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  1. #1
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    Mar 2003
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    Luttenberg (Netherlands)
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    Data over Voice call (DoV)

    Hi,

    is it possible in Symbian OS to have a GSM voice call and send simultaneously data through the voice call channel? That is the user can receive/hear audio from the remote side and talk to the remote side and simultaneouly the phones exchange some data through the same GSM CSD channel as the voice call is using.

    I know this sounds complex - but before voice is transmitted it is encoded using AMR, and the digital signal is transmitted through the network, right? I just want to add a few bytes to this AMR encoded signal. Is that possible? If no, why not? If yes, where to look (I will not be frightened by some low level complexity).

    Sending the data through a simultaneous GPRS connection is no option for this project.

    Best regards,

    Rene Heuven
    Inmote BV
    Rene Heuven
    Inmote - Creative Smartphone Solutions
    Web: www.inmote.com
    E-mail: rene@inmote.com

  2. #2
    Regular Contributor
    Join Date
    May 2007
    Posts
    468

    Re: Data over Voice call (DoV)

    The only way I can think you could transfer data in the voice call is watermarking. I know it has been done but the algorithms are complex to develop and tend to cause voice quality decrease.

    1) record stream from microphone
    2) watermark the data
    3) play the edited data to uplink (this differs between releases how you can do it)

    On the other end you'd have :
    1) dowlink record stream
    2) extract the watermark
    the watermarked audio can be played to earpiece/loudspeaker.

    Regards,
    Jack

  3. #3
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    Re: Data over Voice call (DoV)

    Hi Jack,

    I see - thanks for your answer. This clarifies my thoughts.

    Getting the data from the microphone can be done using APS. Then I have a AMR encoded data stream. Now I have to add my own data to the encoded AMR data stream (watermark).

    - can I add data on top of the AMR data stream or do I first need to decode AMR, add data, encode again in AMR?
    - I assume AMR has error correction features built-in. Can bits be lost during transmission and is AMR tolerant for the loss of bits (in the sense that the voice quality degrades)? How can I ensure I do not loose bits for my binary data (I cannot afford the quality of my binary data degrades).
    - can you give some pointers where to look for more information?
    - I thought GSM is using multiple channels. Is it not possible to allocate an additional channel during a voice call to transmit the data? Is SMS not going through a different channel? Can you point me here too to some additional resources where to find information?

    What classes would I use to play the data to the uplink?

    BR,

    Rene
    Rene Heuven
    Inmote - Creative Smartphone Solutions
    Web: www.inmote.com
    E-mail: rene@inmote.com

  4. #4
    Regular Contributor
    Join Date
    May 2007
    Posts
    468

    Re: Data over Voice call (DoV)

    Hi,
    sorry Rene but here I run out of knowledge.
    As I don't have ready answers all I can tell you is simply to try it

    If you need more detailed help remember technical support,
    http://www.forum.nokia.com/main/tech...ort/index.html

    Cheers,
    Jack

  5. #5
    Registered User
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    Mar 2003
    Location
    Luttenberg (Netherlands)
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    577

    Re: Data over Voice call (DoV)

    Hi Jack,

    OK - thanks so far for the answers. We will see how far we can get with this ... maybe I should indeed start to write a S60 application which just takes the AMR encoded data from the microphone and writes it into a file. That does not seem to be that difficult. Then I can take the samples and test some encoding/decoding routines for adding the binary data. Later we move then back to the phone.

    Thanks for the hint to use Nokia Technical Support!

    BR,

    Rene
    Rene Heuven
    Inmote - Creative Smartphone Solutions
    Web: www.inmote.com
    E-mail: rene@inmote.com

  6. #6
    Registered User
    Join Date
    Jun 2008
    Posts
    283

    Smile Re: Data over Voice call (DoV)

    HTML Code:
    Getting the data from the microphone can be done using APS. Then I have a AMR encoded data stream. Now I have to add my own data to the encoded AMR data stream (watermark). 
    how can you do it , can give me a source code example?
    HTML Code:
    - can I add data on top of the AMR data stream or do I first need to decode AMR, add data, encode again in AMR?
    - I assume AMR has error correction features built-in. Can bits be lost during transmission and is AMR tolerant for the loss of bits (in the sense that the voice quality degrades)? How can I ensure I do not loose bits for my binary data (I cannot afford the quality of my binary data degrades).
    - can you give some pointers where to look for more information?
    - I thought GSM is using multiple channels. Is it not possible to allocate an additional channel during a voice call to transmit the data? Is SMS not going through a different channel? Can you point me here too to some additional resources where to find information?
    
    What classes would I use to play the data to the uplink?
    are you reach for any solution, please told us?
    Ahmed Mahfouz
    Researcher
    Handset

  7. #7
    Registered User
    Join Date
    Dec 2010
    Posts
    1

    Re: Data over Voice call (DoV)

    I am having NOKIA C 5 hand set.kindly let us know whether in this set voice call can be received during data call. because when we use
    data call we are not able to recieve the voice call .and we missed the calls

    yours sincerly

    devendra agrawal
    9425211123

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