X
X
L
L
D
D
C
C
M
M
A
A
N
N
.
.
d
d
o
o
c
c
2
2
-
-
1
1
R
R
E
E
V
V
E
E
SECTION II
INSTALLATION
2-1 OVERVIEW
The XL-DC Time and Frequency receiver consists of the XL-DC receiver, antenna unit and cable. The
XL-DC is capable of basic operation without any RS-232 connection. Since the standard internal
oscillator is a Temperature Compensated Crystal Oscillator (TCXO), it is essential that it be isolated
from rapid fluctuations in air temperature. For this reason, operation with all covers in place is required
in order to obtain specified stability performance levels. When an optional higher stability ovenized
oscillator is used in the XL-DC, this is not necessary.
2-2 PROCEDURE
Place the XL-DC antenna unit with an unobstructed view of the sky. Connect the cable between the
Antenna unit and XL-DC antenna input connector. If Serial I/O communications are desired, make the
necessary connections to your equipment after referring to the Serial Interface information in manual
Section I. The XL-DC-601 and XL-DC-602 will also have display and keypad functionality. These are
thoroughly described in manual Section III.
The receiver can be powered by 95-260 VAC or 120-370 VDC. See Section I for specific limits on the
voltage and frequency ranges.
The power fuse for the AC or DC power input must be the correct amperage rating: 1.0 amp slow-blow.
The instrument is shipped configured with the 1.0 amp fuse installed.
With main power switch to the XL-DC off, connect an appropriate AC or DC power source to the XL-DC
receiver via the IEC power connector. Turn on the power switch. Within a few seconds, the XL-DC will
output elapsed time from power-on via Serial Function F08. (Serial inputs will be ignored until the F08
output is terminated with a CTRL-C character (Hex 03).) If satellites are visible, the output time will
switch from elapsed time to UTC time within a few minutes.
If the XL-DC has been placed in AUTO mode via Function 53, the recommended setting for new
installations, it will not phase lock its internal oscillator to the received time signal until it has computed
a 3-D position. You may wait up to 15 minutes for the XL-DC to independently ascertain its position by
acquiring four satellites, or you may speed up the process by using Function 50 to enter the
approximate location to an accuracy of 1
o
(about 100 km) or better.
When the XL-DC has phase locked its oscillator to the GPS signals and has set its 1 PPS output to the
specified accuracy, the terminating character of the Serial Function F08 continuous time output string
will change from a "?" to a "space" at this time. If satellites are visible and the XL-DC has an accurate
position, lock should be achieved within three minutes. XL-DC units with optional internal or external
ovenized oscillators will require a longer time to lock due to the oscillator warm-up time.
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