14 / 15
— is the average number of synchronization codes required to make a
decision about the absence of the synchronization code (
p
cl
— is the
probability of correct detection of the synchronization code in the “Capture”
state at the threshold value
ε
l
).
From Table 8 it is possible to select the value
ε
l
at which the calculated
value
DL
≤
DL
T
. For example, if the desired value is
DL
T
= 1
%, then
DL
= 0
.
415
can be selected and the threshold value
ε
l
= 6
is considered
to be the best one.
Therefore, the criterion for selecting
ε
l
of the “Capture” mode is as
follows:
ε
l
= arg max
ε
l
{
DL
:
DL
(
ε
l
)
≤
DL
T
}
,
(22)
where
DL
T
is the required minimum value of the information loss.
The results of the experiments with telemetry data (IRIG-106) are
shown in Table 9. The experiments were performed at
p
r
= 0
.
1
, the selected
values
ε
s
, ε
v
, w
v
and for different values of the probability of bit missing
p
d
=
{
0
,
10
−
4
,
10
−
3
,
10
−
2
}
and
ε
l
.
In the case under consideration, it is recommended to select the
parameter value
ε
l
= 6
for the “Capture” synchronization mode.
Conclusions.
The theoretical model of the frame synchronization of
the digital telemetry data stream is considered. The system is represented
as a final state machine with three states. The basic model parameters
determining the conditions of transition between the synchronizer states are
given. The methods of selecting such synchronizer parameters are specified.
The experiments with real telemetry data of the IRIG-106 format are
carried out. A comparative analysis of the obtained results with theoretical
estimates of the parameters of the synchronization system is performed.
It shows that the proposed method of selecting synchronizator parameters
leads to the same results both for the theoretical TMI stream model and
for the real telemetry data, despite the difference in quantitative estimates
of the intermediate results.
REFERENCES
[1] Vil’yard M.V. Russ. ed.: Nekotorye voprosy sinkhronizatsii v tsifrovykh sistemakh:
Dostizhenie v oblasti telemetrii [Some issues of synchronization in digital systems
(translated by L.S. Gelbershteyn): Achievement in the field of telemetry]. Moscow,
Mir Publ., 1970, pp. 58–73.
[2] Techniques for Synchronizing Pulse-Code-Modulated Telemetry.
Report the
theoretical and experimental investigation of synchronization methods for PCM
telemetry
. California: naval ordnance laboratory corona. 1963. 111 p.
[3] Prasad G., Vasantha N. Design and implementation of multi-channel frame
synchronization in FPGA.
International journal of electronics and communication
engineering & technology
(
IJECET
), 2013, vol. 4, pp. 189–199.
130 ISSN 0236-3933. HERALD of the BMSTU. Series Instrument Engineering. 2015. No. 2