Integration Manual

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 Product testing Page 106 of 119
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/N4 series
AT Commands Manual [2] for detail usage of the AT command.
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☞ 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
The overall RF functional test of the device including the antenna can be performed with basic instruments such as a
spectrum analyzer (or an RF power meter) and a signal generator with the assistance of the AT+UTEST command over
the AT command user interface.
The AT+UTEST 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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☞ See the SARA-R4/N4 series AT Commands Manual [2] for the AT+UTEST 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.
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⚠ To avoid module damage during a transmitter test, a suitable antenna according to module specifications or a 50 Ω
termination must be connected to the ANT port.
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⚠ To avoid module damage during a receiver test, the maximum power level received at the ANT port must meet
module specifications.