SARA-R4 series - System integration manual
UBX-16029218 - R20 Product testing Page 120 of 128
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5.2 Test parameters for OEM manufacturers
Because of the testing done by u-blox (with 100% coverage), an OEM manufacturer does not need to
repeat the firmware tests or measurements of the module RF performance or tests over analog and
digital interfaces in their production test.
However, an OEM manufacturer should focus on:
• Module assembly on the device; it should be verified that:
o The soldering and handling process did not damage the module components
o All module pins are well soldered on the device board
o There are no short circuits between pins
• Component assembly on the 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 performance test of the device including the antenna
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” in a location
with excellent network coverage and known signal quality. This test should be performed after the
data connection has been established. AT+CSQ is the typical AT command used to check signal
quality in term of RSSI. See the SARA-R4 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 RF performance measurements.
This test is suitable to check the functionality of communications with the host controller, the SIM
card and the power supply. It is also a means to verify if components at the antenna interface are well-
soldered.
5.2.2 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
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