Method to minimize compatibility error in hierarchical modulation using variable phase
First Claim
1. A method for transmitting at least two levels of data in a hierarchical transmission system comprising the steps of:
- generating a first modulated signal based on first input data;
superimposing at least a second modulation on the first modulated signal based on at least a second input data, the second modulation being spread across a plurality of symbols in the first modulated signal in a predetermined pattern to create a modified signal;
transmitting the modified signal;
decoding the modified signal by performing a first demodulation of the first modulated signal then a second demodulation to obtain the first input data and the second input data.
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Accused Products
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. Alternatively, the additional modulated signal may be a fromed as a direct sequence spread spectrum modulation and the offset sequence appearing as a pseudo-noise distribution. A Hadamard matrix sequence may be used as the direct sequence code.
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Citations
18 Claims
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1. A method for transmitting at least two levels of data in a hierarchical transmission system comprising the steps of:
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generating a first modulated signal based on first input data;
superimposing at least a second modulation on the first modulated signal based on at least a second input data, the second modulation being spread across a plurality of symbols in the first modulated signal in a predetermined pattern to create a modified signal;
transmitting the modified signal;
decoding the modified signal by performing a first demodulation of the first modulated signal then a second demodulation to obtain the first input data and the second input data. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A receiver for receiving at least two levels of data in a hierarchical transmission system comprising:
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an antenna for receiving RF signals;
a demodulator coupled to said antenna for downconverting received RF signals;
a first detector coupled to said demodulator, said first detector having a first output and capable of providing digital information based on a first level of data on said first output; and
at least a second detector coupled to said demodulator, said at least a second detector having at least a second output and capable of providing digital information based on at least a second level of data on said at least a second output, said at least a second detector being adapted to detect the at least a second level of data as a predetermined pattern spread over the first level of data. - View Dependent Claims (8, 9, 10, 11)
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12. The receiver of claim 111 wherein said at least a second detector includes a predetermined pattern comprising a Hadamard matrix sequence.
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13. A transmitter for transmitting at least two levels of data in a hierarchical transmission system comprising:
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an encoder adapted to receive a first and at least a second input data, said encoder capable of providing digital information based on a first level of data on an output stream, said encoder capable of providing digital information based on at least a second level of data on said output stream, said encoder being adapted to superimpose the at least a second level of data as a predetermined pattern spread over the first level of data;
a modulator coupled to said encoder for upconverting said output stream; and
an antenna coupled to said modulator for transmitting RF signals based on the upconverted output stream. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification