User's Manual

Table Of Contents
Orion Reader Options
Use or disclosure of Proprietary Information contained on this sheet is subject to the restriction stated on the title page of this document. D-21
Electrical Protection
ESD
With the GPS assembly installed and operated as part of a complete Orion chassis
assembly, the assembly complies with the requirements of the International Electro-
technical Commission/
Comite, Europe, en de Normalisation (IEC/EN) 61000-4-2,
Class 4 standard (Table D-9).
Antenna Drive and Protection Circuitry
The receiver uses an antenna sense circuit that detects under-current (open), over-cur-
rent (shorted or exceeding maximum), or valid antenna connection. The receiver sup-
plies up to 80 milliamps (mA) of current via the antenna power supply circuit.
If the antenna draws 15 mA or more, a status bit in the antenna status information is
set, giving a good indication that an antenna is attached.
If the antenna draws less than 15 mA, an alarm bit is set indicating an under-current
condition in the antenna status information.
If more then 80 mA is drawn through the antenna port, then the over-current detection
circuitry will reduce the antenna feed current to approximately 45 mA until the fault is
cleared.
Detection of an under-current situation will not prevent the receiver from operating.
The receiver will continue to operate normally, but will issue an error flag indicating a
possible antenna problem.
Antenna Drive Current Limits
Undercurrent detect @+77
o
F (25
o
C)
Good Indication: greater than 15 mA
Undercurrent Indication: less than 15 mA
Over-current Detect @+77
o
F (25
o
C): 80 mA maximum for normal operation
Table D-9 ESD Limits and Conditions
Discharge Voltage
16.0 kV
Polarity
Positive
Number of Repetitions
2 pulses
ESD System
NSG438 system, which complies with a 150-picofarad/330-ohm
discharge network of the IEC/EN 61000-4-2 standard
Test conditions
All ESD tests are performed at +77F (+25C)