SARA-R42 - Application note
UBX-20050829 - R02
Testing
Page 40 of 58
C1-Public
Command
Response
Description
AT+UTEST=2,105060,5000
+UTEST: 105060,5000,0,-21,-
20,-19
OK
Example 2: RX test executed on B12 TX, Ch. 105060,
RX measurement on for 5 s. The signal input to the
receiver is reported at -20 dBm.
Table 12: Entering non-signaling mode with +UTEST
After the desired tests have been executed, perform this to return to normal operating mode:
•
Send
AT+UTEST=0
. Make sure to restore the full operational
+CFUN
mode via
AT+CFUN=0/1
cycle.
10.1.2
Cellular RF functional test
As mentioned before, OEM manufacturers need only to verify proper assembly of the module in the
OEM production line. 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.
In test mode, the module switches off the protocol stack for performing single tests that could not be
performed during signaling. 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 with 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. For a detailed explanation of the hardware setup, see the SARA-R4 series system
integration manual
report examples of RF tests using
+UTEST
, both in transmitting and in receiving
modes.
Command
Response
Description
AT+COPS=2
OK
Deregister the module from the network.
AT+UTEST?
+UTEST: 0
OK
Check the device is in signaling mode.
AT+UTEST=1
OK
Enter the non-signaling mode.
AT+CFUN=15
OK
Perform a reset.
AT+UTEST=1
OK
Enter the non-signaling mode again.
AT+UTEST?
+UTEST: 1
OK
Check the module is in non-signaling mode.
AT+CFUN?
+CFUN: 5
OK
Check +CFUN AT command is set to 5 to ensure the
module is in test mode. The device is now ready for
either TX, RX non-signaling tests.
AT+UTEST=3,119575,-30,,,1000 +UTEST: 119575,-30,5,1,1000
OK
The module transmits at channel 19575 (frequency
1747.50 MHz LTE band 3) for 1 s, after which the "OK"
final result code is returned. After the "OK" final result
code, aUTEST command can be sent.
Table 13: example of +UTEST RF Tx testing
For SARA-R4 series modules the RF output resulting from the
AT+UTEST=3
command is a
QPSK-modulated continuous signal with a bandwidth of 360 kHz (2 resource blocks).
