Garmin International Inc 01443 Manual De Usuario
GTX 3000 Installation Manual
Page 2-5
190-00926-01
Revision A
The maximum one-way propagation delay through the cables must not be more than 125 ns. The
maximum difference in the one-way propagation delay between the top and bottom antenna cables must be
less than or equal to 75 ns. Use Table 2-6 to determine the maximum difference in length between the top
and bottom antenna cables.
maximum difference in the one-way propagation delay between the top and bottom antenna cables must be
less than or equal to 75 ns. Use Table 2-6 to determine the maximum difference in length between the top
and bottom antenna cables.
Absolute cable delay: Each antenna cable must have less than 75 ns of delay. The 75 ns spec is for one-
way cable delay – not delay down the cable and back up it (which one might consider given the receive and
transmit functions). If you meet the 3 dB cable loss requirement, you’ll almost certainly meet the 75 ns
delay requirement.
way cable delay – not delay down the cable and back up it (which one might consider given the receive and
transmit functions). If you meet the 3 dB cable loss requirement, you’ll almost certainly meet the 75 ns
delay requirement.
Differential cable delay: If the cable delay difference between the two cables is less than 25 ns, the unit
does not require cable delay to be configured. The unit’s default values will suffice. Otherwise, we’ll
simply have to configure each channel’s cable delay.
does not require cable delay to be configured. The unit’s default values will suffice. Otherwise, we’ll
simply have to configure each channel’s cable delay.
* Maximum difference in cable length is limited by maximum cable length.
2.4.1 Cable Routing Considerations
When routing cables, observe the following precautions:
• All cable routing should be kept as short and as direct as practical.
• Avoid sharp bends to prevent insulation from being breached.
• Avoid routing close to sharp edges to prevent insulation from being breached due to vibration or
• Avoid sharp bends to prevent insulation from being breached.
• Avoid routing close to sharp edges to prevent insulation from being breached due to vibration or
handling the cable.
• Avoid routing cables near power sources (e.g., 400 Hz generators, trim motors, etc.) or near power
for fluorescent lighting.
• Avoid routing antenna cables near DME, TCAS, radar altimeter, and ADF antenna cables (allow at
least a 12-inch separation).
Table 2-6 Maximum Difference in Cable Lengths
Max. Difference
in Length
(feet – [m])
Velocity of
Propagation
(ns/ft)
ECS Type
MIL-C-17 Type
RG Type
14' 5.2" [4.40m]*
1.46
M17/128-RG400
RG-400
17' 11.7" [5.48m]*
1.46
3C142B
21' 7.8" [6.60m]*
1.46
M17/112-RG304
RG-304
29' 6.7" [9.01m]*
1.25
311601
M17/127-RG393
RG-393
36' 6.2" [11.13m]*
1.25
311501
47' 4.9" [14.25m]*
1.25
311201
59' 11.7" [18.28m]
1.25
310801
DRAFT