Data Set Summary ================ Data Set ID: ULY-J-URAP-4-SUMM-PFR-AVG-E-10MIN-V1.0 Instrument: URAP Plasma Frequency Receiver (PFR) Instrument P.I.: Robert J. MacDowall Data Supplier: Roger Hess Data sampling rate: 10 minutes Data Set Start time: 1991-11-26T00:00:00.000Z Data Set Stop time: 1992-06-07T23:50:00.000Z Naming convention ----------------- Data files in this data set are named according to the convention: Tyyddd.TAB where yy = the last two digits of the year ('92' for 1992) ddd = the day of the year covered by the file Record format ------------- These files can be read according to the FORTRAN format statement: '(a24,2x,2i1,16(1x,1pe9.2))' where 'a24' is the time stamp in PDS format: yyyy-mm-ddThh:mm:ss.sssZ. The individual elements of the time field can be read according to the statement: '(i4,4(1x,i2),1x,f6.3,1x)' year, month, day, hour, minute, seconds. thus a record may be alternatively be read according to the format: '(i4,4(1x,i2),1x,f6.3,3x,2i1,16(1x,1pe9.2))' Data column descriptions ------------------------ time a24 spacecraft event time mode i1 PFR scan mode: 1: Fast mode. 2: Slow mode. 3: Fixed frequency mode. This value should not occur as fixed frequency data is removed from the UDS data. 4: The mode switched from fast to slow or slow to fast during the averaging interval. 5: Unknown mode. This value occurs if there was no valid data during the averaging interval. This could be due to a data gap or bad data. Data acquired while the PFR is in fixed tune mode is ignored so this value for the MODE will also occur if the PFR was in fixed tune mode during the entire averaging interval. bps i1 Telemetry bit rate: 1: 128 bps. 2: 256 bps. 3: 512 bps. 4: 1024 bps. 5: Bit rate changed during averaging period. 6: Bit rate unknown. pfr avg e-field -- 16 1pe9.2 format Plasma Frequency Receiver (PFR) electric field intensities from the 16 PFR frequency channels. These values represent the average intensities over the sampling interval. The center frequency for each channel is given below: F(1): 0.61 kHz F(2): 0.80 kHz F(3): 1.04 kHz F(4): 1.35 kHz F(5): 1.77 kHz F(6): 2.30 kHz F(7): 3.01 kHz F(8): 3.92 kHz F(9): 5.11 kHz F(10): 6.67 kHz F(11): 8.70 kHz F(12): 11.34 kHz F(13): 14.79 kHz F(14): 19.30 kHz F(15): 25.16 kHz F(16): 32.82 kHz Missing data flag value ----------------------- Any data column whose value is -9.99e+10 is a missing data value. Data Description ================ GUIDE TO THE ARCHIVING OF ULYSSES RADIO AND PLASMA WAVE DATA Roger Hess, Robert MacDowall, Denise Lengyel-Frey March 15, 1995 Contents 1 Introduction 3 2 Delivery Schedule 3 3 Description of the Unified Radio and Plasma Wave Instrument 4 3.2 Plasma Frequency Receiver 5 4 World Wide Web Access to URAP Data 7 APPENDICES 8 A UDS data files 8 A.2 Plasma Frequency Receiver 11 1 Introduction The Unified Radio and Plasma wave instrument (URAP) is designed to detect both remotely-generated electromagnetic waves and in-situ plasma waves. The former are radio waves arising from electron beams in the solar wind (type II and type III radio bursts), planetary radio emissions (from Jupiter, the Earth, etc.), and a cosmic background from the local galactic medium. The in-situ waves include thermal plasma fluctuations, electron plasma oscillations (Langmuir waves), ion-acoustic waves, and whistler-mode waves. Wave electric fields from less than 1 Hz to 940 kHz and magnetic fields from less than 1 Hz to 448 Hz can be measured. An extensive description of the five instruments that make up the URAP investigation can be found in [STONEETAL1992A]. Details relevant to the data archive are contained below. The Astron. Astrophys. Suppl. Ser. issue also contains other articles describing the Ulysses spacecraft as a whole and the other Ulysses instruments. Ulysses is spun for stability with a period of approximately 12 sec. The Z axis of the spacecraft is defined as being along the spin axis. The X and Y axes are perpendicular to the spin axis. URAP measures electric field by means of two antennas. One is a dipole formed by two 35 meter long wires along the +/- X axes and the other is a 7.5 meter long monopole that is on the Z axis Because of the longer length of the X antenna compared to the Z antenna, it is much more sensitive and has a much lower background signal level. For these reasons, only the X antenna data are provided in the UDS data files. Magnetic fields are measured by means of a two axis sensor aligned along the spacecraft Y and Z axes. 2 Delivery Schedule The URAP team will provide the archival data products to the Ulysses Data System no later than 2 months after GSFC has received the raw data. These data will be provided to the NSSDC no later than 1 year after GSFC has received the raw data. 3 Description of the Unified Radio and Plasma Wave Instrument The Unified Radio and Plasma Wave instrument on Ulysses is divided into several sub-instruments. Data from three of these sub-instruments, the Radio Astronomy Receiver, the Plasma Frequency Receiver, and the Wave Form Analyzer, are represented in the URAP archival data. 3.2 Plasma Frequency Receiver The Plasma Frequency Receiver (PFR) is intended to monitor a wide spectrum of plasma phenomena with constant frequency coverage, large dynamic range, and good frequency resolution. Two receivers for Ex and Ez are supplied with a frequency range from 0.57 to 35 kHz that is covered in 32 logarithmic frequency steps. The threshold sensitivity is approximately 2 microvolts per channel. There are three modes of operation of the PFR. In "fast scan" mode the receivers are swept through all 32 frequencies twice in each telemetry frame (a frame takes 1 second at the highest telemetry bit rate) and 32 such scans are accumulated. The average values of Ex and Ez and the peak signal on Ex are telemetered. In "slow" scan mode the frequency is stepped only twice per telemetry frame. In each half-frame 32 measurements of the signal at the same frequency are accumulated and the average and peak found and telemetered. There is also a fixed-frequency mode of operation where the receiver remains on a single frequency. The instrument is commonly operated in a manner that places it in fast mode for 23 hour, fixed-frequency mode for 1 hour, slow mode for 23 hour, fixed-frequency for 1 hour, and then the cycle repeats. 4 World Wide Web Access to URAP Data Some of the URAP data are being made available over the World Wide Web (WWW). By this means, the data are made convenient and quick to use by a much larger audience, including anyone with access to the Internet. The URAP home page on the WWW provides more information for those interested. The home page makes available color dynamic spectra of the RAR data and information on the location of Ulysses during the mission. Educational material and a bibliography of papers describing Ulysses and URAP are also provided. The home page also gives links to other WWW sites of interest including NASA, Goddard Space Flight Center, the Jet Propulsion Laboratory and the European Space Agency, as well as other investigators using the Ulysses instruments and data. The Universal Resource Locater for the URAP home page is http://urap.gsfc.nasa.gov/www.urap_homepage.html APPENDICES A UDS data files Eight files are provided that conform to the UDS conventions regarding the naming of files and the format of the data. The eight files are divided into 4 pairs of files with each pair consisting of a file containing data averaged over a 10 minute period and a file containing the maximum data value during the same 10 minute period. The 4 pairs of file contain data for the RAR, the PFR, WFA - magnetic field, and WFA - magnetic field. A.2 Plasma Frequency Receiver To reduce the size of the UDS files only 16 frequency channels are given which represent the combination of every 2 adjacent channels. The UDS average data files are computed by averaging the Ex-average data values all data that falls in each 10 minute period for each of the 32 channels. Then adjacent channels are averaged together to yield the 16 channels present in the UDS files. The UDS peak data files are computed by finding the the peak value of the Ex-peak data that falls in the 10 minute period. Then the peak of adjacent channels is found to yield the 16 channels present in the UDS files. Because of the limited usefulness of fixed-frequency data when averaged, it has been ignored when creating the UDS files so these 1 hour intervals of fixed-frequency will be replaced by the "bad data" value of -9.99e+10. File names (following PDS convention): Tyyddd.TAB -> Average data yy: Last two digits of year. ddd: Day of year (001..366). The files are Ascii and contain one line for each time period (even if there are no valid data for a time period) so they contain 144 lines each. The format of the data is indicated by the following Fortran read statement which can be used to read the files: DIMENSION F(16) READ(1,100) IYEAR,IMON,IDAY,IHOUR,IMIN,SEC,MODE,IBPS,F 100 FORMAT(I4,4(1X,I2),F6.3,3X,2I2),16(1X,1PE9.2) These variables are defined as follows: TIME: spacecraft event time in the format yyyy-mm-ddThh:mm:ss.sssZ MODE: PFR scan mode: 1: Fast mode. 2: Slow mode. 3: Fixed frequency mode. This value should not occur as fixed frequency data is removed from the UDS data. 4: The mode switched from fast to slow or slow to fast during the averaging interval. 5: Unknown mode. This value occurs if there was no valid data during the averaging interval. This could be due to a data gap or bad data. Data acquired while the PFR is in fixed tune mode is ignored so this value for the MODE will also occur if the PFR was in fixed tune mode during the entire averaging interval. BPS: Telemetry bit rate: 1: 128 bps. 2: 256 bps. 3: 512 bps. 4: 1024 bps. 5: Bit rate changed during averaging period. 6: Bit rate unknown. F: Contains the PFR data (either average or peak values, depending on the file) of the 16 frequency channels. The frequencies given below are the average of the two adjacent frequencies that are combined. F(1): 0.61 kHz F(2): 0.80 kHz F(3): 1.04 kHz F(4): 1.35 kHz F(5): 1.77 kHz F(6): 2.30 kHz F(7): 3.01 kHz F(8): 3.92 kHz F(9): 5.11 kHz F(10): 6.67 kHz F(11): 8.70 kHz F(12): 11.34 kHz F(13): 14.79 kHz F(14): 19.30 kHz F(15): 25.16 kHz F(16): 32.82 kHz NOTES: These data are electric field intensities detected by the Plasma Frequency Receiver (PFR) on the X antenna of the URAP instrument. Units: microvolt/Hz**.5 measured at the receiver input terminals. To convert to electric field strength the given data must be divided by the effective length of the antenna. This is complicated by the fact that the effective length depends on the antenna impedance which is affected by the plasma conditions local to the Ulysses spacecraft. The impedance will also depend on the frequency. In general, the PFR frequencies can be affected by the plasma so a single number cannot be used for the effective antenna length. Time resolution: 10 minutes Fill value for bad or missing data is -9.99e+10