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Spectrum Analysis
Published in Jerry C. Whitaker, The RF Transmission Systems Handbook, 2017
The primary application of a spectrum analyzer is the measurement and identification of RF signals. When connected to a small receiving antenna, the analyzer can measure carrier and sideband power levels. By expanding the sweep width of the display, offset or multiple carriers can be observed. By increasing the vertical sensitivity of the analyzer and adjusting the center frequency and sweep width, it is possible to observe the occupied bandwidth of the RF signal. Convention dictates that the vertical axis displays amplitude and the horizontal axis displays frequency. This frequency-domain presentation allows the user to glean more information about the characteristics of an input signal than is possible from an oscilloscope. Figure 21.1 compares the oscilloscope and spectrum analyzer display formats.
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Published in Thomas Noulis, Noise Coupling in System-on-Chip, 2018
Thomas Noulis, Peter Baumgartner
In the specific architecture, the ring oscillator oscillation frequency was 670 MHz. The topology was comprised of a basic 11 stage CML and a five stage output buffer was implemented for extra amplification and for driving both the ring oscillator outputs onto the 50 Ω load of the Spectrum Analyzer. The Spectrum Analyzer used in the measurements had a 3 Hz to 50 GHz min–max frequency range and a resolution bandwidth of 1 Hz to 8 MHz. For the ring oscillator unit, core RF MOSFETs were used. For the buffer, thick gate devices were implemented for higher supply voltage usage and therefore higher allowed output signal swing. The supply of the core ring oscillator architecture was 1.2 V while the buffers supply was 1.8 V.
Vibration and Acoustics Measurements in Rotating Machinery
Published in Rajiv Tiwari, Rotor Systems: Analysis and Identification, 2017
Resolution: A transducer produces a main signal and an inherent noise signal in the output signal. The least variation in the output signal value that can be determined from an instrument is called its resolution. The resolution is often of the same order as the precision; or occasionally, it is lower. The lowest value of the useful signal, which can be distinguished from the noisy signal, is called the resolution. The resolution is usually indicated in absolute values—for instance in μm for a displacement sensor. The noisy signal cannot be enhanced by resolution, but can be improved by low-pass filters. For a spectrum analyzer a resolution of 1 Hz is very common.
Simultaneous determination of AC and DC magnetic field by a whispering gallery mode optical resonator
Published in Instrumentation Science & Technology, 2023
Changqiu Yu, Yuming Yan, Shiqi Hu, Xiaoxu Wang, Haibin Xu, Ziji Shao, Hai Li, Tiejun Zhou
The AC magnetic field sensing performance was measured and the results are shown in Figure 5. The reference magnetic field signal at 450 kHz is applied to the sensor by the coil (180 turns, diameter of 15 cm, resistance of 9.6 Ω). The signal in Figure 5(a) appears on the spectrum analyzer with a signal-to-noise ratio of 48.3 dB. The resolution bandwidth of the spectrum analyzer was set to 1 Hz. The linearity of the reference signal was characterized. The results in Figure 5(b) show that the signal has a linear response and the signal has negligible hysteresis characteristics. The response was characterized by S21 measurement by the network analyzer with an intermediate frequency bandwidth of 10 Hz and the results are shown in Figure 5c.