Hi Team
We are using EG25G LTE modules connected over USB interface with our host processor Qualcom QCS605.
We are testing our unit by Intentionally taking device network signal strength to zero and Network gets disconnected. We are doing this by removing antenna’s and wrapping the unit with Aluminium foil and taking the device in low network area. Once we unwrap the foil and device get’s the network access we are seeing the unsual behaviour in our system where our device is throwing CHI Layer i.e Camera failure error (Called as QMMF errors). Same time to recover back the device we are rebotting the system.
To debug further we have probed the Debug Uart of LTE modem and captured logs. Please see that logs attached. Can you guy’s tell what went wrong when we transition from low network to normal network ? Is the RF front end causing any disturbance in the system ? or LTE modem getting itself is getting hanged. Kindly help on this.
LTE LOG1.txt (34.2 KB)
This modem has weird behaviour in general. It is integrated in RUT241 and results are quite random.
What do you mean by random behaviour ? Is it regarding the power supply or its software or what ?
Hi Team,
During testing, we intentionally changed the LTE band by setting a specific frequency using the AT command [AT+QCFG=“band”].
Now we not able to go back to the default settings
Could you please guide us on how the LTE module to return it to its default factory settings?
HI Quectel team,
OUr same device we kept as shown below
Here we kept the LTE main antenna just below the camera brd so that RF signal will directly radiate to the camera brd and when we do AT+CFUN=0, AT+CFUN=1 we are getting voltage dip, spike on the Analog power of the image sensor
the dip and rise amplitude is around 60mv and some time it became 163mv and that 163mv dip can’t tolerate by image sensor and SOC will show camera fail QMMF error. THe same dip not visible on every power rails of image sensor. And we tried by powering the LTE module from external power supply and same issue is present
THen we changed the AVDD generating LDO to another make and found this dip not coming. We hope it was due to the good transient responce of the new LDO we used. BUt even with the new LDO and dip removed , QMMF error is happening. So there should be another reason for this.
Can you help us to share your thoughts on this. QMMF error will happen if any loss happens in the camera frames.
And may be someone will wonder why we testing by keeping the antenna just below the camera.
Our actual issue is > Our end customer is in canada and they getting QMMF error many times. And in our case antenna is few cm away from camera PCB and main brd. So if LTE radiation have any dependency like above then this can be the issue to the QMMF error our customer facing. and keeping antenna below camera board is a good way to recreate the issue faster
Adding to previous reply,
Below is the dip, spike we getting when we do the CFUN command
The time gap between dip and spike is around 330us. But we have observed different time gap also
