Magnetic Field/Electric Field Instruments
type: Concept

WBD
in scheme: instruments
definition: 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 b…
type: Concept