Voyager 2 Planetary Radio Astronomy (PRA) Highband receiver daily files
during Jupiter Encounter (1979-06-01 to 1979-07-30). Associated with these binary data are a series of quick-look GIF spectrogram plots created using the binary data. The plots are available for both polarization channels. These binary data were also converted into IDL save sets.
The data set provides 48 second resolution highband radio mean power data
in units of millibels. The high-band receiver consisted of 128 channels of
200 kHz bandwidth each, with center frequencies spaced at 307.2 kHz
intervals from 1.2 MHz to 40.4 MHz. The highband receiver was designed
especially for the observation of Jovian decametric radio emissions. The
PRA radiometer was usually operated routinely in the so-called POLLO sweeping
mode, in which all 198 frequency channels of the high- and low-band receivers
together were swept in 6 sec, dwelling at each channel for 25 msec. From one
step to the next in the channel switching sequence, the antenna polarization
sense was reversed, i.e., was changed from RH to LH or vice versa. Thus the
time required for making a measurement of both the RH and LH intensity
components at both senses of elliptical polarization at a given frequency was
12 sec. The data consists of successive averages of 4 pairs of RH and LH
intensity measurements, each average spanning an interval of 48 sec.
The format of these binary data files is as follows:
file separation variable
year, month, day information
millisecond decimal value of the day
Integer array (128,2) for 128 left and right channels (NOTE 128 channels for Hi-band; 70 channels for Lo-band)
file separation variable
There is an IDL program that reads these files into an IDL-format save set. See Information URL for a link to this file.
The data are calibrated and are given in units of
'millibels' which is 1000 times the log of the received power.
Zero millbels corresponds to approximately 1.4 x 10^-21 W m^-2
Hz^-1, however, this value is never seen in practice. The
minimum values detected, which includes receiver internal and
spacecraft generated noise, are about 2300 to 2400 millibels,
or about 3.5 x 10^-19 W m^-2 Hz^-1; even higher values are seen
at the very lowest frequencies.
Note:
The polarization indicated is the received polarization, not
necessarily the emitted polarization. Correct interpretation of
the received polarization depends on the antenna plane
orientation relative to the radio source. A good description of
this concept can be found in
Leblanc Y., Aubier M. G., Ortega-Molina A.,
Lecacheux A., 1987, J.Geophys. Res. 92, 15125 and in
Wang, L. and Carr, T.D.,
Recalibration of the Voyager PRA antenna for polarization sense
measurement, Astron. Astrophys., 281, 945-954, 1994. and references therein.