User Manual
System Tests68P09255A57-2
Aug 2002
SC4812ET Optimization/ATP Manual Software Release R16.1.x.x
PRELIMINARY
3-41
The LFR requires an active external antenna to receive LORAN RF
signals. Timing pulses are derived from this signal, which is
synchronized to Universal Time Coordinates (UTC) and GPS time. The
LFR can maintain system time indefinately after initial GPS lock.
The HSO is a high stability 10 MHz oscillator with the necessary
interface to the CSMs. The HSO is typically installed in those
geographical areas not covered by the LORAN-C system. Since the
HSO is a free-standing oscillator, system time can only be maintained
for 24 hours after 24 hours of GPS lock.
Upgrades and Expansions: LFR2/HSO2/HSOX
LFR2/HSO2 (second generation cards) both export a timing signal to the
expansion frames. The associated expansion frames require an
HSO-expansion (HSOX) whether the starter frame has an LFR2 or an
HSO2. The HSOX accepts input from the starter frame and interfaces
with the CSM cards in the expansion frame. LFR and LFR2 use the
same source code in source selection (see Table 3-26). HSO, HSO2, and
HSOX use the same source code in source selection (see Table 3-26).
NOTE
Allow the base site and test equipment to warm up for 60
minutes after any interruption in oscillator power. CSM board
warm-up allows the oscillator oven temperature and oscillator
frequency to stabilize prior to test. Test equipment warm-up
allows the Rubidium standard timebase to stabilize in frequency
before any measurements are made.
CSM Frequency Verification
The objective of this procedure is the initial verification of the CSM
boards before performing the RF path verification tests. Parts of this
procedure will be repeated for final verification after the overall
optimization has been completed.
Test Equipment Setup
(GPS & LFR/HSO Verification)
Follow the steps outlined in Table 3-25 to set up test equipment.
Table 3-25: Test Equipment Setup (GPS & LFR/HSO Verification)
Step Action
1a For local GPS (RF-GPS): Verify a CSM board with a GPS receiver is installed in primary CSM slot 1
and that CSM-1 is INS.
NOTE
This is verified by checking the board ejectors for kit number SGLN1145 on the board in slot 1.
1b For Remote GPS (RGPS):Verify a CSM2 board is installed in primary slot 1 and that CSM-1 is INS.
NOTE
This is verified by checking the board ejectors for kit number SGLN4132ED or later.
2 Remove CSM-2 (if installed) and connect a serial cable from the LMF COM 1 port (via null modem
board) to the MMI port on CSM-1 (see Figure 3-7).
3