Systems and methods for signal conversion
Systems and methods for signal conversion are provided. Signals are spread in a continuous spectrum by a spread spectrum signal, such as a direct sequence spread spectrum (DS-SS) signal. The signals are then processed, which may include but is not limited to analog-to-digital conversion, digital-to-analog conversion, frequency conversion, clipping, filtering or a plurality of processes. The processed signal is then despread using substantially the same spreading signal that was used to spread the signal.
1. A transmitter system, comprising:
a spreading code generator that produces a spreading code;
a spreader that combines the spreading code with an input signal to provide a spread input signal;
a signal converter that converts the spread input signal from a first domain to a second domain to provide a converted spread input signal;
a mixer for frequency converting the converted spread input signal to provide an upconverted spread input signal;
a despreader that despreads the upconverted spread input signal to provide a despread signal; and
an antenna that transmits the despread signal.
2. The transmitter system of claim 1 , funher comprising a feedback loop coupling the despreader to the spreader for time aligning the despreading with the spreading.
3. The transmitter system of claim 1 , wherein the first domain is one of a digital domain and an analog domain and the second domain is the other of the digital domain and the analog domain.
4. The transmitter system of claim 1 , wherein the signal converter is one of a delta-sigma analog-to-digital converter (ADC) and a delta-sigma digital-to-analog converter (DAC).
5. The transmitter system of claim 1 , further comprising a clipping component that reduces peaks associated with the spread input signal, the despreader mitigates degradation and out-of-band (OOB) emissions associated with the peak reduction.
6. The transmitter system of claim 1 , wherein at least one of the spreader and the despreader circuit comprises a mixer.
7. A transmitter system comprising:
a spreading code generator that produces a direct sequence spread spectrum (DS-SS) spreading code;
a spreading circuit that receives an input signal and combines the input signal with the DS-SS spreading code to provide a spread input signal;
a clipping component that reduces peaks associated with the spread input signal;
a signal converter that converts the spread input signal form a first domain to a second domain;
a despreading circuit that despreads the peak reduced spread input signal;and
an antenna for transmitting the despread peak reduced input signal.
8. The system of claim 7 , wherein at least one of the spreading circuit and despreading circuit comprises a mixer.
9. The system of claim 7 , the signal converter being one of a digital-to-analog converter (DAC) and an analog-to-digital converter (ADC).
10. The system of claim 9 , the signal converter being one of a delta-sigma DAC and a delta-sigma ADC.
11. The system of claim 9 , further comprising a mixer for frequency converting the spread input signal one of before signal conversion and after signal conversion.
12. A method for transmitting a signal, comprising:
spreading a digital signal with a spreading signal code;
converting the digital spread signal to an analog signal;
modulating the analog signal to produce an upconverted analog signal;
despreading the upconverted analog signal to provide a despread signal; and
transmitting the despread signal.
13. The method of claim 12 , further comprising clipping the signal to reduce peaks associated with the signal.
14. A transmitter comprising:
means for generating a direct sequence spread spectrum (DS-SS) spreading code;
means for combining the DS-SS spreading code with an input signal to produce a spread input signal
means for clipping the spread input signal to remove peaks;
means for converting the spread input signal from a first domain to a second domain;
means for despreading the spread input signal in the second domain; and
means for transmitting the despread input signal.