Mocomtech CDM-570 - Manual (Page 184)

CDM-570/570L Satellite Modem with Optional IP Module Revision 4
Front Panel Operation MN/CDM570L.IOM
6–60
value. This will affect the Tx synthesizer (and hence the Tx output frequency),
the Rx synthesizers, and the generation of the Internal Tx baseband clock. For a
CDM-570L operating on its own, this may not be a problem, but if the 10 MHz
reference signal is being used to drive an externally-connected BUC, the
frequency error at the RF output may be large, particularly at Ku or Ka-band.
In order to avoid this problem, the user may choose to enable a warm-up delay,
which will suspend normal operation of the unit until the operating temperature
of the OCXO has stabilized. This is accomplished by selecting Enable, then
pressing ENTER.
Warm-up delay is not fixed. Instead, CDM-570L uses an intelligent algorithm to
minimize this delay, under all circumstances. CDM-570L uses its internal
temperature sensor, and a knowledge of how long the unit has been powered
down, to determine how long the warm-up delay should be.
For example, the worst case occurs when the unit has been powered down
sufficiently long that the unit has reached thermal equilibrium with its
surroundings, and the external temperature is at the lowest value possible. In this
circumstance the CDM-570L will take 2 minutes to warm-up.
If the external temperature is hot, and the unit was powered down, then a short
time later, powered up again, the warm-up period will be very short, perhaps only
several seconds.
In order to alert the user, when the warm-up delay has been enabled, the opening
screen will display the following:
The bottom right of the display counts down, in seconds, until the warm-up
period is complete. During this period, the Tx Carrier is deliberately muted. At
the end of the warm-up period, the bottom line will revert to the ‘normal’ display
of Firmware version, and the unit will enter its normal operational state.
IMPORTANT NOTE: If the user wishes to bypass this feature, the warm-up
period may be over-ridden at any time by pressing the CLEAR key.
Comtech CDM-570L Modem
Ref Warming-up: 045 secs
IMPORTANT