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28,713 results on '"Noise (radio)"'

2. Symptoms of laryngeal cancer as Jamie Theakston diagnosed -including strange noise; Radio presenter Jamie Theakston has told how a change in his voice led him to getting checked out by a doctor but there are other symptoms to watch for

Subjects
Laryngeal cancer, Physicians, General interest, News, opinion and commentary
Abstract

Byline: By, Elaine Blackburne Radio presenter Jamie Theakston has told how he is fighting laryngeal cancer. The star said he got checked out after his voice changed. Writing on Instagram [...]

Published
2024

3. Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers

Abstract

Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1-xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrodinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (similar to 9 x 10(12) cm(-2)) as the non-graded conventional structure, though the mobility drops from similar to 2360 cm(2)/V s in the conventional to similar to 960 cm(2)/V s in the graded structure. The transconductance g(m) of the linearly graded channel HEMTs is shown to be flatter with smaller g(m) and g(m) as compared to the conventional non-graded channel HEMT implying improved device linearity. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)., Funding Agencies|Swedish Governmental Agency for Innovation Systems (VINNOVA); Lund University; Linkoeping University; Chalmers University of Technology [2022-03139]; Ericsson; Epiluvac; FMV; Gotmic; Hexagem; Hitachi Energy; On Semiconductor; Region Skane SAAB; SweGaN; Volvo Cars; UMS; Swedish Research Council VR; Swedish Foundation for Strategic Research; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University; KAW Foundation [2016-00889, 2022-04812]; Swedish Research Council and the Foundation [RIF14-055, EM16-0024, STP19-0008]; [2009-00971]; [2021-00171]; [RIF21-0026]

Published
2023
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4. Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers

Abstract

Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1-xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrodinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (similar to 9 x 10(12) cm(-2)) as the non-graded conventional structure, though the mobility drops from similar to 2360 cm(2)/V s in the conventional to similar to 960 cm(2)/V s in the graded structure. The transconductance g(m) of the linearly graded channel HEMTs is shown to be flatter with smaller g(m) and g(m) as compared to the conventional non-graded channel HEMT implying improved device linearity. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)., Funding Agencies|Swedish Governmental Agency for Innovation Systems (VINNOVA); Lund University; Linkoeping University; Chalmers University of Technology [2022-03139]; Ericsson; Epiluvac; FMV; Gotmic; Hexagem; Hitachi Energy; On Semiconductor; Region Skane SAAB; SweGaN; Volvo Cars; UMS; Swedish Research Council VR; Swedish Foundation for Strategic Research; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University; KAW Foundation [2016-00889, 2022-04812]; Swedish Research Council and the Foundation [RIF14-055, EM16-0024, STP19-0008]; [2009-00971]; [2021-00171]; [RIF21-0026]

Published
2023
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5. Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers

Abstract

Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1-xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrodinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (similar to 9 x 10(12) cm(-2)) as the non-graded conventional structure, though the mobility drops from similar to 2360 cm(2)/V s in the conventional to similar to 960 cm(2)/V s in the graded structure. The transconductance g(m) of the linearly graded channel HEMTs is shown to be flatter with smaller g(m) and g(m) as compared to the conventional non-graded channel HEMT implying improved device linearity. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)., Funding Agencies|Swedish Governmental Agency for Innovation Systems (VINNOVA); Lund University; Linkoeping University; Chalmers University of Technology [2022-03139]; Ericsson; Epiluvac; FMV; Gotmic; Hexagem; Hitachi Energy; On Semiconductor; Region Skane SAAB; SweGaN; Volvo Cars; UMS; Swedish Research Council VR; Swedish Foundation for Strategic Research; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University; KAW Foundation [2016-00889, 2022-04812]; Swedish Research Council and the Foundation [RIF14-055, EM16-0024, STP19-0008]; [2009-00971]; [2021-00171]; [RIF21-0026]

Published
2023
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6. Low Phase-noise Radio-frequency Synthesizers Mbi-2023-0087

Subjects
Business, international
Abstract

Tenders Are Invited For : Low Phase-Noise Radio-Frequency Synthesizers Mbi-2023-0087 Major organization : RESEARCH ASSOCIATION BERLIN E.V. Address : Research Association Berlin E.V. Rudower Chaussee 17 12489 Berlin Germany Country [...]

Published
2023

8. Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers.

Author

Papamichail, A., Persson, A. R., Richter, S., Kühne, P., Stanishev, V., Persson, P. O. Å., Ferrand-Drake Del Castillo, R., Thorsell, M., Hjelmgren, H., Paskov, P. P., Rorsman, N., and Darakchieva, V.

Subjects
*LOW noise amplifiers, *MODULATION-doped field-effect transistors, *SCANNING transmission electron microscopy, *METAL organic chemical vapor deposition, *CHEMICAL vapor deposition, *ELECTRON density, *ELECTRON energy loss spectroscopy
Abstract

Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1−xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrödinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (∼ 9 × 10 12 cm−2) as the non-graded conventional structure, though the mobility drops from ∼ 2360 cm2/V s in the conventional to ∼ 960 cm2/V s in the graded structure. The transconductance gm of the linearly graded channel HEMTs is shown to be flatter with smaller g m ′ and g m ″ as compared to the conventional non-graded channel HEMT implying improved device linearity. [ABSTRACT FROM AUTHOR]

Published
2023
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10. Agile low phase noise radio-frequency sine wave generator applied to experiments on ultracold atoms

Author

Morizot, Olivier, De Bellair, Julien De Lapeyre, Wiotte, Fabrice, Lopez, Olivier, Pottie, Paul-Eric, and Perrin, Hélène

Subjects
Physics - Atomic Physics
Abstract

We report on the frequency performance of a low cost (~500$) radio-frequency sine wave generator, using direct digital synthesis (DDS) and a field-programmable gate array (FPGA). The output frequency of the device may be changed dynamically to any arbitrary value ranging from DC to 10 MHz without any phase slip. Sampling effects are substantially reduced by a high sample rate, up to 1 MHz, and by a large memory length, more than 2.10^5 samples. By using a low noise external oscillator to clock the DDS, we demonstrate a phase noise as low as that of the master clock, that is at the level of -113 dB.rad^2/Hz at 1 Hz from the carrier for an output frequency of 3.75 MHz. The device is successfully used to confine an ultracold atomic cloud of rubidium 87 in a RF-based trap, and there is no extra heating from the RF source., Comment: 10 pages, 6 figures

Published
2007

13. Noise characterisation of GaN current aperture vertical electron transistor metal‐insulated semiconductor field effect transistor with Δ‐shaped gate for low noise radio frequency amplifiers.

Author

Janakiraman, Varadhan, Mohanbabu, Anandan, Maheswari, Shanmugam, Daniel Raj, Androse, Deb, Sanjoy, and VinodhKumar, Nallathambi

Subjects
*METAL oxide semiconductor field-effect transistors, *FIELD-effect transistors, *ELECTRONIC amplifiers, *DRAINAGE, *GALLIUM nitride, *RADIO frequency, *LOW noise amplifiers, *NOISE
Abstract

In this article, vertical CAVET with boron‐doped GaN layer as current blocking layer (CBL) for AlGaN/GaN is proposed in this study, and different electrical characteristics of the devices, such as DC (Ids − Vds), small‐signal radio frequency and high‐frequency microwave noise performances, are characterised using Synopsys TCAD simulations. The vertical CAVET AlGaN/GaN metal‐insulated semiconductor field effect transistor (MIS‐HEMT) has been found to have a high threshold VT = 6.36 V, drain saturation current, Ids,sat = 3.41 kA/cm2, reduced OFF‐state current <10−12 and improved high frequency and noise performances. The findings provide insight on noise sources and provide information on how to improve GaN transistor noise performance. Its useful characterisation tool for learning more about the imperfections in advanced AlGaN/GaN MIS‐HEMTs and how they evolve. A two‐port noise equivalent‐circuit description is used to calculate data for noise. Using data from noise and scattering parameters that have been measured, we evaluated the effect of noise sources due to gate and drain, as well as their correlation. The devices exhibit a minimum noise figure (NFmin) and an equivalent noise resistance (Rn) of 1.21 dB and 20 Ω at 20 GHz, with Vgs = 5 V and Vds = 10 V, which is small and appropriate for low‐noise amplifiers with a wide bandwidth. The maximum output power density Pout of 23 dBm and the maximum PAE of 63.3% are achieved for GaN V‐shaped CAVET MIS‐HEMTs with Vds = 10 V at 3.12 GHz is achieved. A comparison is made between the noise performance of conventional HEMTs, MIS‐HEMTs and FETs. The methods for obtaining the noise figure (NFmin) and other noise metrics are then explained and compared with those found in the literature. [ABSTRACT FROM AUTHOR]

Published
2022
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16. Low-noise radio over graded-index plastic optical fiber

Author

Azusa Inoue and Yasuhiro Koike

Subjects
Multi-mode optical fiber, Optical fiber, Materials science, business.industry, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, law.invention, 010309 optics, Optics, Transmission (telecommunications), law, Modulation, Fiber laser, 0103 physical sciences, Radio frequency, 0210 nano-technology, Plastic optical fiber, business, Noise (radio)
Abstract

We developed a graded-index plastic optical fiber (GI POF) that enables lower-noise radio frequency (RF) transmission than conventional multimode fibers for short-distance household applications ( < 100 m ). It is shown that reflection noise degrades RF transmission, regardless of the carrier frequency, through the spurious generation that accompanies the RF modulation of a vertical-cavity surface-emitting laser. The GI POF with distinctive mode coupling, which is closely related to its microscopic polymer structure, suppresses noise and spurious generation to improve transmission quality. Our low-noise radio-over-GI-POF technology will offer significant advantages for optical wiring systems for broadcast and communication in small- and medium-scale buildings.

Published
2020

17. Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers

Author

A. Papamichail, A. R. Persson, S. Richter, P. Kühne, V. Stanishev, P. O. Å. Persson, R. Ferrand-Drake Del Castillo, M. Thorsell, H. Hjelmgren, P. P. Paskov, N. Rorsman, and V. Darakchieva

Subjects
Physics and Astronomy (miscellaneous)
Abstract

Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick Al xGa1− xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrödinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (∼ 9 [Formula: see text] cm−2) as the non-graded conventional structure, though the mobility drops from [Formula: see text] cm2/V s in the conventional to [Formula: see text] cm2/V s in the graded structure. The transconductance gm of the linearly graded channel HEMTs is shown to be flatter with smaller [Formula: see text] and [Formula: see text] as compared to the conventional non-graded channel HEMT implying improved device linearity.

Published
2023

20. Low noise radio receivers on Torun 32m antenna

Author

E. Pazderski

Subjects
Radio telescope, Intermediate frequency, business.industry, Computer science, Local oscillator, Amplifier, Astrophysics::Instrumentation and Methods for Astrophysics, Electrical engineering, Antenna (radio), business, High dynamic range, Noise (radio), Radio spectrum
Abstract

Obliged to keep the attractiveness of the radio telescope to it's users, one need to improve the sensitivity of receivers all possible ways. Reducing receiver noise by applying newest low noise amplifiers, reducing ambient temperature of the cryogenic amplifiers by improving isolation in the dewar, using wider frequency bands, using high dynamic range intermediate frequency amplifiers and other means for frequency bands full of annoying interferences — all these treatments belong to the art of making the best receivers. Radio receivers need to be ready to be used with many back-ends, like VLBI terminals, spectrometers, pulsar machine, polarimeters, so they need to have many additional functionalities built-in, like switchable stable noise sources, phase calibration sources, switchable 0/180 degrees local oscillator signals and more. Review of the Torun 32 m antenna receivers will discuss the above goals in detail.

Published
2018

21. Low-noise radio over graded-index plastic optical fiber.

Author

Inoue A and Koike Y

Abstract

We developed a graded-index plastic optical fiber (GI POF) that enables lower-noise radio frequency (RF) transmission than conventional multimode fibers for short-distance household applications (<100 m ). It is shown that reflection noise degrades RF transmission, regardless of the carrier frequency, through the spurious generation that accompanies the RF modulation of a vertical-cavity surface-emitting laser. The GI POF with distinctive mode coupling, which is closely related to its microscopic polymer structure, suppresses noise and spurious generation to improve transmission quality. Our low-noise radio-over-GI-POF technology will offer significant advantages for optical wiring systems for broadcast and communication in small- and medium-scale buildings.

Published
2020
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22. Statistical synthesis and analysis of mutual brightness temperature and bearing estimation algorithms for a point source of noise radio-thermal radiation

Abstract

Brightness temperature and bearing estimation algorithms for a point source of noise radio-thermal radiation in a two-antenna radio meter are synthesized and a structure diagram that implements these algorithms is presented. We show that when estimating brightness temperature the optimum output effect is proportional to a power estimate for a sum of de-correlated observations with compensation of receiver’s internal noise temperature. Optimum output effect during bearing determination of a radiation source contains operations of generating mutual coherence functions of radio-thermal signals in first and second channels and maximum finding. Potential precision of estimates is studied and it is shown that brightness temperature and bearing estimates are statistically independent. Despite this fact frequency characteristics of de-correlation filters in the bearing channel depend on estimates generated in the radio brightness estimation channel.

Published
2012

23. Statistical synthesis and analysis of mutual brightness temperature and bearing estimation algorithms for a point source of noise radio-thermal radiation

Author

Valeriy Volosyuk and Vladimir Pavlikov

Subjects
Physics, Brightness, Noise temperature, Mutual coherence, Bearing (mechanical), Point source, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, law.invention, law, Thermal radiation, Brightness temperature, Electrical and Electronic Engineering, Algorithm, Noise (radio)
Abstract

Brightness temperature and bearing estimation algorithms for a point source of noise radio-thermal radiation in a two-antenna radio meter are synthesized and a structure diagram that implements these algorithms is presented. We show that when estimating brightness temperature the optimum output effect is proportional to a power estimate for a sum of de-correlated observations with compensation of receiver’s internal noise temperature. Optimum output effect during bearing determination of a radiation source contains operations of generating mutual coherence functions of radio-thermal signals in first and second channels and maximum finding. Potential precision of estimates is studied and it is shown that brightness temperature and bearing estimates are statistically independent. Despite this fact frequency characteristics of de-correlation filters in the bearing channel depend on estimates generated in the radio brightness estimation channel.

Published
2012

24. Cryogenic hybrid coupler for ultra-low-noise radio astronomy balanced amplifiers

Author

Malo-Gomez, I., Gallego-Puyol, J. D., Diez-Gonzalez, C., Lopez-Fernandez, I., and Briso-Rodriguez, C.

Subjects
Noise barriers -- Design and construction, Radio telescopes -- Analysis, Semiconductor-metal boundaries -- Analysis, Business, Computers, Electronics, Electronics and electrical industries
Published
2009

26. The Panaural People’s Republic: Loudness, Loss of Self, and Sonic Social Control in Mao’s China

Author

Lovell, Joseph

Subjects
China. Loudspeaker. Noise. Radio. Sound. Soundscape, Languages and literature of Eastern Asia, Africa, Oceania, PL1-8844
Abstract

Perspectives on the establishment of social control have long been shaped by theories concerning visibility and observation, such as Foucault’s concept of the Panopticon. In Mao era China, however, sound and hearing had a greater impact on citizens becoming self-disciplined. Reflecting on a variety of sources, with a particular focus on memoirs, this article details how the Mao era soundscape helped to fashion a new form of disciplinary society. This disciplinary society was chaotic, however, and sites of resistance remained, in which some individuals fought to retain their sense of self, even amid all the tumult and violence.

Published
2023
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28. Some Considerations Concerning Low Noise Radio Receiving Systems

Abstract

In order to get a good signal to noise ratio at very high radio frequencies (higher than 20 - 40 MHz), low noise amplifiers are often used. Such amplifiers should have a very low total noise factor (noise figure). Normally it is the noise factor of the first stage of an amplifier which is decisive for the total noise factor. Losses in a system will also influence the noise factor of a system. Consequently the losses in cables and waveguides must be taken into account when considering the total noise factor. The thermal noise radiation from the surroundings may increase the noise temperature of an antenna. For reflector antennas, such as parabolic reflector antennas, the noise temperature is dependent on the elevation angle, and also dependent on the fors of the surroundings, mountains, hills, buildings, etc. The measurements referred to in this article, were done by the Radio interference Division in the Norwegian Telecom., This article is from 'Use or Reduction of Propagation and Noise Propagation in Distributed Military Systems: Electromagnetic Wave Propagation Panel Symposium Held in Rethymno, Crete, Greece on 15-18 October 1990 (Utilisation ou Reduction des Effets de la Propagation et du Bruit dans les Systemes Militaires Distribues,' AD-A244 895, p21-1 thru 21-13.

Published
1991

29. 434 W all-fiber linear-polarization dual-frequency Yb-doped fiber laser carrying low-noise radio frequency signal.

Author

Huang L, Li L, Ma P, Wang X, and Zhou P

Abstract

We demonstrate a high power dual-frequency linear-polarization fiber laser that carries radio frequency signal. Such fiber laser is based on an all-fiber master oscillator power amplifier configuration that consists of a dual-frequency seed laser and three-stage amplifiers. The dual-frequency seed laser is constructed by recombining two beams that are split from a single-frequency linearly-polarized laser. One beam has initial frequency and the other beam is modulated by an acoustic-optical modulator to have a frequency shift of 150 MHz. Then the radio frequency signal of 150 MHz is carried on the laser due to the beat frequency of these two beams. In the main amplifier, a piece of polarization maintaining large-mode-area fiber with short length is used to combine the SBS suppression with high power amplification. As a result, the dual-frequency laser is amplified to 434 W without the occurrence of SBS. The slope efficiency is 81.3%. The polarization degree of the laser and the modulation depth of the optically carried radio frequency signal are both well maintained during the amplification process. Besides, a high signal-noise-ratio of above 75 dB is realized, which demonstrates the low-noise property of the optically carried radio frequency signal. To the best of our knowledge, this is the highest reported output power of the optically carried radio frequency signal.

Published
2016
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31. Diagnostic of environment with the help of low frequency noise radio interference by satellite data

Author

V.I. Larkina

Subjects
Physics, Infrasound, Satellite data, Range (statistics), Communications satellite, Low frequency, Ionosphere, Noise (radio), Electromagnetic interference, Remote sensing
Abstract

Low frequency emission in range of 100 Hz-20 kHz it is accepted to consider as radio interference, actually they are the useful tool for diagnostic and analysis of dynamic processes in environment. The usefulness of noise obtained on the "Intercosmos" satellite data is routine.

Published
2006

32. 434 W all-fiber linear-polarization dual-frequency Yb-doped fiber laser carrying low-noise radio frequency signal

Author

Xiaolin Wang, Lei Li, Long Huang, Pengfei Ma, and Pu Zhou

Subjects
Materials science, business.industry, Far-infrared laser, Physics::Optics, 02 engineering and technology, Laser, 01 natural sciences, Atomic and Molecular Physics, and Optics, law.invention, 010309 optics, Amplitude modulation, 020210 optoelectronics & photonics, Optics, Intermediate frequency, law, Fiber laser, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Laser power scaling, business, Frequency modulation, Laser Doppler vibrometer
Abstract

We demonstrate a high power dual-frequency linear-polarization fiber laser that carries radio frequency signal. Such fiber laser is based on an all-fiber master oscillator power amplifier configuration that consists of a dual-frequency seed laser and three-stage amplifiers. The dual-frequency seed laser is constructed by recombining two beams that are split from a single-frequency linearly-polarized laser. One beam has initial frequency and the other beam is modulated by an acoustic-optical modulator to have a frequency shift of 150 MHz. Then the radio frequency signal of 150 MHz is carried on the laser due to the beat frequency of these two beams. In the main amplifier, a piece of polarization maintaining large-mode-area fiber with short length is used to combine the SBS suppression with high power amplification. As a result, the dual-frequency laser is amplified to 434 W without the occurrence of SBS. The slope efficiency is 81.3%. The polarization degree of the laser and the modulation depth of the optically carried radio frequency signal are both well maintained during the amplification process. Besides, a high signal-noise-ratio of above 75 dB is realized, which demonstrates the low-noise property of the optically carried radio frequency signal. To the best of our knowledge, this is the highest reported output power of the optically carried radio frequency signal.

Published
2016

33. Simultaneous low noise radio frequency tone and narrow linewidth optical comb generation from a regeneratively mode-locked laser.

Author

Ozdur, Ibrahim, Ozharar, Sarper, and Delfyett, Peter J.

Subjects
*RADIO frequency, *FREQUENCIES of oscillating systems, *MODE-locked lasers, *LASERS, *ATOMIC physics
Abstract

A regeneratively mode-locked laser with simul- taneous low noise radio frequency (RF) tone and optical comb generation is presented. The laser does not need any external RF signal and emits a pulse train at -10 GHz repetition rate with a 1.5-ps optical pulse width after compression. The generated RF tone has a signal-to-noise ratio of 121 dB/Hz and an RF fluctuation of 10-9 over 0.1 s. The optical frequency comb spacing is also at -10 GHz and the optical comb tooth has a linewidth of <1 kHz. [ABSTRACT FROM AUTHOR]

Published
2014
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34. Cryogenic Hybrid Coupler for Ultra-Low-Noise Radio Astronomy Balanced Amplifiers

Author

Cesar Briso-Rodriguez, I. Malo-Gomez, J. D. Gallego-Puyol, C. Diez-Gonzalez, and I. Lopez-Fernandez

Subjects
Noise temperature, Engineering, Radiation, Sideband, business.industry, Amplifier, Bandwidth (signal processing), Electrical engineering, Cryogenics, Condensed Matter Physics, Intermediate frequency, Hybrid coupler, Electrical and Electronic Engineering, business, Radio astronomy
Abstract

Modern heterodyne ultra low noise receivers used for radio astronomy have evolved to provide very wide instantaneous bandwidth. Some of the configurations used in present cryogenic front-ends, such as sideband separating mixers and balanced amplifiers, require 90° hybrids as a part of the intermediate frequency (IF) circuitry. A very common choice for the band of operation of these hybrids is 4-12-GHz band. There are devices commercially available covering this band with good ambient temperature characteristics, but their cryogenic performance degrades to unacceptable levels. This paper describes the design, construction and measurement of a multioctave stripline hybrid for the 4-12 GHz band specially conceived to operate satisfactorily when cooled down to 15 K (-258°C). The materials and mechanical construction have been carefully selected and the result is a very compact, reliable and low thermal mass device, capable to withstand extreme thermal cycling. The coupling and reflection characteristics of the prototype show very low temperature dependence. The utility of the hybrid developed is demonstrated in a cryogenic balanced amplifier. The noise temperature obtained using this configuration (6 K) shows clear advantage (about 33%) over the classical isolator-amplifier combination normally used in heterodyne radio astronomy receivers. Besides, a superior insensitivity of the amplifier's noise performance to the input termination mismatch is obtained.

Published
2009

38. What's that noise? ;Radio waves: Low-tech radio stations find a new partner as advertisers explore medium's alternative way to target messages

Author

Beeler, Amanda

Subjects
Radio advertising -- Services -- Innovations, Radio broadcasting -- Innovations -- Services, Radio broadcasting industry -- Innovations -- Services, Marketing industry -- Innovations -- Services, Advertising, marketing and public relations, Business, general, Innovations, Services
Abstract

Commuters will tune in for the morning news and teen-agers will eagerly await the latest pop hit, but radio listeners of the future will not spin the same AM-FM dial. [...]

Published
2000

39. Dual-frequency Brillouin fiber laser for optical generation of tunable low-noise radio frequency/microwave frequency.

Author

Geng J, Staines S, and Jiang S

Abstract

We demonstrate a new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals. Its inherent features of both linewidth narrowing effect in a Brillouin fiber cavity and common mode noise cancellation between two laser modes sharing a common cavity allow us to achieve high frequency stability without using a supercavity. Beat frequency of the dual-frequency Brillouin fiber laser can be tuned from tens of megahertz up to 100 GHz by thermally tuning the wavelengths of the two pump lasers with tuning sensitivity of approximately 1.4 GHz/ degrees C. Allan variance measurements show the beat signals have the hertz-level frequency stability.

Published
2008
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40. Simultaneous low noise radio frequency tone and narrow linewidth optical comb generation from a regeneratively mode-locked laser

Author

Peter J. Delfyett, Sarper Ozharar, Ibrahim Ozdur, and AGÜ, Mühendislik Fakültesi, Elektrik & Elektronik Mühendisliği Bölümü

Subjects
Materials science, Fabry-Perot, business.industry, mode locking, General Engineering, Comb generator, Laser, Atomic and Molecular Physics, and Optics, fiber lasers, law.invention, Laser linewidth, Optics, Mode-locking, law, laser linewidth, Fiber laser, Pulse wave, Radio frequency, business, Fabry–Pérot interferometer
Abstract

A regeneratively mode-locked laser with simultaneous low noise radio frequency (RF) tone and optical comb generation is presented. The laser does not need any external RF signal and emits a pulse train at similar to 10 GHz repetition rate with a 1.5-ps optical pulse width after compression. The generated RF tone has a signal-to-noise ratio of 121 dB/Hz and an RF fluctuation of 10(-9) over 0.1 s. The optical frequency comb spacing is also at similar to 10 GHz and the optical comb tooth has a linewidth of

Published
2014

41. Low noise radio frequency integrated circuits in 90 nm SOI CMOS up to 60 GHz

Author

Uwe Mayer, Ralf Eickhoff, Stefan Hauptmann, Frank Ellinger, and Michael Wickert

Subjects
Third-order intercept point, Voltage-controlled oscillator, Materials science, CMOS, Noise measurement, business.industry, Amplifier, Transconductance, Phase noise, Electrical engineering, Noise figure, business
Abstract

In this paper we present the results of several key circuit blocks such as amplifiers, mixers and an oscillator in a 90 nm SOI CMOS technology. The circuits were optimized for low noise. Leading-edge results such as 3.8 dB noise figure (NF) up to 40 GHz and more than 8 dB gain up to 60 GHz for a wideband amplifier, a low loss of only 4.8 dB for a drain pumped transconductance mixer at 35 GHz consuming zero DC power, a third order intercept point (IIP3) of 15 dBm for a resistive mixer, and a phase noise of - 90 dBc/Hz at 1 MHz offset for a 60 GHz VCO (voltage controlled oscillator) are presented.

Published
2008

42. Dual-frequency Brillouin fiber laser for optical generation of tunable low-noise radio frequency/microwave frequency

Author

Jihong Geng, Shibin Jiang, and Sean Staines

Subjects
Optical fiber, Materials science, business.industry, Physics::Optics, Laser, Atomic and Molecular Physics, and Optics, law.invention, Laser linewidth, Optics, law, Brillouin scattering, Fiber laser, Optoelectronics, Radio frequency, Allan variance, business, Microwave
Abstract

We demonstrate a new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals. Its inherent features of both linewidth narrowing effect in a Brillouin fiber cavity and common mode noise cancellation between two laser modes sharing a common cavity allow us to achieve high frequency stability without using a supercavity. Beat frequency of the dual-frequency Brillouin fiber laser can be tuned from tens of megahertz up to 100 GHz by thermally tuning the wavelengths of the two pump lasers with tuning sensitivity of approximately 1.4 GHz/ degrees C. Allan variance measurements show the beat signals have the hertz-level frequency stability.

Published
2007

43. Making Noise: Radio host, soprano sings the praises of classical music

Subjects
Opera singers, Classical music, Business, General interest, Business, regional
Abstract

Byline: Aimsel Ponti April 11--Suzanne Nance wears two distinct, but related, hats. You might recognize her name as the host of 'Morning Classical Music with Suzanne Nance,' which airs weekdays [...]

Published
2013

49. Patent Issued for Low Noise Radio Frequency Switching Circuitry (USPTO 9379604)

Subjects
RF Micro Devices Inc. -- Intellectual property, Semiconductor industry -- Intellectual property, Patents, Semiconductor industry, Patent/copyright issue, Electronics
Abstract

2016 JUL 12 (VerticalNews) -- By a News Reporter-Staff News Editor at Electronics Newsweekly -- RF Micro Devices, Inc. (Greensboro, NC) has been issued patent number 9379604, according to news [...]

Published
2016

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