PVO Electric Field Detector (OEFD) Data Bundle PVO Electric Field Detector (OEFD) 24 Sec. Avgs. Original Binary Data Collection Description PDS3_DATA_SET_ID = PVO-V-OEFD-4--EFIELD-24SEC-V1.0 DATA_SET_RELEASE_DATE = 1993-06-30 START_TIME = 1978-12-05T07:20:07.282 STOP_TIME = 1992-10-08T16:30:23.299 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 data are averaged over 24 second intervals on 12 second centers. Each averaging interval contains both the minimum amplitude, average amplitude and peak amplitude for that interval at each of the four frequencies. 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 amplitudes are given in V/m/root(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. The wave antenna is a small Y-shaped structure, with effective separation of 0.76 meters. The Electric field data file contains the following information: RECORD LENGTH = 56 NUMBER OF COLUMNS = 13 OPERATING SYSTEM = SUN/UNIX # NAME UNITS SOURCE DESCRIPTION 001 UT s (seconds) PVO Universal Time given in seconds since 1966-01-01T00:00:00.000 where no attempt has been made to account for leap seconds. The time stamp corresponds to the center time of a two spin period averaging window 002 E100HZMX V/m/Hz**.5 PVO EFD Maximum wave amplitude per root Hertz per 24 second interval, measured at 100 Hz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 003 E100HZAV V/m/Hz**.5 PVO EFD Average wave amplitude per root Hertz per 24 second interval, measured at 100 Hz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 004 E100HZMN V/m/Hz**.5 PVO EFD Minimum wave amplitude per root Hertz per 24 second interval, measured at 100 Hz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 005 E730HZMX V/m/Hz**.5 PVO EFD Maximum wave amplitude per root Hertz per 24 second interval, measured at 730 Hz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 006 E730HZAV V/m/Hz**.5 PVO EFD Average wave amplitude per root Hertz per 24 second interval, measured at 730 Hz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidth 007 E730HZMN V/m/Hz**.5 PVO EFD Minimum wave amplitude per root Hertz per 24 second interval, measured at 730 Hz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 008 E5.4KHZMX V/m/Hz**.5 PVO EFD Maximum wave amplitude per root Hertz per 24 second interval, measured at 5.4 kHz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 009 E5.4KHZAV V/m/Hz**.5 PVO EFD Average wave amplitude per root Hertz per 24 second interval, measured at 5.4 kHz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 010 E5.4KHZMN V/m/Hz**.5 PVO EFD Minimum wave amplitude per root Hertz per 24 second interval, measured at 5.4 kHz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 011 E30KHZMX V/m/Hz**.5 PVO EFD Maximum wave amplitude per root Hertz per 24 second interval, measured at 30 kHz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 012 E30KHZAV V/m/Hz**.5 PVO EFD Average wave amplitude per root Hertz per 24 second interval, measured at 30 kHz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths 013 E30KHZMN V/m/Hz**.5 PVO EFD Minimum wave amplitude per root Hertz per 24 second interval, measured at 30 kHz. At a particular frequency the wave electric field amplitude (V/M) is measured over the bandwidth of the filter (30% for OEFD). The square root of the bandwidth is incorporated in order to compare measurements made with this instrument with other wave measurements, which may have different bandwidths MISSING DATA FLAG = 1.000000E+32 AVERAGE INTERVAL = 00:00:24.000 An ASCII version of these data is available in the PVO Venus EFD Browse Electric-Field 24 Sec. Avgs ASCII Data Collection (urn:nasa:pds:pvo-oefd-cal:data-24s-asc) 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. The averaging scheme used can be subject to temporal aliasing when the data rate is sufficiently low, such that only one or two data are obtained per 24 second interval. Since the sampling interval and spin period are not exactly synchronized, periodic noise signals, such as the interference, are aliased by the low sampling frequency. In this case the data display periodic structure, but with a period much longer than the spin period. The instrument was calibrated in air. No attempt to incorporate changes in antenna-plasma coupling due to changes in Debye length have been included in the data processing. 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.