LEA-M8S / LEA-M8T - Hardware Integration Manual
UBX-13003140 - R07
Production Information
Design
Page 16 of 31
External supply
Figure 13 shows an externally powered active antenna design.
Since the external bias voltage is fed into the most sensitive part of the receiver (i.e. 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 13: Module design with active antenna, external supply (for exact pin orientation see the LEA-M8S Data Sheet [1] and
the NEO/LEA-M8T Data Sheet [2])
Antenna supervision with open circuit detection (OCD)
Optionally the
AADET_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 then reported by the module in message MON-
HW. Calculate the threshold current using Equation 1.
Figure 14: Schematic of open circuit detection (for exact pin orientation see the LEA-M8S Data Sheet [1] and the NEO/LEA-M8T
Data Sheet [2].)
