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Insertion Loss Filters
Published in Herbert J. Carlin, Pier Paolo Civalleri, Wideband Circuit Design, 2018
Herbert J. Carlin, Pier Paolo Civalleri
An information-bearing electric signal, f(t), is generally transmitted by varying the properties of a carrier signal in accordance with the characteristics of f(t) (modulation). Commonly used systems modulate the amplitude, frequency, or phase of the carrier. The effect of the modulation is to produce sidebands which contain the information, i.e., sinusoidal signals of suitable amplitude and phase whose frequencies cover two equal bands contiguous to the carrier frequency. The sideband whose frequencies are higher than the carrier frequency is the upper sideband; the one with lower frequencies is the lower sideband (see Example 3.9.5). The width of the sidebands depends on the modulation scheme and on the transmitted signal, particularly the amount of signal information. However, for a given modulation system and a given type of signal (phone, radio, television, etc.), and for a prescribed quality of reception, the bandwidth is more or less determined.
S
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
Si/SiGe/SiGeC silicon-based alloy system providing band offsets that enable heterostructures that can be utilized for heterojunction transistor design and quantum confinement. sideband the signal produced when a carrier signal is modulated. They may be one single sideband, one set of upper and lower sidebands, or a series of sidebands whose number is dependent on the modulation index of the modulation system being used. sidelobe a lobe in an antenna radiation pattern apart from the main lobe and any grating lobes. Sidelobes have peak amplitudes less than that of the main lobe. side lobe level the ratio of a local maximum in a radiation pattern to the global maximum (main beam) of the radiation pattern. sidelobe level (SLL) the peak amplitude of a sidelobe relative to the peak amplitude of the main lobe. The SLL is usually expressed as the number of decibels below the main lobe peak. Siemens, Ernst Werner von (1816-1892) Born: Lenthe, Hanover, Germany Best known for the German and British companies that bear his name. Siemens was a strong believer in basic research, as well as an avid inventor. His early inventions included an improved gutta-percha wrapped telegraph cable that allowed his companies to secure a number of lucrative cable contracts. His discovery of the dynamo principle, and his use of this in heavycurrent applications, allowed his companies to
Typical Sources and Characteristics of Radiated and Conducted Emissions
Published in David A. Weston, Electromagnetic Compatibility, 2017
A transmitter is designed typically to generate a specific frequency or a number of adjacent frequencies. When the transmitter is used to convey information, one or more modulation techniques are used that result in sidebands (i.e., frequency bands on either side of the carrier). For example, when amplitude modulation is used, the upper sideband is the carrier frequency plus the modulating frequencies and the lower sideband is the carrier frequency minus the modulating frequencies. In addition to the frequencies used in the desired transmission, a transmitter generates a number of unwanted, spurious emissions. These include harmonics of the carrier and sidebands and the master oscillator. In addition, the transmitter generates nonharmonically related frequencies and broadband noncoherent noise.
Controlled preparation and vibrational excitation of single ultracold molecular hydrogen ions
Published in Molecular Physics, 2022
Christian Wellers, Magnus R. Schenkel, Gouri S. Giri, Kenneth R. Brown, Stephan Schiller
We have actively frequency-stabilised the 1252 nm laser to an ultra-low expansion (ULE) reference cavity. We use the cavity that was also used in Ref. [36]. For this purpose, a fraction of the laser radiation is phase-modulated by a fibre-coupled waveguide electro-optic modulator (EOM) to imprint sidebands. The modulation frequency is chosen in such a way that the first-order sideband matches the frequency of the TEM00-mode of the reference cavity. A double-modulation technique [37] allows locking the sideband to the cavity, rather than the carrier, and also enables a fine and precise tuning of the laser by adjusting the sideband frequency. The overall sideband tuneability range is 30–800 MHz. Continuous tuning in the locked state is 20 MHz. The Be atomic transition resonance happens to be at a modulation frequency of 743 MHz. Figure 7 shows the beat of the stabilised 1252 nm laser with the frequency comb. The linewidth is 0.4 kHz and the drift is negligible. Usually, the laser stays in a lock for a whole working day, even when the sidebands are tuned in 200 kHz steps (corresponding to 800 kHz in the UV).
Photonic broadband signal frequency conversion and bandwidth multiplication based on a Fourier domain mode-locked optoelectronic oscillator
Published in Journal of Modern Optics, 2021
Yalan Wang, Jin Zhang, Xiang Li, Jianghai Wo, Anle Wang, Xiaoniu Peng
In this paper, we propose a broadband microwave signal conversion and multiplication system based on an FDML-OEO. Different from the frequency-scanning optical light source in conventional FDML-OEO, the optical sideband that is generated from the modulation of the signal to be converted, is selected as the light source of the FDML-OEO. Due to the modulation of the broadband linear frequency modulation (LFM) signal, the modulated optical sideband is a frequency-sweeping signal. When the periodic of the sweeping time is synchronized with the round-trip time of the OEO loop, mode locking is achieved in the frequency domain. This frequency conversion and bandwidth multiplication system is also experimentally demonstrated. The central frequency tunning ability has been investigated, as well as the signal degradation of the converted signal. Meanwhile, broadband signal conversion with tunnable time width is also discussed in terms of fibre length regulation and the harmonically FDML technique. Furthermore, bandwidth doubling has also been proved by filtering the second-harmonic optical side-band as the carrier of the FDML-OEO.
Novel current mode universal filter and dual-mode quadrature oscillator using VDCC and all grounded passive elements
Published in Australian Journal of Electrical and Electronics Engineering, 2019
Manish Gupta, Priyanka Dogra, Tajinder Singh Arora
The quadrature oscillators are attracting researchers for its numerous applications in areas like communication systems, generation of waveforms of desired amplitude and frequency, and modulation systems for the generation of the carrier signal for quadrature amplitude modulation (QAM) and single-sideband modulation (SSB) (Senani et al. 2015b). Henceforth, substantial attempts have been made in designing of the quadrature oscillators from some filter configuration (Arora, Rohil, and Gupta 2018b; Tuntrakool et al. 2017; Tangsrirat 2009). Recent studies of the ABBs have proved that VDCC is amongst one of the most adaptable device for implementing oscillators due its electronic controllability. Owing to this, certain modifications have been made in filter circuit to obtain an oscillator configuration, in this work. The devised oscillator offers features like low component count, voltage mode as well as current mode operation, availability of explicit current outputs, generation of quadrature results, and independent tunability of FO and CO.