GNOME Bugzilla – Bug 663535
Wrong BAUD rate for Huawei EC1260
Last modified: 2014-07-11 16:05:13 UTC
A lot of modems get detected to have low baud rate, as a consequence the speed of connectivity is not upto the mark. Also notice, that wvdial also detects wrong baud rate (too less).
What baud rate is detected? What should the rate be? For the most part, the baud rate doesn't actually make a big difference since newer modems use actual network ports for communication. But if the device does use PPP instead (which actually limits the speed of the connection to about 7Mbit due to PPP overhead) then baud rate might be an issue, but we haven't seen it in practice.
For example, I just tested a USB 3G modem and by default ModemManager selects a baud rate of 57600. But pppd itself uses a baud rate of 9600 (run 'stty -F /dev/ttyUSBx' where X is the port that is being used for PPP which you can find out by running 'ps ax | grep pppd' when connected). Even though the port is using 9600 baud according to the kernel, I still am able to pull 4.5Mb/s down on an HSDPA network; this modem is a max 7.2Mbit device. So it's clearly not limited by the baud rate the serial port. That said, some devices may actually pay attention to the baud rate, but these are quite rare. Can you grab some ModemManager debug logs from your device as described here: http://live.gnome.org/NetworkManager/Debugging which may let us know whether your device is registering with the EVDO network (max 3.2Mb/sec but you'll almost never see more than about 300K/sec transfer rates) or the 1X network (which is max 20K/s).
(In reply to comment #1) > What baud rate is detected? What should the rate be? For the most part, the > baud rate doesn't actually make a big difference since newer modems use actual > network ports for communication. But if the device does use PPP instead (which > actually limits the speed of the connection to about 7Mbit due to PPP overhead) > then baud rate might be an issue, but we haven't seen it in practice. Yes, the connection is over ppp. wvdial detect the baud rate as 9600.. which's too slow, the connection speed limits at ~10 KBps. (In reply to comment #2) > For example, I just tested a USB 3G modem and by default ModemManager selects a > baud rate of 57600. But pppd itself uses a baud rate of 9600 (run 'stty -F > /dev/ttyUSBx' where X is the port that is being used for PPP which you can find > out by running 'ps ax | grep pppd' when connected). Even though the port is > using 9600 baud according to the kernel, I still am able to pull 4.5Mb/s down > on an HSDPA network; this modem is a max 7.2Mbit device. So it's clearly not > limited by the baud rate the serial port. That said, some devices may actually > pay attention to the baud rate, but these are quite rare. > > Can you grab some ModemManager debug logs from your device as described here: > > http://live.gnome.org/NetworkManager/Debugging > > which may let us know whether your device is registering with the EVDO network > (max 3.2Mb/sec but you'll almost never see more than about 300K/sec transfer > rates) or the 1X network (which is max 20K/s). The modem is not currently with me, but I'll collect this info once I have the modem.
de.techno, were you able to collect debug logs ?
Wait for a few days, I'll go to his place and see. Actually I'll SSH to his system......
The output of stty -F /dev/ttyUSBx is the same when connecting using both NM and wvdial/gnomeppp. Baud is 9600 in both cases, however with NM bandwidth is capped at 16KBps.
Hi de.techno, I am closing this bug report as no updated information has been provided. Please feel free to reopen this bug if you can provide the information that was asked for in comment 2.