Novatel Ovation MC950D Fails/Hungs Intermittently

[nhoeller]

I have successfully connected a Novatel MC950D 3G modem to a PC running Unbuntu 8.10 server using a udev rule to release the ZeroCD and a simple wvdial script. I am using the options.ko driver and getting reasonable speeds (800kbps down, 200kbps up).

Intermittently (4 times today), the modem stops working. Symptoms:

• pppd reports modem has hung up (code=16)
• both /dev/ttyUSB0 and /dev/ttyUSB1 disconnect
• 3B modem reconnects to USB port as usb-storage
• udev rule is involved
• option driver detects GSM modem and connects as ttyUSB0&1 or sometimes ttyUSB1&2
• wvdial is not able to communicate with the modem
• modem LED flashing rapidly in sort of a pinkish color (not listed in the manual or troubleshooting guide)

I need to unplug/replug the modem and restart wvdial to get the modem working again. My local provider has no clue (not trained on Linux).

Any ideas what is going on and what I might do to resolve this problem?

Is there a way using software to simulate unplugging/replugging the modem so I can automate recovery?

Thanks, Norbert

[Sylslay]

Mayby it is heatup?
I use bowl from kitchen table as signal amplifier and noise canceling and working great with Huawei 3g modem. Just ordinary BOWL!!!! === internet 3 times faster.

[Sylslay]

Once I tape few ordinary sawing nidles, under my modem and it start behavor very wrong, seems like yours, flashing, disconnectiq with wvdial.So I took off nidles. So I only put it to bowl and test upload and dowlaoad speed.

[GeorgeVita]

Hi nhoeller,
can you check the modem with other PC and/or Operating System?

The disconnect reason could be hardware, software or caused by the provider. Many times you could have 5 bars signal but no mobile internet (stuck) because your provider cannot serve you.

In your case it seems to be a hardware reason because you are missing /dev/ttyUSBx for a while the led is flashing in a weird style and when you remove it and plug it again it works again. Also the problem appears randomly.

Take a look at my thread: http://forum.huawei.com/jive4/thread...hreadID=323666

Hi Sylslay, I thing it would be better to use an extention cable (just cables without circuit) as described in the above link.

Regards,
George

[nhoeller]

George, interesting! I am using a tri-tip USB cable to increase power to the modem and an extension cable so that I can position the modem near a window. I tested without the extension cable and with only one of the USB connections of the tri-tip plugged in, but have not tried with the 3G modem plugged directly into the PC.

I will wire up your 2nd 'patch' and see if that helps. I may also build another PC to try and eliminate hardware issues with the USB port. I would get the 3G modem replaced but am having difficulty convincing tech support that it might be a modem problem. Intermittent issues are always fun...
Thanks, Norbert

[nhoeller]

George, I wired up your 2nd USB cable patch. The good news is that the modem worked when I plugged it in. The bad news is that the modem hung again last night. I double-checked the wiring and the pin connections (the wires on my cable had different colors from your diagram) and am satisfied that the USB cable patch is correct.

Strangely, I am not seeing this problem when the modem is connected to my Vista laptop. Maybe I was just lucky.

I will build another software router with Windows XP and Linux. That should help me narrow down whether the problem is hardware or software.
Thanks, Norbert

[GeorgeVita]

...
I would get the 3G modem replaced but am having difficulty convincing tech support that it might be a modem problem...

Because everything is "compatible" and "they know better"!

...
Strangely, I am not seeing this problem when the modem is connected to my Vista laptop...

You have to cross check by booting a Live CD (Ubuntu 8.10 ?) to the Vista laptop and use Network Manager to connect. This test will show you if it is a h/w reason.

About HSPA and EDGE switching, many users note that they have some problems, I believe this is more Provider oriented that an O.S. problem. There are some AT commands asking from the modem to use only 3G/HSPA but there is no documentation published except some posts to various forums.

I think that you must find a steady condition laptop/modem/good 3G signal and test the modem for the randomly disconnects which may be caused by a h/w (power) reason. This is the only you can solve with the cable patch.

About your /etc/wvdial.conf: most users use "analog modem" instead of "USB modem" and some providers need the APN definition:
Init3 =AT+CGDCONT=1,"IP","internet"
(in place of "internet" you have to place the proper APN for your provider)

After plugging the modem again, wait for the 3G modem state (usually the blue light) and then try to connect.

If you have any system message when disconnected (wvdial, dmesg) post it here. Have you tried to use Network Manager 0.7?

Regards,
George