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Fig. 5. Telemetry parameters (
а
) and telemetry frame structure (
б
):
D.W. — is a data word, D1:D14 — are samples of the signals shown in figure (
a
)
The telemetry word length of a frame is 8 bits. A quantized sensor
sample in the range of 0. . . 255 is stored in the word. The service
information consists of the marker and 48 bits being used to store the
time in the IRIG-106 standard. The total length of the reduced frame (see.
Fig. 5,
b
) is 176 bits.
Analysis of the synchronizer in the “Search” mode.
In the “Search”
mode, the synchronization code is considered to be detected, if comparing
n
successive message symbols with the known synchronization code, the
number of mismatches doesn’t exceed a threshold value
ε
s
. The probability
of correct detection of the synchronization code in the “Search” mode
at an acceptable threshold
ε
s
in the presence of noise
p
r
6
= 0
can be
written as
p
cs
=
ε
s
X
i
=0
n
i
(1
−
p
r
)
n
−
i
p
i
r
,
(3)
where
n
is the length of the synchronization code;
n
i
=
n
!
i
! (
n
−
i
)!
;
p
fs
=
ε
s
P
i
=0
n
i
2
n
(4)
is the probability of the false synchronization code emerging among the
message characters in the “Search” mode with an acceptable number of
errors
ε
s
.
122 ISSN 0236-3933. HERALD of the BMSTU. Series Instrument Engineering. 2015. No. 2