SARA-R4 series - System integration manual
UBX-16029218 - R20
Product testing
Page 121 of 128
C1-Public
The minimum recommended RF verification in production consists in forcing the module to transmit
in a supported frequency the +UTEST AT command, and then checking that some power is emitted
from the antenna system using any suitable power detector, power meter or equivalent equipment.
☞
See the SARA-R4 series AT commands manual
for the +UTEST AT command syntax
description and detail guide of usage.
This feature allows the measurement of the transmitter and receiver power levels to check the
component assembly related to the module antenna interface and to check other device interfaces
on which the RF performance depends.
⚠
To avoid module damage during a transmitter test, a suitable antenna according to module
specifications or a 50
termination must be connected to the ANT port.
⚠
To avoid module damage during a receiver test, the maximum power level received at the ANT port
must meet module specifications.
☞
The +UTEST AT command sets the module to emit RF power ignoring LTE signaling protocol. This
emission can generate interference that can be prohibited by law in some countries. The use of
this feature is intended for testing purposes in controlled environments by qualified users and
must not be used during the normal module operation. Follow the instructions suggested in the
u-blox documentation. u-blox assumes no responsibilities for the inappropriate use of this feature.
illustrates a typical test setup for such an RF functional test.
Application board
SARA-R4
ANT
Application
processor
AT
commands
Cellular
antenna
Spectrum
analyzer
or
power
meter
IN
Wideband
antenna
TX
Application board
SARA-R4
Application
processor
AT
commands
Signal
generator
OUT
Wideband
antenna
RX
ANT
Cellular
antenna
Figure 71: Setup with spectrum analyzer or power meter and signal generator for SARA-R4 series RF measurements