Satellite distribution of digital compressed video audio and data

The quality of hardcopies produced by a video- or laser imager was compared. Laser printing could be performed after analogue or digital data transmission, whereas the video imager allowed only analogue data transfer. Evaluation of CT-, MR-, DSA- and radiographic images showed no difference in diagnostic information between video and laser-produced hardcopies. For large formats (35 X 35 cm.), laser images produced by digital transmission were considerably superior to video signals and analogue transmission. There were advantages and disadvantages of both types of imaging, depending on the size of the matrix, the type of image produced, ease of use and capital cost.

One issue with underwater sensors is how to efficiently transfer large amounts of data collected by the node to an interrogating platform such as an underwater vehicle. It is often impractical to make a physical connection between the node and the vehicle which suggests an acoustic or optical wireless solution. For large amounts of data, the high bandwidth of underwater optical wireless is an advantage. A small, low-cost platform to demonstrate the potential of an optical wireless communications interface for underwater sensor nodes is demonstrated. To enhance the reliability and robustness of the optical wireless communication digital signal processing and error correction techniques are used. The system was tested in 3 and 7.7 meter tanks at 5 Mbps with the turbidity of the water controlled by the addition of Maalox.

5 - How is data transmitted?

The ability of technology to transmit multi-media is very dependent on compression techniques. In particular lossy compression has been used in image compression (jpeg) audio compression (mp3) and video compression (mpg) to allow the transmission of audio and video over broadband network connections. Recently the sense of touch or haptics is becoming more important with its addition in computer games or in cruder applications such as vibrations in a cell phone. As haptic technology improves the ability to transmit compressed force sensations becomes more critical. Most lossy audio and visual compression techniques rely on the lack of sensitivity in humans to pick up detailed information in certain scenarios. Similarly limitations in the sensitivity of human touch could be exploited to create haptic models with much less detail and thus requiring smaller bandwidth. The focus of this paper is on the force thresholds of the human haptic system that can be used in a psychophysically motivated lossy haptic (force) compression technique. Most of the research in this field has measured the just noticeable difference (JND) of the human haptic system with a human user in static interaction with a stationary rigid object. In this paper our focus involves cases where the human user or the object are in relative motion. An example of such an application would be the haptic rendering of the user's hand in contact with of a high-viscous material or interacting with a highly deformable object. Thus an approach is presented to measure the force threshold based on the velocity of the user's hand motion. Two experiments are conducted to detect the absolute force threshold (AFT) of the human haptic system using methodologies from the field of psychophysics. The AFTs are detected for three different ranges of velocity of the user's hand motion. This study implies that when a user's hand is in motion fewer haptic details are required to be stored calculated or transmitted. Finally the implications of this study on a more complete future study will be discussed.

The wide bandwidths of the communication and advanced bilateral robot control technologies have led us to realize multi-sensational teleoperation systems that provide auditory, visual, and haptic information of remote site to its operator simultaneously. Such teleoperation system is expected to be applied to medicine, education, work in hazardous environment, online game or other use. Especially, haptic sensation is extremely required to improve its operability and safety in medical operations. In this chapter, a teleoperation system is assumed to consist of three components, i.e., audio, video, and haptics transmission systems. In addition, each transmission system can be distinguished into local site and remote site. When the distance between the remote site and the local site of a teleoperation system is far enough, the performance of its communication line becomes crucial factor to decide the operability of the teleoperation. In general, since the data rate of video information is higher than the bandwidth of communication line, data compression is indispensable. Moreover, data compression and decompression are considered as time consuming processes. As a result, video transmission system must be delayed in principle. In multi-media context, audio transmission system should be delayed artificially so as to keep its playout delay to be the same as that of video transmission system. For example, lip sync is necessary for its operator to feel the audio and video contents in naturally. From this point of view, the bandwidth of its communication line is the only requirement for realize video and audio transmission systems. Even if these transmission systems are used to make a conversation for its operator with a remote person, it is said that 200ms delay is allowable. This requirement is rather negligible in the Internet in nowadays. On the other hand, a haptics transmission system requires short and stable performance of delay for communication line. This is because the achievable bandwidth of haptic sensation is limited by the round trip time of communication line since haptics transmission controller includes the delay inside of its closed control loop. In fact, a human being can feel the sense of touch at the tip of a finger up to about 400Hz. To recognize this bandwidth of haptic sensation, its sampling period must be higher than 800Hz according to Shannon’s sampling theory. Thus, the round trip time of communication line must be shorter than 1ms. This value is much shorter than the allowable delay of audio and video transmission systems. In short, haptics transmission system requires short delay while video transmission system requires wide bandwidth for communication line. 2

The deployment of federated learning in a wireless network, called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">federated edge learning</i> (FEEL), exploits low-latency access to distributed mobile data to efficiently train an AI model while preserving data privacy. In this work, we study the spatial (i.e., spatially averaged) learning performance of FEEL deployed in a large-scale cellular network with spatially random distributed devices. Both the schemes of digital and analog transmission are considered, providing support of error-free uploading and over-the-air aggregation of local model updates by devices. The derived spatial convergence rate for digital transmission is found to be constrained by a limited number of active devices regardless of device density and converges to the ground-true rate exponentially fast as the number grows. The population of active devices depends on network parameters such as processing gain and signal-to-interference threshold for decoding. On the other hand, the limit does not exist for uncoded analog transmission. In this case, the spatial convergence rate is slowed down due to the direct exposure of signals to the perturbation of inter-cell interference. Nevertheless, the effect diminishes when devices are dense as interference is averaged out by aggressive over-the-air aggregation. In terms of learning latency (in second), analog transmission is preferred to the digital scheme as the former dramatically reduces multi-access latency by enabling simultaneous access.

Digital compression methods based on MPEG2 are now in widespread use for broadcasting of video content. Multiple television and radio programs can be multiplexed and transmitted altogether within the same bandwidth where formerly only one analog program fit. With the analog television video quality was very much a matter of the transmission chain and all the elements along the line. Once a sufficiently high video quality level was achieved, it was nearly independent from the content. In using digital compression and transmission techniques the video quality is now strongly content and compression dependent. The changes in video quality can be very abrupt from scene to scene. A method that is capable of following all these changes in real time and displaying the picture quality, as a function of time, is required for continuous video quality monitoring. — This paper describes a single ended method that does not require a reference signal and is capable of processing the video in real time concerning picture deficiencies of a compressed video.

The growth of high-density television (HDTV) systems, along with the development of peripheral devices, depends on the development of transmission systems. The authors have constructed an HDTV digital transmission system for the purpose of supporting secondary distribution of HDTV signals and developed an HDTV codec intended for application in this system. The HDTV digital transmission system is a transmission system that utilizes a single (36 MHz) channel of a Kuband transponder of a communication satellite, employs a rate 3/4 convolutional code and a (255,239) Reed-Solomon block code for forward error correction, and uses quadriphase-shift keying (QPSK) as the modulation format. The HDTV codec developed for application in this system is a coding method that is based on discrete cosine transform (DCT) and motion compensated prediction, which provides 40 Mb/s coded video signal. In this paper, the structure of the HDTV digital satellite transmission system and the HDTV codec are described. The video coding method of the HDTV codec is also described. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (1): 35–51, 1997

A set of equalized, unmodulated subcarriers were applied to several lasers (including highly linear DFB and ordinary Fabry-Perot types) and the resulting distortion measured. For the carrier-to-nonlinear-distortion (C/NLD) levels required for digital transmission, the distortion was dominated by clipping and was independent of laser type. Inexpensive Fabry-Perot (FP) lasers appear to be completely satisfactory for compressed digital video transmission.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper describes a new digital NTSC TV and audio signal transmission system in which circuit configurations are simplified and made more inexpensive than MPEG 2 on the basis of the subjective evaluation of the picture quality. An NTSC TV signal and an audio signal can easily be transmitted to the receiver at the same time, since the transmission rate is kept unchanged due to the insertion of the digital audio signal into the horizontal sync pulse of the digital NTSC TV signal. The proposed system has three features. Firstly, the system could give a satisfactory picture quality for consumer-use visual appliances even though the quality of the reproduced pictures is lower than that of the normal digital NTSC TV picture codes obtained at a sampling frequency of 4.00/spl times/fsc with a quantisation level of 8 bits. Secondly, the system can satisfactorily transmit NTSC TV picture codes at a low transmission rate of 50 Mbps even if such an advanced compression technique as MPEG 2 has not been used. Thirdly, the system is used for transmission of the digital audio signals which are inserted into the horizontal sync pulse of the digital NTSC TV signal. A combination of edge-emitting LEDs (ELEDs) and single-mode (SM) optical fibers enables the system to easily transmit a digital NTSC TV picture signal together with digital audio signals over a distance of 10 km through the SM optical fibers.

지상파 TV의 디지털 전환이 완료되었지만 지상파 라디오는 전송방식을 결정하지 못해 아날로그 방송을 유지하며 표류하고 있는 상태이다. 본 연구에서는 지상파 방송사의 종사자를 대상으로 상호지향성 모델을 토대로 디지털 라디오 전송방식을 결정하는 중요 요인에 대한 인식차이를 살펴보고 쟁점 요인을 도출하였다. 연구결과, 지상파 방송 3사는 디지털 라디오가 점유할 주파수 대역 선택에서 가장 큰 인식의 차이가 있으며 제작과 송출의 병행 여부, 주파수 이용 효율성, 방송 품질과 서비스 정도는 서로 의견의 차이가 없는 것으로 나타났다. 그리고 디지털 라디오 방송의 전환에 있어 가장 큰 쟁점 요인은 FM 라디오방송이 사용하는 주파수대역(88-108 MHz)과 지상파 DMB방송 주파수대역(VHF Ch7~13), FM 라디오방송 인접대역(76~88MHz: VHF Ch5~6) 중 어떤 주파수 대역을 디지털 라디오용으로 선택하는지의 문제, 즉 DAB+, HD-Radio, DRM+ 가운데 특정 전송방식을 선택하는 문제로 귀결되었다. 이에 본 연구에서는 제작 송출 병행이 가능하고 송 중계소 1-2개로 송신 효율을 높일 수 있고 신규 사업자 진입이 가능한 방식을 채택함으로써 라디오방송서비스의 품질과 이용자의 만족도를 높일 것을 제안하고자 한다. Though the digital transition of terrestrial TV has been completed, the transmission system for terrestrial radio has not been determined and terrestrial radio still keeps its analog transmission. This study, under coorientation model, aims to explore the cognitive difference in recognizing important factors to be considered in deciding the digital radio transmission system between the employees of terrestrial broadcasters and then crucial issues related to the factors are driven. It has been found that the most big cognitive difference among the employees of three major terrestrial broadcasters lies in selecting frequency band for digital radio transmission. But there was little difference of opinion on simultaneous production-transmission, efficiency of frequency usage, broadcast quality and standards of service. The most disputable point in transition to digital radio broadcasting is selecting the frequency band for digital radio between the frequency bands used for FM radio broadcast (88-108MHz), terrestrial DMB (VHF Ch7~13) and FM radio adjacent broadcast band (76~88MHz: VHF Ch5~6). So, the question concludes into the selection issue between DAB+, HD-Radio, and DRM+. To improve the quality of radio broadcasting service and enhance the satisfaction of listeners, it is desirable to allow to operate both production system and transmission station, to enhance high transmission efficiency with minimum transmission facility, and to permit new entrance of broadcasters.

IEEE 802.22 is the cognitive radio-based first worldwide standard for wireless regional area network (WRAN). The primary objective of this standard is to provide broadband access to remote and rural areas. In these remote areas, a large number of vacant TV channels are available, known as white spaces. This standard allows broadband access to the users using these TV white spaces (TVWS). Also, much analog transmission has been moved towards digital transmission in UHF band so this situation has created a digital divide. In this paper, we proposed a novel scheme of simulation for the physical layer of IEEE 802.22 Wireless Regional Area Network (WRAN) with another cyclic prefix. In this paper, we have also demonstrated the effect of length of cyclic prefix in OFDM symbol on the BER performance of the physical layer of WRAN. We simulated the physical layer of WRAN with cyclic prefix 1/4 and 1/32 between successive OFDM symbols. We used convolution code with code rate 1/2 as FEC and evaluated the performance with BPSK, QPSK, and QAM-19 digital modulation schemes in Rayleigh fading condition in MATLAB. We concluded that the effect of ISI can be mitigated with cyclic prefix 1/32 for all three proposed modulation schemes and found that better BER performance in limited SNR. Also, the performance of BPSK with CP 1/32 is superior to QPSK and QAM-16 for CP of 1/4 as well as 1/32.

It is often difficult to imagine how other people perceive the world, let alone other species, so when Ken Lukowiak was approached by The JEB's Editor in Chief, Hans Hoppeler, to draw together reviews discussing Neurosensory Ecology, he decided to steer clear of the usual sensory topics. Taking an

The distribution system for network television signals involves the tandem connection of many different transmission systems, all of which presently operate using analog techniques. During the 1980's, the common carriers will install many digital transmission systems so as to realize the maximum economic benefit from digital switching machines. As a consequence it is virtually certain that by 1990 some, if not most, of the distribution system for network television signals will involve the use of digital transmission techniques. — The present situation regarding digital transmission of television signals in North America is reviewed and some areas of concern are noted. There is an obvious need for close liaison between the broadcaster, the common carriers, the manufacturers and the regulatory authorities if the present quality of the distribution system is to be maintained.

Signal processing comes with a wide range of applications that includes enhancement of signal quality to improve accuracy and selection of required component from a received signal. As technology advances, signal processing systems has become more complex in which filters may operate in parallel. In such complex systems, there is a necessity for an efficient error tolerant implementation as reliability becomes critical. In this paper, a technique for error detection and correction is proposed which can detect and correct two errors by using a section wise single error correcting approach and the technique is explained in two approaches. Both approaches of technique can be applied in a parallel FIR filter configuration where filters use same response for same or different input signals. Thus, system homogeneity plays an important role in proposed technique for error detection and correction.