Showing papers in "IEEE Transactions on Broadcasting in 1994"

Guide to MPEG-1 audio standard

Abstract: This paper is designed to help the reader to unravel the ISO MPEG-1 standard for compressing digital audio data. In comparison to the standards for video, little additional information is available on this standard. The standard describes the implementation of three compression schemes called layer 1, layer 2 and layer 3. The layer 1 scheme is the simplest to implement but its efficiency is not as good as the other layers. The layer 3 scheme provides the best performance at low bit rates but it is also the most difficult one to implement. The compression techniques used psychoacoustic models for predicting the human auditory response to the noise that is introduced by the coding scheme. Using these models, the characteristics of the compression scheme can be changed dynamically in order to minimize the audibility of these noise impairments. The implementation of two such psychoacoustic models are described in the standard. >

Transmission of all-digital advanced television: state of the art and future directions

Abstract: All-digital high definition television (HDTV) and advanced television (ATV) systems have been proposed in the United States and Europe for terrestrial as well as satellite broadcasting. The main goals of the paper are to describe and discuss the theory and methods for error control, modulation and equalization used by these HDTV and ATV systems. The author identifies their similarities and differences in their error control, modulation and equalization methods and discusses possible improvements to them. He also describes recent research directions and trends in error control which pays much more attention to advanced and relatively new theory and techniques in information, coding, and communication theory. Finally, his views are provided, based on the above, about the best choices for error control schemes. The specific HDTV and ATV systems which have been proposed and, in most cases, built and tested in various ways, are described. >

Wide band electromagnetic wave absorber with thin magnetic layers

Abstract: This paper presents the design and the trially made examples of the wideband thin electromagnetic absorber with multiple layers of magnetic materials, which will be useful for the walls in houses and office buildings for protection from thee radiated waves from wireless LANs and electronic equipment.. We achieved an absorbing performance of more than 80% at 1.9 GHz, 2.45 GHz and 19 GHz by using a 0.5 mm layer of the epoxy resin containing a carbonyl iron powder and another 2.5 mm layer of epoxy resin containing a ferrite powder. >

Analysis of new methods for broadcasting digital data to mobile terminals over an FM-channel

Abstract: Two new methods using an FM-radio channel for transmission of digital data to mobile terminals are examined: 1. A modification of the radio data system (RDS). In RDS, additional digital information is multiplexed with a stereo sound signal. A new system is suggested where the data signal can be multiplexed with a mono audio signal. This causes extension to the bandwidth available for the data signal, and therefore the RDS bitrate can be increased. Error calculations are performed both for the original RDS system and for the new system. 2. Orthogonal frequency division multiplexing (OFDM). OFDM is used in the digital audio broadcasting system (DAB), which is designed to transmit digital audio in the FM band. In OFDM a signal is divided over a large number of 2- or 4-PSK modulated orthogonal subcarriers. The subcarriers of 6 different programmes are multiplexed in one beam to reduce the effects of frequency selectivity of the transmission channel. A new system based on OFDM is proposed, in which the carriers of each programme are transmitted in one FM-channel with a bandwidth of 200 kHz instead of multiplexed with the carriers of other programmes. Error calculations are performed for the subcarriers used in the OFDM modulation method. >

The digital audio broadcast single frequency network project in southwest Germany

Abstract: Within a time frame of three years a DAB SFN transmitter network will be brought into operation in the south-western part of Germany. the network is designed to serve at least three million inhabitants. The network performance is analyzed by means of computer simulations. For that purpose, the power density functions (PDFs) of the contributing partial waves are combined in order to determine the local coverage probability. It is shown that SFNs are superior in comparison to multifrequency FM networks. The advantage is identified as SFN gain. A temptative definition is given. Results of model calculations are presented for VHF- and L-band assignments. It is shown that guard interval violations cause intersymbol interference (ISI), deteriorating the SFN's performance. >

A self-steering planar array antenna for satellite broadcast reception

Abstract: The active planar array antenna offers a number of advantages, including use as a portable antenna for easy reception of direct Ku-band satellite television broadcasts. This paper presents a newly developed active planar array antenna which provides electronic beam-tracking without mechanical tracking equipment. The features of the antenna are: (1) use of a series-parallel fed microstrip array, (2) electromagnetically excited array by a coplanar patch connected to the coplanar waveguide, and (3) low noise down-converters and self-phasing units incorporated into the feed circuits for electronic beam-tracking. The paper discusses the design of the coplanar waveguide fed coplanar patch and the configuration of a self-phasing active planar array antenna. The measured gain of the experimental 9-element unit array antenna without active devices is 13.4 dBi at 11.85 GHz. Experimental results for a 216-element self-steering planar array of size 147/spl times/220.5 mm are also presented. >

Subjective-evaluation method for quality of coded images

Abstract: Subjective-evaluation tests for the quality of coded images are conducted usually using the double-stimulus continuous quality-scale method recommended by the ITU-R. A new method named "the modified EBU method", which is different from the EBU method in the presentation of the test sequences, is presented in this paper. The modified EBU method's ability to discriminate small quality differences is examined by comparison with the relative scale of the double-stimulus continuous quality-scale method, for the significant level of 0.05, using four sequences. It is seen for 15 experts that significant differences are not detected though test sequences are apparently degraded in one condition for each of two sequences with the double-stimulus continuous quality-scale method, while a significant difference is not detected in only one condition for one sequence with the modified EBU method. On the other hand, it is seen for 20 non-experts that significant differences are not detected in a total of five conditions for three sequences with the double-stimulus continuous quality-scale method, while significant differences are not detected in one condition for each of two sequences with the EBU method. Therefore, it is clarified that the modified EBU method are more suitable for small impairments than the relative scale of the double-stimulus continuous quality-scale method. >

Jitter considerations in high bit rate digital video signals

Abstract: While digital signals tend to be more immune to noise as measured in analog systems, other noise related phenomena such as bit errors can cause problems which are equally as undesirable. This paper addresses one such noise artifact which is jitter in a digital bit stream. While the typical method of measuring jitter is with a sampling oscilloscope, a new technique using modulation domain analyzers was used. This method allows direct measurement of the spectral content of jitter. This technique has been used in the telecommunications industry and examples of their specifications are provided. >

Measuring audio SNR on digital broadcast systems

Abstract: A spectrum analysis technique is described which will measure the quantization noise in a digital audio system with a signal present. An estimate of the power density spectrum is interpreted to find the signal to quantization noise ratio. Additional information derived from real life spectrum measurements is explained. >

An automatic caption-superimposing system with a new continuous speech recognizer

Abstract: This paper describes an automatic caption-superimposing system with a new continuous speech recognizer for efficient production of TV programs. The system which we have developed can recognize continuous speech announced in a hall of Japanese 'sumo' wrestling and automatically superimpose the recognition results of wrestlers' names and winning tricks as captions on a TV display. The announcements consist of sentences to inform which wrestler has won a match with what kind of winning trick. They are formed out of small-sized vocabulary with a specific uttered style and are spoken nearly at a Japanese 'bunsetsu' unit like a phrase only by some specific speakers. We designed the system to work with the following features: (a) recognition of continuous speech with a specific uttered style; (b) an easy change of vocabulary to be recognized; (c) no requirement of pre-registration of any particular utterances; (d) implementation on multi-microprocessors with high computing speed. The proposed recognizer utilizes general intra-'bunsetsu' grammar which is applicable to various recognition tasks, while conventional Japanese continuous speech recognizers use intra-'bunsetsu' grammar which depends on applied recognition tasks. In a recognition experiment on 40 sentences of 'sumo' announcements by two speakers, the system attained 'bunsetsu' accuracy of 91.0% with quasi-real-time processing. >

A new ghost cancellation system for Korean GCR

Abstract: This paper describes a new ghost cancellation system built-in NTSC television based on the Korean ghost cancellation reference (KGCR) signal. The system has a highly integrated transversal filter, an unique circuit for control of the system and a high performance algorithm for calculating the filter coefficients. Laboratory and field test results confirm that the system is effective in canceling several combination of ghosts, which exist in real situations. >

Scattering from power lines with the skywire insulated from the towers

Abstract: This paper studies the distortion of a commercial AM radio station's radiation pattern due to scattering from a power line with steel lattice towers which carry a skywire that is insulated from all the towers. Despite the insulated skywire, the towers couple strongly to the skywire. The resonant behavior of the power line spans is similar to that described in previous papers with the skywire connected to all the towers. However, the resonant frequencies are much higher when the skywire is insulated and the strongest resonance falls above 1000 kHz for typical power line dimensions. This paper models a real site consisting of a directional broadcast array at 1380 kHz and a power line with 29 towers. Although the resonances of the power line fall at much lower frequencies than 1380 kHz, the antenna induces substantial RF current flow on the towers and skywires of the power line. The power line scatters strongly into the minimum in the station's radiation pattern and the station's protection requirements are seriously violated. Thus, the towers of the power line will need to be treated with detuning stubs to restore the pattern to its intended values. >

Evaluation of channel coding, modulation and interference of digital ATV terrestrial transmission systems

Abstract: This paper presents results of computer simulations and laboratory tests to investigate various digital techniques (i.e., trellis coded QAM, vestigial sideband (VSB) modulation, orthogonal frequency division multiplexing (OFDM), and adaptive equalization) proposed for Advanced Television (ATV) terrestrial broadcasting. The performance of these channel coding and modulation techniques, in the presence of various interferences (i.e., Gaussian noise, ATV and NTSC co-channel interference) and in a multipath distortion environment, is evaluated and compared. The effects of ATV interference into NTSC systems are also investigated. >

Software program "DOKT" for analyzing a HF high-power tuned amplifier

Abstract: A possible application of personal computers for analyzing operating conditions of a HF high-power tuned amplifier is described in this paper. The algorithm and the program description are shown as well as the corresponding results. >

An adjunct tracking system for low altitude sector aircraft

Abstract: This paper advances the concept of using slightly modified commercial ground broadcast TV signals to aid in tracking aircraft at low attitude near major airports. The modification of the TV signal is not major and will not affect normal TV operation. The resulting system should be of utility in augmenting air traffic control and could provide an important dual service role for commercial TV ground broadcast. >

The coding of image sequences by wavelets, wavelet packets and other subband coding schemes

Abstract: For the terrestrial broadcasting of high-definition television (HDTV) in North America the discrete cosine transform (DCT), Huffman (lossless) coding and motion detection, estimation and compensation have been used to compress raw HDTV rates of 1.0-1.2 Gbps. Compressed and compacted video bit rates range from 12.59 Mbps to 13.60 Mbps for 16-QAM transmission and from 17.47 to 18.88 for 32-QAM transmission. MPEG source coding schemes, are used in a proposed HDTV system and in the Grand Alliance proposal. They share features in common with other source coding schemes which have been employed. It seems likely that compression and compaction to an HDTV video bit rate below 10 Mbps should be attainable. The methods discussed in this paper provide hope for realizing this goal. >

A study of HF field strength variation in India and its prediction

Abstract: Measured field strength data pertaining to several HF broadcast transmissions monitored in India during 1987-90 has been analysed to study solar activity, local time and seasonal variations in the field-strength. Values tend to saturate at high solar activity levels when sunspot numbers are beyond 120. Variations in field strength have also been studied with varying ratios of operational frequency to maximum usable frequency (f/sub op//MUF) and equivalent vertical frequency of the links. Based on this study a prediction method for HF field strength has been suggested for India. Comparison of values estimated using this technique has been made with actual measured field strength values for different HF transmissions for different months. This method is to be particularly suitable for field operators. >

A noise resistant synchronization scheme for HDTV images

Abstract: A method that increases the error resistance of the HDTV system and offers graceful picture degradation in the presence of bit errors, is presented. Due to the nature of the presently proposed compression schemes for HDTV systems, an error in a data bit does not only affect the block the bit belongs to, but unfortunately the effects of this error may perpetuate to the following blocks. This is because a bit error may cause loss of synchronization between the data bits and the picture blocks they represent. Our method restricts the effects of a bit error to a picture block whose size is significantly smaller than those used by the HDTV systems. We achieve synchronization by transmitting a header-word for each such synchronization block. Each header-word contains the number of data bits representing the compressed block. This header-word is protected by two levels of FEC code. To decrease the number of extra bits needed by the header-words, two different synchronization block sizes are used, a relatively small block size for the reference frames and a larger size for the inter-frames. The resulting method improves the quality of the picture in the presence of errors and defers the SNR at which the HDTV picture suddenly deteriorates by 2.5 to 3 dB. It also allows operation at higher order modulation transmission schemes, e.g., 32-QAM instead of 16-QAM, without the requirement of increased signal power. >

On the TV ghost image model

Abstract: Multipath interference causes a TV ghost image that is either an attenuated, shifted version of the original image, or an attenuated, shifted Hilbert transform of the original, or a bit of both. This complete model for the ghost image will be proven by modeling the vestigal sideband TV signal as a single sideband signal, after which the multipath signal will be demodulated. >

Video signal noise characteristics with regard to scanning method

Abstract: The evaluation of a television system is finally verified through the subjective assessment of the picture quality on a display. A system evaluation method has been studied in terms of the picture quality degraded by random noise added through a transmission line, using a weighted signal-to-noise ratio considering the human visual characteristics, and an unweighted signal-to-noise ratio, that is, a physical signal-to-noise ratio. In this paper, the relation between the quantity of random noise added through the transmission line and the quantity of random noise on a display is provided in a television system using either an interlace scanning method or a progressive scanning method, and the change in noise characteristics through an interlace-to-progressive scanning conversion is analyzed. Furthermore, the change in noise characteristics mediated by the human visual system is investigated, and finally, these studies and analyses are verified through subjective assessment. >

A spectrally efficient constant envelope modulation technique for PCS and mobile communications

Abstract: A newly developed constant envelope FQPSK modem/radio architecture, which employs a modified double-jump (DJ) filter in the cross-correlated FQPSK system, is proposed for personal communications systems (PCS) and mobile radio applications. Power efficiency, spectrum efficiency, BER, and system capacity of this system are investigated in a non-linear amplified (NLA) Rayleigh fading environment. We demonstrate that with the simplest threshold detectors (binary robust eye diagrams in I and Q channels), this system is 4-7 dB more power efficient than the US digital cellular and Japanese Handyphone standard /spl pi//4-QPSK, 50%-100% more spectrally efficient than the European standard GMSK, and it almost double the capacity of GMSK. >

A multiplexer with coupled quarter wave distributed lines in high dielectric ceramics

Abstract: A multiplexers available several purposes such as for mobile communications, CATV systems and multimedia systems in future, are propped and trially made by authors. This paper present the results the design concept and experimental results. The design principle was based on the theoretical concept proposed by us. >

The effects of a nearby biological body on the parameters of a small hand-held transmitter operating in the HF band (3 MHz-30 MHz)

Abstract: The effects of a nearby biological body on the efficiency and radiation patterns of a small hand-held radio operating in the HF band are determined by computer modeling. The close proximity of the radio operator's body results in the scattered field from the body reradiating and perturbing the known free-space current distribution on the antenna to some extent. However, due to the extremely small electrical size of the radiating system, this body-to-radio coupling is assumed to be minimal and henceforth neglected. Thus, a direct moment method is used to solve a volumetric electric field integral equation with the near field of the radio used as the excitation field. Once the equivalent volumetric currents are determined, the efficiency and radiation patterns are found using these currents and the unperturbed free space current of the radio antenna. >

Quick and effective adjustment of stub detuners by a two-loops method

Abstract: When reradiation of an AM broadcast station's signal from a power line leads to a violation of the station's regulatory requirements, the power line must be "detuned" to suppress the scattered field. At frequencies where the power line towers are comparable to a quarter-wavelength in height, detuning stubs are usually installed on the power line towers. Each stub must be adjusted to minimize the scattered field from its tower. This paper presents a method for stub adjustment using two loop antennas which is quick and simple, and obtains good results in critical situations were more traditional methods were tried and failed. The two-loops method is proven in this paper by numerical computation. The method was applied "in the field" to detune a power line which passes about 900 m from a directional broadcast array. The array's pattern was restored to levels comparable to those before the construction of the power line. >

A theoretical concept of proposed multiplexer with coupled quarter wave distributed lines in high dielectric material

Abstract: Multiplexers are used for several purposes such as for mobile communications and CATV systems. Small size multiplexers will be essential for multimedia systems in the future. This paper shows a new multiplexer with coupled quarter wave distributed lines in high dielectric ceramics. The four way multiplexer is shown together with the experimental results obtained. >

The EIA digital audio sub-committee VHF channel characterization test

Abstract: The Electronic Industries Association (EIA) DAR subcommittee is evaluating proposed digital audio radio (DAR) systems for the United States. As a part of that process, the subcommittee is conducting a "VHF radio channel characterization test". The results of the test will be applied directly to the laboratory testing of the DAR systems and will also find general use within the radio communications industry. >