GSM Modem - PPP

This is a discussion on GSM Modem - PPP ; Hi group, I have a set of questions based around using a GSM modem. Please be patient becuase I am new to this area and I may be asking trivial questions. I have searched various groups but have not found ...

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Thread: GSM Modem

  1. GSM Modem

    Hi group,

    I have a set of questions based around using a GSM modem. Please be
    patient becuase I am new to this area and I may be asking trivial
    questions. I have searched various groups but have not found what I
    would describe as a definitive answer so I thought the best option
    would be to post a question. Here goes:

    I have a Sony-Ericsson GM29 GSM modem which I would like to use to
    transmit remote data. I have sucessfully configured it to access my
    local network and can make voice calls. However, I understand that to
    transfer data I need to use PPP. Is this correct? The application is
    to transmit GPS-derived data from a remote (moving) location and to
    access this data from my PC at home. I would then process this data to
    show the position on a moving map. I have an application that already
    performs processing of NMEA sentences (the GPS data protocol) and I
    will write the firmware for an Atmel A9M9200 microcontroller running an
    embedded Linux OS (based on the 2.6.11 kernel). This embedded target
    will provide the interface between my GPS device and the GSM modem.

    What I don't know how to achieve is to recover the data I send over the
    GSM network.

    Assume I make a successful network connection to my service providers
    GPRS access point, then what? How do I get my hands on the data I have
    transmitted? Do I FTP it or do I write a deamon that polls a
    particular URL looking for data? I just don't know!

    Thank you for any insight offered.

    Regards,

    Neil Bryan.


  2. Re: GSM Modem

    On 2005-10-17, NeilBryan2005 wrote:
    > Assume I make a successful network connection to my service providers
    > GPRS access point, then what? How do I get my hands on the data I have
    > transmitted? Do I FTP it or do I write a deamon that polls a
    > particular URL looking for data? I just don't know!


    After GPRS gives you an IP network connection, for example an Internet
    connection, you can send and receive data through datagrams with UDP or
    through a bit stream with TCP. With datagrams you must prepare for lost,
    duplicate etc. packets and with TCP you must prepare for slow stratup
    and socket errors.

    As GSM/GPRS is wireless, you'll get a lot of errors withit so handle
    them early on. Or spend lots of time wondering why the device is so
    silent in the forest/some other distant place.

    You'll propably want to read a TCP/IP introduction or two. *nix way
    would be to cook a /bin/sh or perl script to give the idea a go. netcat
    is nice for trying it out.

    -Mikko

  3. Re: GSM Modem

    Thanks for your response Mikko,

    So what you are saying is that when my embedded devices opens a GPRS
    data connection to network provider (over the GSM modem), I will be
    issued with an IP address. I can then open a socket on my home,
    Internet-connected PC and receive TCP/IP packets?

    This sounds easier than I expected. My only problem is that each time
    I connect to the Internet my ISP provides me with a new IP address. I
    will need this unique IP when I open the data connection on the GSM
    modem (GPRS link)?

    So does this mean then that it is a case of raw sockets programming and
    I don't need to worry about PPP etc.?

    Thanks in advance for any further help form either Mikko or any other
    network gurus ;-)

    Regards,

    Neil.


  4. Re: GSM Modem

    Thanks for your response Mikko,

    So what you are saying is that when my embedded devices opens a GPRS
    data connection to network provider (over the GSM modem), I will be
    issued with an IP address. I can then open a socket on my home,
    Internet-connected PC and receive TCP/IP packets?

    This sounds easier than I expected. My only problem is that each time
    I connect to the Internet my ISP provides me with a new IP address. I
    will need this unique IP when I open the data connection on the GSM
    modem (GPRS link)?

    So does this mean then that it is a case of raw sockets programming and
    I don't need to worry about PPP etc.?

    Thanks in advance for any further help form either Mikko or any other
    network gurus ;-)

    Regards,

    Neil.


  5. Re: GSM Modem

    On 2005-10-17, NeilBryan2005 wrote:
    > So what you are saying is that when my embedded devices opens a GPRS
    > data connection to network provider (over the GSM modem), I will be
    > issued with an IP address. I can then open a socket on my home,
    > Internet-connected PC and receive TCP/IP packets?


    Yes.

    > This sounds easier than I expected. My only problem is that each time
    > I connect to the Internet my ISP provides me with a new IP address. I
    > will need this unique IP when I open the data connection on the GSM
    > modem (GPRS link)?


    Dynamic DNS services help you out in this case.

    > So does this mean then that it is a case of raw sockets programming and
    > I don't need to worry about PPP etc.?


    Well, normal socket programming rather than raw sockets And you do
    need to set up the Linux PPP daemon to run well with your GPRS modem,
    but Internet search engines and modem manuals will help you out.

    -Mikko

  6. Re: GSM Modem

    Internet search engines and modem manuals will help you out.

    I understand - RTFM!

    Thanks again, I am more optimistic that I can this setup working now.
    Once I have my hardware cobbled together, I may need to ask further
    (hopefully intelligent) questions....


  7. Re: GSM Modem

    hi Neilbryan,
    if your objective is only to transmit data/file, then u can do it using
    DATA CALLS.
    But for that u need 2 GSM modems instead of 1. The other needs to be at
    your PC.

    so the setup is as follows ---(its very easy, reliable and tested).
    keep the modem at pc end in an answering mode, then place a data call
    from remote m/c to modem at pc end.
    once the call is established , transfer the file using any
    protocol(kermit is better)
    vikrant


  8. Re: GSM Modem

    Hi guys,
    I'm sorry for multiple identical replies appearing. I did not send
    them.
    Well I must have, but not sure how.

    In response to Vikrant: I had considered this approach, but I only
    have a
    single GSM modem and I want to use the reduced-cost approach of
    GPRS because (I believe) the service provider will charge me for data
    transfered and not for the connection time. My bandwidth requirements
    will be very low (approx. 100K per hour) which will only cost me
    0.6.

    The other reason for doing it using the Internet is to give me a better
    understanding of the various technical issues involved.

    Thanks for the suggestion, it is appreciated.

    Regards,

    Neil.


  9. Re: GSM Modem

    hi Neilbryan,
    probably go for pppd dialup script.
    the detailed gprs dialup script is as illustrated by the link bellow

    http://www.usenetlinux.com/archive/t.../t-146483.html

    and

    http://www.gnu-linux.net/t610irda/gprs-wvdial.conf

    so place the gprs and gprs-wvdial.conf in /etc/ppp/peers

    and fire command "pppd call gprs"
    plz make sure of the AT+CGDCONT settings and phone no. according to
    your ISP provider
    vikrant


  10. Re: GSM Modem

    Hi friends
    i want to send data with gsm module.
    i need someone help me becuase i want send data with GPRS service.i want to send my data with PPP and UDP data formated.
    my mail is:
    mpch_elec@yahoo.com
    please send your mails to me...
    thanks

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