Lower Sideband Research Articles

Multipath Mitigation Methods of BOC-Family Signals Based on Dual BPSK Tracking Techniques

It is well known that for binary offset carrier (BOC) signals the notorious ambiguity problem due to the multipeaked autocorrelation function must be tackled first in order to obtain the potential of improving ranging performance promised by its broader Gabor bandwidth. The existence of multipath makes it more difficult to solve. Dual binary phase-shift keying (BPSK) tracking (DBT) is a kind of low complexity, unambiguous tracking method for BOC-family signals, which makes full use of the coherence between the upper and lower sidebands and employs subcarrier phase locked loop (SLL) and delay locked loop (DLL) to track subcarrier and code components, respectively. Considering that the thermal noise performance of DBT has been fully studied, this article focuses on the analysis of multipath performance and the design of antimultipath methods under DBT framework. The influence of multipath on SLL and DLL of DBT is analyzed first and the corresponding subcarrier and code multipath error envelopes are obtained. Then according to different requirements of subcarrier and code multipath errors, a multipath mitigation scheme specially designed for DBT is proposed, in which SLL and DLL adopt offset correlator and narrow correlation, respectively. Theoretical analysis and simulation are given to verify the effectiveness of the proposed methods.

Simultaneous Measurement of Microwave Doppler Frequency Shift and Angle of Arrival Based on a Silicon Integrated Chip

A system for simultaneous measurement of micro-wave Doppler frequency shift (DFS) and angle of arrival (AOA) is proposed based on a silicon integrated chip. In the chip, two dual-drive Mach–Zehnder modulators (DDMZMs) with a microring resonator (MRR) inserted between them are integrated. When an external laser is coupled into the chip, it is first modulated by two echo signals via the first DDMZM and then goes through the MRR to introduce an optical phase shift to one of the first-order sidebands that falls into the resonance of the MRR. After being remodulated by the transmitted signal at the other DDMZM, the lightwave is coupled out from the chip and separated into two channels by an optical coupler. In each channel, a bandpass filter (BPF) is employed to select the upper and lower sidebands. By measuring and comparing the powers, frequencies, and phases of the beat signals in the two channels, the DFS (without direction ambiguity) and AOA can be acquired. Based on the proposed method, DFS within ±100 kHz at 10, 15, and 20 GHz is successfully estimated with a maximum error of ±0.028 Hz, and AOA measurement from 0° to 75° with errors less than ±1.53° is also realized.

Generation of phononic high-order sidebands via intra- and inter-mode couplings in interconnected electromechanical resonators

To efficiently manipulate parametric mode mixing is an intriguing physical issue for phonon-cavity electromechanics, which is also crucial for various technological applications ranging from frequency synthesis to nonlinear spectroscopy. Here, we theoretically investigate the dependence of phononic high-order sidebands on intra- and inter-mode couplings in two interconnected electromechanical resonators. When the system operates in a strong inter-mode coupling regime, we report that two inter-mode phonon-scattering pathways allow us to selectively obtain either odd- or even-order sidebands at different output ports. The signal intensities of the separated sidebands can be independently modulated by introducing harmonic actuation forces acting on the interconnected resonators. Once the intra-mode coupling becomes totally dominant, the direct transition between intra-mode phonons only triggers the emergence of full-order sidebands in the nonlinear responses. In this case, increasing the quality factor of the resonators is beneficial for amplifying a few low order sidebands nearby the principal modes of the resonators but sacrificing the order of the sidebands.

A Low Cost all Optical Photonic Technique Based on Brillouin Scattering for mm-Wave Generation

Generation of millimeter wave (mm-wave) in radio over fiber (ROF) systems is suffered from nonlinearity effects in optical fiber communication. In order to mitigate the degrading effects, a low cost all optical photonic method for the generation of mm-wave is proposed in this work. Therefore, work is accentuated on the enhanced frequency shift based on stimulated Brillouin scattering (SBS) by utilizing only one pump source. Effect of length of optical fiber, launched power and photo detector quantum efficiency is investigated over proposed architecture in order to observe power fading effects. Photonically stable, mm-wave is realized productively in the cost effective way using SBS incorporating different frequencies from 20 GHz-80 GHz. Results reveals that USB (upper sidebands) and LSB (lower sidebands) generated with demonstrated system have high power and good SNR. This makes system appropriate for radio over fiber system.

Neutral beam driven ion cyclotron instability of lower hybrid wave in a tokamak plasma

The effect of dust grains on the parametric coupling of neutral beam driven ion–cyclotron wave instability with a lower hybrid pump wave is studied. A high amplitude lower hybrid pump, which is launched into a tokamak for heating purposes in the presence of neutral beam driven ion-cyclotron waves, can excite the parametric coupling involving two lower hybrid sidebands. In a tokamak, the lower hybrid waves result in parametric excitation of the ion-cyclotron mode and quasi-modes near the edge when the electron oscillatory velocity is greater than the sound velocity. This parametric coupling increases the growth rate of instability when the lower sideband wave is resonant. Moreover, the presence of dust grains in the tokamak plasma, their radius, and the number density significantly affect the growth rate of the instability, which in turn can affect the advanced stage operations of a tokamak. The growth rate of parametric instability scales with the amplitude of the pump wave. The growth rate is found to be linearly increased with the dust grain density, but it decreased with increasing size of dust grains, which means large sized dust grains stabilize the instability. The theoretical results explained in the present paper are very helpful in explaining the complexity in the plasma properties of a tokamak due to the dust–plasma interactions, which can diminish the performance of the International Thermonuclear Experimental Reactor due to potential safety issues.

Compact millimeter‐wave 3‐D filtering antenna based on low temperature cofired ceramic substrate integrated waveguide

In this study, a low temperature cofired ceramic (LTCC) based compact millimeter-wave (MMW) 3-D substrate integrated waveguide (SIW) filtering antenna was proposed. First, a band-pass filter with two transmission zeros in the upper and lower sidebands was designed, with a fractional bandwidth of 2.03% at a center frequency of 98.1 GHz. The filtering antenna was developed and manufactured on this premise, by adopting an E-shape patch antenna, achieving a superior frequency selection characteristic with a 1.63% impedance bandwidth and out-of-band gain dropped over 15 dB at 92.7 and 101.2 GHz, respectively. With a compact structure size of 2.4 × 1.6 × 0.5 mm3 (0.78 λ0 × 0.05 λ0 × 0.016 λ0), high gain and high selectivity were realized in the MMW band.

Monitoring evolution of debris-filled damage using pre-modulated wave and guided wave ultrasonic testing (GWUT)

Metals are essentially used to construct structures of high economic importance, but their service life is shortened by damage such as crack, corrosion, cavity, and dents. Damage to structure causes gradual degradation of its strength and compromises its load-carrying capacity. Some damage could be designed against but pitting corrosion, especially when it is filled with debris that would hide it and deepen its perforation activities. In this work, monitoring the evolution of debris-filled damage in structure is studied using pre-modulated wave and guided wave ultrasonic testing (GWUT). The structural responses in the varying percentage of debris-filled damage were processed using Fast Fourier Transform (FFT), Hilbert Transform (HT) and correlation techniques. The regression analysis of debris-filled damage resulted in empirical predictive models that could detect the damage and percentage of debris that might have filled it with average percentage errors of 1.34 and 0.21, respectively. The debris in the damage caused an overmodulation of the high-frequency signal. The intensity of the lower sideband (LSB) was observed to be very sensitive to variations in the damage than the upper sideband (USB). The transmission power efficiency of modulation sidebands increased proportionally with debris-filled damage percentage and could serve as a damage index.

A Hybrid Filter With Extremely Wide Bandwidth and High Selectivity Using FBAR Network

An extremely wideband hybrid bandpass filter (BPF) with high selectivity and low insertion loss is proposed in this brief. The hybrid BPF is composed of three coupled lines (CLs), six matching transmission lines (TLs) and two film bulk acoustic resonator (FBAR) networks with ladder-type structure. These two FBAR networks can help greatly enhance the upper and lower sideband roll-off of the hybrid BPF. At the same time, the passband is compensated by CLs and TLs. The odd-even mode theory is used to analyze the hybrid BPF to obtain the analytical solutions. Through electromagnetic-acoustic co-simulation and optimization, a hybrid BPF with extremely wideband is fabricated and measured. A discussion on the deviation between the simulation and the measured results is presented. The measured hybrid BPF has a 3-dB fractional bandwidth of 56 %, a minimum insertion loss of 1.733 dB and a shape factor of 0.83 simultaneously.

A Wideband Controllable Bandpass Filter Based on Spoof Surface Plasmon Polaritons

A wideband controllable band-pass filter is proposed, which is based on the spoof surface plasmon polaritons (SSPP) and slip ring resonators (SRR). The design concept of the bandpass filter is using the SSPP and SRR to control the high cut-off frequency and filter the low-frequency wave, respectively. The bandpass filter is used diode reconfigurable technology to tunable the bandwidth. The filter has a passband range of 5–9 GHz, an out-band rejection of −20 dB for the lower sideband, and an out-band rejection of −50 dB for the upper sideband. The simulated and measured results are in good agreement over the operating band. Benefit from its low-profile and low-cost, the proposed bandpass filter has a great potential for development in plasmonic functional devices at microwave frequencies.

High Conversion Gain Self-Oscillating Mixer for 5G mm-wave Applications

We develop in this paper, a high conversion gain self-oscillating mixer (SOM) for 5G mm-wave applications using commercial 0.15µm GaAs PHEMT from UMS foundry. The up-conversion SOM transpose the IF signal from 2 GHz to 26 GHz LSB (lower sideband) signal using a 28GHz LO signal. The simulation results show that the SOM has a maximum conversion gain of 19dB, according to our knowledge, this structure presents the highest gain compared to SOMs published in the literature. While the 1dB compression point is obtained for an IF power of -20.6 dBm. The SOM circuit consumes 129mW and it occupies an area of 0.741 mm2.

A SiGe HBT 215–240 GHz DCA IQ TX/RX Chipset With Built-In Test of USB/LSB RF Asymmetry for 100+ Gb/s Data Rates

A highly integrated fundamentally operated direct-conversion quadrature (IQ) TX/RX chipset with a tunable carrier of 215–240 GHz for high-speed wireless communication is presented. The TX/RX front-ends are fabricated in the 0.13- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> SiGe HBT technology and combined with wire-bonded chip-on-board (COB) packaging for high-speed baseband (BB) signaling. For test purposes, the chipset features a dedicated dual-polarization architecture with a suitable on-chip antenna to allow controlled variation in I-to-Q channel leakage resulting from frequency-dependent upper sideband (USB)/lower sideband (LSB) asymmetry in the RF path of the jointly operated TX and RX and the corresponding analysis of its impact on system error vector magnitude (EVM) of the complete link. The analysis is aided by system-level BB-referred problem formulation with similarity to the classical IQ error in the local oscillator (LO) and BB paths. While operated in a loop-back configuration, the front-ends support the LO-dependent BB-referred channel bandwidth (BW) of 16–20 GHz at the board level with the typical free-space-related double sideband (DSB) P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> /OP1 of 7/3.5 dBm and single sideband (SSB) conversion gain (CG)/noise figure (NF) of 7.5/17.5 dB for the TX and RX, respectively. Under regular working conditions, data rates above 80 Gb/s are demonstrated for 16-quadrature amplitude modulation (QAM) modulation in a 0.6-m line-of-sight wireless characterization setup, with the maximum of 100 Gb/s at 225 GHz. The achievable speeds are limited by frequency-dependent USB/LSB asymmetry in the RF path resulting in systematic error vector floor independently of the underlying SNR and IQ error. With elimination of the asymmetry-incurred I-to-Q leakage from the RF path, the potential of increasing the data rates to at least 120–140 Gb/s is shown, indicating the severeness of this RF impairment for wide modulation bandwidth.

Effect of dust grains on the parametric coupling of a lower hybrid wave driven ion cyclotron wave in a tokamak plasma

In this article, the effect of dust charge fluctuations on the parametric upconversion of a lower hybrid wave into an ion cyclotron wave and a side band wave in a two-ion species tokamak plasma is studied. When the oscillatory velocity of plasma electrons is a few percent of the sound velocity, the lower hybrid wave becomes unstable and decays into two modes: an ion cyclotron wave mode and a low frequency lower hybrid side band wave. Furthermore, a ponderomotive force by a lower hybrid pump and a side band wave is exerted on the existing electrons, which drives the ion cyclotron decay mode. The presence of negatively charged dust grains and their shape, size, radius, and density influence the instability. The growth rate of instability is calculated by considering typical existing D–T (Deuterium–Tritium) dusty plasma parameters, and it is observed that the growth rate increases with the relative density of dust grains, number density of dust grains, oscillatory velocity of electrons, and amplitude of pump waves. However, the normalized growth rate increases with the unstable wave frequency, and it also increases as we increase the ratio of deuterium to tritium density. Here, the growth rate decreases with the increase in the size of dust grains and electron cyclotron frequency. The theoretical results summarized in the present study are able to efficiently elaborate the complexity produced in plasma properties in a tokamak due to the dust–plasma interactions, which are briefly discussed here.

Photonic Techniques for Generating a Single RF Sideband With No Second Order Sidebands

Two structures that can realise optical single sideband modulation without generating both second order upper and lower sidebands are presented. They are based on a dual-parallel Mach Zehnder modulator (DP-MZM) with an optical filter and a dual-polarisation dual-parallel Mach Zehnder modulator (DPol-DPMZM) with a 90° hybrid coupler. The former is an all-optical structure and hence it has a very wide bandwidth. The latter uses one DP-MZM to realise single sideband suppressed carrier modulation while the other DP-MZM simply passes the optical carrier. It also suppresses the third order sideband on the same side as the wanted fundamental RF modulation sideband. Hence, in an ideal situation, there is no second order harmonic component generated after photodetection. Experimental results are presented for the novel structures, which demonstrate the realisation of optical single sideband modulation without second order sidebands. The results also show large fundamental to second order harmonic power ratio over a wide input RF signal frequency range even after inserting a long single mode fibre into the system for signal transmission. The new optical single sideband modulators find applications in improving the multioctave spurious free dynamic range in a long-haul fibre optic link and reducing measurement errors in an optical vector analyser.

A Single-Sideband Time-Modulated Phased Array With Low Sideband Level Suitable for Wide-Bandwidth Signals

Single-sideband time-modulated phased arrays (STMPAs) are able to generate a scanned beam at the first sideband while suppressing undesired sidebands. In this article, an STMPA with very low sideband level (SBL) suitable for wide-bandwidth signals is proposed. The design utilizes time-modulated pulses with stepped waveforms, which are realized by digital attenuators. This provides more degrees of freedom to improve the performance of STMPAs compared with previous techniques. Optimization of waveforms to achieve low SBLs as a function of the number of steps is discussed. This optimization is subject to some practical restrictions stemming from the characteristics and limitations of digital attenuators. Compared with previous STMPAs designed to eliminate undesired sidebands, the proposed design results in very low SBLs while reducing the impact of aliasing for wideband signals. Quantitative analysis of hardware complexity and aliasing effects is presented to demonstrate it. To validate the analysis presented, STMPAs with four-step and eight-step waveforms were designed and fabricated. Their measured SBLs are −28.72 and −33.57 dB, respectively. Measured frequency spectrum, waveform of modulating pulse, and radiation pattern of scanned beams are all presented.

A linearized optical single-sideband modulation RoF link with tunable optical carrier-to-sideband ratio

In this paper, an optical single-sideband (OSSB) modulation radio over fiber (RoF) link with tunable optical carrier-to-side-band ratio (OCSR) and simultaneous third-order intermodulation distortion (IMD3) and power fading suppression is proposed. In the proposed link, a phase-modulated signal and an optical carrier are polarization multiplexed using a Sagnac loop. The periodic power fading caused by chromatic dispersion is avoided by filtering the lower sideband. By adjusting the polarization state, the IMD3 is suppressed and a tunable OCSR can be achieved. Compared with the traditional Mach–Zehnder modulator (MZM) based link, the spurious free dynamic range (SFDR) of the proposed link is improved by more than 18 dB with different RF frequencies. In the broadband characteristic test, the proposed link exhibits lower error vector amplitude (EVM) and higher adjacent channel power ratio (ACPR) in a larger input RF power range.

Coherent Combining and Long Coherent Integration for BOC Signal Acquisition under Strong Interference

<h3>Abstract</h3> A coherent combining and long coherent integration (CCLCI) scheme is presented for standalone direct acquisition of binary offset carrier (BOC) signals under strong radio frequency interference (RFI). To mitigate the ambiguity of BOC signals, a split-spectrum method extracts the upper and lower sidebands of a BOC signal, treats them separately as two binary phase shift keying (BPSK) signals, and finally combines the results to recover the loss due to splitting. The CCLCI scheme burns through strong interference by building up the desired weak signal while averaging out noise and interference. It exploits all information available (L1 and L2, upper and lower sidebands, odd and even chips, and I- and Q-components) by applying coherent combining across signal components and long coherent integration over time, followed by noncoherent accumulation if necessary. Issues and enabling techniques are described. The results of an embedded implementation in demonstration with a GPS RF simulator are analyzed.

Feasibility Study of a W-Band Multibeam Heterodyne Receiver for the Gregorian Focus of the Sardinia Radio Telescope

We report on the feasibility study of a W-band multibeam heterodyne receiver for the Sardinia Radio Telescope (SRT), a general purpose fully steerable 64-m diameter antenna located on the Sardinia island, Italy, managed by INAF (“Istituto Nazionale di Astrofisica,” Italy). The W-band front-end is designed for the telescope Gregorian focal plane and will detect both continuum and molecular spectral lines from astronomical sources and radio emission from the Sun in the 3 mm atmospheric window. The goal specification of the receiver is a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> focal plane array operating in dual-linear polarization with a front-end consisting of feed-horns placed in cascade with waveguide Orthomode Transducers (OMTs) and LNAs (Low Noise Amplifiers) cryogenically cooled at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx $ </tex-math></inline-formula> 20 K. The instantaneous FoV (Field of View) of the telescope is limited by the shaping of the 64-m primary and 7.9-m secondary mirrors. The cryogenic modules are designed to fit in the usable area of the focal plane and provide high-quality beam patterns with high antenna efficiency across the 70 – 116 GHz Radio Frequency (RF) band. The FoV covered by the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> array is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.15\times 2.15$ </tex-math></inline-formula> arcmin <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , unfilled, with separation between contiguous elements of 43 arcsec. Dual-sideband separation (2SB) down-conversion mixers are designed to be placed at the cryostat output and arranged in four four-pixel down-conversion modules with 4 – 12 GHz Intermediate Frequency (IF) bands (both Upper Side Band and Lower Side Band selectable for any pixel and polarization). The receiver utilizes a mechanical derotator to track the parallactic angle.

Dual-function measurement system for Doppler-frequency-shift and angle-of-arrival of microwave signals

A photonic method for simultaneously measuring the Doppler frequency shift (DFS) and angle of arrival (AOA) of microwave signal is proposed and verified by simulation. The echo signals are applied to a dual-parallel dual-drive Mach–Zehnder modulator for modulating the lightwave with carrier-suppressed double-sideband pattern. The lightwave carrying the echo signals is coupled with the lightwave carrying the local oscillator signal, and their upper and lower sidebands are separated by an interleaver. Then, the optical signals are converted into low-frequency electrical signals by two identical photodiodes, and the parameters of DFS and AOA are obtained by processing two low-frequency photocurrents. In the simulation, the measurements of the DFSs in the range of ± 1 MHz with errors < ± 9 × 10 − 4 Hz and the AOAs from 1.82 deg to 90 deg with errors <0.9 deg are realized, and the orientation of DFS can also be distinguished by comparing the phase difference of two electrical signals.

Brillouin-assisted frequency-tuning-range-extended and passband-selected microwave photonic filter based on DPol-DPMZM

A frequency-tuning-range-extended and passband-selected microwave photonic filter (MPF) based on dual-polarization dual-parallel Mach-Zehnder modulator (DPol-DPMZM) is proposed and experimentally demonstrated. The upper DPMZM is biased to serve as an equivalent phase modulator, while the lower DPMZM is selectively biased to generate different modulated sideband for pump wave, and then different passband frequency response is selectively realized based on the stimulated Brillouin scattering effect. By using the upper and lower sidebands of carrier-suppression single sideband for pump wave successively, the frequency tuning range of the single-passband MPF can be extended by a value of Brillouin frequency shift, comparing with only one sideband is used. A single-passband MPF with a frequency tuning range of 1.43–19.43 GHz is experimentally obtained, while only a single-tone RF with a frequency range of DC-9 GHz is used. The double-passband MPF with equal passband magnitude and frequency interval tuned is also experimentally achieved.

In-Run Mode-Matching of MEMS Gyroscopes Based on Power Symmetry of Readout Signal in Sense Mode

This paper presents an in-run mode-matching method for MEMS gyroscopes based on the power symmetry between the sideband signals in the sense mode. The method takes advantage of the power symmetry of both the noise and the Coriolis response within the upper sideband (USB) and the lower sideband (LSB) of the driving frequency. The power difference is taken as a mismatch detection and is fed to the mode-matching controller, which regulates the tuning electrodes. During the matching control, the history of the estimated mode order is recorded to adaptively tune the controller gain, speeding up the tracking process and reducing the steady ripples. The experiments exhibited that the frequency loop could converge to the steady-state within a reasonable time and with 0.28Hz peak-peak fluctuation. By the mode-matching, the scale factor of the gyroscope under test was boosted by ten times; the angle random walk was enhanced from 8.13deg/h/sqrt(Hz) to 1.99deg/h/sqrt(Hz); the bias instability was improved from 2.09deg/h to 1.12deg/h. The method proposed in this paper can be implemented with a general platform that MEMS gyroscopes usually utilize.