Integration Guide

4117336 Rev 1.0 May 18, 2015 13
Hardware Integration Guide
RF Specification
3.4. Primary Antenna Diagnostics
The primary antenna diagnostic feature allows the AirPrime AR7552 embedded module to determine
if the primary antenna connected to the module is: open, shorted or normal. The antenna connected
to this interface needs to have a DC resistance to ground of 10 kΩ ± 1k embedded inside.
The ARx55x FW accepts two limits which are used to evaluate the status of the antenna, representing
the short and open thresholds. Refer to document [7] for the syntax of AT+ANTLIMT.
Table 12. Primary Antenna ADC Characteristics
Min
Nom
Max
Units
ADC Voltage Range
0
0.9
1.8
Volts
Resolution
-
15
Bit
ADC Values
0
16383
Voltage/ADC step
~0.0011
Volts
1 Assumes 10kΩ Nominal DC resistance in the attached antenna and internal to AirPrime AR7552 device
The following example illustrates the Antenna states and resistance values for a typical limit setting.
AT+ANTLIMT=1,839,1088
Table 13. Primary Antenna Diagnostics Ranges
Antenna State
Min ADC
Max ADC
Antenna Resistance Range
Short
0
839
~ ≤ 7 kΩ
Normal
841
1086
7 kΩ < x < 13 kΩ
Open
1088
1900
≥ 13 kΩ
Note: Highlighted numbers in the table above are programmed as shortLim and openLim using the
+ANTLIMT command.
3.5. RX2 Antenna Diagnostics
The RX2 antenna diagnostic feature allows the AirPrime AR75520 to determine if the RX2 antenna
connected to the module is: open, shorted or normal. The antenna connected to this interface needs
to have a DC resistance to ground of 10 kΩ ± 1k embedded inside.
The AirPrime AR7552 FW accepts two limits which are used to evaluate the status of the antenna,
representing the short and open thresholds. Refer to document [7] for the syntax of AT+ANTLIMT.
Table 14. RX2 Antenna ADC Characteristics
Min
Nom
Max
Units
ADC Voltage Range
0
0.9
1.8
Volts
Resolution
-
15
Bit
ADC Values
0
16383
Voltage/ADC step
~0.0011
Volts
1 Assumes 10kΩ Nominal DC resistance in the attached antenna and internal to AirPrime AR7552 device