CMW500 RF Conducted Test Fail

[woojin]

Hello Quectel team,

We are currently working with the EC21-KL SKT LTE Cellular Module in our devices.

We did the rf conducted test with cmw500.

However, the following strange result occurs:

1. Signaling failure.
   It connects, but soon disconnects.
   See the “Signaling Failure.jpg” file.

2. Very low TX Power
   Some modules measure very low txpower.
   -2.3dBm, -2.26dBm, -4.97dBm
   See the “TXPower-2.23dBm.jpg TXPower-2.26dBm.jpg TXPower-4.97dBm.jpg” file

3. Very high Tx Power
   Some modules measure very high txpower.
   +27.05dBm
   See the “TXPower+27.05dBm.jpg” file

4. Call is disconnected and not reconnected during the OTA radiation test
   After completing the B3 test, the call was disconnected while testing B5. No calls were made after that.

5. Final result
   Only 33 out of a total of 55 modules operate normally.
   Of these, 15 units are connected only to specific bands. B3 or B5

Even if the rf conducted test result is normal, there are products that fail the OTA radiation test.

Your guidance will be greatly appreciated.

Uploading: Signaling Failure.jpg…

Uploading: TXPower+27.05

dBm.jpg…

[brown.du-Q]

Hi woojin,

1. Signaling failure.
   It connects, but soon disconnects.
   See the “Signaling Failure.jpg” file.
   =>I connot find the “Signaling Failure.jpg”

2. Very low TX Power
   Some modules measure very low txpower.
   -2.3dBm, -2.26dBm, -4.97dBm
   See the “TXPower-2.23dBm.jpg TXPower-2.26dBm.jpg TXPower-4.97dBm.jpg” file
   =>1)Did you set the max power on the CMW500?
   

   
   
   2)Pls use AT+EGMR=0,5 , AT+EGMR=0,7 and AT+EGMR=0,10 to compare SN and IMEI whether same as shielding.
   

3. Very high Tx Power
   Some modules measure very high txpower.
   +27.05dBm
   See the “TXPower+27.05dBm.jpg” file
   =>I cannot find the “TXPower+27.05dBm.jpg”
   Pls use AT+EGMR=0,5 , AT+EGMR=0,7 and AT+EGMR=0,10 to compare SN and IMEI whether same as shielding.

4. Call is disconnected and not reconnected during the OTA radiation test
   After completing the B3 test, the call was disconnected while testing B5. No calls were made after that.
   =>You can try to use “AT+CFUN=0” and “AT+CFUN=1” command when your change the Band.

5. Final result
   Only 33 out of a total of 55 modules operate normally.
   Of these, 15 units are connected only to specific bands. B3 or B5
   =>Pls uer AT+QCFG=“BAND” command to compare the normal module and the abnormal module whether there are differences.
   

[woojin]

Hi~

I’ll answer what you asked.

1. Photo of missing forum.

1-1 Normal operation

1-2. signaling failure

1-3 Very high tx power +27dBm

1-4 very low tx power

2. Set the max power on the CMW500?
   Yes.
   The picture attached to 1-1 is a picture of a module that outputs normally, and +21dBm is output.

3. Compare SN and IMEI whether same as shielding

3-1 Normal operation Module #1 EC21-KL Mini PCIE

3-1-1 QR SCAN Result
861108030414295;
MPA18EH13005396;
80FBF1702F4F

3-1-2 AT
at+gmr
EC21KLFAR04A01M4G_SKT

OK
at+qcfg=“BAND”
+QCFG: “band”,0x0,0xd5,0x0

OK
at+egmr=0,5 // what value is it?
+EGMR: “E187121130005951Z”

OK
at+egmr=0,7 // IMEI
+EGMR: “861108030414295”

OK
at+egmr=0,10 // what value is it?
+EGMR: “8611080304142900”

OK

3-3 Abnormal operation Module #1 EC21-KL Mini PCIE

3-3-1 QR SCAN Result

861108030415763;

MPA18EH13005399;

80FBF1702F52

3-3-2 AT

at+gmr
EC21KLFAR04A01M4G_SKT

OK
at+qcfg=“BAND”
+QCFG: “band”,0x0,0xd5,0x0

OK
at+egmr=0,5
+EGMR: “E187121470007421Z”

OK
at+egmr=0,7
+EGMR: “861108030415763”

OK
at+egmr=0,10
+EGMR: “8611080304157600”

OK

4. “AT+CFUN=0” and “AT+CFUN=1” command when your change the Band.

I did a power reset when it wasn’t connected.

Do I need to run AT+CFUN every time BAND is changed during OTA test?

Other modules proceed without this process.

Thanks for the reply.

[brown.du-Q]

Hi woojin,
Can you test the module with abnormal Tx power as the table below?

at+egmr=0,5 // what value is it? // read module SN
at+egmr=0,10 // what value is it? //read module IMEI2

4. “AT+CFUN=0” and “AT+CFUN=1” command when your change the Band.
   I did a power reset when it wasn’t connected.
   Do I need to run AT+CFUN every time BAND is changed during OTA test?
   Other modules proceed without this process.
   =>No need to use CFUN every time, just for connection difficult.

[woojin]

Hi.

OK. I will test each band.

at+egmr=0,5 // what value is it? // read module SN

The SN of the QR SCAN result and the result of AT+egmr=0,5 are different. why?

[brown.du-Q]

Hi ，
The SN of the QR SCAN result and the result of AT+egmr=0,5 are different. why?
=>Can you confirm whether the normal module also have different SN problem.

[woojin]

Yes.

Regardless of whether it is normal or abnormal, it comes out differently.

The content is included in my second post.

The results of QR scan and laser engraving are the same, but the values ​​of AT+EGMR=0,5 are different.

[brown.du-Q]

Hi woojin,
How many modules do you have? Could you please help to list IMEI and pictures in the table? I will check internally.

[woojin]

We have 55 for development.

Attached is the file created as an excel table.

EC21-MINIPCIE-ABNORMAL.zip (1.4 MB)

[brown.du-Q]

Hi woojin,
Your modules are relatively old from 2018, and the reason why the SN cannot correspond may be due to the sample module. It is recommended that you contact a local agent or salesperson to purchase the latest modules, and for modules with power abnormalities, it may be necessary to return them to the factory for recalibration.

[woojin]

1. Conducted RF test on the entire module today.

Total: 53
Normal: 31
Abnormal: 22

The resulting excel document is attached.
EC21-KL-MiniPcie-ConductedRfTestResult.zip (15.4 KB)

2. About RF Output Power

Quectel_EC21_Mini_PCIe_Hardware_Design_V1.4.pdf

Conducted RF Output Power on the datasheet is 23dBm±2dB, so it is considered a minimum of 21dB.

However, there are many modules that do not reach 21dB as a result of the test.

Only sample No. 51 in this test result is over 21dB in all bands.

Results are mostly low in B7.

Why is that?

[brown.du-Q]

Your modules are relatively old from 2018, It is recommended that you contact a local agent or salesperson to purchase the latest modules. abnormal modules may be need recalibration.