Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.

Method of reducing transmission power in a wireless communication system

Abstract: In the described system, one or more base stations transmit a signal to a mobile station. The signal is transmitted using polarisation diversity, whereby the signal is transmitted in one direction using two signal beams, each signal beam being differently polarised. A method of beam-hoping may be employed whereby the polarisation of the transmitted beams during hand off is varied according to predefined sequence. The sequence may be determined according to the data loading within the respective transmission cells. Also disclosed is a method of soft or softer hand off within a wireless communication system where the total number of signal beams transmitted from two base stations to a single mobile station during hand off is kept constant.

Broadband THz-wave generation by satisfying the noncollinear phase-matching condition with a reflected signal beam.

Abstract: We demonstrated broadband terahertz (THz) wave generation by satisfying the noncollinear phase-matching condition with a reflected signal beam. We constructed a dual-wavelength optical parametric oscillator with two potassium titanium oxide phosphate crystals pumped by a frequency-doubled Nd:YAG laser. The collinear pump and signal waves were irradiated into a lithium niobate crystal. The pump and the signal waves were reflected at the crystal surface. Because the pump and the signal waves have a finite beam diameter, when the reflected signal wave and unreflected pump wave were irradiated at the correct angle, the noncollinear phase-matching condition was satisfied. By changing the incident angle to the crystal, broadband THz-wave generation with a range of over 0.2–7.2 THz was achieved.

System for space scanning with a radiated wave-signal beam

Abstract: The present invention relates to a system for space-scanning with a radiated beam of wave signals and, while the invention is of general application, it is of particular utility in systems of the type disclosed and claimed in the copending application of Harold M. Lewis, Serial No. 507,861,...

One-way image transmission through a thick dynamic distorter without a reference beam

Abstract: We demonstrated a method to perform one-way image transmission through a dynamic distorter without a reference beam. In this method, a photorefractive four-wave mixing configuration was used to pick up the reconstructed image from the image-bearing signal beam, which acted as an erase beam. The fluctuation period of the dynamic distorter must be much shorter than the response time of the nonlinear material. Reconstructed images with high-fidelity have been obtained. Because use of a reference beam is unnecessary this method is simpler and more effective.

The optically gated dye cell - A high-speed shutter and pulse shaper

Abstract: This paper discusses characteristics of a class of devices that use a saturable absorber irradiated by an optical control pulse, or gating pulse, to alter the shape of a transmitted optical signal. We consider two device geometries: a longitudinally gated cell, in which signal and gate beams are nearly parallel, and a transverse cell, in which the medium is bleached by a gating pulse applied at right angles to the signal beam. The longitudinal device permits synthesis of rising exponential signal pulses with arbitrary, subnanosecond time constants. The transverse geometry can provide pulses of complex shape and permits independent optimization of several device parameters. The dynamics of the saturable absorber (with particular emphasis on liquid dye systems) is analyzed in detail, and a pulse-shape synthesis procedure is outlined. Spurious nonlinear effects are considered, and an example of pulse shaping for laser-driven fusion is given.