LOG_VOL_IDENT: USANASANSSDDEA2-0012A LOG_VOL_INITIATION_DATE: 1992-06-22 LOG_VOL_CLOSING_DATE: 1992-06-22 LOG_VOL_CAPACITY: 1 GB/LOG_VOL LOG_VOL_FILE_STRUCTURE: DEC FILES-11 VOLUME_DIAMETER: 12 INCHES VOLUME_DRIVE_MFGR_AND_MODEL: OPTIMEM 1000 COMPUTER_MFGR: DIGITAL EQUIPMENT CORPORATION OPERATING_SYSTEM: VMS 5.1+ TRANSFER_SOFTWARE: SOAR TECHNICAL_CONTACT: ANN M. PERSOON DEPARTMENT OF PHYSICS AND ASTRONOMY UNIVERSITY OF IOWA VAN ALLEN HALL IOWA CITY, IOWA 52242 319/335-1942 INTERNET ANN-PERSOON@UIOWA.EDU RICHARD L. HUFF DEPARTMENT OF PHYSICS AND ASTRONOMY UNIVERSITY OF IOWA VAN ALLEN HALL IOWA CITY, IOWA 52242 319/335-1934 INTERNET RICHARD-HUFF@UIOWA.EDU ROBERT L. BRECHWALD DEPARTMENT OF PHYSICS AND ASTRONOMY UNIVERSITY OF IOWA VAN ALLEN HALL IOWA CITY, IOWA 52242 319/335-1945 INTERNET ROBERT-BRECHWALD@UIOWA.EDU PREV_LOG_VOLS: USANASANSSDDEA2-0001A USANASANSSDDEA2-0002A USANASANSSDDEA2-0003A USANASANSSDDEA2-0004A USANASANSSDDEA2-0005A USANASANSSDDEA2-0006A USANASANSSDDEA2-0007A USANASANSSDDEA2-0008A USANASANSSDDEA2-0009A USANASANSSDDEA2-0010A USANASANSSDDEA2-0011A DATA_SET_NAME: DE PWI PLASMA WAVE DIGITAL DATA DATA_SET_SOURCES: PLASMA WAVE INSTRUMENT ON DYNAMICS EXPLORER 1 SCIENTIFIC_CONTACT: DR. DONALD A. GURNETT DEPARTMENT OF PHYSICS AND ASTRONOMY UNIVERSITY OF IOWA VAN ALLEN HALL IOWA CITY, IOWA 52242 319/335-1697 INTERNET DONALD-GURNETT@UIOWA.EDU ANN M. PERSOON DEPARTMENT OF PHYSICS AND ASTRONOMY UNIVERSITY OF IOWA VAN ALLEN HALL IOWA CITY, IOWA 52242 319/335-1942 INTERNET ANN-PERSOON@UIOWA.EDU SOURCE_CHARACTERISTICS: A. DESCRIPTION_OF_SPACECRAFT: Dynamics Explorer 1 (DE-1) is one of two spacecraft launched for the Dynamics Explorer program on 3 August 1981. The two spacecraft were launched into coplanar polar orbits at different altitudes for the purpose of studying interactive processes within the atmosphere-ionosphere-magnetosphere system. Dynamics Explorer 2 re-entered the atmosphere on 19 February, 1983. Re-entry time of DE-1 cannot yet be determined. Instruments on board DE-1 in addition to the plasma wave instrument (PWI) are: energetic ion composition spectrometer, high altitude plasma instrument, magnetometer, spin-scan aurora imager plasma wave instrument, and retarding ion mass spectrometer. B. ORBIT_INFORMATION: Initial orbital parameters of DE 1 were: an inclination of 89.9 degrees; orbital period of 410 minutes; radial distance at perigee of 6950 km (1.09 RE); and radial distance at apogee of 29650 km (4.65 RE). The initial latitude of apogee was at 78.2 degrees North. Apogee returns to the northern polar region every three years (e.g., the autumns of 1984, 1987, etc.) C. PERFORMANCE: Initial spacecraft duty cycle was about 90%. With spacecraft age and decreasing priority in the NASA tracking system, the duty cycle decreased slowly after the first year of operation. By 1989 the duty cycle varied from 16-55%. Data acquisition in individual orbits is designed to maximize the science return. In 1984 a failure in the circuitry of the spacecraft data- handling system has limited access to data from the plasma wave instrument. After Day 175 in 1984, digital measurements above 100 Hz from the plasma wave instrument (PWI) have not been consistently available. INVESTIGATION_OBJECTIVES: The purpose of the PWI instrumentation is to provide comprehensive measurements of plasma wave emissions which occur along the DE-1 orbit. The PWI measures the intensity and spectrum of electromagnetic and electostatic waves over a dynamic range of about 100 dB and a frequency range of 1 Hz to 2 MHz. Additionally, the PWI has the capability of measuring relative phase between signals from pairs of antennas. This data can be interpreted in terms of propagation direction (Poynting vector) and wave polarization for the various plasma wave phenomena. The PWI instrumentation also measures static (DC) electric fields perpendicular and parallel to the spacecraft spin axis. INSTRUMENT_ATTRIBUTES: A. INSTRUMENT_DESCRIPTION: The Plasma Wave Instrument on DE-1 consists of a set of specialized receivers which, in conjunction with three electric and 2 magnetic sensors, provides measurements of plasma waves over the frequency range DC to 2 MHz. The electric sensors consist of a 200 m long wire dipole antenna (Ex) oriented in the spacecraft spin plane, a boom-mounted 1 m dipole antenna (Es) parallel to the long wire, and a 9 m tubular dipole antenna (Ez) oriented along the spin axis of the spacecraft. The PWI receivers consist of the Sweep Frequency Correlator (SFC), the Low Frequency Correlator (LFC), the Wideband Analog Receiver (WBR), the Linear Wideband Receiver (LWR), and the DC Electric Field system. The SFC consists of a pair of identical high resolution narrow band Sweep Frequency Receivers (SFR's) and a correlator. The SFC provides 128 narrow-band measurements over the frequency range 100 Hz to 410 kHz. The LFC provides measurements from eight filter channels spaced from 1.78 Hz to 100 Hz. The SFC and LFC together provide amplitude and relative phase measurements from selected pairs of sensors, yielding a 136-point logarithmically- spaced spectrum for each 32-second sweep of the instrument. The DC Electric Field system measures components of the static electric field in both the spacecraft spin plane (Ex, Ey) and along the spin axis (Ez) at a rate of 16 samples/sec. The WBR provides wideband waveform measurements in selected bandwidths over the frequency range 650 Hz (baseband) to 2 MHz. The LWR provides waveform measurements over narrower bandwidths ranging from 1.5 kHz to 16 kHz and is used primarily for the study of signals from VLF ground transmitters. Data from the WBR and LWR are acquired via a real-time link between the spacecraft and a ground receiving station. A detailed description of the Plasma Wave Instrument is provided by Shawhan et al. in Space Science Instrumentation, Vol 5, pp 535-550, 1981. B. OPERATION_CYCLE: (Duty Cycle, Periodicities, etc.) Although the instrument can be commanded into a variety of configurations, the modes most often used possess the same basic cycle times. The Sweep Frequency Receiver (SFR) system (two identical receivers) has a measurement cycle time of 32 seconds. Each SFR has four channels of 32 frequency steps each, giving measurements at a total of 128 frequencies. The dwell time at a particular frequency is one second, and during this time, the output of each channel is sampled four times. The Low Frequency Correlator (LFC) system (with two identical receivers) has eight separate frequency bands and two basic cycle times. The LFC cycles through the lower four bands (1.78, 3.11, 5.62, and 10 Hz) in 32 seconds, giving a band dwell time of 8 seconds. During the eight seconds, 64 measurements are collected. The LFC cycles through the four higher bands (17.8, 31.1, 56.2, and 100 Hz) in 4 seconds, giving a band dwell time of 1 second. Eight samples are collected during the 1 second interval. C. PARAMETERS_MEASURED: The PWI sensors/preamplifiers respond to electric or magnetic components of wave emissions. The spectrum analyzers (SFC and LFC) step through a series of filter channels or synthesized narrow passbands to determine the spectral content of the input waveform. The final output at each frequency is a logarithmically compressed DC voltage which is converted to counts by the spacecraft, and which appears in an individual telemetry word. Conversion to geophysically meaningful values is done through the use of tables of calibration data which represent sensor response and log compressor response. A summary of the measured PWI geophysical parameters is given below: Narrowband spectrum measurements of the electric and magnetic fields: AC electric field measurements from 0.03 mmV/m to 100 mV/m from the Step Frequency Receivers (SFR) which comprise the Step Frequency Correlator and from the Low Frequency Correlator (LFC): SFR amplitude measurements from 104 Hz to 410 kHz in 32 seconds; 1% resolution at 128 frequencies. LFC amplitude measurements from 1.78 Hz to 100 Hz in 32 seconds; 30% resolution at 8 frequencies. AC magnetic field measurements from 0.1 gamma-Hz to 3E4 gamma-Hz for frequencies less than 35 kHz and approximately 2E-5 gamma for frequencies greater than 35 kHz from the Step Frequency Receivers (SFR) and from the Low Frequency Correlator (LFC): SFR amplitude measurements from 104 Hz to 410 kHz in 32 seconds; 1% resolution at 128 frequencies. LFC amplitude measurements from 1.78 Hz to 100 Hz in 32 seconds; 30% resolution at 8 frequencies. In-phase and quadrature phase measurements obtained by correlating the signals from selected pairs of antennas for the Step Frequency Receivers (SFR) and for the pair of receivers which comprise the Low Frequency Correlator (LFC): SFR phase measurements from 104 Hz to 410 kHz in the spin period. LFC phase measurements from 1.78 Hz to 100 Hz in the spin period. DC electric field measurements: In spin plane (Ex) LO-gain: 20 mV/m to 2 V/m HI-gain: 0.5 mV/m to 50 mV/m Along spin axis (Ez) LO-gain: 20 mV/m to 2 V/m HI-gain: 2 mV/m to 200 mV/m Wideband analog spectrum measurements (not to be archived): WBR 10 or 40 kHz bandwidth at 1,31,62,125,250, 500, 1000, or 2000 kHz conversion frequencies LWR 1.5-3 KHz, 3-6 kHz, 10-16 KHz, and 3.11 KHz with a 15% bandwidth D. PERFORMANCE_OF_THE_INSTRUMENT: In June of 1984 (day 175) a malfunction in the DE-1 spacecraft data-handling system prevented access to high frequency data from the plasma wave instrument. Digital measurements from the Sweep Frequency Correlator system are not accessible after this date, although internal monitors indicate that the PWI continued to function properly. The telemetry words which contain the SFR science data were briefly restored for a three week period in January of 1987 and again in November of 1989. The PWI continues to provide static electric field measurements and digital amplitude and phase data from 1.78-100 Hz with intermittent access to the high frequency data above 100 Hz. Additionally, the PWI analog wideband subsystem continues to operate within specification. E. RESOLUTION: Each PWI record contains data from a single 8-second major frame of telemetry. Since the Sweep Frequency Receivers require 32 seconds for a complete cycle, four PWI records are needed for one SFR spectrum covering the frequency range 100 Hz to 410 kHz. The basic resolution of the DC electric field measurement is 16 samples/second. F. PARAMETERS: Each PWI record contains the date and time of the start of the record, orbit/attitude data, nadir pulse times, PWI instrument status information, data from the Step Frequency Receivers (SFRs), data from the Low Frequency Correlator, data from the Electric Field measurement system, and digital parameters from the Wideband and Linear Wave receivers. A single PWI record contains all of the PWI data from an 8-second major frame. G. DATA_SET_QUALITY: The overall quality of the PWI data is considered to be very good. Occasionally, records contain fill data, which can result in a gap when the PWI data are displayed in spectrogram format. DATA_PROCESSING_OVERVIEW: A. DATA_PROCESSING_CYCLE: PWI data are routinely extracted from the DE telemetry files and formated into mission analysis files (MAF's) which are collected onto tape and forwarded to the University of Iowa. Each PWI record contains universal time, science data, instrument status information, and a limited set of orbit/attitude data. Routine data processing at Iowa includes the production of two-hour color spectrograms (35mm slides) containing both SFR and LFC data. The DC electric field data is displayed as an 80-minute line plot which gives the static electric field both perpendicular and parallel to a model magnetic field (MAGSAT model). Analog wideband data (WBR and LWR) are acquired via a real-time link between DE-1 and a ground receiving station. Analog data tapes are then mailed to Iowa, and wideband spectra are produced on 70mm film as a routine process. The PWI data which will be archived on optical disks includes the primary data set which contains all of the PWI data acquired by DE-1 from the start of operations (day 81257) until day 84175. Also included on each data volume will be the required FORMAT.SFD and VOLDESC.SFD files, the software to extract and calibrate the PWI data and the SSCDOC.SFD file containing explanatory text and processing algorithms and the calibration tables. Graphics software and wideband analog data will not be archived. B. HISTORY: An effort has been made to minimize the number of duplicate or overlapping PWI Mission Analysis Files. The MAF's identified in the PWI catalog at Iowa are the versions which are used to create routine PWI data products. The PWI Mission Analysis Files at Iowa are stored on 1600 bpi magnetic tapes. These PWI data files will eventually be transferred to optical disk for use at Iowa. The primary PWI routine data products consist of two-hour frequency/time spectrograms in color slide format and 80-minute line plots showing parallel and perpendicular static electric fields. C. DATA_USAGE: Software will be provided to extract the data from the record and to do the appropriate calibrations for the conversion to geophysical units. However the graphics software, which produces the magnetic and electric field spectrograms and the DC electric field line plots, utitilizes in- house plot packages which drive local plot devices. Due to problems with portability and maintainability, the plot software will not be archived. The user will be responsible for the software to display PWI data on his/her own system. D. DATA_ORGANIZATION: The PWI data will be contained in the root directory and each file will contain all the available data for one day. E. TYPE_OF_FILE_RELATIONSHIPS: The PWI data set contains one type of file. Software is supplied to calibrate the data contained in the file. CCSDXSNM0002EMARK003CCSDXKNM0002SMARK005 LOG_VOL_TIME_COVERAGE: 1984-05-01 TO 1984-06-23 TYPE_OF_FILE_TIME_COVERAGE: /* One day per file 1984-05-01T00:00:00 (to) 1984-05-01T23:59:59 1984-05-02T00:00:00 (to) 1984-05-02T23:59:59 1984-05-03T00:00:00 (to) 1984-05-03T23:59:59 . . 1984-06-23T00:00:00 (to) 1984-06-23T23:59:59 DIRECTORY_NAMING_CONVENTION: There will be one root directory and one subdirectory per side. The root directory name will be in the following format. DEPWI_xxxx.DIR Where xxxx is a sequence number indicating the volume number. That is, the first side xxxx=0001; the second side xxxx=0002 etc. The subdirectory will contain the software description, the source files, and the sample output data files (TEST*.DAT). The software directory name will be [.SSC]. FILE_ORGANIZATION: Each data file in the directory will contain the data for one calendar day and will be a binary file. The SFD and software files will be ASCII files. FILE_NAMING_CONVENTION: Each file will use the following name convention. PWI_YYDDD.DAT Where YY is the year and DDD is the day of the data in the file. (January 1 = 1) PREV_LOG_VOL_TIME_COVERAGE: USANASANSSDDEA2-0001A 1981-09-16 TO 1981-12-27 USANASANSSDDEA2-0002A 1981-12-28 TO 1982-03-21 USANASANSSDDEA2-0003A 1982-03-22 TO 1982-06-25 USANASANSSDDEA2-0004A 1982-06-26 TO 1982-10-17 USANASANSSDDEA2-0005A 1982-10-18 TO 1982-12-31 USANASANSSDDEA2-0006A 1983-01-01 TO 1983-03-12 USANASANSSDDEA2-0007A 1983-03-13 TO 1983-06-19 USANASANSSDDEA2-0008A 1983-06-20 TO 1983-09-13 USANASANSSDDEA2-0009A 1983-09-14 TO 1983-12-02 USANASANSSDDEA2-0010A 1983-12-03 TO 1984-02-18 USANASANSSDDEA2-0011A 1984-02-19 TO 1984-04-30 NESTING=L REF=FORMAT.SFD ADI=NSSD0030 CLASS=I NESTING=N SCOPE=EACH REF=SFR_AMP.CAL REF=LFC_AMP.CAL REF=MAG_AMP.CAL REF=SFR_BWD.CAL REF=LFC_BWD.CAL REF=PWI_*.DAT NESTING=L REF=[SSC]SSCDOC.SFD ADI=NSSD0031 CLASS=J NESTING=N SCOPE=EACH REF=[SSC]*.FOR REF=[SSC]TEST*.DAT