Spurious emissions test for nRF9160 based device against CMW500 from R&S

[Iisko84]

Hello,

We have an nRF9160 based IoT device in the pipeline, which should now be tested in a certified test lab. The purpose would be to perform a spurious emissions test using CMW500 tester from R&S.

The original intention was to use MT8821C tester from Anritsu, but with that tester we had problems establishing a connection to our DUT, and in addition to this, the reservations for using the Anritsu MT8821C tester are now fully booked.

At first we had a problem establishing a connection between the nRF9160 and the CMW500 Radio Communication Tester.  However, we used the configuration zip archive "M1_configuration file for signalling.zip" recommended by the  thread
https://devzone.nordicsemi.com/guides/cellular-iot-guides/b/hardware-design/posts/using-nrf9160-against-r-s-cmw500-or-cmw290-in-signalling-callbox-mode

after which the connection was established successfully.

At the moment, the situation is that when the tester commands the DUT to TX mode, everything goes well, i.e. the device remains in test mode. Now the problem is that when the tester commands the DUT to RX mode, at some point (sooner or later, but before the end of the test) the device loses connection with the tester and then connects again. However, this leads to rejection of the spurious emissions test. The following appendix shows the log data of the nRF9160 modem, obtained from the LTE Link Monitor.

2022-11-29T12:49:44.174Z DEBUG modem >> AT+CFUN=4
2022-11-29T12:49:44.207Z DEBUG modem << +CEREG: 0
2022-11-29T12:49:44.215Z DEBUG modem << +CIND: "service",0
2022-11-29T12:49:44.220Z DEBUG modem << +CGEV: ME DETACH
2022-11-29T12:49:44.990Z DEBUG modem << %CESQ: 79,3,30,4
2022-11-29T12:49:45.789Z DEBUG modem << %CESQ: 255,0,255,0
2022-11-29T12:49:45.870Z DEBUG modem << %XSIM: 0
2022-11-29T12:49:45.886Z DEBUG modem << OK
2022-11-29T12:49:45.896Z DEBUG modem >> AT+CGDCONT?
2022-11-29T12:49:45.917Z DEBUG modem << OK
2022-11-29T12:49:45.928Z DEBUG modem >> AT%XSYSTEMMODE=1,0,0,0
2022-11-29T12:49:45.949Z DEBUG modem << OK
2022-11-29T12:49:45.960Z DEBUG modem >> AT+CGACT?
2022-11-29T12:49:45.981Z DEBUG modem << OK
2022-11-29T12:49:50.520Z DEBUG modem >> AT+CFUN=1
2022-11-29T12:49:50.570Z DEBUG modem << OK
2022-11-29T12:49:51.041Z DEBUG modem >> AT+CFUN?
2022-11-29T12:49:51.049Z DEBUG modem << +CFUN: 1
2022-11-29T12:49:51.060Z DEBUG modem << OK
2022-11-29T12:49:51.068Z DEBUG modem >> AT+CGSN=1
2022-11-29T12:49:51.081Z DEBUG modem << +CGSN: "351516172800005"
2022-11-29T12:49:51.083Z DEBUG modem << OK
2022-11-29T12:49:51.095Z DEBUG modem >> AT+CGMI
2022-11-29T12:49:51.113Z DEBUG modem << Nordic Semiconductor ASA
2022-11-29T12:49:51.115Z DEBUG modem << OK
2022-11-29T12:49:51.125Z DEBUG modem >> AT+CGMM
2022-11-29T12:49:51.144Z DEBUG modem << nRF9160-SICA
2022-11-29T12:49:51.146Z DEBUG modem << OK
2022-11-29T12:49:51.150Z DEBUG modem >> AT+CGMR
2022-11-29T12:49:51.160Z DEBUG modem << mfw_nrf9160_1.3.3
2022-11-29T12:49:51.162Z DEBUG modem << OK
2022-11-29T12:49:51.163Z INFO Nordic Semiconductor ASA nRF9160-SICA [mfw_nrf9160_1.3.3] SerNr: 351516172800005
2022-11-29T12:49:51.167Z DEBUG modem >> AT+CEMODE?
2022-11-29T12:49:51.180Z DEBUG modem << +CEMODE: 2
2022-11-29T12:49:51.181Z DEBUG modem << OK
2022-11-29T12:49:51.196Z DEBUG modem >> AT%XCBAND=?
2022-11-29T12:49:51.210Z DEBUG modem << %XCBAND: (1,2,3,4,5,8,12,13,18,19,20,25,26,28,66)
2022-11-29T12:49:51.212Z DEBUG modem << OK
2022-11-29T12:49:51.216Z DEBUG modem >> AT+CMEE?
2022-11-29T12:49:51.241Z DEBUG modem << +CMEE: 1
2022-11-29T12:49:51.243Z DEBUG modem << OK
2022-11-29T12:49:51.250Z DEBUG modem >> AT+CNEC?
2022-11-29T12:49:51.259Z DEBUG modem << +CNEC: 24
2022-11-29T12:49:51.262Z DEBUG modem << OK
2022-11-29T12:49:51.265Z DEBUG modem >> AT+CGEREP?
2022-11-29T12:49:51.274Z DEBUG modem << +CGEREP: 1,0
2022-11-29T12:49:51.276Z DEBUG modem << OK
2022-11-29T12:49:51.279Z DEBUG modem >> AT+CIND=1,1,1
2022-11-29T12:49:51.293Z DEBUG modem << OK
2022-11-29T12:49:51.308Z DEBUG modem >> AT+CEREG=5
2022-11-29T12:49:51.325Z DEBUG modem << OK
2022-11-29T12:49:51.333Z DEBUG modem >> AT+CEREG?
2022-11-29T12:49:51.353Z DEBUG modem << +CEREG: 5,0
2022-11-29T12:49:51.355Z DEBUG modem << OK
2022-11-29T12:49:51.361Z DEBUG modem >> AT%CESQ=1
2022-11-29T12:49:51.374Z DEBUG modem << OK
2022-11-29T12:49:51.382Z DEBUG modem >> AT+CESQ
2022-11-29T12:49:51.401Z DEBUG modem << +CESQ: 99,99,255,255,255,255
2022-11-29T12:49:51.404Z DEBUG modem << OK
2022-11-29T12:49:51.408Z DEBUG modem >> AT%XSIM=1
2022-11-29T12:49:51.417Z DEBUG modem << OK
2022-11-29T12:49:51.427Z DEBUG modem >> AT%XSIM?
2022-11-29T12:49:51.433Z DEBUG modem << %XSIM: 0
2022-11-29T12:49:51.448Z DEBUG modem << 
2022-11-29T12:49:51.451Z DEBUG modem << OK
2022-11-29T12:49:52.792Z DEBUG modem << %XSIM: 1
2022-11-29T12:49:52.811Z DEBUG modem >> AT+CPIN?
2022-11-29T12:49:52.837Z DEBUG modem << %CESQ: 79,3,29,4
2022-11-29T12:49:52.840Z DEBUG modem << +CEREG: 2,"0001","00000100",7
2022-11-29T12:49:52.841Z DEBUG modem << +CPIN: READY
2022-11-29T12:49:52.842Z DEBUG modem << OK
2022-11-29T12:49:52.846Z DEBUG modem >> AT+CPINR="SIM PIN"
2022-11-29T12:49:52.871Z DEBUG modem << +CPINR: "SIM PIN",3
2022-11-29T12:49:52.873Z DEBUG modem << OK
2022-11-29T12:49:52.879Z DEBUG modem >> AT+CIMI
2022-11-29T12:49:52.894Z DEBUG modem << 001010123456063
2022-11-29T12:49:52.896Z DEBUG modem << OK
2022-11-29T12:49:52.897Z INFO IMSIdentity: 001010123456063
2022-11-29T12:49:53.723Z DEBUG modem << +CEREG: 1,"0001","00000100",7,,,"11100000","11100000"
2022-11-29T12:49:53.736Z DEBUG modem << +CIND: "service",1
2022-11-29T12:49:53.748Z DEBUG modem >> AT+COPS=3,2
2022-11-29T12:49:53.761Z DEBUG modem << OK
2022-11-29T12:49:53.775Z DEBUG modem >> AT+COPS?
2022-11-29T12:49:53.792Z DEBUG modem << +COPS: 0,2,"00101",7
2022-11-29T12:49:53.794Z DEBUG modem << OK
2022-11-29T12:49:53.811Z DEBUG modem >> AT%XCBAND
2022-11-29T12:49:53.825Z DEBUG modem << %XCBAND: 1
2022-11-29T12:49:53.828Z DEBUG modem << OK
2022-11-29T12:49:53.842Z DEBUG modem >> AT+CGDCONT?
2022-11-29T12:49:53.872Z DEBUG modem << +CGDCONT: 0,"IPV4V6","cmw500.rohde-schwarz.com","XXX.XXX.XX.XXX 0000:0000:0000:0000:0000:0000:0000:0001",0,0
2022-11-29T12:49:53.874Z DEBUG modem << OK
2022-11-29T12:49:53.880Z DEBUG modem >> AT+CGACT?
2022-11-29T12:49:53.892Z DEBUG modem << +CGACT: 0,1
2022-11-29T12:49:53.893Z DEBUG modem << OK
2022-11-29T12:49:54.303Z DEBUG modem << %CESQ: 79,3,24,3
2022-11-29T12:50:16.702Z DEBUG modem << %CESQ: 79,3,30,4
2022-11-29T12:53:22.182Z DEBUG modem << %CESQ: 42,2,3,0
2022-11-29T12:53:22.388Z DEBUG modem << %CESQ: 21,1,0,0
2022-11-29T12:53:22.580Z DEBUG modem << %CESQ: 49,2,7,1
2022-11-29T12:53:22.789Z DEBUG modem << %CESQ: 64,3,19,2
2022-11-29T12:53:22.981Z DEBUG modem << %CESQ: 72,3,25,3
2022-11-29T12:53:23.396Z DEBUG modem << %CESQ: 77,3,30,4
2022-11-29T12:53:41.532Z DEBUG modem << +CNEC_EMM: 40 ======> At this point the connection drops

What exactly does that +CNEC_EMM: 40 mean? Apparently it's some Network related error code notification though, I just can't find information about it in the datasheets.

Prerequisites for the test:

HW (DUT):     nRF9160 based custom board
MFW:             mfw_nrf9160_1.3.3
App FW:         AT Client (ncs - v2.1.0)
LTE Link Monitor v2.0.2 for sending AT commands

R&S CMW500 Radio Communication Tester

Re-callable config file to CMW500
===> M1_configuration file for signalling.zip
from URL
==> Using nRF9160 against R&S CMW500 (or CMW290) in signalling callbox mode 

The device will only be tested in LTE-M (Cat M1) mode.

Best regards,

-Iisko84-

[ketiljo]

The used CMW500 configuration file is meant for signalling testing.only.

For RF testing at least scheduling type from CMW500 should be changed to "RMC" instead of "eMTC auto mode" but possibly some other parameters needs to be changed as well.

Cause 40 is "No EPS bearer context activated". The modem seems to be registered based on CEREG notification, so this error is most likely received from the tester at TAU Reject or Service Reject. Looks like tester side issue, the modem log needed for further study.

It may be easier to use the AT-commands directly over UART for this kind of testing. 

[Iisko84]

Hi ketiljo,

And thank you for the answer!
Can you tell me if there is a CMW500 configuration file for RF test available anywhere?

-Edit-   Do you mean it would be better to use for example PUTTY instead of LTE Link Monitor?

Best regards
-Iisko84-

[ketiljo]

Yes, use Putty and the AT client on the nRF9160.

You can find the description of the test commands here: https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/production_test/xrftest_tx_set.html

[Iisko84]

Could you please clarify why it is better to use Putty rather than LTE Link Monitor? I understand that the LTE Link Monitor feeds a certain AT command sequence when the modem is put into normal mode, but after that I can still enter the AT commands I want. For example, AT commands related to RF testing.

I have been under the impression that the DUT is simply powered up and put into LTE mode. After which the CMW500 is used to control the DUT to work as desired.

I just want to be sure of things before I make an appointment with the test lab, where I then will find out that using Putty instead of LTE Link Monitor did not help anything.

Best regards
-Iisko84-

[ketiljo]

If the test lab have a setup for using a CMW500 for these kinds of measurements, that will be perfectly fine. The CMW500 is mainly a call box to do signaling measurements but I believe it can also sent the proper AT commands, provided it's setup correctly. 

As we're not using the CMW500 for these kinds of measurements, we don't have the proper setup for this. You should contact the test lab and ask what setup they are using. 

The AT commands are standard for this kind of module so there will be no difference between the nRF9160 and any other manufacturer.