RXM-GPS-F4-T Linx Technologies, RXM-GPS-F4-T Datasheet - Page 12

• Manufacturer Part Number: RXM-GPS-F4-T
• Description: GPS Modules F4 Series GPS Recvr Module Tape and Reel
• Manufacturer: Linx Technologies

Specifications of RXM-GPS-F4-T

• Rohs: yes
• Frequency Band: 1575.42 MHz
• Number Of Channels: 48
• Time To First Fix (cold Start): 32 s
• Acquisition Sensitivity: - 159.5 dBm
• Horizontal Position Accuracy: 3 m
• Operating Supply Voltage: 1.8 V
• Operating Supply Current: 56 mA
• Interface Type: Serial
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Dimensions: 15 mm x 13 mm x 2.2 mm
• Minimum Operating Temperature: - 30 C

Antenna Considerations
The F4 Series module is designed to utilize a wide variety of external
antennas, but care must be taken in antenna selection to ensure optimum
performance. For example, a handheld device may be used in many
varying orientations so an antenna element with a wide and uniform
pattern may yield better overall performance than an antenna element with
high gain and a correspondingly narrower beam. Conversely, an antenna
mounted in a fi xed and predictable manner may benefi t from pattern and
gain characteristics suited to that application. Evaluating multiple antenna
solutions in real-world situations is a good way to rapidly assess which will
best meet the needs of your application.
For GPS, the antenna should have good right hand circular polarization
characteristics (RHCP) to match the polarization of the GPS signals.
Ceramic patches are the most commonly used style of antenna, but
there are many different shapes, sizes and styles of antennas available.
Regardless of the construction, they will generally be either passive or
active types. Passive antennas are simply an antenna tuned to the correct
frequency. Active antennas add a Low Noise Amplifi er (LNA) after the
antenna and before the module to amplify the weak GPS satellite signals.
For active antennas, a 300 ohm ferrite bead can be used to connect the
the RFIN line to an external supply for the antenna. This bead prevents the
RF from getting into the power supply, but allows the DC voltage onto the
RF trace to feed into the antenna. A series capacitor inside the module
prevents this DC voltage from affecting the bias on the module’s internal
LNA.
Maintaining a 50 ohm path between the module and antenna is critical.
Errors in layout can signifi cantly impact the module’s performance. Please
review the layout guidelines elsewhere in this guide carefully to become
more familiar with these considerations.
Power Control
The F4 Series GPS Receiver module offers four power control modes:
Full Power, Adaptive Trickle Power, Push-to-Fix and Hibernate. In Full
Power mode the module is fully active and and continuously tracking.
Measurements are of the highest quality and are continuously output by the
module. This is the highest current consumption state.
In Adaptive Trickle Power mode, the receiver powers on at full power to
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