Odetics
Telecom
GPStar
plus
Model 365
365-8006
Getting Started 4 - 5
To alter the amount of cable delay compensation or offset:
•
Press the Edit key until Internal Offset
+
is flashing.
•
Use the arrow keys to select a positive (+) or negative (-) offset.
•
Press the Enter key to accept the selected offset polarity.
•
Use the numeric and arrow keys to specify the desired delay compensation
(or offset) in nanoseconds.
•
Press the Enter key to accept the new value.
Negative numbers cause the timing outputs to occur later in time to align the unit's
output timing with user's system timing that is offset from GPS or UTC 1 PPS reference.
Positive numbers cause the timing outputs to occur sooner in time.
Positive numbers
are used to compensate for cable delays.
There are several types of recommended cable to connect the unit to the external
antenna: RG-8 (Belden
®
9913), RG-58 (Belden
®
9311), RG-59 (Belden
®
9104), RG-213
(Belden
®
8267), and foam dielectric cable such as Heliax manufactured by Andrew
Corporation. The propagation delay of these cable types is:
Cable Type
Propagation Delay
RG-58
1.33 ns/ft (4.36 ns/m)
RG-213
1.52 ns/ft (4.99 ns/m)
RG-8
1.19 ns/ft (3.90 ns/m
RG-59
1.22 ns/ft (4.00 ns/m)
1/2" Heliax
1.34 ns/ft (4.39 ns/m)
7/8" Heliax
1.12 ns/ft (3.67 ns/m)
Using the above delay values per foot (or meter), the delay for the actual cable length
used can be calculated.
For example, if the antenna system includes 50 feet of RG-58 cable, the antenna cable
delay is computed as follows: 1.33 ns/ft x 50 ft = 67 ns. In this example the user would
enter
+00067
ns for the Internal Offset.
Note: If the unit is operating in the Time Locked mode a temporary fault may occur
when the Internal Offset is changed, resulting in the unit's operating mode switching
from Time Locked to Coasting. Should this occur the unit would correct itself in
approximately ten minutes.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
