simpleRTK2B – SIM card selection for NTRIP client. Any issues/limitations?

Q&A forumCategory: QuestionssimpleRTK2B – SIM card selection for NTRIP client. Any issues/limitations?
Jose asked 3 weeks ago

Hello.
I have successfully configured an simpleRTK2B V3 and an 4G NTRIP client module. I have two 4G SIM cards from the same provider: one of them is associated to a subscription, while the other is a new, prepaid one. Both cards have the same PIN code, and they work fine in a mobile phone, meaning that I can make calls and browse internet using both, 3G and LTE.
Now, with exactly the same configuration of the NTRIP client:

  • When I insert the one associated to a subscription, the NTRIP module behave as expected, and I can get RTK fixes.
  • When I insert the prepaid card, the led of the NTRIP blinks “fast” (5 flashes/sec.), which indicates that the device is in run mode. However, the NTRIP module does not send anything to the F9P through the serial port where the RTCM messages should go through. I can see this in that the `XBee->GPS` led is not blinking, and in that the `Power+XBee` USB port is not sending anything (verified using both, Telit and minicom). Pressing the `XBee reset` button and waiting does not help, nor rebooting the board+NTRIP module.

This behavior is systematic: it happens again and again when I switch the cards. This makes me suspect that there is an issue between the NTRIP module and the prepaid SIM card.
Any ideas about what can be the reason for this behavior?
Is there something that we should know when it comes to selecting SIM cards to be used in the NTRIP Client module?
How to investigate further this issue?
Thanks in advance.

Ardusimple Staff replied 3 weeks ago

Hi Jose,
1. Is the APN the same for both sim cards?
2. Can you share what is output via XBEE+POWER port at 115’200bps? The module outputs some information that might help understand this case.

jose.vallet replied 3 weeks ago

Hi,

1. The APN is the same for both cards. They are from the same company, and I have verified this with the phone and the service provider.

2. Here below I put the the outputs of the XBEE+POWER port after booting up. Note that I have removed the NMEA sentences sent by the u-blox before the NTRIP module sends something. Note also that I have changed the server name, the mountpoint and the user name, so the ones appearing are not valid.

When using the prepaid SIM card
—>
$GPTXT,ARDUSIMPLE 4G NTRIP CLIENT FW V1.53-20200925*09
$GPTXT,STORED CREDENTIALS:*3A
$GPTXT,APN: internet*3D
$GPTXT,SERVER: mycaster.fi*61
$GPTXT,PORT: 2101*62
$GPTXT,PIN: 1234*2A
$GPTXT,BAUDRATE: 115200*6E
$GPTXT,USER:PASS: myname:*****6C
$GPTXT,MOUNTPOINT: SINGLE*62
$GPTXT,ROAMING: 1*19
$GPTXT,DEBUG MESSAGES ENABLED: 0*45
$GPTXT,SPECIAL CONFIG: 0*22
$GPTXT,SEND $$$AS+H?\r\n TO SEE THE COMMAND LIST*5D

$GPTXT,SM_SCK: LOCAL_PORT IS: 15851*70
$GPTXT,SM_SCK: BIND OK*46
ICY 200 OK

ATE1
OK
ati4
LE910-EU V2

OK
ATI0
332

OK
AT+CGSN
353529103332061

OK
AT#CIMI
ERROR
AT+CCID
+CCID: 89358029210115217356

OK
AT#BND=?
#BND: (0),(0,5,6),(1-524485)

OK
AT#BND?
#BND: 0,0,1

OK
AT+CGMI
Telit

OK
AT+CGMM
LE910-EU V2

OK
AT+CGMR
20.00.404

OK
<—

4. I have asked the telephone company, and they have checked everything in their side. It is all supposed to work fine with both cards. They believe the problem is in the modem side. I have also tried to unlock the prepaid SIM card so that the PIN is not required. This did not solve the problem either, as expected.

5. One difference between the SIM cards is the age: while the one that works is more than 6 years old, the prepaid one is new, and therefore from a rather new generation. Could this be an issue for the modem?

1 Answers
Jose answered 3 weeks ago

Hi again,
For some reason (probably the presence of “minor and major than” characters), the text that appears above does not contain what I wrote as I wrote it. Here I post my answer again.
1. The APN is the same for both cards (they are from the same company).
2. Here below I put the the outputs of the XBEE+POWER port after booting up. Note that I have removed the NMEA sentences sent by the u-blox before the NTRIP module sends something. Note also that I have changed the server name, the mountpoint and the user name.
When using the prepaid SIM card

$GPTXT,ARDUSIMPLE 4G NTRIP CLIENT FW V1.53-20200925*09
$GPTXT,STORED CREDENTIALS:*3A
$GPTXT,APN: internet*3D
$GPTXT,SERVER: mycaster.fi*61
$GPTXT,PORT: 2101*62
$GPTXT,PIN: 1234*2A
$GPTXT,BAUDRATE: 115200*6E
$GPTXT,USER:PASS: myname:*****6C
$GPTXT,MOUNTPOINT: SINGLE*62
$GPTXT,ROAMING: 1*19
$GPTXT,DEBUG MESSAGES ENABLED: 0*45
$GPTXT,SPECIAL CONFIG: 0*22
$GPTXT,SEND $$$AS+H?\r\n TO SEE THE COMMAND LIST*5D

It stops here. Nothing else happens, no binding, nothing. Pressing reset (which sometimes works when the modem remains in this status when using the card that works) only brings the modem to the same status.
When using the SIM card that works fine, the output is the same as the previously shown. However, after a short while, it continues with:

$GPTXT,SM_SCK: LOCAL_PORT IS: 15851*70
$GPTXT,SM_SCK: BIND OK*46
ICY 200 OK

after which the RTCM messages start to flow.
In both cases, the red light of the NTRIP modem blinks fast (5 blinks/sec.).
3. In case it matters, here I put the output when opening the AT Terminal in Telit (it is the same when using both cards, except the CCID, which is different for each card):

ATE1
OK
ati4
LE910-EU V2
OK
ATI0
332
OK
AT+CGSN
353529103332061
OK
AT#CIMI
ERROR
AT+CCID
+CCID: 89358029210115217356
OK
AT#BND=?
#BND: (0),(0,5,6),(1-524485)
OK
AT#BND?
#BND: 0,0,1
OK
AT+CGMI
Telit
OK
AT+CGMM
LE910-EU V2
OK
AT+CGMR
20.00.404
OK

4. I have asked the telephone company, and they have checked everything in their side. It is all supposed to work fine with both cards. They believe the problem is in the modem side. I have also tried to unlock the prepaid SIM card so that the PIN is not required. This did not solve the problem either, as expected.
5. One difference between the SIM cards is the age: while the one that works is more than 6 years old, the prepaid one is new, from a new generation. Could this be an issue for the modem?
 

Ardusimple Staff replied 3 weeks ago

Great info.
Could you send $$$AS+D=1 to the modem after the boot message? Then press reset and record as you just did. This will enable debug data. Send this logfile to info@ardusimple.com , it will be very confusing for the community to see all those messages. We can then post the result / solution in this post.

Ardusimple Staff replied 3 weeks ago

Thanks Jose for sending the logfile. For other users with a similar case, the problem is resolved activating the enterprise mode. This can be done by replacing $$$AS+L=0 by $$$AS+L=1 in the parameters file.