This paper analyzes the environmental effect and signal processing approaches for frequency-hopped frequency-shift-keyed (FH FSK) underwater acoustic communications based upon data collected in two experiments: the RDS4 experiment near Halifax, Canada and MREA03 experiment near Elba, Italy. The FH FSK signals have a bandwidth of 4 kHz centered at 17 and 20 kHz. The source was towed at ~4 knots....

We consider the error floor of binary FSK due to intersymbol interference in time-dispersive mobile radio channels, with a limiter-discriminator-integrator detector. The errors are caused by bursts in the instantaneous frequency. We propose and verify that a nonlinear frequency discriminator can achieve zero error floor for pure FSK by clipping off these bursts. For filtered FSK, the error floo...

This paper presents a novel three-point modulation technique for fractional-N frequency synthesizer applications. Convention modulated fractional-N frequency synthesizers suffer from quantization noise, which degrades not only the phase noise performance but also the modulation quality. To solve this problem, this work proposes a three-point modulation technique, which not only cancels the quan...

This paper presents a theoretical and experimental assessment of the performance of a wavelength converter based on semiconductor optical amplifiers (SOA) in a MZI configuration for optical label swapping. The optical labeling of the signal is based on an FSK/IM combined modulation format for the header/payload, respectively. Experimental results are presented for a signaling scheme with payloa...

104705-06-0909 IJECS-IJENS © December 2010 IJENS I J E N S Abstract—Frequency shift keying (FSK) systems enjoy the highest power efficiencies among the available modulation schemes but are accompanied by the lowest bandwidth (BW) efficiencies. Additional receiver complexities arise due to accurate phase estimations required for a large number of carrier frequencies in phase-coherent synchronous...

This work proposes a novel demodulation circuit to address the implementation of Wake-Up Receivers (Wu-Rx) in Wireless Sensor Nodes (WSN). This RF demodulator, namely Modulated Oscillator for envelOpe Detection (MOOD), is compatible with both FSK and OOK/ASK modulation schemes. The system embeds an LC oscillator, an envelope detector and a base-band amplifier. To optimize the trade-off between ...

Intra-body communication (IBC), using the human body as the channel to transmit data, has lower power consumption, less radiation, and easier linking than common wireless communication technologies such as Bluetooth, ZigBee, and ANT. As a result, IBC is greatly suitable for body area network (BAN) applications, such as the medical and health care field. Furthermore, IBC can be implemented in we...

Isoforskolin (ISOF) was isolated from Coleus forskohlii native to Yunnan in China. It is identified as one analog of diterpene forskolin (FSK) which comes from the Indian plant Coleus forskohlii. Researches found that the Yunnan native plant Coleus forskohlii contained rich ISOF but not FSK. ISOF was reported to activate adenylyl cyclase (AC) isoforms. The ophthalmologic and cardiovascular effe...