Aerospace and Electronic Systems - March 2019 - 35

Femina Beegum et al.

Figure 2.
Block schematic of Pisharoty sonde.

Figure 3.
Photograph of Pisharoty sonde.

Figure 4.
Gain profile of monopole and QHF antennae for Pisharoty sonde
ground station.

effect of wind on the vehicle will be minimal [1]. The
descent phase wind profile is generated primarily from the
sonde ascent from the ship near to the impact point, supplemented with available HAB data and sounding rocket
data (chaff data). This profile contains wind data at 300-m
interval up to 39 km and at 1-km interval thereafter up to
60 km.
As part of DOL WB campaign, sonde ground station
was set up in Coast Guard ship "ICG RANI ABBAKA"
for ship-based ascents and data collection. Three ascents
were conducted from the ship positioned at the Bay of
Bengal 13.323262 latitude and 83.550278 longitude, the
nearest permitted location to the touch-down point, on the
launch day and data collected using the Ground Station
onboard the ship. Wind data from each ascent was
transferred from ship to Coast Guard Head Quarters at
Chennai; this is sent to SDSC SHAR.
To validate ship-based measurements, two trial
campaigns were conducted from the Bay of Bengal during May 2015 and December 2015. During these campaigns, sonde ascents were conducted from three
different locations down the range of RLV TD's
estimated path to assess the wind pattern over the Bay
of Bengal.
As part of the RLV-TD launch campaign, six-shipbased soundings were conducted on the previous two
days of launch, with simultaneous sonde release from
SDSC SHAR. The corresponding data from ship and
SHAR were compared and analyzed to understand the
spatial variation of wind data. The wind variation
between two successive ascents was also studied to
assess the effect of time elapsed between data collection and vehicle actually experiencing the wind. These
inputs are essential to generate a backup plan, in the
case of nonavailability of the latest identified profile.
The sonde ascent timings for the launch day are given
in Figure 9. Staggered ascent scheme was identified
for SHAR based measurement and single ascent
scheme for ship-based measurement. In case that the
data from the ship is not available, SHAR data are
used for wind profile generation.

MEASURED DATA
Figure 5.
Block schematic of the receiver in the Pisharoty sonde ground
station.

of 20 km. Measured wind is to be stored as an onboard
table in INS, to attain better accuracies in the estimation
of air-data parameters. So the wind data from 20 km to 40
km is crucial in the mission design. Above this height, the
MARCH 2019

This section briefly presents the wind and sensor data from
Pisharoty Sondes during RLV-TD launch campaign. The
wind variation plots at 300-m interval of staggered ascents
are shown in Figure 10 as zonal and meridional components. A comparison of wind plots from ship and SHARbased measurements is shown in Figure 11 and the corresponding difference plot is shown in Figure 12. The difference in wind values is expected due to geographical
separation between the sonde release stations, which was
about 200 km.

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Aerospace and Electronic Systems - March 2019

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