EG916 AT command for detecting the RF quality without valid SIM card

IoT Modules LTE Standard Module
1

Hi,
Is there command similar to ‘at+qscan’ that can be used to detect RF quality without valid SIM information?
This could help on the manufacturing side.

2

Dear Customer,

Does this test involve measurement in manufacturing? Can you help to provide the equipment been used?
Do you need the test run in factory mode as well?

Regards,
Fazrul Redzuan

3

This is just for a quick test to see if the antenna is well installed over connector.
So, a simple RF signal indicator will be enough. No precise measurement required.
No additional equipment will be used. My idea is to have the at command to show the RF indicator, and judgment will be done by simply check difference between with/without antenna.
In our device, the RF signal is simply not visible when antennal is not installed.

Thanks for the support

4

Dear Customer,

If that is the case, I will suggest you use AT+CSQ to check the signal quality.

It is very simple as below:
AT+CSQ
Response: +CSQ: rssi, ber

Example response:
AT+CSQ
Response: +CSQ: 23, 99

Focus on the value of rssi only for checking antenna strength.
good antenna value: around 5 to 31

if you get 0, 1 or 99 means the signal is very weak and not connected

Where:

  • <rssi> = Received Signal Strength Indicator (signal power)
  • <ber> = Bit Error Rate (signal quality / error level)
RSSI Value Signal Strength
0 ≤ -113 dBm (very weak)
1 -111 dBm
2–30 -109 dBm to -53 dBm
31 ≥ -51 dBm (excellent)
99 Unknown / not detectable

Regards,
Fazrul Redzuan

5

Hi,

But is ‘CSQ’ working with NO VALID SIM case? In my practice, the CSQ is always 99 when no valid SIM (not able to register to a real network).

6

Hi Dunk,

In my experience, a returned value between 20 and 30 typically indicates that the antenna is properly connected and functioning as expected. You may try rebooting the module after installing the antenna to ensure the RF path is correctly initialized.

I can also introduce other AT commands for further verification; however, those methods are more complex and may not be suitable for production‑level testing.

7

Hi,

Yes, I can get 20 ~ 30 reported when a valid SIM card is installed. So this stands for correct installation of my antenna.

But when an invalid SIM (no network can be registered) installed, I always got 99,99. The registration state is ‘+CREG: 0,3’

So, just want your suggestion on the usage of CSQ. Will it support RF report when state in ‘searching’ or ‘denied’?