Appendix D - Antenna Delay Compensation; Signal Attenuation; Propagation Delay; Table 45: Antenna Cables Attenuation @ 1500 Mhz (±1 Db) - GE Reason RT430 Technical Manual

RT430/434
Appendix D – Antenna Delay Compensation

Signal Attenuation

Propagation Delay

96
The antenna cable affects the unit's performance in two different ways: signal
attenuation and signal propagation delay.
Signal attenuation is related to cable type and overall cable length. When using the
active antenna supplied by GE Grid Solutions, total attenuation should not exceed 32
dB.
Total attenuation can be computed by using:
Where �� is the attenuation per unit length for the given cable and �� is the overall
��
cable length.
The table below shows a few typical cable configurations and the associated total
attenuation.
Table 45: Antenna cables attenuation @ 1500 MHz (±1 dB)
Cable length
15 m (50 ft)
25 m (82 ft)
40 m (131 ft)
75 m (246 ft)
100 m (328 ft)
125 m (410 ft)
150 m (492 ft)
The antenna cable delays the signal received from the satellites. In applications in
which the ultimate time accuracy is desired, this delay should be compensated inside
the unit.
Typically, the delay introduced by coaxial cables is in the magnitude of 4 ns/m (1.2
ns/ft) of cable length.
The exact delay can be computed by using:
8
Where �� = 3×10 m/s is the speed of light, ��
depends on the cable and �� is the cable length in meters.
The table below summarizes some typical delays caused by coaxial cables.
�� = �� ��
��
Cable RG58
7 dB
12 dB
19 dB
―
―
―
―
1
�� = ��
����
��
= 0.8 ... 0.85 is a constant which
��
Chapter 10 - Appendixes
Cable RG8
―
―
―
13 dB
18 dB
22 dB
26 dB
RT430/434