Analog Transmission Research Articles

Software architecture for integration of video services in the Etherphone system

Software mechanisms that make use of analog transmission and storage of video for computer-controlled video communication and file storage are described. The authors extended the Etherphone voice management system to support video conferencing and file storage. The software mechanisms for conference management consist of a central connection manager, and video and user interface agents running on client workstations. A conferencing architecture that supports multiplicity in the number of conferences and media is presented. The video file server stores and retrieves full-motion video information within conferences. It uses optical disks to store video frames and builds a high-level file and directory interface. The user interface to the directory interface is a multimedia document editor that permits video annotations to be freely interspersed with text. The performance of the system, which spans multiple media networks, has been highly satisfactory. >

Distortion in analog transmission for subsampled picture signals

AbstractIn sampled‐value transmission such as TAT where pixel values are transmitted, the transmission characteristics must be equalized so that the transmission distortion caused by the interference between sampled values is reduced below the detectable limit or tolerable limit. This paper considers the situation where the image signal bandwidth compressed by subsampling is to be transmitted by baseband or VSB transmission.The analysis and computer simulation for the transmission distortion are presented. The relation of the maximum transmission distortion to the deviation of the frequency characteristics or the deviation of resampling timing of the transmission system is examined quantitatively. The detectable limit and the tolerable limit of the distortion, for the case where the distortion spreads by the interpolation, are determined by subjective experiment. Their relation to the compression ratio and interpolation scheme is examined.The following properties were obtained. The maximum distortions are nearly the same for the transmitted and interpolated pixels, independently of the bandwidth compression ratio and the scheme of compression. The detectable limit and the tolerable limit become smaller with the extent of compression, imposing more severe requirements on the transmission characteristics. The effect of the interpolation scheme is small.

Mode partition of high‐definition television signals using adaptive subsampling

AbstractIn the analog transmission of high‐definition television signal using satellites, the transmission must be performed within a limited band. For this purpose, an adaptive subsampling system is proposed and is used in the highly efficient transmission of the high‐definition television signal. One of the important problems in the adaptive subsampling for improving the picture quality is to partition the picture into as many subsampling modes as possible in an efficient way.This paper proposes an adaptive subsampling system with four different subsampling modes. The four modes are composed of three modes for the moving part and one mode for the still part. Discussions are made on the partitioning of three modes in the moving part, and the partitioning between moving and still parts. In the mode partitioning in the moving part, a method (histogram method) is proposed where the distortion over the whole picture is reduced, based on the histogram derived from the distortion for each subsampling block to determine the subsampling mode partitioning.The proposed method is compared with the traditional method by computer simulation, and it is verified that the SN ratio is improved by the proposed method. As to the partitioning between moving and still parts, a control method for the motion detection threshold is proposed, which seeks a balance between the distortions of still and moving parts. The performance of the control method is verified by a computer simulation for the picture data containing a scene change. Finally, the usefulness of the proposed method is verified by a simulation using motion pictures.

A total solution for a 9600-b/s modem transmitter chip

A single-chip analog transmitter (TX chip) for a V29-V32 9600-b/s modem has been implemented in a 3- mu m CMOS n-well process. A high level of integration permits a low-cost, high-performance modem to be built. The TX chip is composed of analog, switched capacitor, and digital circuits. The important functions realized are the phase-point generator, the cosine roll-off low-pass filter, the modulator, and the programmable equalization filters. The chip occupies 29 mm/sup 2/ and dissipates 300 mW. >

Optical data transmission at the Superconducting Super Collider

Digital and analog data transmission via fiber optics for the Superconducting Super Collider have been investigated. The state of the art of optical transmitters, low-loss fiber waveguides, receivers, and associated electronics components are reviewed and summarized. Emphasis is placed on the effects of the radiation environment on the performance of optical data transmission system components. The performance of candidate components of the wideband digital and analog transmission systems intended for deployment of the Superconducting Super Collider Detector is discussed. It is concluded that, using available digital ICs, electrooptical transducers, and fiber optic cable, the design and implementation of a digital optical wideband data transmission system with approximately 1-Gb/s data rate capability can be accomplished.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

HDS/NA-6: an analog simulcast high definition television system

A high-definition system for North America (HDS/NA) embracing the simulcast mode of transmission for amplitude-modulated terrestrial and cable environments is described. The AM RF packaging techniques and the pertinent concerns for future tailoring of the system format for taboo channel utilization for broadcast-compatible terrestrial HDTV delivery in 6 MHz are highlighted. Without the constraint of direct NTSC compatibility with this system, carriers may be suppressed and standard NTSC sync headroom may be eliminated. Due to time expansion of all video components, there is a built-in advantage in multipath/echo performance, particularly beneficial for the cable short-echo scenario. The system is naturally expandable to permit an increase in resolution in the presence of additional channel bandwidth. This simulcast format is linked to a linear analog subband subsampling scheme used as a cornerstone for all HDS/NA analog transmission systems, including satellite (FSS and DBS) and augmentation terrestrial and cable formats. The generic HDS/NA subsampling scheme and the packaging of the components for a 6-MHz AM environment are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Subcarrier multiplexing for lightwave networks and video distribution systems

Applications for subcarrier multiplexing include a variety of analog and digital lightwave transmission systems. An overview of the requirements and capabilities of these systems is presented by describing specific examples of the most popular system types. These examples include multiuser interactive local area networks and multichannel digital, FM, and AM-VSB (vestigal sideband) video distribution systems. Limitations imposed on each by the linearity of directly or externally modulated sources, receiver noise, and relative-intensity noise are discussed. >

The realization of integrated services in a digital distributed star local network

AbstractThe BIDS system will go on trial in early 1990 and it will be a unique system for combining broadband, telephony and data services. The present design uses analogue and digital transmission techniques, but a design for a completely digital system may be required. A study of future requirements had to be undertaken to ensure that the system would adequately serve the customer of the year 2000 and onwards. A design for a digital secondary link is presented employing a modular optical dual‐wavelength diplex system.

Distributed feedback laser diode and module for CATV systems

Harmonic distortion of distributed feedback laser diodes (DFB-LDs) for analog transmission systems is investigated. It is shown that, under a modulation frequency of less than 1 GHz, the harmonic distortion depends on the nonlinearity of the light output power-current (P-I) curve under the continuous wave (CW) condition, which is determined by the coupling constant kappa L, and that the distortion can be minimized at kappa L approximately 1. A 1.3 mu m wavelength InGaAsP DFB-PPIBH (p-substrate partially inverted buried heterostructure) LD and its module, with low distortion by the control of a coupling constant, have been developed. >

The information index: An objective measure of speech transmission performance *

The maximal mutual information (channel capacity) between the input and output of a telephone connection was calculated, taking into account both the frequency and time domain aspects of this problem. This leads to define an « information index » which can be computed from objective measurements. Several examples are given, both for digital coders and for analogue transmission: they show that the information index has a very good correlation with the results of opinion tests. This index therefore constitutes the basis of a mathematical model for predicting the transmission performance of speech in a telephone network.

Electrophonic Hearing and Cochlear Implants.

It has been difficult to explain the good speech understanding obtained by some cochlear implant patients fitted with a single-channel electrode and analog transmissions of the speech signal (Vienna/3M implant). It has also been difficult to explain the variation in results reported by different groups using the same implant. One hypothesis asserts that the above differences can be explained by the observation that electric stimulation with an implanted electrode might result in two different auditory sensations, the first resulting from the stimulation of the remaining hair cells (electrophonic component) and the second from the electric stimulation of the auditory nerve (electro-neural component). The two sensations are very different. As a result of different definitions of total deafness (functional or threshold definition), patients with remaining hair cells are operated on by some groups, but not by other groups. Some published results from different studies are discussed with reference to the above hypothesis and the possible consequences for the selection of the patients, the use of extra-or intracochlear electrodes, and the selection of the speech coding strategy are discussed.

Excitatory amino acid receptors in the parallel fibre pathway in rat cerebellar slices

The grease-gap technique was used on young rat cerebellar slices to study the synaptic pharmacology of the parallel fibre pathway. Electrical stimulation of the parallel fibres produced a characteristic response in Purkinje cells: a sharp negative (N) potential, representing the population action potential and underlying parallel fibre EPSP, followed by a slow positive (P) wave, the population inhibitory postsynaptic potential (IPSP). In the presence of 1.2 mM Mg 2+, d-2-amino-5-phosphonovalerate (APV, 30 μM) had no effect but both potentials could be inhibited by 6-cyano-2,3-dihydroxy-7-nitro-quinoxaline (CNQX, 10 μM). Removal of Mg 2+ had no effect on the N-potential but enhanced the P-wave in an APV-sensitive fashion, particularly when CNQX was present. The results provide further evidence that glutamate is the parallel fibre transmitter and suggest that its acts only on non-NMDA ( non-N- methyl- d-aspartate ) receptors at synapses with Purkinje cells but on both NMDA and non-NMDA receptors at synapses with inhibitory interneurones. At the latter synapses, the NMDA system is likely to be brought into operation in an activity-dependent manner.

Monoamine-accumulating ganglion cell type of the cat's retina.

A monoamine-accumulating ganglion cell type has been identified in an in vitro preparation of the cat's retina by a catecholamine-like fluorescence that appears following intravitreal injections of dopamine and the indoleaminergic transmitter analog, 5,7-dihydroxytryptamine (5,7-DHT). A subpopulation of large, weakly fluorescing neurons were identified as composing a single, morphologically distinct ganglion cell type by intracellular injections of horseradish peroxidase (HRP). In a sample of 374 HRP-filled cells soma diameter ranged from 13-21 microns (mean +/- SD = 16.6 +/- 1.3). Dendritic field size increased with increasing retinal eccentricity from 150-200 microns diameter at 0.5 mm from the area centralis to 600-800 microns diameter in the far retinal periphery. Dendrites are thin (approximately 1 micron diameter), show a characteristic branching pattern, and are narrowly stratified at the outer border of the inner plexiform layer. The monoamine-accumulating ganglion cell and the outer (OFF-center) alpha cell occupy distinct strata within sublamina a of the inner plexiform layer separated by a gap of about 5 microns. The total number of monoamine-accumulating (MA) ganglion cells was estimated at 5,400, about 3.5% of the total ganglion cell population. Spatial density of the MA ganglion cells, calculated from cell counts made in vitro, ranges from 60 cells/mm2 near the area centralis to 5 cells/mm2 in the far retinal periphery. A coverage factor (density x dendritic field area) of 2.2 was maintained from central to peripheral retina. The nature of the dendritic overlap was observed directly by making HRP injections into several neighboring ganglion cells. Five to seven neighboring dendritic trees extensively overlapped a given cell's dendritic field. However the dendritic processes did not intersect randomly but tended to interdigitate such that a uniform interdendritic spacing and density of dendritic processes was constructed locally within the dendritic plexus. Rotation of individual dendritic trees from their normal orientation produced a dramatic 4-5-fold increase in the number of dendritic intersections, suggesting that an active, local mechanism operates in the precise placement of individual dendrites within the plexus. The monoamine-accumulating ganglion cell appears morphologically equivalent to the delta ganglion cell (Boycott and Wässle; J. Physiol. (Lond.) 240:397-419, '74; Kolb et al.; Vision Res. 21:1081-1114, '81) and to the recently recognized indoleamine-accumulating ganglion cell (Wässle et al: J. Neurosci. 7:1574-1585, '87).(ABSTRACT TRUNCATED AT 400 WORDS)

Black box analysis of the skin senses as a multiple communication channel.

The skin senses have been investigated as a multichannel parallel information system. In psychophysical experiments using two cold two warmth and two vibration stimuli the capability of these senses have been determined for transmitting independent parallel information. A black box model is used to describe interactions within the system between pairs of signals causing two different response components in a multiple response after multimodal activation. The theory distinguishes two kinds of interaction, those between internal noise sources and between internal signal sources. It appears that the skin senses show only a very small interaction of their respective noise sources whereas their signal sources interact extensively. The repercussions for the skin as a parallel information transmitter is discussed shortly in the context of a development of an optimum "skin vision" system, which should project an environment onto the skin, employing both the sense of touch and the sense of temperature.

A video codec LSI for high-definition TV systems with one-transistor DRAM line memories

A video codec LSI for high-definition television (HDTV) systems has been developed. By using a time-compressed integration encoding technique, it converts a 20.0-MHz bandwidth luminance signal and two 5.0-MHz chrominance signals into a compressed image signal at 48.6-MHz sampling frequency. It is useful in many HDTV application systems, such as 400-Mb/s digital transmission system, a video disk player system, or an analog transmission system. Over 288000 elements, including a 52-kb one-transistor DRAM (dynamic random access memory) line memory specially developed for this LSI, were integrated on a 12.16*12.10-mm/sup 2/ chip. A standard cell layout method and a 1.2- mu m CMOS logic LSI process were used. >

Optical architecture and interface lightguide unit for fiber-to-the-home feature of the AT&amp;T SLC Series 5 carrier system

The subscriber loop has evolved from analog transmission on passive copper through digital carrier on copper to initial applications of fiber to customer premises. In planning its initial deployment of fiber to customer premises, ATT the lightguide unit; and the system characteristics. >

Materials Aspects of the SL Lightguide Undersea Cable Design: 1988 MRS Spring Meeting Plenary Addres

Starting in the 1950s, AT&amp;T has been involved in the design, installation, and operation of undersea coaxial cable systems to provide international and inter-island telecommunication services. These systems are analog transmission systems, utilizing frequency division multiplexing to simultaneously transmit multiple channels over a single cable. With the passage of time, and in response to an ever growing demand for services, the frequency bandwidths of successive systems have been increased to accommodate the need for increased traffic density. The increases in bandwidth have been accompanied by increases in copper ohmic losses, brought about by the skin effect phenomenon, mandating ever shorter spacing between repeaters, and consequently larger numbers of repeaters for a given system length. The reliability outlook for extending coaxial cable technology beyond its present capacity, with a decrease in repeater spacing below the current value of about 9 km, is not favorable.Fortunately, we now have available optical fibers for transmission media. Unlike coaxial cable, the fiber medium is not limited by the skin effect phenomenon. Using fiber technology, we can transmit large amounts of traffic through a very small cross-sectional areas, using repeaters at infrequent intervals. Moreover, undersea fiber optical systems utilize digital (as opposed to analog) transmission, a format extremely advantageous in terms of transmission quality and the types of services that can be offered.

Dopamine-accumulating retinal neurons revealed by in vitro fluorescence display a unique morphology.

Dopamine is the principal catecholamine neurotransmitter in the vertebrate retina. The shape of retinal neurons that accumulate dopamine has been demonstrated in an in vitro preparation of cat retina. This was achieved by the discovery that the combined uptake of dopamine and the indoleaminergic transmitter analog 5,7-dihydroxytryptamine leads to an intense, catecholamine-like fluorescence in the cell bodies and processes of presumed dopaminergic amacrine cells in the living retina. This fluorescence served as an in vitro marker for these cells, and their detailed morphology was analyzed after intracellular injection of horseradish peroxidase under direct microscopic control. The horseradish peroxidase-filled cells show an unprecedented neuronal morphology: each cell gives rise to multiple, axon-like processes that arise from, and extend for millimeters beyond, the dendritic tree. The unique structure of this type of amacrine cell suggests a function for dopamine in long-range lateral interactions in the inner plexiform layer.

The conversion of the New Jersey Public Broadcasting System, 'New Jersey Network' to MTS stereo operation

A description is given of the history of New Jersey Network (WNJN, the New Jersey state public television system), the decision to convert the system to MTS stereo, the goals of the technical improvement program, and representative test results. The author discusses origination, production, switching, microwave relay systems, transmitter conversion and interfacing, and off-air monitoring facilities for MTS stereo, including analog and digital SAP transmission.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Origin of Rice's formula

The origin of S.O. Rice's formula for the average rate of level crossings of a rather general random process is traced to his 1936 private notes entitled Singing Transmission Lines. The notes formulate an engineering problem in terms of the probability distribution of the absolute maximum of an envelope process in a closed interval. Rice showed that if the envelope of the reflected wave on a loaded transmission line were to equal or exceed the maximum value in the closed interval, then 'singing' or oscillation could be expected to occur and the analog transmission system would become unstable and useless for the transmission of information. The formula and its generalizations are now basic for the analysis of level crossings and first and second passage times of random processes. >