GPS RF Front End User Manual
Rev 1.0
8
Figure 3: Micro-D Socket Locations
Note: with respect to orientation depicted in Figure 2 above
4.2 DC POWER
The nominal supply voltage for the GPS RF Front End is +28 VDC; The acceptable supply voltage range is
+27 to +32 VDC. If a voltage above 32VDC is applied, the drain bias to internal amplifiers will be removed
and the transmit path will be non-operational. Input voltage below +27VDC will result in degraded RF
performance and specifications are not guaranteed below the spe27 to +32VDC range.
4.3 GROUND
The signal and power grounds are tied together in the GPS RF Front End module.
4.4 RF ENABLE
This signal is the logic control input that designates whether the unit is in transmit or standby mode. The
RF Enable line is pulled high internally placing the GPS RF Front End module in
standby
mode. If the pin is
left floating (i.e. not connected), the unit will default to
standby
mode.
Grounding the pin (i.e. a voltage below +0.2 VDC) places the unit in
transmit
mode. The user can either
connect the RF Enable line to pins 1, 2, 6 & 8 on the CTRL/PWR interface connector, or an open drain
logic line capable of sinking 500
μ
A to place the unit in
transmit
mode.
4.5 TEMP FLAG
This signal is an output to indicate an over-temperature condition in the GPS RF Front End. A logic high
(+5 VDC) indicates normal operation, while a logic low (0 VDC) indicates an over-temperature condition.
The GPS RF Front End incorporates internal logic circuitry that turns off the DC bias to the RF transistors.
Caution: The amplifier should be shut down and allowed to cool off when the
overtemperature flag is set low to avoid damage to the module.
