Cable TV channel controller

Discussion in 'Embedded Systems and Microcontrollers' started by Anuradha, Jan 26, 2010.

  1. Anuradha

    Thread Starter Member

    Mar 3, 2008
    11
    0
    hello
    Me and my friend try to designed a circuit for a cable tv system. what we are trying is to automate the connecting and disconnecting of channels for a specific user. once we are finished the TV service provider can view all the users from a PC and he can disconnect any user as he wants. I'm a computer programmer(C/C++,C#). my friend has some knowledge about MCU and stuff.
    but the problem is that we don't have a high level idea to archive this.

    can any one have a idea on this???

    Thanks
    Anuradha
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Some specific means of communicating with each cable box will be necessary. Each box will need a microprocessor in it to handle the communications and other functions like downconverting the received channels.
     
  3. Anuradha

    Thread Starter Member

    Mar 3, 2008
    11
    0
    first of all thank you beenthere for the reply. Yah each box must have a MCU. But how can I interface it to a computer?

    All the communications are wired. so sending a signal to a specific box will not be a problem. will the signal strength get lost due to the distance ??

    Also what kind of PIC is suitable for this project ??

    many thanks
    Anuradha
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You are ahead of yourself. You need to identify all of the functions of the control circuit, including the ability to do more in the future. You need to design the board to fit into the existing cable box (or so it seems), so determining if the power supply as it now exists will support the additional load is necessary.

    Then there is a list:
    1. How will the cable box get switched on and off?
    2. Will some channels get passed and others blocked?
    3. Are there additional functions to accomplish?
    4. How will the control signal be composed?
    5. How will each cable box be properly identified?
    6. How will the control signal be placed into the existing cable signals?
    7. Why have you identified a PIC as most suitable?
     
  5. Anuradha

    Thread Starter Member

    Mar 3, 2008
    11
    0
    Thx for the reply beenthere. I can answer some of these questions. I need your opinion on this. So here we go....

    1. How will the cable box get switched on and off?
    We are planning to use relay switches for this.PIC must have an EPROM. From that way even the power goes down the previous configuration will remain as it is.

    2. Will some channels get passed and others blocked?
    No. for the time being they need only to block the connection. (For eg. if the user doesn’t pay the monthly bill service provider can disconnect it using his PC).

    3. Are there additional functions to accomplish?
    For the time being none.

    4. How will the control signal be composed?
    Planning to generate a unique frequency for the specific box. So once he chooses to block a specific user, the unique frequency for that box will be transmitted form his PC.

    5. How will each cable box be properly identified?
    By using a unique frequency.

    6. How will the control signal be placed into the existing cable signals?
    Now this is a problem. Still no idea.

    7. Why have you identified a PIC as most suitable?
    Well that’s because for the low cost. (I know in technical wise there may have some best options other than the PIC)

    please let me know your suggestions on this.
    Thank you very much
    Anuradha
     
  6. Art

    Distinguished Member

    Sep 10, 2007
    785
    61
    Usually, every cable box receives the commands for every other cable box,
    but each individual cable box ignores all of the commands that are not addressed to the specific cable box's serial number.
    The access control data is usually sent on the same cable as the TV,
    in an FM modulated signal.

    Whenever there is spare bandwidth left in the FM modulated stream,
    the headend unit spend's it's time sending out commands to disable channels
    that the client should not be receiving, in case the customer has worked out
    how to send his own codes to enable channels on his cable box.
    Art.
     
  7. Anuradha

    Thread Starter Member

    Mar 3, 2008
    11
    0
    Thank you Art.Thank you very much
     
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