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Hardware Integration Guide
Minimum isolation between the GNSS and WWAN Antenna must be 10 dB for the AirPrime AR7558.
Table 22.
GNSS Antenna Interface Pads
Pad
Name
BA4
GND
BA5
GNSS_ANT
BA6
GND
5.2.1.
GNSS Antenna Recommendations
The table below defines the key characteristics to consider for antenna selection.
Table 23.
GNSS Recommended Antenna Characteristics
Characteristics
Frequency
RF Impedance
VSWR max
LNA Bias Voltage
LNA Noise Figure
LNA Current Consumption
Antenna System Gain (Antenna + LNA - Cable)
Polarization
5.3.
GNSS Antenna Diagnostics
The GNSS Antenna Diagnostic feature measures the current drawn by an active GNSS antenna to
determine the state of this antenna interface. Based on the current draw an assessment of open,
short, normal or over-current is made. If an over-current is detected, the bias for the active antenna is
removed to eliminate the fault for drawing excess current which could potentially damage the antenna.
The limits between open/normal and normal/short can be set by the application through an AT
Command.
ADC Value
GNSS Antenna State
The Over Current limit is set by hardware and cannot be altered.
Table 24.
GNSS Antenna Diagnostics Ranges
Control
HW
The GNSS antenna supply is powered from VBATT through a boost regulator.
4116922
Direction
Input
GPS L1 (Wideband)
Glonass L1 FDMA
RX
<
Open
State
Over Current
Function
GNSS Antenna Ground
GNSS Antenna Interface
GNSS Antenna Ground
GNSS
1575.42 ± 20 MHz
1597.5 – 1605.8 MHz
50 Ω
1.5: 1
4.4 – 4.9V
2.0 dB Max
50 mA Max
20 – 24 dB
Right Hand Circular Polarization
openLim
Min
78
Rev 1.1
< >
shortLim
Normal
Max
100
January 21, 2015
GNSS Specification
>
Short
Units
mA
25
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