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Analog shortwave radio on bands up to 30 MHz has typically been limited in applicability for long-distance broadcast applications requiring high signal fidelity. This is because of the vulnerability of analog modulation schemes to atmospheric dispersion; however, the Digital Radio Mondiale (DRM) standard, introduced in 2001, is a promising solution for shortwave radio. DRM provides various audio and...
Superconductor digital receiver systems of increasing functionality, modularity and user-friendliness have been developed. The modular design methodology ensures that within its input-output and heat load capacity, the system can be reconfigured to perform a different function by changing the chip module and by reprogramming FPGA-based digital signal processors. One of the systems (ADR-004), originally...
Radio communications possessing high signal quality and long-distance propagation have traditionally been difficult to achieve reliably over shortwave bands (up to 30 MHz). This is due to the analog modulation schemes in use and the vulnerability of shortwave radio to atmospheric disturbances. The development of the Digital Radio Mondiale (DRM) standard in 2001 provided digital coding methods, audio...
An improved Digital Radio Frequency Memory (DRFM) system based on digital channelized receiver is stated, which employs digital channelized receiver to slow down the high speed input data flow, and uses Digital Up Converter (DUC) to generate digital intermediate frequency (IF) signal from digital baseband signal. This system can achieve broad instantaneous frequency coverage, reduce the demand for...
This paper describes a novel design approach for the DDS (direct digital synthesizer) required to correct the frequency shift in the received signal of a digital OFDM receiver. The traditional phase accumulator has been modified to perform modulus 2N-1 accumulation. This modification provides fine frequency tuning capabilities using a very small sine/cosine look-up-table. Current systems use hundreds...
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