EndRun Meridian II, User Manual

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M e r i d i a n I I U s e r M a n u a l 178
A P P E N D I X E
179 M e r i d i a n I I U s e r M a n u a l
I N S T A L L I N G T H E G P S A N T E N N A
Calibrate Your Receiver
In order for the Meridian II to synchronize with maximum accuracy to UTC, the delay for the cable
and all devices between the antenna and the GPS receiver input (i.e. GPS preamplifiers, signal split-
ters, lightning arrestors, etc.) must be compensated for. You can do this via the keypad/display (see
Chapter 12 - Front-Panel Keypad/Display, Receiver: Calibrate
) or via the console port
caldelay
and
setcaldelay
commands (see Chapter 3 - Console Port Control & Status) .
Calibration is used to compensate for the propagation delay between the GPS antenna and the Merid-
ian II GPS receiver input connector. Positive values remove delay by advancing Meridian II’s 1 PPS
on-time reference by the specified number of nanoseconds. Negative values add delay by retarding
the 1 PPS and are used in special circumstances. The calibration value is determined by summing all
the delays.
The calibration range is ±500,000 nanoseconds. The default value as shipped from the factory is 0.
The table below lists nominal propagation delays for the GPS cable and accessories supplied by
EndRun Technologies. For the most demanding timing applications, it is recommended that the delay
between the antenna and Meridian II receiver input be precisely measured.
EndRun Part # Description Nominal Delay Notes
Antenna Cable
0610-0009-001 Kit with 50’ (15m) cable 62 nanoseconds Belden 9104, 1.24 ns/foot
0600-0013-050 50’ (15m) cable 62 nanoseconds Belden 9104, 1.24 ns/foot
0600-0013-100 100’ (30m) cable 124 nanoseconds Belden 9104, 1.24 ns/foot
0600-0013-150 150’ (46m) cable 186 nanoseconds Belden 9104, 1.24 ns/foot
0600-0013-200 200’ (61m) cable 248 nanoseconds Belden 9104, 1.24 ns/foot
0600-0013-250 250’ (76m) cable 310 nanoseconds Belden 9104, 1.24 ns/foot
0600-0060-800 800’ (244m) cable 992 nanoseconds Belden 1505A, 1.24 ns/foot
0600-0060-A00 1000’ (304m) cable 1240 nanoseconds Belden 1505A, 1.24 ns/foot
GPS Low-Noise Amplifier
3509-0001-000 G-LNA2 20 nanoseconds See device label for exact delay.
4011-0002-000 G-LNA2 Kit
(with 1’ cable)
21 nanoseconds See device label for exact delay
and add 1.24 ns for the 1’ cable.
0502-0009-000
Lightning Arrestor
<1 nanosecond
0502-0011-000 GPS Signal Splitter <1 nanosecond
Fiber Optic Link
3430-0003-000
3430-0004-000
3430-0005-000 Fiber Optic Receiver
Fiber Optic Transmitter
Fiber Optic Transmitter
17 nanoseconds
per
Receiver/Transmitter
pair.
Add the delay of single mode
fiber optic cable which is
typically 1.4/1.5 ns/foot.
See cable specification.