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DIGISONDE-4D
SYSTEM MANUAL
VERSION 1.2.11
SECTION 5 - SYSTEM SOFTWARE – ANNEX A 5-41
SCIENCE DATA PACKETS
Science Data considerations
5:94. Science Data that produced by running some Sounding Program are called Measurement.
5:95. From the general point of view, Measurement characterized by Location, Time, Program, and Applied
Processes List and contains scientific data that was taken at these location and time by implementing this Pro-
gram and then have been processed further by applying all the processes in the Applied Processes List.
5:96. Each Measurement data are produced by running some Program that sends, using transmitter, a series
of “Pulses” with specified interval between them. After any Pulse transmitted and before next Pulse, Program
samples incoming signal many times producing Raw Science Data. Say, Raw Science Data are Science Data
without any process applied to them. So we can see that Raw Science Data grouped by Pulses.
5:97. Further Raw Sciences Data undergo several known processes. Here are most popular of them given in
the sequence of applying:
1. Channel Equalizing, mandatory. No data reduction.
2. RFI mitigation, recommended but may be omitted. No data reduction.
3. Pulse compression if applicable. No data reduction.
4. Sum complementary codes if applicable. Data are reduced by two times.
5. Regrouping by frequencies and calculation of Dopplers. No data reduction.
6. Ionogram calculation:
i. Choosing the strongest (having maximum amplitude over all antennas) Doppler for
each height.
ii. Calculating angle of arrival for strongest Doppler.
iii. For each height (for both ordinary and extraordinary data), leaving only, Doppler value
itself, average amplitude over antennas of strongest Doppler, and angles of arrival.
5:98. We see that Science Data are grouped either by Look (=Pulse) or by Frequency so we can say about
Look or Frequency Groups, or simply Groups, where each Group has one Group Header (containing infor-
mation unique to this Group) and calculated, using Program and Applied Processes List, number of Databins.
5:99. Science Data are grouped by Pulse up to step 4 and grouped by Frequency after step 4.
5:100. Measurement size is big enough to fit into one or several packets. Usually hundreds or thousands of
packets are needed to transmit data from DESC to DCART. One measurement may often exceed 100MB. So
DESC, at the time of producing Measurement data, makes packets of this data and sends them to DCART.
Having this in mind and the fact that even Frequency Group is big enough to fit into one packet, next section
will be clearer for understanding.
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