Multiple Frequency Shift Keying Modulation Research Articles

In brief

PAGE 644 Researchers in Hong Kong have created flexible pentacene organic thin-film transistors (OTFTs) with HfYO gate dielectric at room temperature on adhesive vacuum tape. Their results suggest that this method, and the combination of materials, are promising for high-performance flexible pentacene OTFTs. Such TFTs could be used in adhesive RFID devices and flexible bending and strain sensors. PAGE 642 An in-situ calibration method for dual-mask spatial light modulators (SLMs) is presented in work from Germany. Using an evolutionary algorithm to determine phase-voltage relationships of the SLM liquid-crystal masks, it avoids the ambiguity of manual methods and the separate setups required by interferometry approaches. The proposed method simplifies calibration of SLM pulse shapers for applications including ultra-short pulse shaping, particularly using external-cavity semiconductor lasers with intra-cavity pulse-shaping. Flexible and adhesive pentacene OTFTs made at room temperature with vacuum tape and HfYO PAGE 595 A waveform generator for a 77-GHz automotive radar using multiple frequency shift keying (MFSK) modulation is demonstrated in research from Korea. MFSK modulation can improve detection in multi-target applications such as adaptive cruise control. The key innovation in this generator is the use of MFSK modulation control logic (MMCL), which has the ability to track the linear frequency increase while generating the FSK in each time step. The method provides accurate in-situ calibration of SLMs for applications such as high-resolution femtosecond pulse shaping PAGE 601 Researchers in China present a high-power cavity-backed helical antenna with unit ceramic radome. Using a unit ceramic radome in a thin-wall structure, a vacuum seal for a single element is achieved and using a backed cavity, mutual coupling among elements is significantly reduced. S-band prototypes applied in 16- and 256-element array antennas demonstrate circularly polarised radiation in the axial direction at 2.7-3.0 GHz and single element average power-handing capacity of at least 4.7 MW. The waveform generator uses MMCL to improve multi-target detection for automotive applications like adaptive cruise control PAGE 640 The first results of using SiGe microwave phototransistors in radio-over-fibre applications is presented by researchers in France. They show error-free transmission of a 3.08 Gbps IEEE 802.15.3c HSI signal at 5 GHz, after cycle redundancy check correction, demonstrating the potential of these devices for radio-over-fibre links. Individually vacuum sealed and backed for reduced coupling, each unit has an average power-handling capacity of at least 4.7 MW The results are the first reported that concentrate on the devices in a radio-over-fibre application context

77 GHz waveform generator with multiple frequency shift keying modulation for multi‐target detection automotive radar applications

A waveform generator for a 77 GHz automotive radar that uses multiple frequency shift keying (MFSK) modulation is presented. The use of this modulation can improve the detection ability of radar applications in multi-target situations. The proposed generator consists of a conventional 77 GHz Σ-Δ fractional-N synthesiser and MFSK modulation control logic (MMCL). The key innovation is the introduction of the MMCL, which has the ability to track the linear frequency increase while generating the frequency shift keying in each time step. Prior to realising the hardware implementation, a behavioural simulation was evaluated. In addition, a 77 GHz generator module was designed using 130 nm CMOS technology. In a chirp time of 6 ms, there were a total of 128 modulation steps. The bandwidth and frequency step of the chirp were 100 MHz and 300 kHz, respectively.

Nonbinary convolutional codes and modified M-FSK detectors for power-line communications channel

The Viterbi decoding algorithm, which provides maximum ¿ likelihood decoding, is currently considered the most widely used technique for the decoding of codes having a state description, including the class of linear error-correcting convolutional codes. Two classes of nonbinary convolutional codes are presented. Distance preserving mapping convolutional codes and M-ary convolutional codes are designed, respectively, from the distance-preserving mappings technique and the implementation of the conventional convolutional codes in Galois fields of order higher than two. We also investigated the performance of these codes when combined with a multiple frequency-shift keying (M-FSK) modulation scheme to correct narrowband interference (NBI) in powerline communications channel. The modification of certain detectors of the M-FSK demodulator to refine the selection and the detection at the decoder is also presented. M-FSK detectors used in our simulations are discussed, and their chosen values are justified. Interesting and promising obtained results have shown a very strong link between the designed codes and the selected detector for M-FSK modulation. An important improvement in gain for certain values of the modified detectors was also observed. The paper also shows that the newly designed codes outperform the conventional convolutional codes in a NBI environment.

Performance of asynchronous slow frequency-hop multiple-access networks with MFSK modulation

The performance of asynchronous slow frequency-hop spread-spectrum multiple-access networks where each user transmits L, M-ary symbols per hop using M-ary frequency-shift keying (FSK) modulation with noncoherent demodulation is investigated. Expressions for the decision variables are derived for a given multiple FSK (MFSK) symbol within a hop hit by K' interfering users under additive white Gaussian noise and Rayleigh fading channel models. For the special case when M=2, an accurate analytic approximation for the average error probability is derived as a function of L and K' and semianalytic Monte Carlo simulations are performed to estimate the probability of error for M larger than 2. The results are used to investigate the dependence of the average symbol error probability on L and M. Finally, the effect of enforcing phase transition between the MFSK symbols within a hop is investigated.