How to set ID-timer ?

I found the good example implementing IR_TX.

Refer to below link. I succeed my ir_tx function.

http://community.broadcom.com/message/3621#3621

I am looking for any ID-timer defined by programmer.

I use bt_clock_based_periodic_timer_Enable() function to implement various Timers.

I manage to implement IR LED on-off functions .

I wonder my ir code produces different timing in IR_LED on`.

My ir code is as below.(Repeating between   holding IR_LED on 200ms and IR LED off 200ms)

I call bt_clock_based_periodic_timer_Enable(application_timer_expired_callback, NULL, 400000/625);

The registered callback function repeats.

int application_timer_expired_callback(void* context)

{

     // 400 ms timer callback, do something.

  ble_trace1("\rtimer_expired_callback()=%ld",ir_tx_ms);

  irtx_abortCurrentTransaction();

    //Todo: do you actions here every 1 second

    send_buffer[0]=HIGH(3400);

    send_buffer[1]=HIGH(3400);

    send_buffer[2]=HIGH(3400);

    send_buffer[3]=HIGH(3400);

    send_buffer[4]=HIGH(3400);

    send_buffer[5]=HIGH(3400);

    send_buffer[6]=HIGH(3400);

    send_buffer[7]=HIGH(3400);

    //Send IR Code in 120 second.

    if(ir_tx_ms < 120000)

    {

  irtx_sendData(send_buffer, 8, irtxClockSet);

  ir_tx_ms=ir_tx_ms+400;

  }else{

  bt_clock_based_periodic_timer_Disable();

  }

     // Context was not allocated and so does not need to be freed. So return no action.

     return BLE_APP_EVENT_NO_ACTION;

}

The below picture says IR timing in the oscilloscope measurement.

The red rectangles show IR wave forms. I wonder why my code produces different IR wave forms.

I just repeat the same buffer value in my source code.

Thanks in advance.