2
2
2
2
2
2
1
1
0
2
2
20
1
1
cos2
2
4
2
1
cos2
2
2
QD
ADD
SM
F
QD
SG
u
K
K
KKUU
nft
ft
t
nft
ft
t
=
−
+
+
+
−
+
(3.13)
or
(
)
(
)
(
)
(
)
2
2
2
2
2
2
1
1
0
2
1
2
1
2
0
2
20
1
1
cos4
4
2
8
4
1
1
cos2
2
cos2
2
4
2
4
4
1
cos4
4
2
.
8
QD
ADD
SM
F
QD
ADD
SG
u
K
K
KKU
U
nft
ft
t
nft
nft
nft
nft
ft
t
nft
ft
t
=
−
−
++
+
−
+
+
−
−
+
+
−
−
(3.14)
The voltage
QD
u
(3.14) consists of a constant component, three components with
rapidly changing frequencies, with the participation of the second harmonic of the
swip-generator voltage, and the required component with the fixed frequency:
21
()
F
nf
f
=−
. (3.15)
As follows, the voltage, which is allocated by the filter LPF2 with the band
12
()
MAX
n
f
f
−
and transfer coefficient
2
F
К at the output of the quadrator (
MAX
n
–maximum harmonics number of reference generators), basically contains
component with fixed frequency F:
(
)
2
2
2
2
2
1
2
1
2
1
cos2
.
4
OUT
ADD
SM
F
QD
F
ADD
SG
u
K
K
KК
KU
U
nf
ft
=
−
(3. 16)
Exception is the short time intervals around the point of transition of difference
frequencies (3.14) through zero. These intervals are shorter than the duration of the
pulse from the output of the marker (fig. 3.1). Replacing the LPF1 filter (Fig. 3.3) with
the bandwidth filter with the lowest limiting frequency
12
()
MAX
n
f
f
−
, significantly
weakens three components mentioned above.
Knowing the frequency F, using the (3.1) we can calculate frequency of the swip-
generator.
The velocity of frequency change in the swip-generator
can be zero (
0
=
–
the mode of generation with fixed frequency), or depend on time (
()
t
, nonlinear
frequency change).
Mentioned factors don’t affect the accuracy frequency measurements.
4. Computer simulation. Next step is performing computer simulation of
developed device. There are many programs for computer simulating of electric
circuits. The most common are Electronics Workbench, Circuit Master, Microcap
Evaluation, MatLab, Orcad, and others. Among those programs we need to choose one
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