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To ensure the frame synchronization, one of 18 markers listed in
the IRIG-106 standard is selected. The selected marker is used as the
synchronization code and is added to each frame [8]. The list of markers
is shown in Table 1.
Table 1
Standard synchronization codes of TMI in the IRIG-106 standard
Optimal frame synchronization codes of TMI in the IRIG-106 standard
Code length
Code format
16
111 0101110010000
17
111 10011010100000
18
111 100110101000000
19
111 1100110010100000
20
111 01101111000100000
21
111 011101001011000000
22
111 1001101101010000000
23
111 10101110011010000000
24
111 110101111001100100000
25
111 1100101101110001000000
26
111 11010011010110011000000
27
111 110101101001100110000000
28
111 1010111100101100110000000
29
111 10101111001100110100000000
30
111 110101111001100110100000000
31
111 1111001101111101010000100000
32
111 11110011010110010100001000000
33
111 110111010011101001010010011000
Preparing data for the experiments.
Digitized analog sensory data
were included in the frame of telemetry data. The sensors measured typical
parameters for the telemetry system: temperature, pressure, positional
values. These parameters were obtained in the laboratory, examples of
the signals are shown in Fig. 5,
a
. The frame structure shown in Fig. 5,
b
was developed for the experiments, the test telemetry data bitstream was
formed on its basis.
A frame contains 14 channels. Digitized analog sensor readings are
transmitted over each channel. The frame also contains service information,
which provides frame synchronization in the telemetry stream. The service
information of the frame is composed of the selected synchronization code
(the marker), and the registration time in the IRIG-106 standard [8]. The
frame stream to be used in the experiments was formed with the help of
a telemetry data simulator [10].
ISSN 0236-3933. HERALD of the BMSTU. Series Instrument Engineering. 2015. No. 2 121