| DATA_SET_DESCRIPTION |
Data Set Overview
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C USER'S GUIDE TO RAR 144 SECOND AVERAGED DATA FILES
This document describes the contents and format of the RAR 144
second averaged data files.
The time period of 144 seconds was used for the averaging
period because that is the basic cycling time of the
instrument. The RAR continually cycles through a list of
frequencies. There are 16 lists and the list currently in use
is chosen by telecommand. The time period to complete the list
is 144 seconds for the high band of the receiver (for
telemetry bit rates of 1024 and 512 bps, the cycle time is 64
seconds for bit rates of 256 and 128 bps), after which the
instrument begins with the list again. Therefore this period
was chosen for the averaging period.
The format of the data is indicated by the following Fortran
statement which can be used to read the data:
DIMENSION F(0:75)
READ(A24,5(1X,A1),75(1X,1PE11.4))
+ TIME, LO_POL_MODE, LO_SUM_MODE,
+ HI_POL_MODE, HI_SUM_MODE, IBPS, F
The variables are defined as follows:
The date and time of the beginning of the averaging period is
given in TIME in the format yyyy-mm-ddThh:mm:ss.sssZ.
LO_POL_MODE and HI_POL_MODE are the polarization modes of the
low and high receiver bands. Their values are defined as:
1: Polarization on.
2: Polarization off.
3: Polarization mode switched during the averaging interval.
4: Polarization mode was unknown (usually due to a data gap).
LO_SUM_MODE and HI_SUM_MODE are the polarization modes of the
low and high receiver bands. Their values are defined as:
1: Summation on.
2: Summation off.
3: Summation mode switched during the averaging interval.
4: Summation mode was unknown (usually due to a data gap).
IBPS indicates the telemetry bit rate during the averaging
interval. Its values are defined as:
1: 128 bps.
2: 256 bps.
3: 512 bps.
4: 1024 bps.
5: Bit rate changed during the averaging period.
6: Bit rate unknown - usually due to a data gap.
F is a vector containing the average signal for the 76
frequencies of the low and high bands. Elements 0 through 63
are from the low band receiver and correspond to frequencies
of 1.25+0.75*N KHz where N is the element number (0..63). The
frequency channels from 64 to 75 correspond to the following
frequencies:
F(64): 52 KHz
F(65): 63 KHz
F(66): 71 KHz
F(67): 100 KHz
F(68): 120 KHz
F(69): 148 KHz
F(70): 196 KHz
F(71): 272 KHz
F(72): 387 KHz
F(73): 540 KHz
F(74): 740 KHz
F(75): 940 KHz
The units of the data are 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 RAR frequency channels that are well above the
local electron plasma frequency are not affected by the plasma
conditions and the effective length of 23 meters can be used.
When the RAR is in summed, rather than separate, mode the
determination of field strengths is even more difficult.
SUMMARY PLOTS
=============
URAP SUMMARY PLOT DESCRIPTION
A URAP Summary Plot is a plot of one day of Ulysses Unified Radio
and Plasma (URAP) experiment data. The URAP experiment consists
of five instruments: Radio Astronomy Receiver (RAR), Plasma
Frequency Receiver (PFR), Wave Form Analyzer (WFA), Fast Envelope
Sampler (FES), and Sounder (SND). The Summary Plot consists of
six plot panels. Data are plotted in the form of dynamic spectra
(3 dimensional plots of wave intensity versus frequency and time,
with the degree of darkness proportional to the wave intensity.
Frequency is plotted along the vertical axis, and time along the
horizontal axis.
Most of the data are stretched (assigned a grey shade) between
minimum and maximum data values, the maximum being the minimum
plus dynamic range designated for a receiver. The specified
dynamic ranges are shown at the right side of the plot, under the
heading 'Dyn. Range'. A linear interpolation is done between
minimum and maximum values to determine the degree of darkness of
the plotted data point. Data at or below the minimum are plotted
as white, and data at or above the maximum value are shown as
black. The pixel-font uses a 4x4 dot pattern to represent 16
shades of gray.
The plot consists of six panels, the first four of which are
plotted with time along the horizontal axis. For these plots the
time increment is 128 seconds, which means that 675 time steps
are represented along the horizontal axis, corresponding to 24
hours of data. For data with a higher time resolution than this,
the maximum data value occurring during a 128 second interval is
plotted. Frequency is plotted along the vertical axis.
Frequency labels such as 100K refer to 100 KHz; otherwise the
labels refer to Hz. Dynamic ranges shown at the right of the
panels are in telemetry units, except for the WFA ranges, which
are in logarithm of floating point DPU-FFT output. The panels
are described in order from top to bottom.
Panel 1 This is a dynamic spectrum of RAR X antenna electric
field data. The full set of 12 high receiver frequencies
and 64 low receiver frequencies is plotted, with
interpolation done for any missing frequencies
(extrapolation is not done). The high receiver frequencies
have a logarithmic spacing between approximately 50 KHz and
1 MHz. The low receiver frequencies are spaced linearly in
frequency between 1.25 and 48.5 KHz.
Panel 2 This panel is a dynamic spectrum of electric field data
from RAR, PFR and WFA instruments. The 12 frequencies of
the RAR high receiver Z antenna data are plotted. A gap
separates RAR and PFR data. The PFR data is the peak data
from the X antenna. Thirty-two PFR frequencies are plotted,
ranging from 0.5 to 35 KHz. When the PFR is in fixed tune
mode, there are 32 times as many PFR samples at a single
frequency. They are spread across the 32 frequencies, to
permit a better representation of the single frequency data.
Twenty-four WFA frequencies from the X electric field
antenna are plotted at the bottom of the panel. The low
receiver frequencies range between about 0.1 to 5 Hz; the
high receiver frequencies range from 9 to 448 Hz. The
frequencies are approximately logarithmically spaced. The
data plotted are average data from the WFA instrument.
Panel 3 WFA magnetic field data are plotted here. The high
receiver data (upper 12 frequencies) are always from the Y
search coil. The low receiver (lower 12 frequencies) will
be either Y or Z search coil data, depending on which search
coil was being sampled (indicated in panel 4). Frequencies
and units are as for the WFA Ex data.
Panel 4 This panel indicates various instrument statuses. A dark
line indicates an 'on' condition, and a light line indicates
'off'. Six status flags are shown. These are: a) RAR SUM:
The flag indicates whether the RAR is in summation (X+Z)
mode. A dark line indicates summation is on. There are a
pair of lines for this flag. The top line of the pair
indicates RAR high receiver summation, and the second line
indicates low RAR receiver summation. b) RAR POLAR: This
flag indicates RAR polarization mode on or off. Again, the
first of the two polarization lines is for the high receiver
and the next is for the low receiver. c) PFR Fast: a dark
line indicates that the PFR is in fast-scan mode; a light
line indicates that the mode is slow-scan; no line indicates
fixed-tune (single-frequency) mode. The fixed tune
frequency is shown during the fixed tune interval. Note
that the PFR causes a mode (and bit rate) dependent
interference in the WFA data. d) Greater than 10 Hz Ez:
This flag indicates that the WFA high receiver data is from
the Ez antenna (dark) or, alternatively, from the WFA Bz
antenna (light). Note that neither of these types of data
is plotted on the Summary Plot. (Only Ex data is plotted
for the high band EWFA; only By data is plotted for the high
band BWFA.) e) Less than 10 Hz By: This indicates whether
the magnetic data in the low receiver is from the By (dark)
or Bz (light) antenna. This flag does correspond to the
data plotted for the B lo receiver. f) 1024 bps: A dark
line indicates 1024 bps data. A light line indicates 512
bps. A blank corresponds to a bit rate lower than 512 bps
or a data gap.
Panels 5,6 The bottom two side-by-side panels (to the right of
the plot label) show data for each observed FES event for
high band and low band detectors. For each event, shown by
a straight horizontal line, 1024 data points are taken. On
the plot, however, only the maximum value of 4 contiguous
points is displayed. Up to 56 individual events may be
plotted. The events are plotted from bottom to top of panel
in order of their occurrence. The vertical scale is time of
event in hours of the day. Each event shown represents the
most intense FES event observed during 49 formats (a format
is 32 sec at 1024 bps). These panels are in the form of
dynamic spectra; therefore the degree of darkness is
proportional to the intensity of data observed during event.
The FES low and hi band plots show two vertical lines at the
beginning of each plot. These indicate the instrument
antenna and filter status. For the FES high band the Ex
antenna is flagged by a black point, and the Ez antenna by a
light point. The 6-60 kHz filter is shown by black, the
2-20 kHz filter is designated by a light point and all
filters with an upper limit of 6 kHz or lower are designated
by a blank. For the low receiver antenna, a black point
indicates Ex, a light point, Ez, and no point, the B search
coils. For the low band filter, a black point indicates
2-10 Khz, a light point .6-6 kHz, and no point indicates the
upper frequency limit is lower than 2 kHz. When the FES
receiver is attached to the B antenna, the band is always
0.01-1 kHz.
The option exists for plotting electron plasma frequency fpe, ion
plasma frequency fpi and electron gyrofrequency fce as lines on
the dynamic spectra. The fpe data is plotted on the PFR plot,
fpi is plotted on the EWFA panel, and fce is shown on the BWFA
panel. These data are obtained from Ulysses files of plasma
(SWOOPS) and magnetometer (MAG) data, provided by the respective
instrument teams.
Various plot labels are printed in the lower left-hand corner of
the Summary Plot. The first 3 lines give date of the plotted
data, version number of the Summary Plot program, and date the
plot was generated. The next 2 lines designate the RAR high and
low receiver modes at the beginning and end of the plotted time
interval. The modes are M (measure mode), L (linear sweep), and
F (freeze mode). For measure mode, the list number is given
after the '#' sign. For freeze mode, the frequency number
follows the '#' sign. For the low receiver in measure mode, 'F'
designates full list, 'E' indicates first half of list, and 'O'
implies the second half of the list is used.
The next line indicates RAR background type and offset.
Designation for the RAR background determination is as follows:
Background type '0' indicates offset values (computed minus
standard background values) and dynamic ranges may be specified
for the RAR receiver. Background type '1' indicates that for
each frequency a background is computed from the data for that
day, and a histogram of data minus background for all frequencies
is used to automatically set the offset and dynamic range for
each RAR receiver. The offset and range depend on the percentage
of white and black pixels chosen by the user. The offsets
(either chosen or computed) are shown after the '/'. The 3
offsets shown correspond to offsets for the RAR X high, X low,
and Z high, respectively.
The next line shows the minimum and maximum data values in
telemetry units for the RAR low X data for the day. In the next
3 lines, distances and angles are given as determined using
various locations, namely, Ulysses (U), Sun (S), Jupiter (J), and
Earth (E). The last 2 lines give the longitude and latitude of
the spacecraft in either heliographic coordinates (_H) or
ecliptic coordinates (_E), as determined from the SEDR database.
Backgrounds may be computed from the data. This is done
separately for each RAR receiver (RAR X high, RAR X low, RAR Z
high) as well as for the non-RAR receivers (PFR, WFA high, WFA
low, B WFA high and B WFA low). The goal is to achieve a full
utilization of the gray scale. To accomplish this, a percentage
of white and black pixels is specified, typically 4% white and 4%
black. Histograms of the data values are computed for each
panel. The background and range are defined by these histograms;
i.e. they are calculated to provide the percentages of black and
white pixels specified.
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