SARA-R42 - Application note
UBX-20050829 - R02 Testing Page 41 of 58
C1-Public
Deregister the module from the network.
Enter the non-signaling mode again.
Check the module is in non-signaling mode.
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.
+UTEST: 101575,1500,0,-70,-
70,-70
OK
The module measures the receiver power level for 1.5 s
at channel 1575 (frequency 1842.50 MHz LTE band 3).
After the time interval, the information text response
contains: the channel number, the time interval and
the minimum, average, maximum power levels.
Table 14: Example of +UTEST RF Rx testing
For any module (factory brand-new or not) when exiting the non-signaling mode to get back into the
signaling mode, it is important to check that the device has properly been restored to signaling mode.
This requires a check between the +UTEST and +CFUN state to see if they are in agreement.
Example of checking module is properly in signaling mode after it exits +UTEST non-signaling mode:
The device is in normal mode.
The device is not completely in non-signaling mode
because +CFUN reports that it is in test mode. Below
is the sequence to correct this.
Set the MT to minimum functionality.
Sets the MT to full functionality.
The device is now set to full functionality.
The device is in signaling mode.
Both the +CFUN and +UTEST AT commands agree
that the device is in signaling mode.
10.1.3 UTEST RX and TX non-signaling test sequence
☞ It is recommended to perform all RX UTEST grouped sequentially together, separate from the TX
UTESTs test grouped sequentially together. This may help avoid measurement glitches.
A glitch is defined as a measurement output of an expected value, but reports a value with a
significant differential. Example: if the module were instructed to transmit 20 dBm, but the device
actually transmits 0 dBm, and there is no RF connectivity hardware at fault, then this is likely a glitch.
If a glitch should be encountered then a reset (AT+CFUN=15) and re-entry back into UTEST
non-signaling mode is required to clear the glitch.
A measurement glitch does not occur randomly; it can happen through a combination of TX and RX
measurements and is reproducible. Therefore, if a glitch is encountered in the development of the
+UTEST sequence, then it will not unexpectedly change the behavior with the same sequence
repeated.
☞ Any +UTEST sequence should be verified with measurements before deploying into production.
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