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- The Wide Band Data instrumentation (WBD) on the Cluster-II spacecraft is part
of the WEC consortium of wave experiments and consists of a digital wideband
receiver which can provide electric or magnetic field waveforms over a wide
range of frequencies up to 577 kHz.
The wideband technique involves transmitting band-limited waveforms directly to
the ground using a high-rate data link. The primary advantage of this approach
is that continuous waveforms are available for detailed high-resolution
frequency-time analysis.
The instrument processes signals from one of four sensors which can be chosen
via command. The four selectable inputs consist of two electric antennas (Ey,
Ez) provided by the EFW investigation, and two magnetic search coils (Bx , By )
provided by the STAFF investigation. Primarily, WBD will utilise the electric
antennas.
The input frequency range of the wideband receiver can be shifted by a
frequency converter to any one of four ranges (0, 125 ,250, or 500 kHz), where
the conversion frequency determines the lower edge of the frequency range to be
received.
The bandwidth of the WBD instrument's output waveform is determined by one of
three bandpass filters (9.5, 19, or 77 kHz) selected in combination with a
given output mode. The output waveform is sampled by an 8-bit
analogue-to-digital converter which provides the sampling resolution and data
output rates listed in Table 33. For sample rates where the bit rate exceeds
the spacecraft telemetry data rate (220 kbit/s), the digitised wideband data
are buffered by the format generator and read out at a reduced average bit rate
of 220 kbits/sec. The format generator organises the digitised waveform data
into a 1096-byte output frame, which includes appropriate timing and status
information.
The WBD instrument utilises two separate telemetry acquisition modes for
transferring frames of digitised data to the spacecraft data handling system.
The primary mode (TDA 8) supports real-time acquisition of WBD data by the NASA
DSN. The second data mode (TDA 5.2) supports burst data acquisition through the
WEC DWP onto an onboard Solid State Recorder. In this second mode, DWP reduces
the WBD data rate (and bandwidth) by a factor of 3 via digital filtering.
The WBD instruments were designed and built at The University of Iowa through
funding provided by NASA's Goddard Space Flight Center.
See:
http://www-pw.physics.uiowa.edu/plasma-wave/istp/cluster/
Group: Instrument_Details
Entry_ID: WBD
Group: Instrument_Identification
Instrument_Category: Solar/Space Observing Instruments
Instrument_Class: Magnetic Field/Electric Field Instruments
Short_Name: WBD
Long_Name: Wide Band Data Instrument
End_Group
Group: Associated_Platforms
Short_Name: CLUSTER-II
End_Group
Online_Resource: http://www-pw.physics.uiowa.edu/plasma-wave/istp/cluster/
Sample_Image: http://sci.esa.int/science-e-media/img/36/hires_36662.JPG
Group: Instrument_Logistics
Data_Rate: 73 kbps
Instrument_Start_Date: 2000-07-16
Instrument_Owner: University of Iowa
End_Group
End_Group
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