System for generating an analogue I/Q signal from two or more data streams
A system and method for generating an I/Q signal for an I/Q modulator ( 10 ). The signal is composed of two or more data streams, which have been edited according to identical or different modulation methods. A known modulation encoder is used to generate corresponding digital I/Q values from a first inputted digital data stream. The I/Q values then undergo a digital-analogue conversion ( 8 ) that generates the corresponding analogue I/Q signals. The system includes an additional modulation generator that calculates digital I/Q values, or generates I/Q values from an additional inputted digital data stream. The digital I/Q values of the modulation encoder and the digital I/Q values of the modulation generator ( 10 ) are then added together, using digital adders (A 3 ) located upstream of the digital-analogue converter ( 8 ).
1. An arrangement for generating an I/Q signal for an I/Q modulator using a modulation encoder, the arrangement comprising:
a modulation encoder including:
an encoding and mapping unit;
a digital base-band filter whose filter properties are adjustable,
said digital base-band filter disposed after said encoding and mapping unit;
a digital modulation format converter disposed after said base-band filter;
an interpolation filter disposed after said modulation format converter;
a digital/analog converter disposed after said interpolation filter;
an analog low-pass filter disposed after said digital/analog converter; and
at least one adder disposed after said encoding and mapping unit and before said digital/analog converter,
wherein, in said modulation encoder, corresponding digital I/Q values are generated from a first digital input data stream and the corresponding analog I/Q signals are generated therefrom after digital/analog conversion, and
at least one modulation generator in which calculated digital I/Q values or digital I/Q values generated from a further digital input data stream are generated,
wherein the digital I/Q values of the modulation encoder and the digital I/Q values of the modulation generator are added via said at least one adder.
2. The arrangement of claim 1 , characterized in that at least one of said at least one adder is disposed before said band-pass filter.
3. The arrangement of claim 1 , characterized in that at least one of said at least one adder is disposed between the modulation format converter and the interpolation filter.
4. The arrangement of claim 1 , characterized in that at least one of said at least one adder is disposed after said interpolation filter.
5. The arrangement of claim 1 wherein said modulation encoder further includes a digital correction filter disposed after said interpolation filter.
6. The arrangement of claim 5 , characterized in that at least one of said at least one adder is disposed after said interpolation filter but before said digital correction filter.
7. An arrangement for generating an I/Q signal for an I/Q modulator using a modulation encoder, the arrangement comprising:
a modulation encoder including:
an encoding and mapping unit;
a digital base-band filter whose filter properties are adjustable, said digital base-band filter disposed after said encoding and mapping unit;
an interpolation filter disposed after said base-band filter;
a digital modulation format converter disposed after said interpolation filter;
a digital/analog converter disposed after said digital modulation format converter;
an analog low-pass filter disposed after said digital/analog converter; and
at least one adder disposed after said encoding and mapping unit and before said digital/analog converter,
wherein, in said modulation encoder, corresponding digital I/Q values are generated from a first digital input data stream and the corresponding analog I/Q signals are generated therefrom after digital/analog conversion, and
at least one modulation generator in which calculated digital I/Q values or digital I/Q values generated from a further digital input data stream are generated,
wherein the digital I/Q values of the modulation encoder and the digital I/Q values of the modulation generator are added via said at least one adder.
8. The arrangement of claim 7 characterized in that at least one of said at least one adder is disposed between base-band filter ( 4 ) and interpolation filter ( 6 ).
9. The arrangement of claim 7 wherein said modulation encoder further includes a digital correction filter disposed after said interpolation filter.
10. The arrangement of claim 7 , characterized in that at least one of said at least one adder is disposed before said band-pass filter.