filters in the range
    1.78-100 Hz). The sweep rate is 8 s/spectra at the high frequency end
    (above 18 Hz); it is 32 s/spectra for frequencies for 1.8-10 Hz;
    * (4) dc monitors that measured
    the voltage difference between the two sets of long dipole
    antennas; and
    * (5) a linear wave receiver, selectable from
    1.5 to 3.0, 3 to 6, or 10 to 16 kHz bands.
   
    The wideband receiver
    was flown to transmit wideband waveform signals to the ground
    via an analog transmitter, so that detailed high-resolution
    frequency-time analysis could be performed.
   
    Since June 23, 1984
    a malfunction in the spacecraft data- handling system has
    prevented access to some PWI data. Digital measurements from the
    sweep frequency receiver system were no longer accessible.
   
    More
    details are found in S. D. Shawhan et al., Space Sci. Instrum.,
    v. 5, n. 4, p. 535, 1981.