Trimble Outdoors thunderbolt 64057-00-eng 사용자 설명서
3 Hardware Integration
28 Trimble ThunderBolt E GPS Disciplined Clock User Guide
In cases where the distance between the Bullet and the ThunderBolt E is excessive ( for
example when the loss exceeds 18 dB), an inline amplifier is necessary.
example when the loss exceeds 18 dB), an inline amplifier is necessary.
The following table shows the loss relationships:
In cases where the run length is such that the loss exceeds 18 dB, an inline amplifier
(LNA) with the following specifications is required:
(LNA) with the following specifications is required:
•
Place the LNA at a point in the coaxial line so that the loss between the Bullet
antenna and the LNA does not exceed 18 dB.
antenna and the LNA does not exceed 18 dB.
•
The noise figure of the LNA must be 3 dB or less. The gain of the LNA should be
at least 3 dB greater than the cable loss between the output of the inline LNA
and the ThunderBolt E input. Trimble recommends that a filtered LNA is used
to reduce overload by out-of-and signals. (Filtered LNAs are made by GPS
Networking.)
at least 3 dB greater than the cable loss between the output of the inline LNA
and the ThunderBolt E input. Trimble recommends that a filtered LNA is used
to reduce overload by out-of-and signals. (Filtered LNAs are made by GPS
Networking.)
For example, if you choose an RG-6 cable with 40 dB/100 meter loss, and the
required run-length is 90 meters, the total loss for his run would be
(0.9)(40 dB/100 meters) = 36 dB. This exceeds 18 dB and means that you need to
use an inline amplifier.
required run-length is 90 meters, the total loss for his run would be
(0.9)(40 dB/100 meters) = 36 dB. This exceeds 18 dB and means that you need to
use an inline amplifier.
However, if you select an LMR-400 or LMR-600 cable, you would
not need an
inline amplifier.
•
The noise figure of the inline amplifier must be 3 dB or less. The gain of this LNA
would be 21 dB (18 dB loss precedes LNA, 18 dB of loss follows LNA, and drives
requirement for 18 + 3 = 21 dB gain for the LNA).
would be 21 dB (18 dB loss precedes LNA, 18 dB of loss follows LNA, and drives
requirement for 18 + 3 = 21 dB gain for the LNA).
Cable type
dB / 100 ft
dB / 100 meter
Max lenght for 18 dB loss at
1575 MHz (feet / meter)
1575 MHz (feet / meter)
RG-6
12
40
150/45
RG8 (and 8/U)
9.6
31
185/58
RG-8X
16.8
55
107/33
RG-58
19.6
64
92/28
RG-59
14.7
48.2
122/37
LMR-400
5.3
17.2
340/105
LMR-600
3.4
11.2
530/161
/161