DIFFERENTIAL AMPLITUDE PHASE SHIFT KEYING: A NEW MODULATION METHOD FOR TURBO CODE IN DIGITAL RADIO BROADCASTING

The multilevel modulation techniques nf M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Comparison of this modulation method with channel coding in an Additive White Gaussian Noise (AWGN) and multi-path fading channels has been presented. The analysis provides an iterative decoding of the Turbo code.

PERFORMANCE EVALUATION OF LOW DENSITY PARITY CHECK CODES FOR DIGITAL RADIO MONDIALE (DRM) SYSTEM

In Digital Radio Mondiale （DRM） system, achieving good audio quality becomes a challenge due to its limited band-width of 9 or 10kHz and the very bad lading channels. Therefore, DRM needs highly efficient channel coding schemes. This paper, proposes the schemes which use the Low-Density Parity-Check （LDPC） coded Bit-Interleaved Coded Modulation （BICM） schemes for the implementation of DRM systems. Simulation results show that the proposed system is more efficient than the Rate Compatible Punctured Convolutional （RCPC） coded DRM system on various broadcast channels, and may be recommended as a coding technology for Digital Amplitude Modulation Broadcasting （DAMB） systems of China.

Modulation for Digital Radio Broadcasting Using Amplitude Autocorrelation of Pseudo Random Noise Codes to Carry Information

The frequency bands used in mobile communications are allocated according to the type of application. With the need for more channels, the frequency spectrum has become a scarce natural resource. This study shows the results of a proposed modulation using a variation of the autocorrelation of pseudo-random codes to carry information. The work also presents the generation of multiple orthogonal axes to increase the bit rate thus improving the channel efficiency.

Digital Radio Broadcasting for Community Radios Using Pseudo-random Codes

This paper aims to present a digital radio broadcasting system that explores the advantages of pseudo-random codes. In this context, a transmitter and its dual receiver are able to reuse frequency spectrum bands without interfering on other existing communication systems. It is proposed a communication system that allows radio broadcasting with the following characteristics: lower transmission power, new communication channels and digital signal processing techinques to add positioning services in two dimensions.

Digital broadcast channel estimation with compressive sensing

In order to reduce the pilot number and improve spectral efficiency, recently emerged compressive sensing （CS） is applied to the digital broadcast channel estimation. According to the six channel profiles of the European Telecommunication Standards Institute（ETSI） digital radio mondiale （DRM） standard, the subspace pursuit （SP） algorithm is employed for delay spread and attenuation estimation of each path in the case where the channel profile is identified and the multipath number is known. The stop condition for SP is that the sparsity of the estimation equals the multipath number. For the case where the multipath number is unknown, the orthogonal matching pursuit （OMP） algorithm is employed for channel estimation, while the stop condition is that the estimation achieves the noise variance. Simulation results show that with the same number of pilots, CS algorithms outperform the traditional cubic-spline-interpolation-based least squares （LS） channel estimation. SP is also demonstrated to be better than OMP when the multipath number is known as a priori.

ECCM schemes in netted radar system based ontemporal pulse diversity

For a netted radar system to counteract the deceptionelectronic countermeasure （ECM） signals, an effective electroniccounter countermeasure （ECCM） approach is proposed. The proposedapproach is realized based on the new signaling strategyfor the temporal pulse diversity, which makes use of transmittingpulses at each pulse repetition interval （PRI） with specific transmissionpulse block, and then following proper processing andinformation fusion. The existence of the deceptive ECM signal isconfirmed by one station, while the other stations in the nettedradar with same parameters applied the pulse diversity skillfully.Meanwhile, this method ensured that, pulse diversity can be appliedin netted radar. The performance assessment shows that theproposed solutions are effective in presence of ECM signals. Thisalgorithm has been demonstrated by simulations. The presentedsimulation results are in excellent consensus with theoretical predictions.

Researching on quadrature conversion structures For an UWB demonstrative receiver

Some structures of digital quadrature AD conversion for soft-ware-defined radio （SDR） systems are studied. Their performances and affections on the SDR systems are also analyzed. Two generalized quadrature AD schemes are proposed. In one of them, the AD sampling speed can be reduced by 2 times; and in the other both the output data rate of every channel and AD sampling speed can be lowered by paralleling the digital quadrature filtering structure. These structures can be also easily implemented into modules, and the polyphase filters can be flexibly realized by VHDL language based one chip of FPGA. To assess the proposed schemes, their applications to a particular ultra wideband （UWB） demonstrative receiver system are introduced. Some experimental results are also given. It is shown that the generalized quadrature AD structures are reliable and feasible for its module design, and performances are improved obviously for its better performance to price ratio.

Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

Hardware-in-the-loop （HWIL） simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory （DRFM） system, the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile （HRRP） are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.

Compact phase-lock loop for external cavity diode lasers

We present a compact, low-noise, and inexpensive optical phase-lock loop （OPLL） system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer tech- nique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.