Vortex Radiometer for Wireless Communications

Glenn's revolutionary new multi-tone, high-frequency synthesizer can enable a major upgrade in the design of high data rate, wide-band satellite communications links, in addition to the study of atmospheric effects. Conventional single-frequency beacon transmitters have a major limitation: they must assume that atmospheric attenuation and group delay effects are constant at all frequencies across the band of interest. Glenn's synthesizer overcomes this limitation by enabling measurements to be made at multiple frequencies across the entire multi-GHz wide frequency, providing much more accurate and actionable readings. This novel synthesizer consists of a solid-state frequency comb or harmonic generator that uses step-recovery semiconductor diodes to generate a broad range of evenly spaced harmonic frequencies, which are coherent and tunable over a wide frequency range. These harmonics are then filtered by a tunable bandpass filter and amplified to the necessary power level by a tunable millimeter-wave power amplifier. Next, the amplified signals are transmitted as beacon signals from a satellite to a ground receiving station. By measuring the relative signal strength and phase at ground sites the atmospheric induced effects can be determined, enabling scientists to gather essential climate data on hurricanes and climate change. In addition, the synthesizer can serve as a wideband source in place of a satellite transponder, making it easier to downlink high volumes of collected data to the scientific community. Glenn's synthesizer enables a beacon transmitter that, from the economical CubeSat platform, offers simultaneous, fast, and more accurate wideband transmission from space through the Earth's atmosphere than has ever been possible before.

Langley has developed various technologies to enable the portable detection system, including: - 3-inch electret condenser microphone - unprecedented sensitivity of -45 dB/Hz - compact nonporous windscreen - suitable for replacing spatially demanding soaker hoses in current use - infrasonic calibrator for field use - piston phone with a test signal of 110 dB at 14Hz. - laboratory calibration apparatus - to very low frequencies - vacuum isolation vessel - sufficiently anechoic to permit measurement of background noise in microphones at frequencies down to a few Hz - mobile source for reference - a Helmholtz resonator that provides pure tone at 19 Hz The NASA system uses a three-element array in the field to locate sources of infrasound and their direction. This information has been correlated with PIREPs available in real time via the Internet, with 10 examples of good correlation.

The Wind Event Warning System (WEWS) is high-energy Doppler LIDAR sensor that measures approaching changes of wind such as an oncoming variation of wind speed that will change the power output of a wind farm. Different from low-energy, the high-energy Doppler LIDAR has the energy to reach the long distances necessary to provide adequate warning time of a wind event. With the time provided by WEWS, the blades of a wind turbine could be feathered to prevent strong wind from damaging the turbine. In addition, airports could use WEWS to protect aircraft from sudden wind hazards.

Radiosondes are launched twice a day from different locations of the world and meteorological data is collected to plot the STUV diagram and determining CAPE (Cumulative Average Potential Energy) values. Radiosondes are not re-usable and used only at pre-determined locations around the globe. Moreover, a radiosonde can drift up to 125 miles from its release point. About 75,000 radiosondes are used every year. Given this unmet need, an inventor at NASA has developed an advanced airborne meteorological system which can provide meteorological parameters at any location at any desired time. In additional to routinely used meteorological sensors, an infrasonic sensor is also included to determine wind shear at local and regional levels. The airborne system may also be used in towns and cities to track drones and UAVs in the area. The airborne vehicle (UAV or drone) should be able to track seismic waves, magnetic storms, magneto-hydrodynamic waves, tornadoes, meteor, and lightning, etc. This technology can be use to measure environmental turbulence including wind shear, vortices as well as large and small eddies is an important factor in forecasting local and regional weather. It can also detect infrasound at ranges of many miles from the source and the shape of the acoustic power spectrum can be used to identify type of turbulence in the atmosphere.

Large aircraft can generate air vortices in their wake, turbulence that can prove hazardous to aircraft that follow too closely. Because wake vortices are invisible, all takeoffs at busy airports are spaced several minutes apart. This separation gives the vortices time to dissipate, even though they only occur 10% of the time, with resulting loss of operational efficiency. Similarly, clear air turbulence is invisible and can also be hazardous to aircraft. By detecting such disturbances through their infrasound emissions, precautions can be taken to avoid them. Other phenomena can be detected through infrasound, including tornadoes, helicopters on the other side of mountains, underground nuclear explosions and digging tunnels. Through the unique properties of infrasound, many of these can be detected from hundreds of miles away. NASA's infrasound sensor is a highly refined microphone that is capable of detecting acoustic waves from 20 Hz down to dc, the infrasound range. The design is robust and compact, eliminating the bulk and weight found in other technologies. Where most alternative methods are restricted to certain weather conditions and locations, the NASA sensor filters noise from wind and other sources, allowing its use under any weather or geographic conditions.