Digital FSK Research Articles

Photonic Approach for Generation and Fast Switching of Binary Digitally Modulated RF Signals

A photonic method to generate hybrid binary digitally modulated radio frequency (RF) signals (i.e. ASK, PSK, and FSK) by using a polarization-division-multiplexed Mach-Zehnder modulator (PDM-MZM) is proposed. The PDM-MZM is driven by two RF signals with different carrier frequencies and two multiplied digital signals. By properly controlling the offsets and the amplitudes of the digital signals, ASK, PSK, and FSK signals can be generated and switched fastly. RF signals at 4/6 GHz and 10/15 GHz with switchable modulation formats are experimentally generated. Moreover, the performances of the generated signals are evaluated in a wireless transmission system and corresponding bit error rate (BER) curves of the signals are presented.

Desain Transmitter Portabel Untuk Komunikasi Data

Digital data is one of the data or information that is often misused, therefore this research begins by studying various literatures related to the encryption system used in cryptographic techniques. And based on the literature that was read, made a series of design and encryption system design program based on Thonny Python. The results of the design are then realized by creating a series of file encryption systems through the application program. The results obtained from this study are the encryption system created in Thonny Python has been able to randomize the original information in this case in the form of a file and is able to transmit the encrypted data with various limitations. This study discusses digital data communication systems using HF radio waves with its main device as a complete communication radio with antenna and power supply, and is equipped with a Raspberry as an enhancement to digital data processing and FSK Modulator as an interface between Raspberry and HF radio that functions as a digital signal modifier that out of Raspberry becomes an analog signal as input for HF radio.

광역 WPAN 응용을 위한 주파수 오차에 강인한 최적 다중비트 디지털 FSK 수신기

본 논문은 최근 표준화가 진행 중인 광역 WPAN에서 주파수 옵셋에 강인한 최적화된 다중 비트 기반 디지털 FSK 수신기에 대해서 제안한다. 광역 WPAN FSK 표준에서는 기존보다 짧은 프리앰블을 사용하고 있으며, 통신반경이 늘어남에 따라 엄격한 BER 요구사항을 제시하고 있다. 이러한 요구사항을 만족하기 위해서 본 논문에서는 CFO가 있는 상황에서도 간단하면서 BER 성능을 만족할 수 있는 최적화된 디지털 FSK 수신기를 설계하였다. 시뮬레이션을 통해 광역 WPAN FSK 시스템에서 필요한 비트 수를 결정하고, 짧은 프리앰블을 사용함에도 CFO에 상관없이 요구 BER 성능을 만족시킬 수 있음을 증명하여 제안된 FSK 수신기가 최근 광역 WPAN 응용에 적절함을 보였다. This paper proposes an optimized multi-bit digital FSK receiver robust to large carrier frequency offset (CFO) toward recently emerging long-range WPAN standards. Due to a short preamble length and strict BER requirements, we design a simple multi-bit digital demodulator combined with CFO estimator which guarantees the target BER performance. Simulation results verify that the proposed FSK receiver achieves CFO-free BER performance with the short preamble and satisfies the BER requirement by the recent WPAN applications.

Robust Ultra-Low Latency Soft-Decision Decoding of Linear PCM Audio

Applications such as professional wireless digital microphones require a transmission of practically uncoded high-quality audio with ultra-low latency on the one hand and robustness to error-prone channels on the other hand. The delay restrictions, however, prohibit the utilization of efficient block or convolutional channel codes for error protection. The contribution of this work is fourfold: We revise and summarize concisely a Bayesian framework for soft-decision audio decoding and present three novel approaches to (almost) latency-free robust decoding of uncompressed audio. Bit reliability information from the transmission channel is exploited, as well as short-term and long-term residual redundancy within the audio signal, and optionally some explicit redundancy in terms of a sample-individual block code. In all cases we utilize variants of higher-order linear prediction to compute prediction probabilities in three novel ways: Firstly by employing a serial cascade of multiple predictors, secondly by exploiting explicit redundancy in form of parity bits, and thirdly by utilizing an interpolative forward/backward prediction algorithm. The first two presented approaches work fully delayless, while the third one introduces an ultra-low algorithmic delay of just a few samples. The effectiveness of the proposed algorithms is proven in simulations with BPSK and typical digital microphone FSK modulation schemes on AWGN and bursty fading channels.

Fully integrated low‐power area‐efficient FSK demodulator for inductively powered biomedical implants

A fully integrated low-power digital FSK demodulator is presented. Employing a novel clock extractor, the clock can be reliably retrieved from the FSK carrier, which also enables robust synchronisation of the clock and data without using a phase-locked loop. This implantable demodulator was fabricated in a 0.35 μm CMOS process and tested using inductively coupled coils.

A Survey on FM-UWB Transceivers

his paper surveys the research on frequency modulated ultra- wideband (FM-UWB) transceivers. FM-UWB system uses low modulation index digital FSK followed by high modulation index analog FM to generate a constant envelope UWB signal with a flat power spectral density and steep spectral roll-off. FM-UWB can be seen as an analog implementation of a spread spectrum system with spreading gain equal to the modulation index. FM-UWB system is suitable for low data rate and short-range applications. The advantages of FM-UWB system such as low power consumption, very low radiated power (−41.3 dBm/MHz), good coexistence with other existing wireless technologies, and robustness to interference and multipath making it suitable for Wireless Body Area Network (WBAN) in medical applications.

Principles and Limitations of Ultra-Wideband FM Communications Systems

This paper presents a novel UWB communications system using double FM: a low-modulation index digital FSK followed by a high-modulation index analog FM to create a constant-envelope UWB signal. FDMA techniques at the subcarrier level are exploited to accommodate multiple users. The system is intended for low (1–10 kbps) and medium (100–1000 kbps) bit rate, and short-range WPAN systems. A wideband delay-line FM demodulator that is not preceded by any limiting amplifier constitutes the key component of the UWBFM receiver. This unusual approach permits multiple users to share the same RF bandwidth. Multipath, however, may limit the useful subcarrier bandwidth to one octave. This paper addresses the performance with AWGN and multipath, the resistance to narrowband interference, as well as the simultaneous detection of multiple FM signals at the same carrier frequency. SPICE and Matlab simulation results illustrate the principles and limitations of this new technology. A hardware demonstrator has been realized and has allowed the confirmation of theory with practical results.

Probability of erasure in non-Rayleigh fading channels-a simulation study

This paper examines the probability of erasure for a digital FSK mobile communication channel containing between 2 and 10 effective scatterers using Monte Carlo simulations. Quantitative results indicate the probability of erasure can be up to 25% more than that predicted by the Rayleigh model for the 2 scatterer channel.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The performance of a digital FSK system with actual discriminator: time distortions effects

The performance of a digital FSK system with actual discriminator: time distortions effects

Radio propagation within buildings at 900 MHz

The letter reports some results of a survey which studied the propagation of radio signals at 900 MHz within buildings for the operation of cordless telephones. Histograms are presented of signal strength together with computed values for bit-error ratio for digital FSK modulation. A distance/power law is derived appertaining to the propagation characteristics of the building.