Is it possible to play an audio file with a GSM modem

Hi All,

I am doing a GSM project for my third year, and I am clueless where to begin. Please advice me. The requirements are:

A microcontroller receives a signal from a door sensor. Whenever the signal is received (i.e. door opened), the microcontroller must send a command to the GSM modem, and the GSM modem must initiate a call to some pre-defined number. When the called party answers the call, the GSM modem must play-back a voice that says something like "Door opened". So there must be an audio file stored somewhere and played-back whenever a call is answered.

So my main problem is, how do I use a GSM modem or microcontroller to play-back an audio file? Where do I store this file and retrieve it? Your advice will be highly appreciated.

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  • Isn't it expected that, by the third year, you should have at least some clue...?

    Yes, it is possible.

    As far as the GSM modem is concerned, it neither knows nor cares where its audio input signal comes from - just so long as it meets the input specifications.
    Just make sure that the particular "modem" does have an audio input - ie, it isn't just a data-only modem!

    Dialling the call is just a matter of issuing the appropriate AT Commands.

    Note that some modems can embed an application within the modem - so you might not need an external microcontroller at all!

    http://www.wavecom.com/openat
    www.telit.com/.../gsm-gprs.php
    etc, etc,...

    There are chips available to do speech synthesis;
    There are chips available to do text-to-speech;
    There are chips available to store & play-back sampled audio;
    Or you could just store the data in a microcontroller, and use simple PWM to convert it to analogue audio.

Reply
  • Isn't it expected that, by the third year, you should have at least some clue...?

    Yes, it is possible.

    As far as the GSM modem is concerned, it neither knows nor cares where its audio input signal comes from - just so long as it meets the input specifications.
    Just make sure that the particular "modem" does have an audio input - ie, it isn't just a data-only modem!

    Dialling the call is just a matter of issuing the appropriate AT Commands.

    Note that some modems can embed an application within the modem - so you might not need an external microcontroller at all!

    http://www.wavecom.com/openat
    www.telit.com/.../gsm-gprs.php
    etc, etc,...

    There are chips available to do speech synthesis;
    There are chips available to do text-to-speech;
    There are chips available to store & play-back sampled audio;
    Or you could just store the data in a microcontroller, and use simple PWM to convert it to analogue audio.

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