WAVES Instrument Overview

The WAVES instrument is a joint effort of the Paris-Meudon Observatory, the University of Minnesota, and the Goddard Space Flight Center.

WAVES block diagram

WAVES block diagram

Sensors

  1. Three electric dipolar antenna systems supplied by Fairchild Space (two are coplanar, orthogonal wire dipole antennas in the spin-plane, the other a rigid spin-axis dipole)
  2. Three magnetic search coils mounted orthogonally (designed and built by the University of Iowa).

After preamplification, the sensor outputs are routed to the analysis electronics, consisting of a low frequency (DC - 10 kHz) FFT receiver, a broadband (4 kHz - 256 kHz) multi-channel analyzer designed principally to study the electron thermal noise, two dual radio receivers covering the band 20 kHz to 13.825 MHz, and a time-domain waveform sampler (sampling to 120,000/s).

The experiment is controlled by a central microprocessor (DPU) which will be used in flight to reconfigure the sensor outputs and to maximize the science return for the bit rate and power allotments that are available. A DC/DC power converter is also part of the electronics stack.

The frequency coverage is shown on the following plot:

frequency coverage

Electronics

The principal characteristics of the analysis electronics are summarized below. The spin-plane electric antennas are referred to as Ex and Ey, the axial electric antenna as Ez and the 3 search coil magnetic axes as Bx, By and Bz.

Low Frequency FFT Receiver (FFT)

Low Band

Inputs 4 of Ex, Ey, Ez, Bx, By or Bz
Frequency range 0.3 Hz - 170 Hz
No. channels 4
Sensitivity 250 microvolts (RMS)
Dynamic Range 72 dB

Mid Band

Inputs 4 of Ex, Ey, Ez, Bx, By or Bz
Frequency range 7 Hz - 3.5 kHz
No. channels 4
Sensitivity 10 microvolts (RMS)
Dynamic Range 110 dB

High Band

Inputs 2 of Ex, Ey, or Ez
Frequency range 20 Hz - 10 kHz
No. channels 2
Sensitivity 1 microvolts (RMS)
Dynamic Range 128 dB

Thermal Noise Receiver (TNR)

Inputs Ex, Ey, or Ez
Frequency range 4 kHz - 256 kHz
No. channels 32 or 16 per band (5 bands)
Bandwidth 400 Hz - 6.4 kHz
Sensitivity 7 nV/sqrt(Hz)

Radio Receiver Band 1 (RAD1)

Inputs Ex+Ez, Ez
Frequency range 20 kHz - 1,040 kHz
No. channels 256
Bandwidth 3 kHz
Sensitivity 7 nV/sqrt(Hz)

Radio Receiver Band 2 (RAD2)

Inputs Ey+Ez, Ez
Frequency range 1.075 MHz - 13.825 MHz
No. channels 256
Bandwidth 20 kHz
Sensitivity 7 nV/sqrt(Hz)

Time Domain Sampler (TDS)

Fast Sampler

Inputs 2 of Ex, Ey, or Ez
Sample rate up to 120 ksamples per second per channel
Memory 2 Mbits
Sensitivity 80 microvolts (RMS)
Dynamic Range 90 dB

Slow Sampler

Inputs 4 of Ex, Ey, Ez, Bx, By, or Bz
Sample rate up to 7.5 ksamples per second per channel
Memory 2 Mbits
Sensitivity 80 microvolts (RMS)
Dynamic Range 90 dB