SARA-R5 series - System integration manual
UBX-19041356 - R04 Product testing Page 111 of 118
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• Component assembly on the application device; it should be verified that:
o Communication with the host controller can be established
o The interfaces between the module and device are working
o Overall RF functional test of the device including the antenna/s
Dedicated tests can be implemented to check the device. For example, the measurement of the
module current consumption when set in a specified status can detect a short circuit if compared with
a “Golden Device” result.
In addition, module AT commands can be used to perform functional tests on the digital interfaces
(communication with the host controller, check the SIM interface, GPIOs, etc.) or to perform RF
functional tests (see the following section 5.2.2 for details).
5.2.1 “Go / No go” tests for integrated devices
A “Go / No go” test is typically used to compare the signal quality with a “Golden Device”.
The cellular RF functionality should be checked with the DUT (Device Under Test) placed in a location
with excellent cellular network coverage and known cellular signal quality. This test should be
performed after the data connection has been established. +CSQ is the typical AT command used to
check signal quality in term of RSSI, comparing the DUT with a “Golden Device”. See the SARA-R5
series AT commands manual [2] for detail usage of the AT command.
☞ These kinds of test may be useful as a “go / no go” test but not for cellular RF performance
measurements neither for certifications purpose.
This test is suitable also to check the communications with the host controller, the SIM card and the
power supply. It is also a mean to verify if components at the cellular RF interface are well soldered.
The GNSS RF functionality should be checked with the device under test (DUT) placed in an outdoor
position, with excellent sky view (HDOP < 3.0). Let the receiver acquire satellites and compare the
signal strength with a “Golden Device”.
☞ As the electro-magnetic field of a redistribution antenna is not homogenous, indoor tests are in
most cases not reliable to check the GNSS RF functionality. These kind of tests may be useful as
a ‘go/no go’ test but not for GNSS sensitivity measurements.
5.2.2 Cellular RF functional tests
As mentioned before, OEM manufacturers need only to verify proper assembly of the module in the
OEM production line, i.e. proper soldering joint of the ANT pad and related parts along the RF path,
and this can be done by performing a simple RF functional test with basic instruments such as a
spectrum analyzer (or an RF power meter), and optionally a signal generator, with the assistance of
the +UTEST AT command over the AT command user interface.
The +UTEST AT command provides a simple interface to set the module to Rx or Tx test modes
ignoring the LTE signaling protocol. The command can set the module into:
• transmitting mode in a specified channel and power level in all supported bands
• receiving mode in a specified channel to return the measured power level in all supported bands
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-R5 series AT commands manual [2] and the SARA-R5 series application
development guide [22] for the +UTEST AT command syntax description and detail guide of
usage.
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