LEA-M8S / LEA-M8T - Hardware integration manual
UBX-15030060 - R06
Design
Page 18 of 33
Production information
Short-circuit is detected if the voltage at the antenna supply falls close to zero and is indicated as an
alarm in message MON-HW.
Figure 11: Module design with active antenna, internal supply from VCC_RF
External supply
Figure 12 shows an externally powered active antenna design.
Since the external bias voltage is fed into the most sensitive part of the receiver (the RF input), this
supply should be free of noise. Usually, low frequency analog noise is less critical than digital noise of
spurious frequencies with harmonics up to the GPS/QZSS band of 1.575 GHz, GLONASS band of
1.602 GHz and BeiDou band at 1.561 GHz. Therefore, it is not recommended to use digital supply nets
to feed the V_ANT pin.
Figure 12: Module design with active antenna, external supply
2.4.4
Power, short and open detection antenna supervisor
Optionally the ANT_DET_N pin may be reassigned to antenna supervision, allowing an external circuit
to indicate to the module that the antenna is open-circuit. This condition is reported by the module in
message MON-HW. Calculate the threshold current using Equation 1.
