Masterclock GPSPCI Spécifications télécharger pdf (Page 5)

GPSPC 2/17/2003 2 Masterclock, Inc.

satellite acquisition and lock (generation of time information by the GPSPC). It is possible that the system will

operate indoors and under other obstructions. However this can only be determined empirically; it is not

guaranteed.

If a longer cable is required, cables of various lengths (up to 500 feet) with pre-amplified antennas are

available from Masterclock. Bringing the GPSPC up for the first time with an indoor antenna may prevent

or significantly increase the time to first fix.

INITIAL OPERATIONS AND I/O CONNECTIONS

1. Locate the antenna in a suitable area so that the top of the antenna module has a clear view of the sky.

Do not move it until after the GPSPC has initiated operation (explained below).

2. Connect the antenna coax to the SMA connector on the PC card bracket.

3. The unit first calculates coordinates and distances for acquisition of GPS satellites. The LED will remain

off until satellites are acquired and precise location and timing references are established.

NORMAL OPERATION

After acquisition of satellites the GPSPC will begin generating time information and the card LED will

illuminate steadily.

FREEWHEELING

During continuous operation it is likely that the GPSPC will experience occasional outages and loss of satellite

reference time. This can be caused by atmospheric and many other outside conditions which are essentially

unavoidable with a simplex system. Such signal losses can last from a few minutes to hours. When the

condition disappears and the unit re-acquires satellite timing reference, it will automatically resync to the

satellite time reference.

During such outages the GPSPC will continue to generate time information referenced to the last available

satellite timing information. This mode is referred to as freewheeling. When the unit first acquires satellite

time, it calibrates an internal reference oscillator against the incoming atomic time. During freewheeling the

time information will be referenced to this calibrated oscillator and will typically be accurate to within a few

milliseconds over a 24 hour period (if the power is not disconnected). As is covered in other areas of this

instruction book, the freewheeling status is encoded/decoded by the TCRSYNC software supplied by

Masterclock and the operator is given the option of synchronizing to the time information during the

freewheeling state.

The transition to and from freewheeling mode is seamless - it does not interrupt time information output.

FREEWHEELING/NON LOCKED LED INDICATION

During a freewheeling period the card LED will be off.

HARDWARE

OPERATING ENVIRONMENT

The GPSPC is not water or moisture proof. Treat it as you would any other delicate electronic device and do

not expose it to water, excessive heat or physical abuse.

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