Dual Mode Amplitude Modulation

  Transmit two signals over an amplitude modulated carrier wave 
  Patent application no. -  3302/MUM/2010 

This invention relates to amplitude modulation used in electronic communication devices. Existing method of amplitude modulation employs change in amplitude of a carrier signal with respect to amplitude of a modulating signal. In this method amplitude of carrier signal is modulated on positive and negative side of carrier wave and both sides carry same modulating signal.

  Invention (What is New)  

The method of modulating two different modulating signals on one carrier comprises of a device that modulates one modulating signal on positive side of the carrier wave and another signal on negative side of a carrier wave before transmission.

  Modulation1                  Modulation2 

A diagram shows 1 as carrier signal generator.  This signal is first modulated using a sine wave created by source shown as 5.  (The modulation is only on one amplitude side of the AM carrier signal). This signal is fed the block 3 where the other amplitude of AM carrier is modulated with another signal (Shown as square wave) Thus an AM Carrier signal has two different modulating signals to be transmitted. The final modulated signal is shown above as 36 where top amplitude is modulated with square wave and bottom amplitude is modulated with sine wave.



  Demodulation Block Diagram         Modulation3
  Sample Circuit to demodulate signal transmitted by dual mode transmitter described before. A receiver comprises of two de-modulators to retrieve the two signals transmitted on one carrier wave.. The output signals are shown as 48 and 54 which are two signals transmitted over one amplitude modulated signal