Jackson Labs LC_XO, Руководство пользователя

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© 2012 Jackson Labs Technologies, Inc. 3
LC_XO GPSDO User Manual
2
Quick-Start
Instructions
2.1 Powering Up the Unit
The unit is powered from an external 3.3V supply on pin 8. The module will present significant
current variations to the external 3.3V power supply during normal operations and it is recommended
that the user bypass pins 8 and 6 with small Tantalum capacitors. The user may use up to 100mA for
external circuitry from the internal low-noise 3.3V to 5V voltage regulator.
The user should provide an L1 antenna signal routed on a microstrip or stripline to pin 10 on the unit.
The antenna can be active or passive, with an amplification range of up to 50dB to compensate for
cable loss. The LC_XO provides 5V with up to 40mA to the antenna and the output is short-circuit
protected.
The unit will start to search for Satellites as soon as power is applied, and will start to lock the
internal OCXO/TCXO to UTC as soon as the 1PPS LED starts blinking with a GPS antenna
attached. After 1 hour or less, the unit should stabilize the frequency, and all event indicators should
be off resulting in the Green LOCK LED to be lit up. At this time the Green LOCK LED will indicate
the unit is fully synchronized to UTC, and generating a stable and accurate 10MHz output signal. The
Green LOCK LED may go off momentarily as airflow touches the unit or Sats come in and out of
view, this is normal behavior.
You may place the GPS antenna in a window, but it is recommended to place the GPS antenna with a
full view of the sky for best performance. The antenna cable can be extended to 10m or more with
high quality antenna cable (use quad shielded RG-6 75 Ohms cable, or high-quality 50 Ohms coax
cable) without significant loss of signal quality.
2.1.1 LC_XO Photos
The LC_XO GPSDO board is shown in : Figure 2.1 .