MAX-7 / NEO-7 / LEA-7 - Hardware Integration Manual
GPS.G7-HW-11006-1
Design
Page 29 of 55
3.4.3.1
Status reporting
At startup and on every change of the antenna supervisor configuration the u-blox 7 GPS/GALILEO module will
output an NMEA
($GPTXT
) or UBX (
INF-NOTICE
) message with the internal status of the antenna supervisor
(disabled, short detection only, enabled).
None, one or several of the strings below are part of this message to inform about the status of the active
antenna supervisor circuitry (e.g. “
ANTSUPERV= AC SD OD PdoS
”).
Abbreviation
Description
AC
Antenna Control (e.g. the antenna will be switched on/ off controlled by the GPS receiver)
SD
Short Circuit Detection Enabled
SR
Short Circuit Recovery Enabled
OD
Open Circuit Detection Enabled
PdoS
Power Down on short
Table 7: Active Antenna Supervisor Message on startup (UBX binary protocol)
To activate the antenna supervisor use the UBX-CFG-ANT message. For further information refer to the
u-blox 7 Receiver Description Including Protocol Specification [4].
Similar to the antenna supervisor configuration, the status of the antenna supervisor will be reported in an
NMEA (
$GPTXT
) or UBX (
INF-NOTICE
) message at start-up and on every change.
Message
Description
ANTSTATUS=DONTKNOW
Active antenna supervisor is not configured and deactivated.
ANTSTATUS=OK
Active antenna connected and powered
ANTSTATUS=SHORT
Antenna short
ANTSTATUS=OPEN
Antenna not connected or antenna defective
Table 8: Active antenna supervisor message on startup (NMEA protocol)
3.4.3.2
Module design with active antenna, short circuit protection / detection (LEA-7N, MAX-7W)
If a suitably dimensioned series resistor
R_BIAS
is placed in front of pin
V_ANT
, a short circuit can be detected in
the antenna supply. This is detected inside the u-blox 7 module and the antenna supply voltage will be
immediately shut down. After which, periodic attempts to re-establish antenna power are made by default.
An internal switch (under control of the receiver) can turn off the supply to the external antenna whenever it is
not needed. This feature helps to reduce power consumption in power save mode.
To configure the antenna supervisor use the UBX-CFG-ANT message. For further information see u-blox
7 Receiver Description Including Protocol Specification [4]
Short circuits on the antenna input without limitation (R_BIAS) of the current can result in
permanent damage to the receiver! Therefore, it is mandatory to implement an R_BIAS in all
risk applications, such as situations where the antenna can be disconnected by the end-user or
that have long antenna cables.
In case VCC_RF voltage does not match with the antenna supply voltage, use a filtered external supply
as shown in Figure 26
