Sheffield team interests

1
Sheffield team interests

• Keith Yearby, Michael Balikhin

2
Current and previous space missions

• The Sheffield team provided the DWP instrument
  for the Cluster Wave Consortium, still operating
  after almost 12 years in space.
• The DWP handles commanding and control for all
  consortium instruments, and telemetry data
  handling for all except Wideband data. The DWP is
  particularly closely involved with the operation
  of Whisper the relaxation sounder.
• The Sheffield team coordinates the operations of
  the Wave consortium.
• Similar DWP instruments were provided for the
  MARS96 ELISMA consortium and Double Star TC1
  spacecraft.
• All current instruments are based on the Inmos
  Transputer, a 16 bit micro-processor including 4
  serial links.
• The MARS96 instrument in particular exploited the
  transputer links to implement a fault tolerant
  multi-processor design.
• The Transputer itself is now obsolete, but the
  links evolved to become IEEE 1355 and then
  SpaceWire.
• The Double Star instrument added a low frequency
  direct sampling receiver (3 10 kHz, 14 bit) and
  spectrum analyser software.

3
Current instrument developments

• The receiver and analyser of the Double Star DWP
  instrument have been implemented in a Xilinx FPGA
  using several alternative architectures (Power
  PC, MicroBlaze, and LEON3). This provides around
  30x processing speed improvement over the
  transputer, for less power.
• Existing research on radiation tolerant
  programming of Xilinx FPGAs has been reviewed.
• The high rate of single event upsets in the
  configuration memory is a particular concern.
• While techniques exist to mitigate these, the
  overheads and complexity required to produce a
  dependable design mean that Actel FPGAs or ASICs
  are often preferred.
• However, for a front end processor performing
  simple repetitive tasks under the supervision of
  a main processor, the higher speed, lower power
  and reconfiguration ability of the Xilinx devices
  are a considerable advantage.
• A study has been performed on the disturbance of
  the spacecraft potential resulting from the
  operation of the relaxation sounder (Whisper) on
  Cluster.
• It should be possible to substantially reduce the
  disturbance by modifying the sounding waveform
  (cosine window plus DC offset).

4
Scientific Interests

• Observations of ducting of Chorus waves, using
  Cluster wave data, electron density and
  spacecraft potential.
• Observation of Chorus waveforms and propagation,
  using Cluster EFW internal burst data.

5
Possible Contributions to RPWI

• To attract funding the teams contribution should
  be associated with a specific scientific data
  product.
• Based on our previous experience and interests,
  we could contribute to RPWI in the following
  areas
• Control and signal processing for Mutual
  Impedance Measurements.
• Software/HDL for wave analysis.
• Direct sampling receiver.