System and method for nondisruptively embedding an OFDM modulated data signal into a composite video signal

An apparatus for modulating a binary bit stream in a composite video signal, the composite video signal includes luminance, chrominance and audio components, the apparatus comprising:

• a sync pulse stripper configured to obtain sync pulse information from the composite video signal;
• a modulator configured to modulate the binary bit stream according to quadrature amplitude modulation, the modulator comprising:
• a symbol mapper configured to generate in-phase and quadrature symbol streams;
• a symbol stream combiner configured to combine the in-phase and quadrature symbol streams according to quadrature amplitude modulation techniques;
• and
• pre-equalizer operating on the generated in-phase and quadrature symbol streams to compensate for comb filtering effects
• a digital to analog converter configured to convert the combined symbol streams into an analog signal;
• and
• a combiner configured to combine the analog signal with the composite video signal according to the obtained sync pulse information.

A method for demodulating a binary bit stream modulated in a composite video signal as a gated and windowed orthogonal frequency division modulation (OFDM) offset carrier modulated signal, the composite video signal includes luminance, chrominance and audio components, the method comprising:

• converting the composite video signal modulated with the carrier centered OFDM modulated signal into a digital signal;
• splitting the digital signal into synch pulses and a quadrature amplitude modulated data stream;
• gating the active video line interval and applying a window to the interval to help suppress the video signal components;
• separating the offset OFDM modulated data stream into in-phase and quadrature symbol frames streams according to the synch pulses;
• and
• combining the in-phase and quadrature demodulated symbol frames into a single binary data stream.

A receiver for demodulating a binary bit stream modulated in a composite video signal as an offset orthogonal frequency division modulation (OFDM) modulated signal, the composite video signal includes luminance, chrominance and audio components, the receiver comprising:

• an analog to digital converter configured to convert the composite video signal modulated with the offset OFDM modulated signal into a digital signal;
• a gating and windowing unit operating on the digital signal;
• a splitter configured to split the digital signal into synch pulses and an I-Q OFDM modulated data stream;
• a separator configured to separate the offset OFDM modulated data frame into in -phase and quadrature symbol frames according to the synch pulses;
• and
• a combiner configured to combine the in-phase and quadrature data frames into a single binary data stream.