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INSTALLATION & SET-UP
9
3. 2 LV2000 Crypto Resynch Operation
When operating with a serial encryption unit, it is possible that the decryption function will
lose synchronisation, with the result that the data being received by the LV2000 unit is
invalid. When synchronisation is lost, it is useful for the LV2000 to be able to detect this and
automatically take action to resynchronise and restore the data link.
The LV2000 uses HDLC encapsulation for the serial data link and uses this protocol to detect
synchronisation loss. HDLC uses a checksum to validate all frames and the LV2000 will
declare loss of synch if 10 consecutive frames are received containing errors.
Providing that Crypto resynch function is ENABLED, when the LV2000 finds that it has lost
synch it will pulse the RS output signal for half a second before then restoring it to its normal
state. It will then wait for 5 seconds to allow the crypto to perform its initialisation and
synchronisation functions before checking for synch again. If the link is still out of synch, the
process will repeat with another RS pulse.
To ensure maximum flexibility, the state of the RS pulse can be set to either High or Low to
initiate Resynch action. When Crypto resynch is DIASABLED, the RS output will assume the
normal High (ON) state.
In addition, in order to support the widest range of Crypto equipment, the RS signal may be
set to be driven as either Differential LVDS, or as a single ended LVTTL signal.
3. 3 Connecting up
Safety Notice:
Ports that are identified as SELV in this manual should only be connected to
SELV ports on other equipment in accordance with EN 60950 clause 2.3.
Step 1: Mounting
.
The LV2000 is housed in a convenient 1U table top enclosure. 19 inch rack nests for two
or 18 units are available as options.
Step 2: Set up Bit-switches
These switches are located on the base of the unit and are used to configure the unit.
Step 3: Power Supply
Finally, connect the main power lead and re-check all connections for security. Then turn on
the power supply.
Warning:
Do not connect the LV2000 to excessive voltage. Read the safety information
before continuing.
Step 4: LAN ports
Connect the LV2000 to the RJ45 LAN port on the rear panel. The indicator lights on the lower
corners of the RJ45 socket indicate the LAN speed and activity status.
Step 5: LVDS port
Connect the satellite modem to the EIA-644 LVDS port using an appropriate cable type for
the satellite modem interface. The DTE activity LED on the rear panel will indicate the link
status.