PVO Electric Field Detector (OEFD) Data Bundle PVO Electric Field Detector (OEFD) High-Res. ASCII Data Collection Description PDS3_DATA_SET_ID = PVO-V-OEFD-3--EFIELD-HIRES-V1.0 DATA_SET_RELEASE_DATE = 1993-06-30 START_TIME = 1978-12-05T07:20:07.282 STOP_TIME = 1992-10-08T16:30:37.204 PRODUCER_FULL_NAME = DR. FREDERICK SCARF, DR. ROBERT STRANGEWAY, MURIEL KNIFFIN Collection Overview =================== This data collection contains wave electric field amplitudes measured at four different frequencies by the Pioneer Venus Orbiter Electric Field Detector. The four frequencies are 100 Hz, 730 Hz, 5.4 kHz, 30 kHz. The frequency filters are narrow-band, with a 30% bandwidth. Thus wave intensities are given in V2/m2/Hz. The filters are continuously active, but data are only provided at a rate determined by the spacecraft telemetry rate. The wave antenna is oriented perpendicular to the spacecraft spin axis, and so the wave instrument measures only wave fields in the spacecraft spin plane. Spin modulation of naturally occurring signals can be used to obtain two dimensional wave field information. The wave antenna is a small Y-shaped structure, with effective separation of 0.76 meters. The spin phase of the effective dipole is included within the high resolution data collection for each of the channels, which are sampled at different times. The Electric field data file contains the following information: RECORD LENGTH = 121 NUMBER OF COLUMNS = 9 OPERATING SYSTEM = SUN/UNIX # NAME UNITS SOURCE DESCRIPTION 001 UT SECONDS PVO Universal Time given in PDS format: yyyy-mm-ddThh:mm:ss.sss 002 E100HZ (V/m)**2/Hz PVO EFD Wave intensity per Hertz, measured at 100 Hz. The wave intensity is the square of the wave electric field amplitude. At a particular frequency the wave intensity (V/M)^2 is measured over the bandwidth of the filter (30% bandwidth for OEFD). The bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 003 E730HZ (V/m)**2/Hz PVO EFD Wave intensity per Hertz, measured at 730 Hz. The wave intensity is the square of the wave electric field amplitude. At a particular frequency the wave intensity (V/M)^2 is measured over the bandwidth of the filter (30% bandwidth for OEFD). The bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 004 E5.4KHZ (V/m)**2/Hz PVO EFD Wave intensity per Hertz, measured at 5.4 kHz. The wave intensity is the square of the wave electric field amplitude. At a particular frequency the wave intensity (V/M)^2 is measured over the bandwidth of the filter (30% bandwidth for OEFD). The bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 005 E30KHZ (V/m)**2/Hz PVO EFD Wave intensity per Hertz, measured at 30 kHz. The wave intensity is the square of the wave electric field amplitude. At a particular frequency the wave intensity (V/M)^2 is measured over the bandwidth of the filter (30% bandwidth for OEFD). The bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 006 E100_PH deg PVO EFD PHASE Instantaneous phase angle with respect to the sun of the wave instrument dipole axis for the 100 Hz channel. The antenna dipole is 267.5 degrees behind the sun-sensor (i.e., the spacecraft must rotate through 267.5 degrees after the sun pulse time for the dipole axis to be aligned with the sun). The phase angle is corrected for differences between the record time tag and the actual sample time within a data frame 007 E730_PH deg PVO EFD PHASE Instantaneous phase angle with respect to the sun of the wave instrument dipole axis for the 730 Hz channel. The antenna dipole is 267.5 degrees behind the sun-sensor (i.e., the spacecraft must rotate through 267.5 degrees after the sun pulse time for the dipole axis to be aligned with the sun). The phase angle is corrected for differences between the record time tag and the actual sample time within a data frame 008 E5.4K_PH deg PVO EFD PHASE Instantaneous phase angle with respect to the sun of the wave instrument dipole axis for the 5.4 kHz channel. The antenna dipole is 267.5 degrees behind the sun-sensor (i.e., the spacecraft must rotate through 267.5 degrees after the sun pulse time for the dipole axis to be aligned with the sun). The phase angle is corrected for differences between the record time tag and the actual sample time within a data frame 009 E30K_PH deg PVO EFD PHASE Instantaneous phase angle with respect to the sun of the wave instrument dipole axis for the 30 kHz channel. The antenna dipole is 267.5 degrees behind the sun-sensor (i.e., the spacecraft must rotate through 267.5 degrees after the sun pulse time for the dipole axis to be aligned with the sun). The phase angle is corrected for differences between the record time tag and the actual sample time within a data frame MISSING DATA FLAG = 999.999 AVERAGE INTERVAL = HIGH RESOLUTION A binary version of these data is available in the PVO Electric-Field Spacecraft Position Derived Coords. High-Res. Original Binary Data Collection (urn:nasa:pds:pvo-oefd-cal:data- highres-bin) The following additional ancillary data are also available: The engineering data collections contain engineering data from the OMAG instrument, PVO spacecraft, and Supplemental Experimenter Data Records (SEDR, which provide spacecraft ephemeris and orientation information). These data collections contain instrument sensor temperature and mode information, and spacecraft downlink and spin rate information. There are both ASCII and binary versions of these data which are located in the following collections: PVO OMAG/OEFD Engineering ASCII Data Collection (urn:nasa:pds:pvo-omag-oefd-anc:data-eng-asc) PVO OMAG/OEFD Engineering Binary Data Collection (urn:nasa:pds:pvo-omag-oefd-anc:data-eng-bin) The phase and offset data collections contain OEFD modulation phase and offset and OMAG sensor offset and corrections. There are both ASCII and binary versions of these data which are located in the following collections: PVO OMAG/OEFD Phase and Offset ASCII Data Collection (urn:nasa:pds:pvo-omag-oefd-anc:data- phaseoff-asc) PVO OMAG/OEFD Phase and Offset Binary Data Collection (urn:nasa:pds:pvo-omag-oefd-anc:data- phaseoff-bin) The OMAG Instrument Status data collections contain data which may be used to assess the quality of the OMAG science data. There are both ASCII and binary versions of these data which are located in the following collections: PVO OMAG Instrument Status ASCII Data Collection (urn:nasa:pds:pvo-omag-cal:data-anc- inststat-asc) PVO OMAG Instrument Status Binary Data Collection (urn:nasa:pds:pvo-omag-cal:data-anc- inststat-bin) Confidence Level Overview ========================= The instrument noise level (and hence sensitivity) is determined by the ambient environment at the time of observation. Photo-electrons emitted from various spacecraft surfaces appear to be a strong source of electric field interference. As a consequence data acquired when the spacecraft is in sunlight often are contaminated by spin modulated interference, especially when the spacecraft is in the low density solar wind, where the Debye length is several meters. The noise is usually lowest when the antenna elements are in the spacecraft shadow. The noise level is also reduced when the spacecraft is deep within the dayside ionosphere, where the Debye length is much smaller than the antenna size. The noise is not present when the spacecraft is within the optical shadow of the planet. In this case, however, additional noise features are observed (mainly at 100 Hz) when the spacecraft is at low altitude within the nightside ionosphere. This interference is readily discriminated in the high resolution data, where the noise is present as a sharp pulse occurring twice per spin. References ========== Scarf, F.L., W.W.L. Taylor, and I.M. Green, 'Plasma waves near Venus: Initial observations', Science, vol. 203, p.748, 1979. Taylor, W.W.L., F.L. Scarf, C.T. Russell, and L.H. Brace, 'Evidence for lightning on Venus', Nature, vol. 279, p.614, 1979. Taylor, W.W.L, F.L. Scarf, C.T. Russell, and L.H. Brace, 'Absorption of whistler mode waves in the ionosphere of Venus', Science, vol. 205, p. 112, 1979 Scarf, F.L., W.W.L. Taylor, and P.F. Virobik, 'The Pioneer Venus Orbiter Plasma Investigation', Ieee Trans. Geoscience and Remote Sensing, Volume GE-18 Number 1, p. 36, 1980. Scarf, F.L., W.W.L. Taylor, and C.T. Russell, and L.H. Brace, 'Lightning on Venus:Orbiter detection of whistler signals, J. Geophys. Res., vol. 85, p. 8158, 1980. Scarf, F.L., W.W.L. Taylor, and C.T. Russell, and R.C. Elphic, 'Pioneer Venus plasma wave observations: The solar wind - Venus interaction', J. Geophys. Res., vol. 85, p. 7599, 1980. Scarf, F.L., and C.T. Russell, 'Lightning measurements from the Pioneer Venus Orbiter, Geophys. Res. Lett., vol. 10, p.1192, 1983. C.T. Russell, 'Venus Lightning', Space Science Review, vol. 55, p. 317, 1991. R.J. Strangeway, 'Plasma waves at Venus', Space Science Review, vol. 55, p.317, 1991.