MAX-7 / NEO-7 / LEA-7 - Hardware Integration Manual
GPS.G7-HW-11006-1
Design
Page 28 of 55
3.4.3
Antenna design with active antenna using antenna supervisor (LEA-7N, MAX-
7W)
An active antenna supervisor provides the means to check the antenna for open and short circuits and to shut
off the antenna supply if a short circuit is detected. The Antenna Supervisor is configured using serial port UBX
binary protocol message. Once enabled, the active antenna supervisor produces status messages, reporting in
NMEA and/or UBX binary protocol (see section 3.4.3.1). These indicate the particular state of the antenna
supervisor shown in the state diagram below (Figure 24).
The current active antenna status can be determined by polling the UBX-MON-HW monitor command. If an
antenna is connected, the initial state after power-up is “Active Antenna OK.”
No
Super-
vision
Active
Antenna
OK
Open
Circuit
detected
Short
Circuit
detected
Powerup
Events AADET0_N
User controlled events
Disable Supervision
Enable Supervision
Short Circuit
detected
Disable
Supervision
Antenna
connected
Short Circuit
detected
open circuit
detected, given
OCD enabled
Periodic
reconnection
attempts
Figure 24: State diagram of active antenna supervisor
The module firmware supports an active antenna supervisor circuit, which is connected to the pin
AADET_N
. For
an example of an open circuit detection circuit, see
. High on
AADET_N
means that an external
antenna is not connected.