Power and spatial mode measurements of sideband generated,spatially filtered, submillimeter radiation

The first coherent measurement of submillimeter-wave sideband generator (SBG) output power is reported here. This SBG utilizes a submillimeter laser, microwave synthesizer, and high frequency Schottky diode to produce tunable radiation. Record efficiency and output power (10.5 μW) at a drive frequency of 1.6 THz has been obtained, and SBG radiation was efficiently separated from the laser driver with Si etalons. The power measurements were made using a dual CO₂-submillimeter laser system and two Schottky diodes, one as the sideband generator and one as the receiver. The SBG efficiency of four different models of University of Virginia (UVa) diodes were studied and the first measurement of the output mode of the sideband (without the unshifted laser present) was also performed. Finally, confirmation of the optimal parameters for coupling a Gaussian beam into a corner-reflector mounted Schottky diode is presented     

The Effects of Vestigial Sideband Passband Characteristics upon Television Transient Response

The task of ensuring acceptable detected transient response in consumer television receivers is complicated by the large variety of different transmitter vestigial sideband and receiver IF filter characteristics in use. In this paper, the effects of different typical transmitter and receiver passband characteristics in the vestigial sideband region upon detected transient response are analytically examined. Both envelope and synchronous demodulation systems are investigated, and various levels of carrier modulation are assumed. In addition, the effects on transient response of alternate methods for transmitter vestigial sideband filter (VSBF) phase correction are described. In general, it is found that even with the substantial response of many receiver IF filters in the 1-MHz region of the vestigial sideband, acceptable transient response can be obtained provided that appropriate phase correction of the transmitter VSBF is used. Experimental verification of the analytical results is also presented.     

A low-voltage 5.1-5.8-GHz image-reject receiver with wide dynamicrange

A monolithic 5-6-GHz band receiver, consisting of a differential preamplifier, dual doubly balanced mixers, cascaded injection-locked frequency doublers, and a quadrature local oscillator generator and prescaler, realizes over 45 dB of image-rejection in a mature 25-GHz silicon bipolar technology. The measured single sideband (50 Ω) noise figure is 5.1 dB with an IIP3 of -4.5 dBm and 17-dB conversion gain at 5.3 GHz. The 1.9×1.2 mm² IC is packaged in a standard 32-pin ceramic quad flatpack and consumes less than 50 mW from a 2.2-V supply     

A low noise receiver for millimeter and submillimeter wavelengths

A broadband, low noise heterodyne receiver, suitable for astronomical use, has been built using a Pb alloy superconducting tunnel junction (SIS). The RF coupling is quasioptical via a bowtie antenna on a quartz lens and is accomplished without any tuning elements. In this preliminary version the double sideband receiver noise temperature rises from 205 K at 116 GHz to 375 K at 349 Ghz, and to 815 K at 466 GHz. This is the most versatile and sensitive receiver yet reported for sub-mm wavelengths.     

System Temperatures, Single Versus Double Sideband Operation, and Optimum Receiver Performance

This paper discusses the relative observing efficiency of single sideband (SSB) and double sideband (DSB) receiver systems in the presence of atmospheric and antenna losses. We use the antenna parameters currently specified for the NRAO Millimeter Array (MMA) antennas and atmospheric opacities appropriate to an excellent site such as Mauna Kea or the MMA site on the Llano de Chajnantor in northern Chile. We find that for spectroscopic observations in one sideband, SSB measurements are always more efficient. Below 400 GHz, the observing time advantage is 50-80%. Above 400 GHz, the advantage is over a factor of 2, indicating that SSB-mode observing is more efficient even if spectral lines of interest are present in both sidebands. We discuss the goals for the ultimate, practical receiver performance that one should aim for in the presence of atmospheric and telescope losses. Observing efficiencies are displayed as a function of frequency using atmospheric opacity models as input. We also develop some analytic expressions for SSB and DSB observing.     

A Very Low-Noise Single-Sideband Receiver for 200-260 GHz

A cryogenic Schottky diode mixer receiver has been built for the 230-GHz region with true single-sideband operation and a receiver noise temperature as low as 330 K. Local oscillator power is provided by a frequency tripler, with LO injection and sideband filtering accomplished through quasi-optical interferometers. The image sideband is terminated in a cryogenic load with an effective temperature of 33 K. The IF bandwidth is 600 MHz with nearly flat noise, and the RF band is nearly flat over 50 GHz using backshort tuning of the mixer.     

Optimal reception of digital data over the Gaussian channel with unknown delay and phase jitter

Asymptotically optimum (in the sense of minimum per-symbol error rate) receiver structures for data communication over the white Gaussian channel with unknown time delay and carrier phase jitter are developed. The receiver structures apply to the following suppressed-carrier modulation systems: double sideband (DSB), quadrature amplitude modulation (QAM) with an arbitrary constellation, vestigial sideband (VSB) and single sideband. The resulting minimum error probability receivers are asymptotically equivalent to maximum-likelihood digital {em sequence}-estimating receivers. The optimum structures implicitly derive joint maximum-likelihood estimates of the unknown parameters and of the sequence of data symbols. It is shown that the parameter estimates can be obtained from two data-directed stochastic approximation algorithms. Unlike traditional theoretical treatments of this communication situation, which have separated the highly important carrier phase and timing recovery problem from the detection problem, a unified theory is presented from which the complete ideal receiver structure can be deduced.     

Fiber-optic millimeter-wave downlink system using 60 GHz-bandexternal modulation

In this paper, a fiber-optic millimeter-wave (mm-wave) downlink system using 60 GHz-band external modulation is investigated. We prepare the fiber-optic 60 GHz-band mm-wave downlink testbed. It consists of an optical modulation section with a mm-wave signal generator, an optical single sideband (SSB) filter, a standard single-mode fiber (SMF), an optical detection section with a 60 GHz-band radio transmitter and a 60 GHz-band radio receiver. To modulate the laser output with 60 GHz-band mm-wave signals directly, a specially designed electro-absorption modulator with high-efficiency at around 60 GHz is used. The use of this modulator makes the simpler system configuration possible. Using the downlink testbed, the 5 m-long free-space propagation of subcarrier multiplexed 156 Mb/s-DPSK 60 GHz-band mm-wave signals recovered by optical direct detection is successfully demonstrated. The transmission of the mm-wave signals over 85 km-long standard SMF is also successfully demonstrated, using an optical SSB filtering technique to overcome the fiber dispersion. The BER of 10^-9 is achievable at the optical received power of -7.0 dBm     

Optical single sideband transmission at 10 Gb/s using onlyelectrical dispersion compensation

A system is presented which uses optical single sideband transmission at 10 Gb/s together with electrical dispersion compensation at the receiver. Transmission with a bit error rate better than 10^-10 on nondispersion shifted fiber is experimentally demonstrated over 320 km and the dispersion from 1000 km of fiber was effectively equalized in simulation. In the transmitter, driving one or two modulators with a combination of a baseband digital signal and the Hilbert transform of that signal creates an optical single sideband signal. In terms of reducing the effects of chromatic dispersion, transmitting the signal in a single sideband format has two advantages over a double sideband format. First, the optical bandwidth of the transmitted single sideband signal is approximately one half of a conventional double sideband signal. Second, an optical single sideband signal with transmitted carrier can be “self-homodyne” detected and the majority of the phase information preserved since no spectrum back folding occurs upon detection. This allows the received signal to be partially equalized in the electrical domain     

Nb-Al-Al2O3-Nb junctions with inductivetuning elements for a very low noise 205-250 GHz heterodynereceiver

The authors have developed a Nb-Al-Al₂O₃-Nb junction fabrication process which allows the use of planar tuning circuits integrated with the junctions. These tuning elements permit the use of junctions with relatively large areas and small current densities with excellent results. Recent measurements have yielded a double sideband receiver noise temperature of less than 50 K from 205 to 240 GHz and 44 K at 230 GHz. The Nb-Al-Al₂O₃-Nb trilayer technology is being extended to the fabrication of sub-square-micron-area planar junctions for submillimeter wavelengths     

POWER-side [independent sideband system of AM stereo]

The independent sideband system of AM stereo can, by use of special audio processing, significantly improve mono reception. The resulting transmitted signal, called a `POWER-side' signal, allows listeners to `sideband tune' with new types of mono receivers so as to reduce co and adjacent channel interference, improve the effective fidelity of the AM receiver, and make the receiver's tuning significantly less critical. Furthermore, due to the inequality of low frequency sideband components, the system reduces selective fading, antenna null distortion and re-radiation problems when the POWER-side signal is received by both `sideband tuned' mono receivers as well as digitally tuned stereo and mono receivers which center tune to the carrier frequency. Most importantly, this type of wave substantially reduces co-channel `beating' effects that have, since the earliest days of broadcasting, plagued AM signal reception     

A low-noise 492 GHz SIS waveguide receiver

In this paper we discuss the design and performance of an SIS waveguide receiver which provides low noise performance from 375 to 510 GHz. At its design frequency of 492 GHz the receiver has a double sideband noise temperature of ～172 K. By using embedded magnetic field concentrators, we are able to effectively suppress Josephson pair tunneling. Techniques for improving receiver performance are discussed.     

基于偏振调制的最优接收灵敏度的ROF链路研究

提出了一个基于偏振调制的最佳接收灵敏度ROF链路系统。其根本原理在于实现具有最佳光载波边带比(OCSR)的光单边带调制技术,为此,利用偏振调制和滤波技术,线偏光首先经由一个特定偏振角进入偏振调制器,然后一个固定起偏角的起偏器被用来合并偏振信息,最后利用一个光滤波器实现光双边带调制到光单边带调制的转换。研究发现所获得的OCSR只与两个偏振角(和)有关,通过仔细调节上述指标,可以将OCSR调谐至最佳值0 dB。利用仿真验证了上述结论,仿真发现通过将OCSR调谐至最佳值将大大提高ROF链路的接收灵敏度。     

Spectrally Shaped DS–CDMA with Dual Sideband Combining for Increased Diversity on Dispersive Fading Channels

A new modulation scheme is proposed in this paper. This scheme uses sinusoidal chip waveforms to shape the spectrum of a direct sequence spread spectrum (DS-SS) signal such that the transmitted signal has two distinct spectral lobes, one from a lower sideband (LSB) and the other from an upper sideband (USB). By properly selecting the frequency of the sinusoidal chip waveforms, the two sideband signals can be made to undergo independent fading in a dispersive fading channel. These two independent sideband signals, when combined at the receiver, provide diversity gain. Our analysis and simulation results show that the bit error ratio (BER) performance of the proposed scheme is superior to that of the equivalent DS-SS system that uses conventional rectangular chip waveforms for severely faded channels.     

All-Optical Vestigial Sideband Generation Using a Semiconductor Optical Amplifier

An all-optical setup to generate vestigial sideband signals based on self-phase modulation in a semiconductor optical amplifier is experimentally demonstrated at 10 Gb/s. Sideband suppressions higher than 15 dB are reported with improved eye opening. Wavelength-independent operation over 26 nm is demonstrated. Increased chromatic dispersion tolerance is verified: a receiver sensitivity penalty of 5.3 dB, relative to back-to-back, is obtained after transmission over 2720 ps/nm; whereas conventional double sideband is penalized by 4.0 dB after 1360 ps/nm     

A low noise SIS array receiver for radioastronomical applications in the 35–50 GHz band

Arrays of six superconducting tunnel junctions have been used in a heterodyne receiver over the frequency range 35–50 GHz. The mixer array and a 3.7–4.2 GHz parametric amplifier used as the if amplifier are immersed in liquid helium and operated at 2 K. The high if allows single sideband operation with a system noise temperature varying rather smoothly from 220 K at 35 GHz to 140 K at 50 GHz. Mixer noise temperatures between 11 and 21 K were measured over the band indicating that the use of arrays to enhance the dynamic range does not seriously affect the mixer noise performance in this frequency range. The receiver is used for radio astronomical observations in the Onsala 20 m telescope in Sweden.     

5-GHz CMOS radio transceiver front-end chipset

Incorporating the direct-conversion architecture, a 5-GHz band radio transceiver front end chipset for wireless LAN applications is implemented in a 0.25-μm CMOS technology. The 4-mm² 5.25-GHz receiver IC contains a low noise amplifier with 2.5-dB noise figure (NF) and 16-dB power gain, a receive mixer with 12.0 dB single sideband NF, 13.7-dB voltage gain, and -5 dBm input 1-dB compression point. The 2.7-mm² transmitter IC achieves an output 1-dB compression of -2.5 dBm at 5.7 GHz with 33.4-dB (image) sideband rejection by using an integrated quadrature voltage-controlled oscillator. Operating from a 3-V supply, the power consumptions for the receiver and transmitter are 114 and 120 mW, respectively     

250MHZ单边带接收机前端电路的设计与实现

为了有效地抑制各种干扰,提高甚高频单边带接收机性能,关键是有一个性能良好的前端电路.就这一问题,文章介绍了前端电路在甚高频单边带接收机中的作用和研制250MHZ单边带接收机前端电路的设计方法,同时给出了实验结果,结果表明各种干扰被有效地抑制了.     

Performance of a cryogenic 3 mm Schottky-mixer receiver on the Mets?hovi 14 m radio telescope

A cooled receiver with some novel features and a noise temperature of 80?140 K double sideband in the frequency range 75?95 GHz has been built for radio astronomical observations. The quasioptical beam switch is followed by a 3 mm Schottky mixer and FET amplifier at 1.4 GHz. For calibration the receiver is provided with a cold reference load within the Dewar.     

Near Pseudolinear Regime in 10-Gb/s Single Sideband-Alternate Mark Inversion Systems Using Electrical Dispersion Precompensation

A 10-Gb/s optical single sideband (OSSB) system using alternate mark inversion return-to-zero and ideal electrical precompensation of dispersion is optimized numerically by means of an optical dispersion compensator at the receiver side. The transmission regime observed in the optimized system resembles the pseudolinear regime previously described for systems with bit rates of 40 Gb/s and above. Considering multichannel transmission, the OSSB system has a Q -factor penalty of 2 dB compared to an intensity modulated optical double sideband system with optimized optical dispersion map.