PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 1998-05-01 NOTE = "DATASET.TXT contains the data set description." END_OBJECT = TEXT END Data Set Summary ================ Data Set ID: VG1-J-PRA-4-SUMM-BROWSE-48SEC-V1.0 Instrument: PRA Instrument P.I.: James W. Warwick Data Supplier: Michael L. Kaiser Data sampling rate: 48 seconds Data Set Start time: 1979-01-06T00:00:48.000Z Data Set Stop time: 1979-04-13T23:58:24.000Z Data column descriptions ------------------------ year integer_2 year past 1900 day integer_2 day of year starting at 1 (on 01 Jan) hour integer_2 hour of day starting at 0 minute integer_2 minute of hour starting at 0 second integer_2 second of minute starting at 0 (rounded to nearest sec) sc_no integer_2 spacecraft id: 1 == VG1, 2 == VG2 sc_mode integer_2 spacecraft mode (0-31) start_ch integer_2 start channel of data end_ch integer_2 end channel of data lh_data integer_140 70 2-byte data values (in millibells) for left hand polarization state for channels 131-200 in ascending channel number order rh_data integer_140 70 2-byte data values (in millibells) for right hand polarization state for channels 131-200 in ascending channel number order Data Description ================ Instrument P.I. : James W. Warwick Data Supplier : Michael L. Kaiser Data sampling rate : 48 seconds Data Set Start Time : 1979-01-06T00:00:48.000Z Data Set Stop Time : 1979-04-13T23:58:24.000Z This data set consists of edited browse data derived from an original data set obtained from the Voyager 1 Planetary Radio Astronomy (PRA) instrument in the vicinity of Jupiter. Data are provided for 70 instrument channels covering the range from 1.2 kHz to 1326 kHz in uniform 19.2 kHz steps, each 1 kHz wide. Data are included for the period 1979-01-06 00:00:48 through 1979-04-13 23:58:24. In order to produce this data set from the original raw PRA data, several steps have been taken: 1. The PRA operates in a variety of modes; data from modes in which the receiver does not scan rapidly through its frequency range have been removed; 2. The data have been calibrated as best we know how; 3. The data have been split into Left Hand Circular (LHC) and Right Hand Circular (RHC) components; 4. The data have been binned into 48-second intervals. Thus, values at a given channel are separated in time by an increment of 48 seconds; each 48-second time interval has associated with it a value for LHC polarization and one for RHC polarization. During data gaps, the entire record is absent from the data set; that is, missing records have not been zero-filled or otherwise marked. Bad data within a record is indicated by the value zero, which cannot otherwise occur. Each datum is returned as a 16-bit quantity; it represents the mean power received in the given channel at the specified time and polarization. The returned quantity is the value in mB about a reference flux density. To convert a returned quantity to flux, use the formula: flux = 7.0x10^(-22)x10^(mB/1000) W m-2 Hz-1 Parameters ---------- Data Set Parameter 'RADIO WAVE SPECTRUM' ---------------------------------------- Data Set Parameter Name : RADIO WAVE SPECTRUM Data Set Parameter Unit : MILLIBEL Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Sampling Parameter Resolution : 0.001 Sampling Parameter Interval : 48 Minimum Available Sampling Int : 12 Noise Level : 2400 A set of derived parameters consisting of power fluxes at various contiguous frequencies over a range of frequencies. Millibels may be converted to watts/m**2/Hz by using the formula for flux indicated above. Source Instrument Parameters ---------------------------- Instrument Host ID : VG1 Data Set Parameter Name : RADIO WAVE SPECTRUM Instrument Parameter Name : WAVE FLUX DENSITY ELECTRIC FIELD WAVEFORM ELECTRIC FIELD COMPONENT MAGNETIC FIELD COMPONENT WAVE ELECTRIC FIELD INTENSITY WAVE MAGNETIC FIELD INTENSITY Important Instrument Parameters : 1 (for all parameters) Confidence Level Overview ------------------------- This data set includes all the available low-rate scanning mode data for the frequency range below 1326 kHz for the time interval covered. Known bad data have been set to zero. Data which appear to exceed the Full Scale Deflection (FSD) of the instrument (i.e. the most intense signal which can be measured reliably) have also been set to a zero (should they occur). Planetary Radio Astronomy (PRA) suffers from interference from many other instruments aboard the spacecraft. No attempt had been made to remove these interferences in this data set. Two obvious examples are the 136 and 193 kHz channels which are nearly always contaminated by interference. The separation into LHC and RHC polarization components is performed on the basis of the polarization of the incoming wave as perceived by the instrument. This takes into account neither the antenna transfer function nor the spacecraft orientation with respect to the source. In general, the mapping of perceived polarization back to emitted polarization cannot be solved without a knowledge of both of these factors, as well as a knowledge of the type of polarization coming from the source region (e.g. is it linear or circularly polarized?). Most planetary emissions are circularly polarized. Below is a table showing the response of the experiment to a low frequency (100 kHz) LHC wave. The response does not change much up to about 5 MHz. The coordinate system used is: THETA == 0 is along the MAG boom; PHI == 0 is the bisector of the two PRA antennas. The third column is the apparent value of the left hand component as perceived by the receiver. That is, a value of +1.0 indicates that the incoming LHC wave is correctly detected as a pure LHC wave. A value of -1.0 will be detected as being of the correct strength, but incorrect polarity. A value of, say, 0.6 indicates that the total energy is split 60% into the apparent LHC component and 40% into the apparent RHC component.