5.1 Operational Range of Radar Location and Radio Navigation Systems
83
As we can see from (5.10) formula, recognition coefficient represents a relation
of signal to noise at output of receiver linear part, minimally necessary for signal
detection from a target. All operations for extraction of desired signal and filtering
of random processes, which are executed in receiver and terminal unit of radar, are
considered by recognition coefficient. Reducing of recognition coefficient testifies
to a more effective processing in radar and leads to reducing of baseline minimum
of threshold signal E rcv min (P rcv min ).
From formulas (5.8)–(5.10), we have:
E rcv min = K r E n = K r K n kT 0 ,
P rcv min = K r P n = K r K n kT 0 f.
.
(5.11)
Formula (5.11) shows that target detection effectiveness depends on relation
between signal and noise (K r ).
Obtained relations give a possibility to get another form of range equation by
introducing E rcv min and P rcv min values:
D max =
4
E G 2 λ 2 A
(4π )
3 kT 0 K n K r
=
4
E S
2
eff A
4πλ 2 kT 0 K n K r
.
(5.12)
or
D max =
4
P G 2 λ 2 A
(4π )
3 kT 0 K n K r f
=
4
P S
2
eff A
4πλ 2 kT 0 K n K r f
.
(5.13)
In favor of best filtering of receiver internal noises a band of intermediatefrequency amplifier (IFA) of receiver is coincided with duration of sounding (and
receiving pulse from point targets) pulse ∼ =1/τ in the most pulse radars. In this
case, (5.12) and (5.13) formulas will be as follows:
D max =
4
P G 2 λ 2 Aτ
(4π )
3 kT 0 K n K r
=
4
P S
2
eff Aτ
4πλ 2 kT 0 K n K r
.
(5.14)
At calculations, the most difficulties are at calculation of recognition coefficient
value K r .
Calculation of recognition coefficient if necessary is a probabilistic, since a determinated (non-probabilistic) value K r should “embody” all fluctuations processes
preventing to detection, and also all measures for filtering in radar of these processes
are in favor of desired signal extraction—reflected target signal. Recognition coefficient value depends on probability distribution law of a target RCS value and rate
of its fluctuations, on intensity and rate of fluctuations of additional external and
internal noises matching along with common internal noises to a desired signal, on
signal processing principle in radar, particularly on degree of non-ideality of signal
83
As we can see from (5.10) formula, recognition coefficient represents a relation
of signal to noise at output of receiver linear part, minimally necessary for signal
detection from a target. All operations for extraction of desired signal and filtering
of random processes, which are executed in receiver and terminal unit of radar, are
considered by recognition coefficient. Reducing of recognition coefficient testifies
to a more effective processing in radar and leads to reducing of baseline minimum
of threshold signal E rcv min (P rcv min ).
From formulas (5.8)–(5.10), we have:
E rcv min = K r E n = K r K n kT 0 ,
P rcv min = K r P n = K r K n kT 0 f.
.
(5.11)
Formula (5.11) shows that target detection effectiveness depends on relation
between signal and noise (K r ).
Obtained relations give a possibility to get another form of range equation by
introducing E rcv min and P rcv min values:
D max =
4
E G 2 λ 2 A
(4π )
3 kT 0 K n K r
=
4
E S
2
eff A
4πλ 2 kT 0 K n K r
.
(5.12)
or
D max =
4
P G 2 λ 2 A
(4π )
3 kT 0 K n K r f
=
4
P S
2
eff A
4πλ 2 kT 0 K n K r f
.
(5.13)
In favor of best filtering of receiver internal noises a band of intermediatefrequency amplifier (IFA) of receiver is coincided with duration of sounding (and
receiving pulse from point targets) pulse ∼ =1/τ in the most pulse radars. In this
case, (5.12) and (5.13) formulas will be as follows:
D max =
4
P G 2 λ 2 Aτ
(4π )
3 kT 0 K n K r
=
4
P S
2
eff Aτ
4πλ 2 kT 0 K n K r
.
(5.14)
At calculations, the most difficulties are at calculation of recognition coefficient
value K r .
Calculation of recognition coefficient if necessary is a probabilistic, since a determinated (non-probabilistic) value K r should “embody” all fluctuations processes
preventing to detection, and also all measures for filtering in radar of these processes
are in favor of desired signal extraction—reflected target signal. Recognition coefficient value depends on probability distribution law of a target RCS value and rate
of its fluctuations, on intensity and rate of fluctuations of additional external and
internal noises matching along with common internal noises to a desired signal, on
signal processing principle in radar, particularly on degree of non-ideality of signal