Single-sideband Amplitude Modulation Research Articles

Single Sideband Hartley Amplitude Modulation

It is developed a method of information transmission with application of amplitude Single Sideband Hartley modulation (SSBH) allowing to increase of radio channel length for optical and fiber optic signal transmission systems where single sideband amplitude modulation (SSB) is used. Increase of communication range is provided due to application a sum of two orthogonal oscillations of the same frequency as a carrier (Hartley wave). It provides energy gain in 6 dB and 1.41 times increase of the amplitude of output signal of synchronous detector comparing to SSB in case of the same radiation power of transmitter and the same sensitivities of SSBH and SSB signals receivers. Application of SSBH and SSB modulation allows to provide the energy gain in transmitting channel approximately 15–20 times comparing to amplitude modulation (AM) application. It also provides increased security of SSBH transmission since in case of absence of modulation signal the transmitter does not radiate, that allows to provide energy saving in case of transmitter power supply with battery. Depending on the need we can use both upper and lower side bands.

Device localization and dynamic scan plane selection using a wireless magnetic resonance imaging detector array

A prototype wireless guidance device using single sideband amplitude modulation (SSB) is presented for a 1.5T magnetic resonance imaging system. The device contained three fiducial markers each mounted to an independent receiver coil equipped with wireless SSB technology. Acquiring orthogonal projections of these markers determined the position and orientation of the device, which was used to define the scan plane for a subsequent image acquisition. Device localization and scan plane update required approximately 30 ms, so it could be interleaved with high temporal resolution imaging. Since the wireless device is used for localization and does not require full imaging capability, the design of the SSB wireless system was simplified by allowing an asynchronous clock between the transmitter and receiver. When coupled to a high readout bandwidth, the error caused by the lack of a shared frequency reference was quantified to be less than one pixel (0.78 mm) in the projection acquisitions. Image guidance with the prototype was demonstrated with a phantom where a needle was successfully guided to a target and contrast was delivered. The feasibility of active tracking with a wireless detector array is demonstrated. Wireless arrays could be incorporated into devices to assist in image-guided procedures.

Identification and mitigation of interference sources present in SSB‐based wireless MRI receiver arrays

Single sideband amplitude modulation (SSB) is an appealing platform for highly parallel wireless MRI detector arrays because the spacing between channels is ideally limited only by the MRI signal bandwidth. However this assumes that no other sources of interference are present outside that bandwidth. This work investigates the practical interference between multiple SSB-encoded MRI signals. Noise from coil preamplifiers and carrier bleed-through are identified as sources of interference. Two different SSB systems were designed for 1.5 T with different noise filtering properties. We show how the differences between the filtered noise profiles impact the received MR signal's dynamic range (DRsig ) and image signal-to-noise ratio through simulation, bench measurements, and phantom imaging experiments. When operating individually in the MR scanner, both SSB systems were shown to minimally impact the original DRsig and signal-to-noise ratio. Conversely, when all eight channels were operating simultaneously, an average signal-to-noise ratio loss was observed to be 12% in the one system, while a second system with more complex filtering was able to achieve a 3% loss in signal-to-noise ratio. Successful wireless transmission of multiple SSB-encoded MRI signals is possible as long as channel interference is properly managed through design and simulation.

Effects on the Performance of Parametric Loudspeaker Caused by Nonideal Ultrasound Transducer

In this paper, we report the effects on the performance of a parametric loudspeaker caused by a nonideal ultrasound transducer. The frequency contents of self-demodulated secondary wave pressure for the nonideal ultrasound transducer are first derived on the basis of Berktay's solution. Then, according to the relationship between the input signal and the envelope of primary wave pressure, the harmonic distortion and intermodulation distortion are obtained for different modulation techniques. Simulation experiments show that in the case of using the double-sideband amplitude modulation (DSB-AM) technique, the amplitudes of the fundamental frequency and intermodulation distortion components are affected by both the phase and magnitude response of the ultrasound transducer, whereas the harmonic distortion component is only affected by the phase response. In the case of using the single-sideband amplitude modulation (SSB-AM) technique, the amplitudes of the fundamental frequency component and intermodulation distortion components are only affected by the magnitude response of the transducer.

High-Voltage Multicarrier Spread-Spectrum System Field Test

High-voltage (HV) power lines have been used as a communications medium since the 1920s. Those point-to-point links were typically based on single-sideband amplitude modulation. These days, the state of the art in HV power-line carrier (PLC) communications comprises the combination of analog systems, mainly for teleprotection tasks, and digital systems, used for voice and data transmission. Beside traditional core services (monitoring, operation management, and limitation and removal of failures), electrical utilities would like to satisfy the increasing need of new internal applications. In that way, quadrature amplitude modulation and, most recently, multicarrier modulation (MCM)-based modems are beginning to play an important role in HV PLC systems. Although the typical 4-kHz bandwidth has been recently increased up to 32 kHz, this paper proposes a low-power 256-kHz bandwidth multicarrier-spread-spectrum (MC-SS)-based physical layer. Based on channel measurements, the MC-SS symbol has been designed and tested in order to increase the user bit rate while delivering reduced power spectral density and bit-error rate.

Optical phase-based beamformer using MZM SSB modulation combined with crystal polarization optics and a spatial light modulator

The performance of a widely tunable phase-based beamformer for phased array antennas using a new technique to cross-polarized the carrier and the sideband, in order to allow the phase control by means of a spatial light modulator, is experimentally demonstrated. The technique relies on the combination of single sideband amplitude modulation (SSB) using a Mach–Zehnder modulator (MZM) and birefringence (to cross-polarized the carrier and the sideband). The architecture has the potential of controlling multiple independent beams simultaneously. The beamformer feeds an eight elements array showing an insertion loss and a reset speed of around 12dB and 70ms, respectively. Far-field antenna patterns between 7.5GHz and 8.5GHz for nine elevation angles within a range of ±20° have been measured showing beam steering capability, amplitude distribution weighting as well as multibeam operation.

Design of two‐dimensional digital fan filters with complex coefficients using 90‐degree phase‐difference network

AbstractIn two‐dimensional digital filters with complex coefficients, design flexibility is gained and the filter order can be lowered as compared with real coefficient filters. On the other hand, in the signal theory, the concept of analytic signal is well known in connection with single side‐band amplitude modulator, which can be implemented by using a bandpass filter or a 90‐degree phase‐difference network. The latter implementation, which uses all‐pass networks, yields far better characteristics as compared with the former.The conventional fan filter with complex coefficients is designed by shifting one‐dimensional low‐pass digital filters with a cutoff frequency of 0.5 π on the real frequency axis and applying a variable transformation. In contrast, we propose a new design method of fan filters with complex coefficients that combines the approach of the forementioned 90‐degree phase‐difference network for the single sideband amplitude modulation and the theory of complex coefficient filters; i.e., two all‐pass networks with 90‐degree phase‐difference are used in the new fan filters.

The AR6A Single-Sideband Microwave Radio System: System Design and Performance

This paper describes the overall architecture of the first long-distance microwave telephone transmission system to use Single-Sideband Amplitude Modulation in the microwave transmission path. Compared with commonly used frequency modulation systems, the AR6A Single-Sideband Microwave Radio System more than doubles the number of telephone circuits that can be carried per unit of microwave bandwidth. Included in the description are the system design model, performance objectives, and the allocation of performance impairments. Also discussed are the computer-controlled automated maintenance features and the results of laboratory and field tests.

The AR6A Single-Sideband Microwave Radio System: Prologue

The AR6A Single-Sideband Amplitude Modulation (SSBAM) Transmission System makes very efficient use of the radio spectrum by transmitting 6000 message circuits in a 29.65-MHz radio channel. This capability is achieved by maintaining a tighter frequency spacing of the multiplexed mastergroup signals and by discarding redundant sideband signals before transmission over the radio path. The AR6A System can provide a maximum capacity of 42,000 message circuits for the 6-GHz portion of the radio network when all eight channels are utilized. This capability, combined with the alternate use of the 4-GHz spectrum for message or digital circuits, provides the proper mix of network capability choices. This introduction gives an overview of the AR6A System and a brief history of single-sideband evolvement in the Bell System. It also is a prologue to the papers in this volume, which describe some of the specifics of the system design.

Analysis of Single Sideband Modulation in Microwave Systems for Television (Video) Transmission

This paper analyzes the problem of intermodulation distortion of single sideband amplitude modulation (SSB-AM) for the transmission of multi-channel video signals using microwave radio systems. Microwave television transmission using SSB-AM is attractive due to its potential to reduce costs and to improve spectrum utilization. However, the usage of SSB-AM for multi-channel microwave video transmission has been restricted mainly because of the unacceptable level of third order distortion components generated in a microwave system.

The Design of Nonlinear Phase-Tracking Loops by Simulation

The design of carrier phase and timing recovery methods for data transmission by means of simulation is described. Results are given for a partial response class 4 data signal transmitted by single-sideband amplitude modulation.

The Effects of Equalization, Timing, and Carrier Phase on the Eye Patterns of Class-4 Partial-Response Data Signals

A general expression is derived for the eye pattern boundaries of a multilevel class-4 partial-response (PR) signal after single-sideband amplitude-modulation (SSBAM) transmission with a carrier phase error. From the expression particular results are obtained for the horizontal and vertical eye openings of the signal. Expressions are derived for the tap settings of a linear transversal equalizer using the minimum mean-square error (MMSE) criterion when the class-4 PR signal is distorted by a carrier phase error and sampled with timing error. The values of the tap settings can be used to reduce the carrier and timing phase errors. Finally, an expression for the vertical eye opening of the equalized signal is derived as a function of the carrier phase and the number of stages in the equalizer.

Distortionless Demodulation of Filtered Single-Sided Angle Modulation

In this paper the recovery of the modulation signal from filtered versions of single-sided angle modulation (SSBØM) by using a simple angle detector is investigated. A general analysis is made which suggests that for modulation signals of small amplitude and for relatively well behaved filters distortionless reception of the modulation signal is possible at the receiver if the angle detector is followed by an ideal low-pass filter. This result is proved for modulation signals which are band-limited and square-integrable functions of time, and for the pure sinusoid, when the modulated signals are ideally band limited. Of special practical and theoretical interest is the case where the ideally filtered SSBØM signal has the bandwidth saving of conventional single-sideband amplitude modulation (SSBAM). In this case a sufficient condition for distortionless reception of a signal <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s(t)</tex> with energy E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf> and one-sided bandwidth <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</tex> is that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(2E_{s}W)^{1/2} &lt; 0.8</tex> , the maximum amplitude of the unmodulated carrier being 1. A necessary and sufficient condition for distortionless reception of the pure sinusoid <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s(t) = d \cos w_{1)t</tex> is: <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d &lt; 1</tex> .

Spectrum Conservation and Characteristics of Single-Sideband Phase Modulation

Phase modulation with an analytic signal, which is a Gaussian random process, is examined in order to determine the amount of spectrum conservation that may be achieved by using single-sideband phase modulation (SSB-PM) rather than conventional phase modulation (PM). The autocorrelation function is derived and found to be an analytic signal in terms of the autocorrelation function of the actual modulating signal and its Hilbert transform. When the modulating signal strength is very low, the sideband spectral distribution is the same as that of the actual modulating signal or single-sideband amplitude modulation. As the modulating signal mean-square value is increased, the sideband spectrum broadens and approaches a Gaussian shape. The average power output of an SSB-PM system increases exponentially with input modulating signal strength, while the carrier power remains constant. For the same modulating signal mean-square value, a greater fraction of power is in the one sideband of an SSB-PM system than in the two sidebands of conventional PM. Single-sideband phase or frequency modulation always effectuates spectrum conservation in the continuum when it is compared with conventional phase or frequency modulation on the basis of equal relative sideband power. A Fourier transform computer program is used to generate SSB-PM spectral distributions with varying modulating signal mean-square values, when the modulating signal spectrum is a low-pass rectangular spectrum, a narrowband pass spectrum, and the shape of an average voice spectrum. These examples illustrate the power series formulation of the output spectrum as well as the theoretical analysis of bandwidth.

Joint Optimization of Automatic Equalization and Carrier Acquisition for Digital Communication

In this paper, we analyze single-sideband amplitude-modulation digital communication systems to develop a method for jointly and optimally setting the carrier phase and the automatic transversal equalizer of such systems. Mean-square equalization error is used as the performance criterion. We develop a simple receiver structure and study the convergence of the method. Exact locations of the stationary points in the parameter space are determined and the classifications of the stationary points are obtained. We show that the mean-square equalization error has only global minima and saddlepoints, but not local minima and maxima. Thus, the mean-square equalization error will converge to the absolute minimum by the proposed method, regardless of the initial settings of the parameters. A simple condition on the step sizes of the adjustments is also obtained which ensures the convergence of the process. Explicit formulas of the joint optimum parameter settings and of the corresponding minimum mean-square error are obtained. For illustration purposes, a single-sideband digital communication system using a five- or nine-tap transversal equalizer is simulated on a computer. Both theory and simulation show that the equalization error depends critically on the carrier phase when the number of equalizer taps is not large, and that the minimum equalization error can be obtained by using the proposed method.

A New Fast Approximate Hilbert Transform with Different Applications

A new and fast approximate Hilbert transform based on subband decomposition is presented. This new algorithm is called the subband (SB)-Hilbert transform. The reduction in complexity is obtained for narrow-band signal applications by considering only the band of most energy. Different properties of the SB-Hilbert transform are discussed with simulation examples. The new algorithm is compared with the full band Hilbert transform in terms of complexity and accuracy. The aliasing errors taking place in the algorithm are found by applying the Hilbert transform to the inverse FFT (time signal) of the aliasing errors of the SB-FFT of the input signal. Different examples are given to find the analytic signal using SB-Hilbert transform with a varying number of subbands. Applications of the new algorithm are given in single-sideband amplitude modulation and in demodulating frequency-modulated signals in communication systems.Key Words: Fast Algorithms, Hilbert Transform, Analytic Signal Processing.

Analysis, Subjective Evaluation, Optimization, and Comparison of the Performance Capabilities of PCM, DPCM, ΔM, AM, and PM Voice Communication Systems

The research described was conducted in order to provide a partial answer to the question: Which of a set voice communication systems provides satisfactory performance for the least cost?. Since the ultimate measure of performance is the subjective quality of the received message, a subjective evaluation procedure was developed and used to subjectively evaluate, optimize, and compare the performance capabilities of pulse-code modulation (PCM), differential PCM (DPCM), deltamodulation ( \DeltaM ); double- and single-sideband amplitude modulation (AM), and phase modulation (PM) systems. The results can also be used to evaluate pulse amplitude modulation systems. For each type of System a unique set of optimum parameters was obtained, and the maximum subjective quality was determined as a function of the characteristics of the transmission channel. For good channels, DPCM is superior to PCM, which in turn is superior to AM and PM. For lower quality channels, AM systems are sometimes best. Only for bit rates of less than 10 and 18 kbit/s, respectively, is AM competitive with DPCM and PCM. Since the mean-square difference \varepsilon^{2} between the transmitted and received message is often indicative of received message quality, \varepsilon^{2} for PCM, DPCM, AM, PM, and FM was derived, its minimization by proper choice of system variables was considered,and a method was developed for comparing \varepsilon^{2} for various systems. A description of the real-time system used to prepare speech samples for the listening tests is also included.

Single-Sideband Techniques in UHF Long-Range Communications

Several factors relevant to the design of uhf longrange communication systems are analyzed. In particular, singlesideband amplitude modulation is evaluated and compared to frequency modulation, with special regard to: a) spectrum conservation; b) performance in the presence of multipath; and c) realized channel signal-to-noise ratio vs total transmitted rf power. It is shown that: 1) SSB requires one-sixth to one-tenth of the spectrum width required by fm. 2) The useful bandwidth of the transmission medium in the presence of multipath is at least four times as great for SSB as for fm. 3) The average power required for a twenty-four channel SSB system is about 20 decibels less than that required for an equivalent fm system, providing equal usable communications. System design considerations are discussed for uhf single sideband, as well as the design parameters of a particular set of equipment operating in the 300 to 400-megacycle band. The linearity of high-power klystrons is discussed, and a promising technique for achieving highly efficient operation of such devices is described.

V.H.F. propagation by ionospheric scattering and its application to long-distance communication

The paper describes an investigation of the propagation of v.h.f. radio waves by scattering from the E-region of the ionosphere. The dependence of the characteristics of the received signal on frequency, distance and aerial directivity is examined, and observations are made on the diurnal and seasonal variations of the received signal strength; the results are discussed in relation to existing theories.Investigations are also described on the suitability of this form of propagation for the transmission of frequency-shift telegraphy signals, and for telephony signals transmitted by single-sideband amplitude modulation, and by phase modulation, of a carrier. A form of waveangle diversity reception which yields a substantial improvement in the performance of a telegraphy system is described. The possible applications of v.h.f. scatter propagation to commercial services are discussed.