Abstract: The present invention involves a transmitter for transmitting two levels of data in a hierarchical transmission system. The transmitter has encoders, a modulator, an adjuster, and an up converter. The first encoder has a first output and capable of providing digital information based on a first level of data on the first output. The second encoder has a second output and is capable of providing digital information based on a second level of data on the second output. The modulator is coupled to the first encoder and has I and Q outputs. The adjuster is coupled to the modulator and second encoder and modifies signals on the I and Q outputs of the modulator to produce transmission I and transmission Q outputs. The up converter is coupled to the adjuster and is capable of transmitting broadcast radio signals based on the transmission I and transmission Q outputs. The modulator may include a root raised cosine filter and/or a QPSK modulator.

Abstract: The present invention provides a method, receiver and transmitter for use in a SDAR system. The method involves generating a first modulated signal based on first input data. Additional modulation is superimposed on the first modulated signal based on additional input data, being spread across a plurality of symbols in the first modulated signal in a predetermined pattern to generate a modified signal which is then transmitted. The modified signal is decoded by performing a first demodulation of the first modulated signal then additional demodulation is performed to obtain additional input data. The superimposing step uses a plurality of offset sequence values to add the additional modulation to the first modulated signal. The offset sequence may appear as a pseudo-random distribution of offset sequence values, and may include at least one zero offset value.

Abstract: The present invention provides a receiver for use in a SDAR system, the receiver including a receiving unit having satellite signal detection means for detecting a first transmit signal transmitted from a first communication satellite and a second transmit signal transmitted from a second communication satellite, the first transmit signal produced when the transmitter modulates a primary data stream with a secondary data stream on a first carrier wave associated with the first communication satellite and the second transmit signal produced when the transmitter modulates the primary and secondary data streams on a second carrier wave associated with the second communication satellite; and at least one demodulator coupled to the receiving unit and configured to demodulate the at least one of the first and the second transmit signals.

Abstract: The present invention involves a method and system for transmitting two levels of data in a hierarchical transmission schema. A first modulated signal is generated based on first input. A second modulation signal is generated based on a second input that has a data rate that is a fraction of the data rate of the first modulated signal. The second modulation signal has known instances where the second modulation signal has no energy. In a system where the first modulation is quadrature phase shift keying (QPSK), the second modulation signal can be a secondary phase offset. A receiver in the system that has a priori knowledge about the timing relationship between the first data signal and the instances when the second data signal is present will be able to detect both data signals optimally.