Onboard data collecting system (STS)
Panska Ves Ionospheric and Telemetric Observatory
In the INTERBALL project the ODCS version was chosen as the
system of data collection (STS) since this version together with
the STO telemetry on the main satellite provides acceptably
high resolution in real time. The channel of digital data
transmission can operate with the rate up to 40 Kbit/s and the
channel of analog information makes it possible to transmit the data
with the band width up to 60 KHz.
In this case it is especially important that the data received from both spacecraft would match in time with high accuracy, otherwise some approaches to interpreting the measurement results
would be impossible. However, for long distances from the
Earth,the TM-rate (the band width) is rather limited.
An important component of the TM-system is the digital
onboard memory device with the capacity of 4 Mbyte designed for
recording the housekeeping data out of the zone of the
radio-visibility from the ground-based stations and for registering
the scientific data in several operation modes depending on the
The onboard data collecting unit, STS, is installed to collect
the analog and digital information from the complex of scientific
payload and from the subsatellite service systems. This unit
performs also the formation of the digital TM frame structure.
STS unit has the following features:
1. STS can operate in receiving/transmitting modes through
14 digital and 15 analog channels (or through 120 analog channels
with the use of multiplexer controlled by STS 3-bit parallel codes).
The largest information block in the STS is the main block
(512bytes) consisting of 4 subframes of 128 bytes.
2. STS includes the onboard computer on the basis of the
NSC-800 microprocessor. The onboard computer can receive digital
data directly from scientific instrument and from service systems,
and after the data processing sends the resulting digital data both
to the TM-frame (and, if needed, backward to the system) in the form
of 8-bit words to control the operation modes and the programs
of operation of the instruments and systems.
3. The rate of data transmission has 4 fixed values: 1.23,
5.12,20.48 and 40.96 kbit/s. The operative rate of data
transmission is valid both for the telemetry and for data
transmission from the onboard computer to instruments.
4. The system has 8 prefixed independent TM-frame structures
and gives a possibility to form in flight an arbitrary
additional structure. Each of the 8 versions of the TM-frame
structures provide the optimum distribution of the TM information
in a block depending on particular conditions of the experiment
and on the program of studies.
The signal to transmitter from the STS unit output has the
form of bi-phase modulation.
The following organizations took part in design of the data collecting system:
-Microvawe Department of the Budapest Technical University, Hungary;
-Geophysical Institute of the Czech Acad. Sci., Prague, Czech Republic;
-BL Electronics, Hungary;
-Institute of Atmospheric Physics of the Czech Acad. Sci., Prague, Czech Republic.
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